responses to the survey on 'redefining the large break ... · “redefining the large break...
TRANSCRIPT
Unclassified NEA/CSNI/R(2003)16
Organisation de Coopération et de Développement EconomiquesOrganisation for Economic Co-operation and Development 30-Sep-2003___________________________________________________________________________________________
English text onlyNUCLEAR ENERGY AGENCYCOMMITTEE ON THE SAFETY OF NUCLEAR INSTALLATIONS
RESPONSES TO THE SURVEY ON "REDEFINING THE LARGE BREAK LOCA: TECHNICALBASIS AND ITS IMPLICATIONS"
Zurich, SwitzerlandJune 23-24 2003
JT00150408
Document complet disponible sur OLIS dans son format d'origineComplete document available on OLIS in its original format
NE
A/C
SNI/R
(2003)16U
nclassified
English text only
Cancels & replaces the same document of 10 September 2003
NEA/CSNI/R(2003)16
2
ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT
Pursuant to Article 1 of the Convention signed in Paris on 14th December 1960, and which came into force on 30th September 1961, the Organisation for Economic Co-operation and Development (OECD) shall promote policies designed:
− to achieve the highest sustainable economic growth and employment and a rising standard of living in Member countries, while maintaining financial stability, and thus to contribute to the development of the world economy;
− to contribute to sound economic expansion in Member as well as non-member countries in the process of economic development; and
− to contribute to the expansion of world trade on a multilateral, non-discriminatory basis in accordance with international obligations.
The original Member countries of the OECD are Austria, Belgium, Canada, Denmark, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The following countries became Members subsequently through accession at the dates indicated hereafter: Japan (28th April 1964), Finland (28th January 1969), Australia (7th June 1971), New Zealand (29th May 1973), Mexico (18th May 1994), the Czech Republic (21st December 1995), Hungary (7th May 1996), Poland (22nd November 1996), Korea (12th December 1996) and the Slovak Republic (14 December 2000). The Commission of the European Communities takes part in the work of the OECD (Article 13 of the OECD Convention).
NUCLEAR ENERGY AGENCY
The OECD Nuclear Energy Agency (NEA) was established on 1st February 1958 under the name of the OEEC European Nuclear Energy Agency. It received its present designation on 20th April 1972, when Japan became its first non-European full Member. NEA membership today consists of 28 OECD Member countries: Australia, Austria, Belgium, Canada, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Japan, Luxembourg, Mexico, the Netherlands, Norway, Portugal, Republic of Korea, Slovak Republic, Spain, Sweden, Switzerland, Turkey, the United Kingdom and the United States. The Commission of the European Communities also takes part in the work of the Agency.
The mission of the NEA is:
− to assist its Member countries in maintaining and further developing, through international co-operation, the scientific, technological and legal bases required for a safe, environmentally friendly and economical use of nuclear energy for peaceful purposes, as well as
− to provide authoritative assessments and to forge common understandings on key issues, as input to government decisions on nuclear energy policy and to broader OECD policy analyses in areas such as energy and sustainable development.
Specific areas of competence of the NEA include safety and regulation of nuclear activities, radioactive waste management, radiological protection, nuclear science, economic and technical analyses of the nuclear fuel cycle, nuclear law and liability, and public information. The NEA Data Bank provides nuclear data and computer program services for participating countries.
In these and related tasks, the NEA works in close collaboration with the International Atomic Energy Agency in Vienna, with which it has a Co-operation Agreement, as well as with other international organisations in the nuclear field.
© OECD 2003 Permission to reproduce a portion of this work for non-commercial purposes or classroom use should be obtained through the Centre français d’eSpecific areas of competence of the NEA include safety and regulation of nuclear activities, radioactive waste management, radiological protection, nuclear science, economic and technical analyses of the nuclear fuel cycle, nuclear law and liability, and public information. The NEA Data Bank provides nuclear data and computer program services for participating countries.
In these and related tasks, the NEA works in close collaboration with the International Atomic Energy Agency in Viennaxploitation du droit de copie (CCF), 20, rue des Grands-Augustins, 75006 Paris, France, Tel. (33-1) 44 07 47 70, Fax (33-1) 46 34 67 19, for every country except the United States. In the United States permission should be obtained through the Copyright Clearance Center, Customer Service, (508)750-8400, 222 Rosewood Drive, Danvers, MA 01923, USA, or CCC Online: http://www.copyright.com/. All other applications for permission to reproduce or translate all or part of this book should be made to OECD Publications, 2, rue André-Pascal, 75775 Paris Cedex 16, France.
NEA/CSNI/R(2003)16
3
COMMITTEE ON NUCLEAR REGULATORY ACTIVITIES
The Committee on Nuclear Regulatory Activities (CNRA) of the OECD Nuclear Energy Agency (NEA) is an international committee made up primarily of senior nuclear regulators. It was set up in 1989 as a forum for the exchange of information and experience among regulatory organisations and for the review of developments that could affect regulatory requirements.
The Committee is responsible for the NEA programme, concerning the regulation, licensing and inspection of nuclear
installations. The Committee reviews developments that could affect regulatory requirements with the objective of providing members with an understanding of the motivation for new regulatory requirements under consideration and an opportunity to offer suggestions that might improve them or avoid disparities among member countries. In particular, the Committee reviews current practices and operating experience.
The Committee focuses primarily on power reactors and other nuclear installations currently being built and operated. It
also may consider the regulatory implications of new designs of power reactors and other types of nuclear installations. In implementing its programme, the CNRA establishes co-operative mechanisms with the NEA Committee on the Safety
of Nuclear Installations (CSNI), responsible for co-ordinating the activities of the Agency concerning the technical aspects of design, construction and operation of nuclear installations insofar as they affect the safety of such installations. It also co-operates with the NEA Committee on Radiation Protection and Public Health (CRPPH) and the NEA Radioactive Waste Management Committee (RWMC) on matters of common interest.
COMMITTEE ON THE SAFETY OF NUCLEAR INSTALLATIONS The Committee on the Safety of Nuclear Installations (CSNI) of the OECD Nuclear Energy Agency (NEA) is an international committee made up of senior scientists and engineers. It was set up in 1973 to develop, and co-ordinate the activities of the Nuclear Energy Agency concerning the technical aspects of the design, construction and operation of nuclear installations insofar as they affect the safety of such installations. The Committee's purpose is to foster international co-operation in nuclear safety among the OECD Member countries. The CSNI constitutes a forum for the exchange of technical information and for collaboration between organisations, which can contribute, from their respective backgrounds in research, development, engineering or regulation, to these activities and to the definition of the programme of work. It also reviews the state of knowledge on selected topics on nuclear safety technology and safety assessment, including operating experience. It initiates and conducts programmes identified by these reviews and assessments in order to overcome discrepancies, develop improvements and reach international consensus on technical issues of common interest. It promotes the co-ordination of work in different Member countries including the establishment of co-operative research projects and assists in the feedback of the results to participating organisations. Full use is also made of traditional methods of co-operation, such as information exchanges, establishment of working groups, and organisation of conferences and specialist meetings. The greater part of the CSNI's current programme is concerned with the technology of water reactors. The principal areas covered are operating experience and the human factor, reactor coolant system behaviour, various aspects of reactor component integrity, the phenomenology of radioactive releases in reactor accidents and their confinement, containment performance, risk assessment, and severe accidents. The Committee also studies the safety of the nuclear fuel cycle, conducts periodic surveys of the reactor safety research programmes and operates an international mechanism for exchanging reports on safety related nuclear power plant accidents. In implementing its programme, the CSNI establishes co-operative mechanisms with NEA's Committee on Nuclear Regulatory Activities (CNRA), responsible for the activities of the Agency concerning the regulation, licensing and inspection of nuclear installations with regard to safety. It also co-operates with NEA's Committee on Radiation Protection and Public Health and NEA's Radioactive Waste Management Committee on matters of common interest.
NEA/CSNI/R(2003)16
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A. Foreword
The Committee on the Safety of Nuclear Installations (CSNI) of the OECD-NEA co-ordinates the NEA activities concerning the technical aspects of design, construction and operation of nuclear installations insofar as they affect the safety of such installations.
The Committee on the Nuclear Regulatory Activities (CNRA) of the OECD-NEA co-ordinates the NEA activities concerning the regulation, licensing and inspection of nuclear installations with regard to safety.
In December 2002, the CNRA and the CSNI jointly requested the NEA to organize a workshop on
“Redefining the Large Break LOCA: Technical basis and its implications". The Workshop was held on June 23-24, 2003 in Zurich, Switzerland hosted by HSK (Swiss Federal
Nuclear Safety Inspectorate), PSI (Paul Scherrer Institut) and the OECD/NEA. While the Workshop addressed technical aspects, the survey, completed by member countries, gave
the participants a clear view on the current regulatory status and issues. The survey was intended to complement the workshop's discussions and provide general background information.
It was designed • To provide material for discussion;
• To clearly summarize current national regulations;
• To understand rationales and incentives for changing or not the regulation with regard to the Large LOCA;
• To list technical issues to be resolved before implementing a new regulation, if any.
The workshop was articulated over three questions: • What drives the need to redefine the LB-LOCA?
• Does an adequate technical basis exist to support a redefinition of the LB-LOCA?
• What are possible new definitions for the LB-LOCA? What are their implications on current and future reactors?
The Workshop proceedings have been divided into two separate volumes under the references NEA/CSNI/R(2003)17/VOL 1 and VOL 2 .
The complete list of CSNI reports, and the text of reports from 1993 on, is available on
http://www.nea.fr/html/nsd/docs.
NEA/CSNI/R(2003)16
7
Joint CSNI/CNRA Workshop on "Redefining the Large Break LOCA: Technical basis and its implications"
June 23-24, 2003 - Zurich, Switzerland
Synthesis and compilation of Responses to the survey
A. Foreword 5
B. Table of Contents 9
C. Synthesis and compilation of responses 11
• Current regulatory framework 17
• Current technical framework 39
• Consideration for the future 47
• Other issues 63
Appendix 1 65
Appendix 2 71
Appendix 3 77
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B. Table of Contents
Current regulatory framework
1. What is the largest or limiting break size assumed as design basis (LOCA) in your regulation?
17
2. Are there any "risk" considerations in the current LOCA break size definition?
21
3. Describe regulatory implications on design, operational procedures, testing, inspection program associated with the current LOCA break size definition?
23
4. Is Leak-Before-Break accepted (or being considered) in your regulation ? If so, what are the consequences on component or piping supports, system analysis, fuel assembly, containment…
33
Current technical framework
1. What technical issues are currently of concerns for Structures, Systems and Components (associated with the current LOCA definition)? (please list)
39
2. What technical issues would be needed to be addressed by Researchers to support the regulatory decision making process to change the current LOCA definition?
43
Consideration for the future
1. Are you considering changes in your regulation? For operating plants? For future plants?
47
2 What would be the incentives? From the regulatory viewpoint? From the Industry viewpoint?
51
3. If you are considering replacing large break LOCA by a smaller break size within the design basis, some degree of core damage, short of core melt resulting in vessel failure, may be expected if a large break LOCA actually occurred.
3.a How would you establish performance requirements for the emergency cooling systems
in order to provide some assurance that damage following a large break LOCAs can still be mitigated before vessel failure? What is the technical basis?
55
3.b Are currently available computer codes and models adequate for the required analyses or new tools will have to be developed?
59
NEA/CSNI/R(2003)16
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Other issues
What other issues concerning LOCA do you feel should be discussed during the workshop?
63
Appendices
I. Information provided by USNRC to complement the answer on question future 2
65
II. Information provided by GRS to complement the answer to question "Current Regulatory Framework 4"
71
III. Information provided by STUK on the LBB and failure frequency requirements in the Finnish guideline YVL 3.5
77
11
Joint CSNI/CNRA Workshop on "Redefining the Large Break LOCA:
Technical basis and its implications" June 23-24, 2003 - Zurich, Switzerland
C. Synthesis and Compilation of Responses
Objectives of the survey: - to provide material for discussion - to clearly summarize current national regulations - to understand rationales and incentives for changing or not - to list technical issues to be resolved before implementing a new regulation, if any - to focus the workshop on technical issues
NEA/CSNI/R(2003)16
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Current regulatory framework 1. What is the largest or limiting break size assumed as design basis (LOCA) in your
regulation?
Most of the countries consider the Double Ended Break Guillotine of the largest pipe in the reactor coolant system. The Slovak Republic assumes instantaneous guillotine break of pressurizer surge line with the diameter of 200 mm for VVER-440/230 reactors. For these reactors, the 2x500 mm LLOCA is considered as a beyond design basis events. 2. Are there any "risk" considerations in the current LOCA break size definition ?
The LLOCA is in the design basis. There are no explicit risk consideration in the likelihood of this initiating event and in analysis. 3. Describe regulatory implications on design, operational procedures, testing, inspection
program associated with the current LOCA break size definition ?
LLOCA has obviously a broad impact on structural design (containments, pipe restraints, capacity of emergency systems(PORVs, ECCS), redundancy), testing (containment, piping), environmental qualification of equipments, operating procedures. ISI programs are sometimes governed more by structural integrity considerations (i.e. degradation) than by LLOCA considerations.
It is interesting to note that some countries mentioned that no changes would be made to procedures to mitigate a LLOCA as procedures are similar for the SLOCA (Small LOCA).
One organization indicates that LLOCA requirements influence every level of plant operations as well as design and that some restrictions on plant operations might be removed if the LOCA definition is changed. 4. Is Leak-Before-Break accepted (or being considered) in your regulation ? If so, what are
the consequences on component or piping supports, system analysis, fuel assembly, containment…
A vast majority of countries is using LBB. It is used in all cases only to remove (or not
installing) whip restraints, snubbers, modify supports or justify internals behavior. One country approved LBB only for analysis and did no physical changes in the plants. Current technical framework 1. What technical issues are currently of concerns for Structures, Systems and Components
(associated with the current LOCA definition)? (please list)
The most frequently listed are: - sump debris generation and sump blockage; - fuel behavior; - containment leak tightness; - Diesel (EDG); - Bimetallic welds failure mode. 2. What technical issues would be needed to be addressed by Researchers to support the
regulatory decision making process to change the current LOCA definition?
LOCA initiating event frequency and best estimate analysis methods and uncertainties are the most frequent answers. Inspection programs, fracture mechanics and probabilistic fracture mechanics, leak detection systems and the integration of the
NEA/CSNI/R(2003)16
13
deterministic, defense in depth principle within a risk-informed framework are also mentioned. Consideration for the future 1. Are you considering changes in your regulation? For operating plants? For future plants?
Except the USA, regulators are not considering changes in the regulation. Nevertheless Canadian regulators would be ready to discuss a more balance approach to LLOCA for both existing and future plants. As to the Industry, only the USA has done some detailed work. 2. What would be the incentives? From the regulatory viewpoint? From the Industry
viewpoint? - Regulatory viewpoint
As said before, very few countries have already considered the topic. Nevertheless, the Canadian answers give a good overview. It has to be noted that an important incentive mentioned is to focus resources in areas of greater risk significance It is also mentioned by one country that unnecessary conservative could be removed and safety margins better used. The latter is consistent with what is said about best-estimate analysis methods and uncertainties. - Industry viewpoint power uprates, EDG start times, testing, economical benefits, …. 3. If you are considering replacing large break LOCA by a smaller break size within the
design basis, some degree of core damage, short of core melt resulting in vessel failure, may be expected if a large break LOCA actually occurred.
3.a How would you establish performance requirements for the emergency cooling
systems in order to provide some assurance that damage following a large break LOCAs can still be mitigated before vessel failure? What is the technical basis?
No clear answers but several approaches
- LLOCA would not totally disappear. It would be considered as a beyond design basis event and analyzed using state of the art and best estimate methods.
- LLOCA probability considered as low as vessel rupture probability and thus excluded - ECCS would be based on the break of the largest pipe but ancillary requirements (e.g.,
technical specifications for safety injection flow rates and inspection frequencies for accumulator condition) will be subject to risk-informed modification.
3.b Are currently available computer codes and models adequate for the required
analyses or new tools will have to be developed?
Available codes seem to be mature enough although applicability range for codes may need to be reexamined. Struture reliability models, PRA models and probabilistic fracture mechanics may need to be further developed Also core reflooding and vessel-corium interaction could be further developed.
What other issues concerning LOCA do you feel should be discussed during the workshop?
NEA/CSNI/R(2003)16
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Appendices
I Information provided by USNRC to complement the answer on question future 2
II. Information provided by GRS to complement the answer to question "Current Regulatory Framework 4"
III. Information provided by STUK on the LBB and failure frequency requirements in the Finnish guideline YVL 3.5
Operation/maintenance consequences Sump clogging PRA quality and completeness Frequency of the LLOCA "Realistic" operator response assumptions High burn-up fuel under LOCAs conditions Pilot submittal to validate.
NE
A/C
SNI/
R(2
003)
16
15
A
nsw
ers
rece
ived
fro
m
BE
LG
IUM
A
VN
(A
ssoc
iatio
n V
inço
tte N
ucle
ar)
CA
NA
DA
C
NSC
(C
anad
ian
Nuc
lear
Saf
ety
Com
mis
sion
) SU
JB (
Stat
e O
ffic
e fo
r N
ucle
ar S
afet
y)
CZ
EC
H R
EP
UB
LIC
N
RI
Rez
(N
ucle
ar R
esea
rch
Inst
itut
e)
FIN
LA
ND
ST
UK
(R
adia
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and
Nuc
lear
Saf
ety
Aut
hori
ty)
IRSN
(In
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e R
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prot
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on e
t de
Sûre
té N
uclé
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) F
RA
NC
E
ED
F SE
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N (
Serv
ice
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des
et P
roje
ts T
herm
ique
s &
Nuc
léai
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G
ER
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NY
G
RS
(Ges
ells
chaf
t für
Anl
agen
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d R
eakt
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cher
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) JA
PA
N
NU
PEC
(N
ucle
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ower
Eng
inee
ring
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pora
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JA
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I (J
apan
Ato
mic
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rgy
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earc
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stit
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M
EX
ICO
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omis
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ucle
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ucle
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Nuc
lear
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lant
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earc
h In
stit
ute)
T
rnav
a, I
nc. (
Thi
s is
the
view
of
VU
JE a
nd it
was
dis
cuss
ed w
ith
Slov
ak r
egul
ator
as
wel
l as
with
B
ohun
ice
NPP
) SP
AIN
C
SN (
Con
sejo
de
Segu
rida
d N
ucle
ar)
SWE
DE
N
SKI
(Sw
edis
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ucle
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ower
Ins
pect
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SWIT
ZE
RL
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HSK
(S
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ety
Insp
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II (
Nuc
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tall
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ucle
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and
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enia
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r Sl
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lear
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ety
Adm
inis
trat
ion
NE
A/C
SNI/
R(2
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16
C
urre
nt r
egul
ator
y fr
amew
ork
1.
W
hat
is t
he la
rges
t or
lim
itin
g br
eak
size
ass
umed
as
desi
gn b
asis
(LO
CA
) in
you
r re
gula
tion
? B
EL
GIU
M
T
he B
elgi
an r
egul
atio
n do
es n
ot s
peci
fy a
lim
itin
g br
eak
size
for
DB
A (
LO
CA
), b
ut a
ll op
erat
ing
plan
ts (
all
PWR
s)
wer
e de
sign
ed a
nd li
cens
ed o
n th
e ba
sis
of th
e do
uble
end
ed b
reak
of
the
larg
est p
ipe
in th
e pr
imar
y ci
rcui
t. C
AN
AD
A
L
arge
st –
ins
tant
aneo
us g
uillo
tine
failu
re o
f th
e la
rges
t di
amet
er p
ipe
in t
he p
rim
ary
syst
em (
reac
tor
head
er).
Thi
s is
no
rmal
ly m
odel
led
as a
bre
ak o
f 20
0% p
ipe
area
. L
imit
ing
– “c
riti
cal”
bre
ak th
at le
ads
to f
low
spl
it in
cor
e is
lim
iting
for
som
e de
rive
d ac
cept
ance
cri
teri
a.
Lic
ensi
ng b
asis
ana
lysi
s is
det
erm
inis
tic,
with
con
serv
ativ
e as
sum
ptio
ns,
such
as
reac
tor
initi
al c
ondi
tion
s at
lim
it o
f op
erat
ing
enve
lope
(L
OE
) an
d m
inim
um s
afet
y sy
stem
per
form
ance
(e.
g. r
eact
or t
rip
on s
econ
d tr
ip p
aram
eter
of
seco
nd
shut
dow
n sy
stem
, tw
o ro
ds u
nava
ilabl
e, m
inim
um E
CC
flo
w).
Ana
lysi
s is
nor
mal
ly w
ith
best
est
imat
e ph
ysic
s an
d th
erm
al-
hydr
aulic
s co
des.
SUJB
Sa
fety
A
utho
rity
Dou
ble
End
ed G
uillo
tine
LB
LO
CA
(2x
500
for
VV
ER
440
/213
or
2x85
0 fo
r V
VE
R 1
000)
C
ZE
CH
R
EP
UB
LIC
NR
I R
ez
D
N 5
00 I
DN
850
FIN
LA
ND
It is
2A
, a d
oubl
e-en
ded
guill
otin
e br
eak
of a
ny p
ipel
ine.
FR
AN
CE
IR
SN
For
the
exis
ting
pla
nts
the
fram
es o
f la
rge
brea
k st
udie
s co
ncer
n br
eak
diam
eter
s, th
e la
rges
t bre
ak s
ize
assu
med
bei
ng
the
doub
le-e
nded
bre
ak o
f an
y li
ne o
f th
e P
rim
ary
Cir
cuit;
the
mos
t li
mit
ing
brea
k si
ze i
s de
term
ined
thr
ough
sen
sitiv
itie
s st
udie
s be
twee
n 14
inch
es a
nd 2
A.
Con
cern
ing
the
EPR
pro
ject
, th
e po
ssib
ility
to
excl
ude
the
2A L
LO
CA
on
the
basi
s of
LB
B d
emon
stra
tion
was
ac
cept
ed.
How
ever
the
met
hodo
logy
use
d fo
r th
is d
emon
stra
tion
(des
ign,
man
ufac
turi
ng a
nd c
ontr
ol r
ules
, ca
lcul
atio
n of
cr
itica
l de
fect
s, b
reak
s ar
ea, l
eak
flow
, saf
ety
coef
fici
ent,
natu
re a
nd s
ensi
tivi
ty o
f le
ak d
etec
tion
devi
ces)
was
not
pre
sent
ed
to t
he S
afet
y A
utho
rity
by
the
desi
gner
s an
d co
nseq
uent
ly w
as n
ot a
ppro
ved.
Any
way
the
bre
ak s
ize
cons
ider
ed a
s de
sign
ba
sis
acci
dent
will
be
at le
ast t
he r
uptu
re o
f th
e su
rge
line.
NE
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R(2
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16
17
E
DF
SE
PT
EN
D
EG
B in
11
loca
tions
in 1
ms.
GE
RM
AN
Y
Fo
r th
e lig
ht w
ater
rea
ctor
s th
e gu
illot
ine
type
bre
ak o
f th
e pr
imar
y co
olan
t li
ne i
s th
e de
sign
bas
is i
n pr
inci
pal.
The
br
eak
assu
mpt
ions
to
be u
sed
for
the
safe
ty c
once
pt a
re l
aid
dow
n in
the
RSK
gui
delin
es,
chap
ter
2.1.
1. I
n th
e ye
ars
1979
/198
1 a
chan
ge in
the
requ
irem
ents
took
pla
ce. R
egar
ding
the
capa
city
of
the
EC
CS
as w
ell a
s th
e de
sign
pre
ssur
e of
the
cont
ainm
ent
the
inst
anta
neou
s br
eak
of t
he l
arge
st l
ine
has
been
kep
t as
the
des
ign
requ
irem
ent.
For
pipi
ng s
yste
ms
whi
ch
have
bee
n qu
alif
ied
acco
rdin
g to
the
bas
ic s
afet
y co
ncep
t th
e de
sign
req
uire
men
ts r
egar
ding
pip
e w
hip,
jet i
mpi
ngem
ent
and
stab
ility
of
inte
rnal
s ha
ve b
een
base
d on
a o
peni
ng o
f a
pipe
wit
h a
10 %
of
the
cros
s se
ctio
n of
the
larg
est p
ipe.
JA
PA
N
D
oubl
e en
ded
guill
otin
e（％％
200
M
EX
ICO
The
inst
anta
neou
s do
uble
-end
ed b
reak
of
one
of r
ecir
cula
tion
pip
es.
SLO
VA
K
RE
PU
BL
IC
Safe
ty
Aut
hori
ty
Acc
ordi
ng to
a c
urre
nt le
gisl
atio
n (R
egul
atio
n N
o. 2
/197
8), t
he li
mit
ing
brea
k si
ze is
con
side
red
as a
n ac
cide
nt w
ith
the
bigg
est r
adio
logi
cal i
mpa
ct to
the
envi
nron
men
t.
Fo
r N
PPs
of W
WE
R 4
40/2
13 ty
pe th
e de
sign
bas
is L
OC
A is
Dou
ble
End
ed G
uillo
tine
Bre
ak (
DE
GB
) of
inne
r di
amet
er (
ID)
of 5
00 m
m.
For
NPP
of
WW
ER
440
/230
type
(tw
o un
its o
f B
ohun
ice
V-1
NPP
) th
e or
igin
al d
esig
n ba
sis
LO
CA
has
bee
n D
EG
B o
f ID
of
32 m
m. A
fter
the
“sm
all”
and
“gr
adua
l” r
econ
stru
ctio
n th
e de
sign
bas
is L
OC
A h
as b
een
incr
ease
d up
to I
D o
f 20
0 m
m
for
all,
norm
al, u
pset
and
em
erge
ncy
oper
atio
nal r
egim
es u
sing
a c
onse
rvat
ive
appr
oach
and
ID
of
500
mm
usi
ng th
e be
st
estim
ate
assu
mpt
ions
. The
req
uire
men
ts a
nd c
ondi
tion
s fo
r gr
adua
l rec
onst
ruct
ion
have
bee
n is
sued
in th
e re
gula
tory
de
cisi
on N
o. 1
/94
incl
udin
g de
fini
tion
of
crite
ria
for
impr
ovem
ent o
f E
CC
S sy
stem
to b
e ab
le m
anag
e th
is s
ize
of b
reak
.
NE
A/C
SNI/
R(2
003)
16
18
V
UJE
L
imit
ing
brea
k si
ze:
VV
ER
-440
/213
– i
nsta
ntan
eous
gui
llotin
e br
eak
of R
eact
or C
oola
nt S
yste
m m
ain
circ
ulat
ion
line
with
the
lar
gest
di
amet
er (
diam
eter
of
500
mm
, dou
ble-
end
cool
ant d
isch
arge
).
VV
ER
-440
/230
– i
nsta
ntan
eous
gui
llotin
e br
eak
of p
ress
uriz
er s
urge
lin
e w
ith t
he d
iam
eter
of
200
mm
(do
uble
- end
co
olan
t di
scha
rge)
, re
sp.
wit
h a
part
ial
brea
k of
RC
S li
ne w
ith
equi
vale
nt d
iam
eter
of
200
mm
. Fo
r th
is t
ype
of r
eact
or,
LB
LO
CA
2x5
00 m
m is
ass
umed
as
Bey
ond
DB
A.
Bre
ak lo
catio
n:
Bre
ak l
ocat
ion
is a
ssum
ed a
t th
e m
ost
adve
rse
poin
t. It
mea
ns t
hat
brea
k lo
catio
n ca
n di
ffer
for
eva
luat
ion
acce
ptan
ce
crite
ria
from
poi
nt o
f vi
ew o
f co
re c
ooli
ng (
max
imum
cla
ddin
g te
mpe
ratu
re)
and
from
poi
nt o
f vi
ew o
f m
ass
and
ener
gy
rele
ase
into
the
conf
inem
ent (
conf
inem
ent l
oads
cal
cula
tion,
rad
iolo
gica
l con
sequ
ence
s).
Des
ign
basi
c an
alys
es a
re p
erfo
rmed
usi
ng t
he b
est
esti
mat
e th
erm
al-h
ydra
ulic
s co
de a
nd c
onse
rvat
ive
assu
mpt
ions
(i
nitia
l an
d bo
unda
ry c
ondi
tions
) in
ter
m o
f ac
cept
ance
cri
teri
on e
valu
atio
n. F
or V
VE
R-4
40/2
30,
whe
re L
B L
OC
A 2
x500
m
m i
s as
sum
ed a
s B
DB
A, a
ccep
tanc
e cr
iteri
a fu
lfill
men
t ha
s to
be
dem
onst
rate
d us
ing
the
best
est
imat
e th
erm
al- h
ydra
ulic
s co
de a
nd b
est e
stim
ate
(or
real
isti
c) a
ssum
ptio
ns.
SPA
IN
W
e fo
llow
the
regu
latio
ns o
f ou
r ve
ndor
s: U
SA a
nd G
erm
any
SWE
DE
N
A
ll S
wed
ish
reac
tors
hav
e be
en a
naly
sed
for
a L
OC
A e
quiv
alen
t to
the
dim
ensi
on o
f th
e la
rges
t pip
e co
nnec
ted
to th
e re
acto
r pr
essu
re v
esse
l. T
his
has
been
a p
rere
quis
ite in
the
PSA
R a
nd F
SAR
as
a ba
sis
for
the
licen
ce. F
or th
e B
WR
wit
h in
tern
al r
e-ci
rcul
atio
n pu
mps
a h
ypot
hetic
al b
reak
siz
e of
80
cm2 h
as b
een
basi
s fo
r th
e lic
ence
and
the
desi
gn o
f em
erge
ncy
core
coo
ling
sys
tem
. (Se
e al
so th
e an
swer
to th
e qu
estio
ns o
f “C
urre
nt te
chni
cal f
ram
ewor
k”)
SKI
has
not y
et is
sued
any
gen
eral
reg
ulat
ions
that
spe
cifi
cally
add
ress
thes
e as
pect
s. H
owev
er, S
KI’
s ge
nera
l des
ign
regu
latio
ns th
at n
ow a
re b
eing
pre
pare
d w
ill r
equi
re th
at th
e re
acto
r co
re m
ust b
e co
oled
by
spri
nklin
g or
wat
er c
over
ing
in
even
t of
a lo
ss o
f co
olan
t tha
t can
fol
low
a b
reak
of
any
pipe
con
nect
ed to
the
reac
tor
pres
sure
ves
sel.
It m
ust a
lso
be p
ossi
ble
to r
each
sta
ble
cond
ition
s w
ith
a w
ater
-cov
ered
cor
e or
cor
e m
elt a
nd e
stab
lishe
d re
sidu
al h
eat r
emov
al.
SW
ITZ
ER
LA
ND
A c
ompl
ete
doub
le-e
nded
bre
ak o
f a
mai
n co
olan
t pi
pe (
200%
bre
ak)
acco
rdin
g to
HSK
-Gui
deli
ne R
-101
"D
esig
n C
rite
ria
for
Safe
ty S
yste
ms
of L
ight
-Wat
er R
eact
ors"
(M
ay 1
987)
. U
NIT
ED
K
ING
DO
M
F
or P
WR
, ful
l dou
ble
ende
d co
ld le
g gu
illo
tine
prim
ary
loop
pip
ewor
k br
eak.
NE
A/C
SNI/
R(2
003)
16
19
USA
U
S N
RC
10
CFR
50.
46 A
ccep
tanc
e cr
iteri
a fo
r em
erge
ncy
core
coo
ling
syst
ems
(EC
CS)
for
ligh
t-w
ater
coo
led
nucl
ear
pow
er
reac
tors
, Sec
tion
c
and
App
endi
x A
to P
art 5
0 --
Gen
eral
Des
ign
Cri
teri
a fo
r N
ucle
ar P
ower
Pla
nts,
Def
initi
on o
f L
oss
of C
oola
nt a
ccid
ents
. B
oth
incl
ude
the
follo
win
g te
xt d
efin
ing
the
desi
gn b
ase
LO
CA
: “
..acc
iden
ts th
at w
ould
res
ult f
rom
the
loss
of r
eact
or c
oola
nt a
t a r
ate
in e
xces
s of
the
capa
bili
ty o
f the
rea
ctor
co
olan
t mak
eup
syst
em, f
rom
bre
aks
in p
ipes
in th
e re
acto
r co
olan
t pre
ssur
e bo
unda
ry u
p to
and
incl
udin
g a
brea
k eq
uiva
lent
in s
ize
to th
e do
uble
-end
ed r
uptu
re o
f the
larg
est p
ipe
in th
e re
acto
r co
olan
t sys
tem
.”
App
endi
x K
to P
art 5
0 --
EC
CS
Eva
luat
ion
Mod
els
Incl
udes
the
foll
owin
g te
xt d
efin
ing
the
spec
trum
of
poss
ible
bre
ak s
izes
that
sha
ll be
con
side
red
in a
naly
sis
of L
OC
As:
”
Thi
s sp
ectr
um s
hall
incl
ude
inst
anta
neou
s do
uble
-end
ed b
reak
s ra
ngin
g in
cro
ss s
ecti
onal
are
a up
to a
nd in
clud
ing
that
of t
he la
rges
t pip
e in
the
prim
ary
cool
ant s
yste
m”
W
OG
A
dou
ble-
ende
d ru
ptur
e of
the
larg
est p
ipe
in th
e re
acto
r co
olan
t sys
tem
.
RU
SSIA
O
bser
ver
Gid
ropr
ess
The
re i
s no
dir
ect
indi
catio
n of
the
lar
gest
or
limit
ing
brea
k si
ze i
n th
e cu
rren
t sa
fety
sta
ndar
ds a
ppro
ved
by t
he
Rus
sian
reg
ulat
ory
body
. In
fac
t, cu
rren
t de
sign
pra
ctic
e is
stil
l ba
sed
on o
ld r
egul
atio
ns w
here
the
bre
ak o
f th
e la
rges
t pr
imar
y pi
pelin
e w
as i
mpl
ied
(OPB
-73)
or
dire
ctly
pre
scri
bed
(OPB
-82)
. In
par
ticul
ar,
the
OPB
- 82
item
4.1
.1 s
ound
s:
“Ins
tant
aneo
us r
uptu
re o
f th
e la
rges
t pi
pelin
e w
ith u
nim
pede
d co
olan
t di
scha
rge
… m
ust
be c
onsi
dere
d in
des
ign
as t
he
max
imum
des
ign
acci
dent
wit
h th
e pr
imar
y ci
rcui
t dep
ress
uriz
atio
n”.
Als
o, t
he U
SSR
sta
ndar
d ca
lled
“Nuc
lear
pow
er p
ress
uriz
ed w
ater
rea
ctor
s. G
ener
al t
echn
ical
req
uire
men
ts”
(GO
ST
2472
2-81
) is
stil
l in
for
ce i
n R
ussi
a. T
he i
tem
1.5
.1 o
f th
is s
tand
ard
soun
ds:
“Ins
tant
aneo
us t
rans
vers
e ru
ptur
e of
the
mai
n ci
rcul
atio
n pi
peli
ne w
ith d
oubl
e-en
ded
cool
ant d
isch
arge
… m
ust b
e co
nsid
ered
in d
esig
n as
the
max
imum
acc
iden
t…”.
G
AN
In
stan
tane
ous
guill
otin
e br
eak
of p
rim
ary
pipe
of
max
imum
dia
met
er o
n ho
t or
col
d le
g fo
r W
WE
R r
eact
ors
and
of
mai
n ci
rcul
atio
n pu
mp
pipe
or
mai
n ci
rcul
atio
n pu
mp
head
er f
or R
BM
K r
eact
ors.
Slov
enia
O
bser
ver
L
imit
ing
brea
k is
DE
CL
GB
(do
uble
end
ed c
old
leg
guill
otin
e br
eak)
for
the
case
of
our
only
NPP
.
NE
A/C
SNI/
R(2
003)
16
20
C
urre
nt r
egul
ator
y fr
amew
ork
2. A
re t
here
any
"ri
sk"
cons
ider
atio
ns in
the
cur
rent
LO
CA
bre
ak s
ize
defi
niti
on ?
BE
LG
IUM
No.
C
AN
AD
A
N
ot in
cur
rent
lice
nsin
g ba
sis.
Bre
ak s
ize
up to
ful
l gui
llot
ine
brea
k is
in th
e de
sign
bas
is. T
here
is n
o co
nsid
erat
ion
of
the
like
lihoo
d of
the
initi
atin
g ev
ent.
Ana
lysi
s is
“de
term
inis
tic”
safe
ty a
naly
sis
as d
escr
ibed
abo
ve.
Lic
ense
es a
re p
ropo
sing
Bes
t E
stim
ate
Ana
lysi
s +
Unc
erta
inty
(B
EA
U)
met
hodo
logy
(si
mil
ar to
CSA
U)
as a
bas
is f
or
cons
eque
nce
anal
ysis
. Thi
s is
und
er c
onsi
dera
tion
In
cred
ibili
ty o
f fa
ilure
arg
umen
ts a
re a
ccep
ted
for
larg
e ve
ssel
s th
at w
ere
appr
opri
atel
y de
sign
ed,
fabr
icat
ed a
nd a
re
appr
opri
atel
y op
erat
ed a
nd in
spec
ted
(e.g
. ste
am g
ener
ator
s).
SUJB
Saf
ety
Aut
hori
ty
No.
C
ZE
CH
R
EP
UB
LIC
NR
I R
ez
No.
FIN
LA
ND
Not
qua
ntita
tive
ly. Q
ualit
ativ
ely
seam
s w
elde
d in
the
fie
ld m
ay b
e m
ore
like
ly t
o cr
ack,
as
oper
atin
g ex
peri
ence
fro
m
Sum
mer
and
Rin
ghal
s pl
ants
impl
ies.
IRSN
If
"ri
sk"
mea
ns p
roba
bilit
y/co
nseq
uenc
es c
onsi
dera
tions
: No.
F
RA
NC
E
ED
F
SEP
TE
N
No.
GE
RM
AN
Y
In
the
cur
rent
LO
CA
bre
ak s
ize
defi
nitio
ns t
here
are
no
expl
icit
risk
con
side
rati
ons
but
impl
icit
jud
gem
ents
on
com
pone
nt r
elia
bilit
y ha
ve p
laye
d a
maj
or r
ole
in th
e ch
ange
of
the
regu
lato
ry r
equi
rem
ents
. JA
PA
N
N
o.
NE
A/C
SNI/
R(2
003)
16
21
ME
XIC
O
In
gen
eral
, al
l br
eaks
are
ass
umed
to
occu
r in
the
rec
ircu
latio
n pi
ping
bec
ause
the
y ar
e th
e m
ost
seve
re f
rom
the
cla
ddin
g he
atup
vie
wpo
int.
Bec
ause
the
ste
am q
ualit
y of
the
flu
id l
eavi
ng b
reak
in
a re
circ
ulat
ion
line
is z
ero
initi
ally
, th
ese
are
gene
rall
y kn
ow a
s liq
uid
brea
ks, h
owev
er b
reak
s on
oth
er lo
caliz
atio
ns, i
nclu
ding
fee
dwat
er, c
ore
spra
y an
d st
eam
line
s ar
e al
so a
naly
zed.
T
he l
arge
bre
ak L
OC
A i
s an
eve
nt w
ith l
ow p
roba
bilit
y, h
owev
er t
he s
mal
l L
OC
A a
nd s
mal
l-sm
all
LO
CA
hav
e a
high
er
prob
abili
ty a
nd th
eref
ore
this
kin
d of
LO
CA
’s s
houl
d be
con
side
red
seri
ousl
y in
the
defi
nitio
n of
the
desi
gn b
asis
LO
CA
.
SLO
VA
K
RE
PU
BL
IC
Safe
ty
Aut
hori
ty
At p
rese
nt th
ere
are
no r
isk
cons
ider
atio
ns in
the
LO
CA
bre
ak s
ize
defi
nitio
n.
VU
JE
Not
in c
urre
nt li
cens
ing
basi
s.
SPA
IN
N
o.
SWE
DE
N
N
o ri
sk c
onsi
dera
tions
hav
e be
en u
sed
in p
rese
nt L
OC
A b
reak
siz
e de
fini
tion.
SW
ITZ
ER
LA
ND
No.
U
NIT
ED
KIN
GD
OM
N
o, la
rge
LO
CA
s ar
e in
freq
uent
eve
nts,
ver
y sm
all
& s
mal
l LO
CA
s ar
e fr
eque
nt e
vent
s.
USA
U
SNR
C
Ris
k is
con
side
red
impl
icitl
y in
sofa
r as
ver
y lo
w f
requ
ency
eve
nts
are
not i
nclu
ded
in th
e sp
ectr
um o
f L
OC
A s
izes
that
mus
t be
incl
uded
in th
e de
sign
bas
is.
For
exam
ple,
the
larg
est l
oss
of c
oola
nt a
ccid
ent,
reac
tor
vess
el r
uptu
re, i
s no
t inc
lude
d in
the
desi
gn
basi
s. I
t was
als
o as
sum
ed (
whe
n th
e de
fini
tion
was
est
ablis
hed)
that
the
desi
gn f
or d
oubl
e-en
ded
rupt
ure
wou
ld b
ound
all
pote
ntia
l ri
sk-s
igni
fica
nt s
cena
rios
. T
he 1
984
revi
sion
to
Gen
eral
Des
ign
Cri
teri
a (G
DC
) 4,
bas
ed i
n pa
rt o
n th
e lo
w p
roba
bilit
y of
pip
e ru
ptur
e,
allo
ws
the
use
of l
eak-
befo
re-b
reak
(L
BB
) to
exc
lude
the
dyn
amic
eff
ects
of
post
ulat
ed p
ipe
rupt
ure
subj
ect
to c
erta
in c
ondi
tions
. (S
ee a
dditi
onal
di
scus
sion
in it
em 4
).
WO
G
No,
it is
sol
ely
dete
rmin
istic
.
RU
SSIA
Obs
erve
r G
idro
pres
s T
he “
risk
” as
pect
doe
s no
t exi
st e
xplic
itly.
How
ever
, lar
ger
freq
uenc
ies
for
smal
ler
brea
ks a
re a
ssum
ed in
PSA
.
GA
N
Rup
ture
s of
equ
ipm
ent
casi
ngs
and
vess
els,
who
se m
anuf
actu
re a
nd o
pera
tion
shal
l be
car
ried
out
in
acco
rdan
ce w
ith t
he
mos
t st
ring
ent
requ
irem
ents
of
fede
ral
regu
latio
ns a
nd r
ules
in
the
fiel
d of
use
of
nucl
ear
ener
gy,
are
not
incl
uded
int
o th
e lis
t of
in
itiat
ing
even
ts.
In t
his
case
it
shou
ld b
e de
mon
stra
ted
that
the
pro
babi
lity
rate
of
reac
tor
vess
el d
estr
ucti
on d
oes
not
exce
ed 1
0-7
per
reac
tor
per
year
.
Slov
enia
Obs
erve
r N
o.
NE
A/C
SNI/
R(2
003)
16
22
Cur
rent
reg
ulat
ory
fram
ewor
k
3.
D
escr
ibe
regu
lato
ry i
mpl
icat
ions
on
desi
gn,
oper
atio
nal
proc
edur
es,
test
ing,
ins
pect
ion
prog
ram
ass
ocia
ted
wit
h th
e cu
rren
t L
OC
A b
reak
siz
e de
fini
tion
?
BE
LG
IUM
Impl
icat
ions
of
the
curr
ent
LO
CA
bre
ak s
ize
defi
nitio
n ar
e m
ulti
ple.
Ind
eed,
at
the
desi
gn,
the
capa
city
of
man
y sy
stem
s (c
onta
inm
ent
stru
ctur
es,
core
sup
port
str
uctu
res,
EC
CS,
con
tain
men
t he
at r
emov
al,
supp
ort
syst
ems,
...)
has
bee
n de
term
ined
by
requ
irem
ents
def
ined
by
the
Lar
ge B
reak
LO
CA
(an
d/or
ste
am l
ine
brea
k).
Con
cern
ing
test
ing,
the
cur
rent
def
initi
on o
f L
BL
OC
A
has
still
an
impa
ct, f
or e
xam
ple,
on
the
ten
year
per
iodi
c te
st p
ress
ure
of t
he c
onta
inm
ent.
Als
o fo
r th
e qu
alif
icat
ion
of c
ompo
nent
s fo
r po
st-a
ccid
enta
l con
ditio
ns, t
he c
urre
nt d
efin
ition
of
LB
LO
CA
sti
ll ha
s an
impa
ct.
CA
NA
DA
Des
ign
– L
LO
CA
has
alw
ays
been
par
t of
the
des
ign
basi
s fo
r C
anad
ian
reac
tors
and
it
sets
per
form
ance
req
uire
men
ts f
or
shut
dow
n, e
mer
genc
y co
re c
oolin
g an
d co
ntai
nmen
t sy
stem
s (t
he S
peci
al S
afet
y S
yste
ms)
. R
elia
bilit
y re
quir
emen
ts a
re s
et
inde
pend
ent o
f L
LO
CA
. O
pera
tion
al p
roce
dure
s –
proc
edur
es i
nclu
de r
espo
nse
to L
LO
CA
and
als
o re
spon
se t
o ac
cide
nt p
recu
rsor
s su
ch a
s sh
utdo
wn
limit
s fo
r pr
imar
y le
akag
e. T
he p
roce
dure
s fo
r re
spon
se t
o L
OC
A w
ould
be
larg
ely
unch
ange
d if
LL
OC
A w
as n
ot i
n de
sign
bas
is s
ince
the
sam
e pr
oced
ures
cov
er s
mal
l and
larg
e L
OC
A.
Tes
ting
– e
xten
sive
on-
line
tes
ting
of s
peci
al s
afet
y sy
stem
s en
sure
s th
at t
hese
sys
tem
s sa
tisf
y m
inim
um p
erfo
rman
ce
stan
dard
s an
d th
at s
yste
ms
mee
t un
avai
labi
lity/
reli
abili
ty t
arge
ts.
Thi
s w
ould
be
larg
ely
unch
ange
d if
LL
OC
A w
as n
ot i
n de
sign
ba
sis
as a
ll s
yste
ms
are
still
req
uire
d fo
r SL
OC
A. I
t may
be
poss
ible
to r
educ
e so
me
perf
orm
ance
targ
ets,
e.g
. sta
ndby
gen
erat
or s
tart
ti
me,
shu
tdow
n sy
stem
ope
ratio
n ti
mes
. In
spec
tion
– in
-ser
vice
insp
ectio
n pr
ogra
ms
requ
ire
insp
ecti
on o
f cl
ass
1 pi
ping
at p
rede
fine
d in
terv
als.
Ins
pect
ion
prog
ram
is
base
d on
initi
al w
eld
insp
ectio
n re
sults
and
pip
e st
ress
/ fa
tigu
e ch
arac
teri
stic
s. T
his
wou
ld b
e la
rgel
y un
chan
ged
if L
LO
CA
was
not
in
des
ign
basi
s. M
ore
exte
nsiv
e in
spec
tion
pro
gram
wou
ld b
e re
quir
ed to
sup
port
a L
BB
app
roac
h.
NE
A/C
SNI/
R(2
003)
16
23
SUJB
Sa
fety
A
utho
rity
LB
LO
CA
has
bee
n al
way
s as
sess
ed i
n th
e Sa
fety
Ana
lysi
s R
epor
ts a
s th
e de
sign
bas
is f
or b
oth
NPP
in
the
Cze
ch R
epub
lic
(4xW
WE
R-4
40,
2xW
WE
R-1
000)
. T
he c
urre
nt L
OC
A b
reak
dow
n de
fini
tion
has
bee
n an
d m
ust
be c
onsi
dere
d in
the
des
ign
of t
he
emer
genc
y co
re c
oolin
g sy
stem
s an
d th
e co
ntai
nmen
t sys
tem
s (i
nclu
ding
bub
ble
cond
ense
r).
Prim
ary
circ
uit:
–
Saf
ety
anal
yses
:
Use
the
val
idat
ed c
ompu
ter
code
. Sa
fety
mar
gin
defi
niti
on.
Def
initi
on o
f sa
fety
lim
its (
als
o fo
r hi
gh b
ur u
p fu
el).
Lon
g te
rm C
ool a
bilit
y of
the
core
–
Follo
w u
p co
ntro
l fue
l ass
embl
y in
tegr
ity
( fo
r W
WE
R 4
40/2
13)
– C
oola
nt –
in v
esse
l str
uctu
re in
tera
ctio
n C
onta
inm
ent
inte
grit
y. B
ubbl
e co
nden
ser
inte
grit
y (W
WE
R 4
40/2
13)
CZ
EC
H
RE
PU
BL
IC
NR
I R
ez
Des
ign
and
mai
nten
ance
of
pipe
whi
p re
stra
ints
, hi
gher
rad
iatio
n ex
posu
re o
f m
aint
enan
ce p
erso
nal,
wor
se a
cces
s to
pip
e w
elds
for
IS
I, c
ost s
avin
g
FIN
LA
ND
LO
CA
ser
ves
as a
con
veni
ent “
enve
lope
” de
fini
tion
for
an e
xtre
me
cond
ition
for
e.g
. E
CC
S (f
lood
ing
capa
city
vs.
pre
ssur
e, r
ecir
cula
tion
filte
rs, e
tc.)
/ C
onta
inm
ent
over
pres
sure
, -te
mpe
ratu
re a
nd l
eakt
ight
ness
/
Rea
ctor
cor
e -
tota
l po
wer
and
pow
er d
istr
ibut
ion/
Nuc
lear
fue
l (b
urnu
p; p
elle
t cr
acki
ng,
inte
rnal
gas
pre
ssur
e, e
tc).
. /
..Rea
ctor
in
tern
als,
inc
ludi
ng m
echa
nica
l pa
rt o
f sc
ram
sys
tem
/ P
rote
ctio
n an
d sh
ield
ing
from
dyn
amic
loa
ds (
pipe
whi
p re
stra
ints
etc
.) /
E
nvir
onm
enta
l qua
lific
atio
n of
equ
ipm
ent i
nsid
e th
e co
ntai
nmen
t.
NE
A/C
SNI/
R(2
003)
16
24
FR
AN
CE
IR
SN
For
exis
ting
plan
ts,
conc
erni
ng o
pera
tion
al l
imit
atio
ns,
LL
OC
A a
ccid
ent
desi
gns
the
Fq m
ax e
nsur
ing
the
resp
ect
of t
he
acci
dent
cri
teri
a.
LL
OC
A i
s al
so u
sed
for
the
desi
gn o
f pi
ping
sup
port
s, o
f w
hip
rest
rain
ts,
of r
eact
or v
esse
l in
tern
als
, of
Saf
ety
Inje
ctio
n Sy
stem
and
Sum
p re
circ
ulat
ion,
for
qua
lific
atio
n of
mec
hani
cal a
nd e
lect
rica
l equ
ipm
ent i
mpo
rtan
t for
saf
ety.
LL
OC
A p
artic
ipat
es to
co
ntai
nmen
t des
ign,
toge
ther
with
SL
B.
The
LL
OC
A c
onse
quen
ces
for
mai
nten
ance
are
on
the
one
hand
the
per
iodi
c ca
libra
tion
of t
he g
ap b
etw
een
pipe
s an
d w
hip
rest
rain
t dev
ices
, and
on
the
othe
r ha
nd th
e de
cenn
ial c
onta
inm
ent p
ress
ure
test
. C
once
rnin
g E
PR, t
he m
axim
um b
reak
siz
e co
nsid
ered
as
desi
gn b
asis
acc
iden
t is
at le
ast t
he r
uptu
re o
f th
e su
rge
line.
But
, the
m
ass
flow
equ
ival
ent
to a
2A
- ope
ning
of
a m
ain
cool
ant
line
has
to
be a
ssum
ed f
or t
he d
esig
n of
the
em
erge
ncy
core
coo
ling
fu
ncti
on (
usin
g re
alis
tic a
ssum
ptio
ns a
nd m
odel
s an
d ap
prop
riat
e cr
iteri
a to
be
prop
osed
by
the
desi
gner
) an
d of
the
con
tain
men
t pr
essu
re b
ound
ary,
so
as t
o im
plem
ent
safe
ty m
argi
ns c
once
rnin
g th
e co
olin
g of
the
cor
e to
pre
vent
cor
e m
elt
and
conc
erni
ng t
he
cont
ainm
ent
func
tion;
the
2A
-ope
ning
is
also
to
be a
ssum
ed f
or t
he s
uppo
rts
of t
he c
ompo
nent
s an
d fo
r th
e qu
alif
icat
ion
of
equi
pmen
t.
NE
A/C
SNI/
R(2
003)
16
25
E
DF
SE
PT
EN
–
larg
e br
eak
LO
CA
s ar
e in
the
desi
gn tr
ansi
ent l
ist t
o de
sign
all
con
cern
ed c
ompo
nent
s –
LB
LO
CA
are
con
side
red
for
cont
ainm
ent
desi
gn,
safe
ty s
yste
ms
desi
gn,
com
pone
nt q
ualif
icat
ion
,fue
l de
sign
and
saf
ety
anal
ysis
G
ER
MA
NY
The
LO
CA
bre
ak s
ize
defi
nitio
n de
term
ines
to
a m
ajor
par
t th
e ov
eral
l sa
fety
con
cept
of
light
wat
er r
eact
ors.
Thi
s m
eans
tha
t th
ere
are
stro
ng i
mpl
icat
ions
reg
ardi
ng t
he o
vera
ll de
sign
. T
here
are
det
aile
d te
stin
g re
quir
emen
ts r
egar
ding
the
rel
iabi
lity
of t
he
rela
ted
safe
ty s
yste
ms.
The
ins
pect
ion
prog
ram
for
the
rea
ctor
pre
ssur
e bo
unda
ry i
s no
t re
ally
gov
erne
d by
LO
CA
con
side
ratio
ns. I
t is
mor
e di
rect
ed b
y th
e go
al to
det
ect a
ny d
egra
datio
ns w
hich
cou
ld p
oten
tially
cha
lleng
e th
e in
tegr
ity o
f th
e co
mpo
nent
is p
icke
d up
at
a v
ery
earl
y st
age.
JAP
AN
In t
he c
urre
nt r
egul
atio
n fo
r a
desi
gn,
oper
atio
n, a
nd t
he e
xam
inat
ion,
the
ass
umpt
ion
of L
OC
A b
reak
siz
e sp
ecif
ies
or
cons
trai
ns s
uch
as th
e ca
paci
ty, i
nteg
rity
, the
per
form
ance
etc
. of
an E
CC
S sy
stem
, a c
onta
inm
ent,
an in
flam
mab
le g
as c
once
ntra
tion
cont
rol s
yste
m, s
tart
-up
tim
e of
ED
G, p
lugg
ing
num
ber
of S
G tu
be, r
adia
tion
mea
sure
men
t etc
.
ME
XIC
O
T
he 1
0 C
FR p
art
50 A
ppen
dix
A “
Gen
eral
Des
ign
Cri
teri
a fo
r N
ucle
ar P
ower
Pla
nt”
and
the
ASM
E c
ode
esta
blis
h th
at t
hat
the
stru
ctur
es,
syst
ems
and
com
pone
nts
impo
rtan
t to
saf
ety
shal
l be
des
igne
d, f
abri
cate
d, e
rect
ed,
and
test
ed t
o qu
alit
y st
anda
rds
com
men
sura
te w
ith t
he i
mpo
rtan
ce o
f th
e sa
fety
fun
ctio
n to
be
perf
orm
ed.
The
com
pone
nt C
lass
1, t
hat
are
impo
rtan
t to
the
saf
ety
whi
ch a
re p
art
of t
he c
oola
nt p
ress
ure
boun
dary
, ar
e te
sted
and
sub
ject
to
insp
ecti
on p
rogr
am a
ccor
ding
with
the
ASM
E c
ode,
but
th
ere
is n
ot a
n ex
plic
it r
efer
ent t
o L
OC
A d
efin
ition
eve
n m
any
of th
e sa
fety
sys
tem
s ar
e de
sign
ed in
cas
e of
LO
CA
’s.
SL
OV
AK
R
EP
UB
LIC
Sa
fety
A
utho
rity
R
egul
ator
y au
thor
ity is
sued
its
requ
irem
ents
for
gra
dual
rec
onst
ruct
ion
of V
-1 N
PP
in th
e de
cisi
on N
o. 1
/94.
One
of
the
grou
p of
req
uire
men
ts d
eals
with
cor
e co
olin
g at
the
LO
CA
con
ditio
ns, i
nclu
ding
ana
lyse
s of
ID
200
mm
and
ID
500
mm
LO
CA
, el
abor
atio
n of
em
erge
ncy
oper
atio
nal p
roce
dure
s, e
tc.
S
imil
arly
, for
V-2
NPP
, in
the
regu
lato
ry d
ecis
ion
No.
4/9
6 (b
ased
on
asse
ssm
ent o
f Sa
fety
Ana
lysi
s R
epor
t aft
er 1
0 ye
ars
of
oper
atio
n) is
dir
ect r
equi
rem
ents
“T
o su
bmit
new
ana
lysi
s of
LB
LO
CA
usi
ng b
ette
r m
odel
ing
of th
erm
al-h
ydra
ulic
pro
cess
es in
re
acto
r an
d pr
imar
y ci
rcui
t and
in b
ubbl
e co
nden
ser
com
part
emen
ts o
f c
onfi
nem
ent”
. It
was
als
o re
com
men
ded
to u
se th
e IA
EA
do
cum
ent
No.
IA
EA
--E
BP
-WW
ER
-01
– G
uide
lines
for
Acc
iden
t Ana
lysi
s of
WW
ER
Nuc
lear
Pow
er P
lant
s fo
r th
ese
anal
ysis
.
NE
A/C
SNI/
R(2
003)
16
26
V
UJE
D
esig
n –
LB
LO
CA
has
alw
ays
been
par
t of
the
des
ign
basi
s fo
r V
VE
R-4
40 r
eact
ors
and
it se
ts p
erfo
rman
ce a
nd r
elia
bilit
y re
quir
emen
ts f
or s
hutd
own,
em
erge
ncy
core
coo
ling
and
con
tain
men
t sys
tem
s.
The
LB
LO
CA
res
pons
e pr
oced
ures
wou
ld b
e un
chan
ged
if L
B L
OC
A w
as n
ot i
n de
sign
bas
is s
ince
the
sam
e pr
oced
ures
co
ver
smal
l and
larg
e L
OC
A.
At t
he p
rese
nt th
ere
is n
o re
ason
to c
hang
e L
B L
OC
A d
efin
ition
in S
lova
kia.
SPA
IN
Se
e an
swer
to q
uest
ion
1 SW
ED
EN
The
re a
re n
o sp
ecif
ic r
egul
ator
y im
plic
atio
ns o
n de
sign
(in
add
ition
to
the
requ
irem
ents
of
core
coo
ling)
, op
erat
iona
l pr
oced
ures
, tes
ting
, ins
pect
ion
prog
ram
ass
ocia
ted
wit
h th
e pr
esen
tly u
sed
LO
CA
bre
ak s
ize
defi
niti
on.
The
des
ign
requ
irem
ents
for
pip
ing
syst
ems
in S
wed
ish
reac
tors
cor
resp
ond
to t
he r
equi
rem
ents
in
ASM
E S
ecti
on I
II.
Com
pone
nts
in t
he c
oolin
g sy
stem
s m
ust
be t
este
d pe
riod
ical
ly.
For
in-s
ervi
ce i
nspe
ctio
n a
qual
itativ
e ri
sk i
nfor
med
app
roac
h is
us
ed w
hich
take
into
acc
ount
bot
h th
e sa
fety
sig
nifi
canc
e as
wel
l as
the
susc
epti
bilit
y of
dif
fere
nt d
egra
datio
n m
echa
nism
s.
SWIT
ZE
RL
AN
D
T
he c
urre
nt L
OC
A b
reak
siz
e de
fini
tion
mus
t be
con
side
red
in t
he d
esig
n of
the
em
erge
ncy
core
coo
ling
sys
tem
s an
d in
the
ev
alua
tion
of th
e pr
imar
y co
ntai
nmen
t beh
avio
ur.
UN
ITE
D
KIN
GD
OM
UK
PW
R d
esig
n an
d sa
fety
cas
e as
sum
es f
ull
doub
le e
nded
gui
llotin
e br
eak.
Giv
en t
hat
the
case
has
bee
n m
ade,
no
know
n re
ason
for
cha
ngin
g.
NE
A/C
SNI/
R(2
003)
16
27
USA
U
S N
RC
T
he L
BL
OC
A r
equi
rem
ents
bro
adly
aff
ect
desi
gn,
oper
atio
n, t
estin
g, i
nspe
ctio
n, a
nd m
aint
enan
ce a
spec
ts o
f st
ruct
ures
, sy
stem
s, a
nd c
ompo
nent
s (S
SCs)
of
a nu
clea
r po
wer
pla
nt. I
n ad
ditio
n to
the
im
plic
atio
ns f
or t
he E
mer
genc
y C
ore
Coo
ling
Syst
em
whi
ch is
dis
cuss
ed in
mor
e de
tail
bel
ow, t
he L
BL
OC
A a
ffec
ts s
ome
of th
e ke
y re
quir
emen
ts a
s lis
ted
belo
w.
Env
iron
men
tal
and
dyna
mic
eff
ects
des
ign
basi
s (
GD
C 4
) –
SSC
s ar
e re
quir
ed to
be
desi
gned
to
acco
mm
odat
e th
e ef
fect
s of
an
d to
be
com
patib
le w
ith t
he e
nvir
onm
enta
l co
nditi
ons
asso
ciat
ed w
ith n
orm
al o
pera
tion
, m
aint
enan
ce,
test
ing,
and
pos
tula
ted
acci
dent
s, i
nclu
ding
LO
CA
s.
The
se S
SCs
are
to b
e pr
otec
ted
agai
nst
dyna
mic
eff
ects
, in
clud
ing
the
effe
cts
of m
issi
les,
pip
e w
hipp
ing,
and
dis
char
ging
flu
ids.
Pi
ping
lay
out,
rest
rain
ts,
jet
impi
ngem
ent
shie
lds,
and
int
erio
r co
mpa
rtm
ent
desi
gn a
re d
irec
tly
affe
cted
by
this
req
uire
men
t.
Con
tain
men
t D
esig
n B
asis
(G
DC
50)
– T
he r
eact
or c
onta
inm
ent
stru
ctur
e, i
nclu
ding
acc
ess
open
ings
, pe
netr
atio
n, a
nd t
he
cont
ainm
ent h
eat r
emov
al s
yste
m a
re d
esig
ned
so
that
con
tain
men
t str
uctu
re a
nd it
s in
tern
al c
ompo
nent
s ca
n ac
com
mod
ate,
wit
hout
ex
ceed
ing
the
desi
gn l
eaka
ge r
ate
and
with
suf
fici
ent
mar
gins
, th
e ca
lcul
ated
pre
ssur
e-te
mpe
ratu
re c
ondi
tions
res
ultin
g fr
om a
ny
loss
-of
cool
ant a
ccid
ent.
The
con
tain
men
t lea
kage
rat
e te
st p
ress
ure
is b
ased
on
the
LB
LO
CA
pre
ssur
e.
Env
iron
men
tal
qual
ific
atio
n of
ele
ctri
cal
equi
pmen
t (1
0 C
FR 5
0.49
) –
Thi
s re
gula
tion
, in
par
t, re
quir
es t
hat
the
elec
tric
al
equi
pmen
t qu
alif
icat
ion
prog
ram
inc
lude
and
be
base
d on
the
tem
pera
ture
-pre
ssur
e, h
umid
ity, r
adia
tion,
and
oth
er e
ffec
ts a
ssoc
iate
d w
ith
mos
t sev
ere
desi
gn b
asis
acc
iden
t. Fu
el (
10 C
FR P
art
50,
App
endi
x K
)– T
he L
BL
OC
A
affe
cts
fuel
des
ign
lim
its
such
as
peak
cla
ddin
g te
mpe
ratu
re,
and
max
imum
cla
ddin
g ox
idat
ion.
L
BL
OC
A a
ffec
t con
tain
men
t sum
p de
sign
and
per
form
ance
req
uire
men
ts.
Ult
imat
e he
at s
ink
requ
irem
ents
are
ass
ocia
ted
with
the
LB
LO
CA
. Fo
r th
e E
mer
genc
y C
ore
Coo
ling
Syst
em (
EC
CS)
des
ign,
10
CFR
50,
App
endi
x A
, Gen
eral
Des
ign
Cri
teri
on 3
5 re
quir
es th
at,
“sui
tabl
e re
dund
ancy
in
co
mpo
nent
s an
d fe
atur
es,
and
suita
ble
inte
rcon
nect
ions
, le
ak
dete
ctio
n,
isol
atio
n an
d co
ntai
nmen
t ca
pabi
litie
s sh
all
be p
rovi
ded
to a
ssur
e th
at f
or o
nsite
ele
ctri
c po
wer
sys
tem
ope
ratio
n (a
ssum
ing
offs
ite p
ower
is
not
avai
labl
e) a
nd
for
offs
ite
elec
tric
pow
er s
yste
m o
pera
tion
(ass
umin
g on
site
pow
er is
not
ava
ilabl
e) th
e sy
stem
saf
ety
func
tion
can
be
acco
mpl
ishe
d,
assu
min
g a
sing
le f
ailu
re.”
To
achi
eve
this
saf
ety
func
tion
ove
r th
e sp
ectr
um o
f L
OC
A b
reak
siz
es, E
CC
S sy
stem
s ar
e de
sign
ed w
ith
redu
ndan
t tra
ins
of h
igh
and
low
pre
ssur
e E
CC
S pi
ping
, pum
ps, v
alve
s an
d ot
her
nece
ssar
y eq
uipm
ent.
NE
A/C
SNI/
R(2
003)
16
28
The
EC
CS
is d
esig
ned
to p
rovi
de c
ore
cool
ing
and
nega
tive
rea
ctiv
ity
inse
rtio
n (P
ress
uriz
ed W
ater
Rea
ctor
s) f
ollo
win
g pi
pe
brea
ks i
n th
e R
eact
or C
oola
nt S
yste
m (
RC
S) w
hich
cau
se a
dis
char
ge l
arge
r th
an t
hat
whi
ch c
an b
e m
ade
up b
y th
e no
rmal
mak
eup
syst
em, u
p to
and
incl
udin
g th
e in
stan
tane
ous
circ
umfe
rent
ial r
uptu
re o
f th
e la
rges
t pi
pe i
n th
e R
CS.
10
CFR
50.
46 a
nd 1
0 C
FR 5
0,
App
endi
x K
pro
vide
the
acce
ptan
ce c
rite
ria
and
eval
uati
on m
odel
req
uire
men
ts f
or E
CC
S de
sign
. 10
CFR
50.
46 a
llow
s us
e of
eith
er
an e
valu
atio
n m
odel
con
tain
ing
man
y co
nser
vativ
e or
bou
ndin
g as
sum
ptio
ns, o
r a
less
res
tric
tive
Bes
t-E
stim
ate
mod
el f
or e
valu
atin
g E
CC
S pe
rfor
man
ce.
Reg
ulat
ory
Gui
de 1
.157
des
crib
es a
Bes
t-E
stim
ate
appr
oach
whi
ch d
efin
es t
he f
ull
brea
k sp
ectr
um a
nd
acco
mpa
nyin
g un
cert
aint
y an
alys
es.
In a
dditi
on t
o th
e br
eak
size
s co
nsid
ered
, th
e m
etho
dolo
gy,
part
icul
arly
the
App
endi
x K
ap
proa
ch, w
ill in
flue
nce
desi
gn d
ue to
the
cons
erva
tism
in th
e an
alys
is.
Som
e ex
ampl
es o
f E
CC
S re
quir
emen
ts b
ased
on
an a
naly
sis
of t
he f
ull
spec
trum
of
LO
CA
bre
ak s
izes
in
a Pr
essu
rize
d W
ater
R
eact
ors
(PW
R)
incl
ude:
•
Lar
ge b
reak
s up
to a
dou
ble
ende
d gu
illot
ine
brea
k re
quir
e 3
or 4
acc
umul
ator
s w
hich
can
rap
idly
ref
ill a
nd r
eflo
od th
e co
re
• B
reak
siz
e w
ill in
flue
nce
oper
ator
act
ions
to c
ontr
ol b
oric
aci
d pr
ecip
itati
on a
nd th
e ne
ed f
or o
pera
tor
acti
on to
sw
itch
to
hot/c
old
leg
inje
ctio
n •
Peak
line
ar h
eat g
ener
atio
n ra
te (
PLH
GR
) is
typi
call
y lim
ited
by
the
LB
LO
CA
and
can
be
quite
res
tric
tive
for
ear
lier
ge
nera
tion
nucl
ear
plan
ts
• L
imit
s on
Axi
al S
hape
Ind
ex (
ASI
) or
axi
al o
ffse
t to
prec
lude
hig
hly
skew
ed p
ower
sha
pes
in th
e to
p of
the
core
are
impo
rtan
t an
d es
tabl
ishe
d by
the
smal
l bre
ak L
OC
A a
naly
ses,
oft
en r
esul
ting
in a
loss
of
oper
atin
g m
argi
n •
Smal
l Bre
ak L
OC
A’s
infl
uenc
e th
e ca
paci
ty f
or h
igh
pres
sure
saf
ety
inje
ctio
n pu
mps
and
the
need
for
load
ing
char
ging
pum
ps
on th
e di
esel
gen
erat
ors
to m
eet 1
0 C
FR 5
0.46
cri
teri
a fo
r po
wer
upr
ates
•
LO
CA
bre
ak s
ize
will
infl
uenc
e si
zing
of
the
atm
osph
eric
dum
p va
lves
and
PO
RV
s •
The
mos
t pos
itive
mod
erat
or te
mpe
ratu
re c
oeff
icie
nts
(MT
C’s
) ar
e so
met
imes
set
by
the
LO
CA
ana
lyse
s be
caus
e a
posi
tive
MT
C w
ill p
rodu
ce m
oder
ator
-den
sity
fee
dbac
k w
hich
can
res
ult i
n an
initi
al o
ver-
pow
er f
ollo
win
g op
enin
g of
the
brea
k •
The
rea
lignm
ent t
o es
tabl
ish
long
term
coo
ling
is d
eter
min
ed b
y th
e ne
ed to
con
trol
bor
ic a
cid
prec
ipita
tion
aft
er a
LO
CA
. T
he B
oilin
g w
ater
Rea
ctor
(B
WR
) E
CC
S sy
stem
s ar
e ty
pica
lly m
ore
dive
rse
as c
ompa
red
to P
WR
des
igns
, an
d ar
e no
t im
pact
ed a
s si
gnif
ican
tly b
y L
OC
A b
reak
siz
e.
For
BW
Rs,
an
impo
rtan
t f
acto
r is
die
sel
gene
rato
r st
art
tim
es a
nd l
oad
sequ
enci
ng
dela
ys w
hich
can
bur
den
dies
el g
ener
ator
rel
iabi
lity.
T
he E
CC
S an
d E
CC
S co
mpo
nent
s ar
e te
sted
dur
ing
the
initi
al p
lant
sta
rtup
test
pro
gram
to e
nsur
e th
at th
e sy
stem
can
per
form
it
s in
tend
ed d
esig
n fu
nctio
n.
Surv
eilla
nce
test
ing
is a
lso
perf
orm
ed p
erio
dica
lly t
o co
nfir
m t
he a
ssum
ptio
ns o
f th
e sa
fety
ana
lyse
s.
Tec
hnic
al
Spec
ific
atio
ns
incl
ude
limit
ing
cond
ition
s fo
r op
erat
ion,
re
quir
ed
actio
ns
and
com
plet
ion
times
, an
d su
rvei
llanc
e
NE
A/C
SNI/
R(2
003)
16
29
requ
irem
ents
for
the
EC
CS
and
vari
ous
EC
CS
com
pone
nts.
T
hese
spe
cifi
catio
ns i
dent
ify
the
num
ber
of E
CC
S tr
ains
nee
ded
to b
e op
erab
le,
and
the
requ
irem
ents
for
spe
cifi
c E
CC
S co
mpo
nent
s in
clud
ing
pum
ps,
valv
es,
wat
er s
tora
ge t
anks
and
oth
er e
quip
men
t. Fo
r PW
Rs,
bor
on c
once
ntra
tion
requ
irem
ents
are
als
o in
clud
ed.
Pla
nt s
peci
fic
Em
erge
ncy
Ope
ratin
g Pr
oced
ures
, w
hich
are
sy
mpt
om b
ased
, not
eve
nt b
ased
, als
o pr
ovid
e gu
idan
ce to
ope
rato
rs f
or r
espo
ndin
g to
LO
CA
’s o
f va
riou
s br
eak
size
s. T
he ti
min
g of
op
erat
or a
ctio
ns i
s go
vern
ed b
y th
e an
alys
es r
equi
red
by 1
0 C
FR 5
0.46
and
App
endi
x K
, and
som
etim
es p
rovi
de l
imit
ed m
argi
n fo
r op
erat
or e
rror
and
equ
ipm
ent f
ailu
res.
G
ener
al im
plic
atio
ns to
the
insp
ectio
n pr
ogra
ms
are
sum
mar
ized
as
follo
ws.
To
chec
k th
e fu
ncti
onal
ity o
f w
hole
sys
tem
s, th
e N
RC
ass
embl
es a
tea
m o
f in
spec
tors
and
im
plem
ents
bas
elin
e in
spec
tion
proc
edur
e, “
Safe
ty S
yste
m D
esig
n an
d pe
rfor
man
ce
Cap
abili
ty.”
T
his
proc
edur
e re
quir
es t
hat
a pa
rtic
ular
mit
igat
ion
syst
em b
e se
lect
ed a
nd r
evie
wed
in
seve
ral
engi
neer
ing
disc
iplin
es
like
ele
ctri
cal,
mec
hani
cal,
inst
rum
enta
tion
, etc
. The
bas
is f
or s
elec
ting
a sy
stem
is w
heth
er it
mit
igat
es s
ome
type
of
acci
dent
. If
the
acci
dent
was
a L
OC
A th
en E
CC
S sy
stem
s w
ould
be
conc
entr
ated
on
espe
cial
ly. F
or s
mal
l bre
ak L
OC
As,
this
wou
ld ty
pica
lly
be th
e hi
gh h
ead
inje
ctio
n sy
stem
and
int
erfa
cing
sys
tem
s.
For
lar
ge b
reak
LO
CA
s, t
he s
yste
ms
revi
ewed
wou
ld b
e th
e lo
w h
ead
inje
ctio
n sy
stem
s in
clud
ing
any
pass
ive
EC
CS
syst
ems(
e.g
., fo
r PW
Rs
the
accu
mul
ator
s).
In a
ddit
ion,
the
insp
ecto
rs m
ay
revi
ew t
he d
esig
n an
d op
erat
iona
l ca
pabi
lity
of s
uppo
rt s
yste
ms
such
as
Die
sel
syst
ems,
coo
ling
wat
er, a
nd D
C s
yste
ms.
T
he s
yste
ms
to b
e re
view
ed
are
dete
rmin
ed b
y lo
okin
g at
the
resu
lts o
f In
divi
dual
Pla
nt E
xam
inat
ions
(IP
Es)
or
som
e eq
uiva
lent
mea
ns f
or th
e pl
ants
in q
uest
ion
and
dete
rmin
ing
for
a pa
rtic
ular
pla
nt w
hich
acc
iden
ts a
re th
e m
ost r
isk
sign
ific
ant.
Onc
e th
at is
det
erm
ined
then
acc
iden
t seq
uenc
es
are
revi
ewed
to
asce
rtai
n w
hich
acc
iden
t se
quen
ce i
s m
ost
dam
agin
g. T
hen
the
insp
ectio
n w
ill c
once
ntra
te o
n th
ose
syst
ems
whi
ch
com
pris
e th
at a
ccid
ent s
eque
nces
.
WO
G
The
lar
ge b
reak
LO
CA
(L
BL
OC
A)
is t
he m
ain
driv
er o
f m
any
of t
he c
urre
nt a
naly
tical
ass
umpt
ions
suc
h as
no
cont
rol
rod
inse
rtio
n fo
llow
ing
a L
BL
OC
A,
EC
CS
hot
leg
swit
chov
er r
ecir
cula
tion,
bre
ak o
peni
ng t
imes
, an
d co
ntai
nmen
t su
mp
debr
is
gene
ratio
n, a
s w
ell
as o
ther
iss
ues
such
as
the
ultim
ate
heat
sin
k te
mpe
ratu
re l
imit
atio
ns. T
he m
argi
ns c
onta
ined
in
the
Lar
ge B
reak
L
OC
A a
naly
sis
esta
blis
h th
e te
stin
g an
d su
rvei
llanc
e re
quir
emen
ts f
or e
quip
men
t of
saf
ety
sign
ific
ance
(e.
g.,
fast
sta
rt d
iese
l ge
nera
tor
test
ing)
. T
he L
BL
OC
A a
lso
affe
cts
fuel
des
ign
lim
its
The
Tec
hnic
al S
peci
fica
tions
im
pose
lim
iting
con
ditio
ns f
or o
pera
tion
base
d on
the
ope
rabi
lity
of c
ompo
nent
s re
quir
ed t
o m
itig
ate
the
desi
gn b
asis
lar
ge b
reak
LO
CA
. T
hese
LC
Os
are
ofte
n un
nece
ssar
ily r
estr
ictiv
e w
ith
resp
ect
to s
hutd
own
actio
ns a
nd
requ
ired
act
ion
times
. In
gen
eral
, the
des
ign
basi
s L
BL
OC
A r
equi
rem
ents
infl
uenc
e pl
ant d
esig
n an
d op
erat
ion
at e
very
leve
l.
NE
A/C
SNI/
R(2
003)
16
30
RU
SSIA
O
bser
ver
Gid
ropr
ess
In f
act,
all
the
plan
t co
nfig
urat
ion
(i.e
., de
sign
fea
ture
s, E
OPs
, in
spec
tion
and
mai
nten
ance
pro
gram
s, e
tc)
take
s in
to a
ccou
nt
the
curr
ent d
esig
n br
eak
size
(la
rges
t pip
elin
e). H
owev
er, m
any
lim
itat
ions
are
mad
e w
ith th
e L
BB
con
cept
impl
emen
tatio
n.
GA
N
For
the
desi
gn b
asis
acc
iden
ts i
nclu
ding
the
lim
itin
g L
OC
A t
he f
ollo
win
g de
sign
lim
its
of f
uel
rod
dam
age
shou
ld n
ot b
e ex
ceed
ed:
• ! fu
el c
ladd
ing
tem
pera
ture
not
hig
her
then
120
0 0
C;
• ! lo
cal c
ladd
ing
oxid
atio
n no
t hig
her
then
18
% o
f or
igin
al w
all t
hick
ness
; •
! tota
l am
ount
of
oxid
ized
zir
coni
um n
ot h
ighe
r th
en 1
% o
f its
initi
al m
ass
in c
ladd
ings
. D
urin
g de
sign
bas
is a
ccid
ents
the
cor
e sh
ould
ret
ain
its m
echa
nica
l st
abili
ty a
nd a
bsen
ce o
f de
form
atio
ns a
ble
to i
mpa
ir
norm
al f
unct
ioni
ng o
f re
activ
ity
cont
rol a
nd r
eact
or s
cram
dev
ices
or
to im
pede
fue
l ele
men
ts c
oolin
g.
All
equ
ipm
ent
and
pipe
line
s of
the
rea
ctor
coo
lant
cir
cuit
shou
ld w
iths
tand
non
dest
ruct
ivel
y dy
nam
ic l
oads
and
tem
pera
ture
ef
fect
s ar
isin
g du
ring
all
DB
A c
onsi
dere
d. P
rim
ary
pipe
s sh
ould
be
equi
pped
wit
h di
spla
cem
ent
limit
ers
to p
reve
nt u
nacc
epta
ble
defo
rmat
ions
due
to r
eact
ive
forc
e re
sulti
ng f
rom
LO
CA
. L
imit
ing
LO
CA
bou
ndar
y co
nditi
ons
shou
ld b
e co
nsid
ered
als
o in
the
des
ign
of E
CC
S an
d C
onta
inm
ent
syst
em c
onsi
deri
ng
the
inde
pend
ent f
ailu
re p
rinc
iple
. The
lim
itin
g L
OC
A a
long
wit
h ot
her
DB
As
shou
ld b
e co
vere
d by
EO
Ps.
Sl
oven
ia
Obs
erve
r
Con
sist
ent w
ith th
e U
S re
gula
tion
s, g
uide
s an
d st
anda
rds
.
NE
A/C
SNI/
R(2
003)
16
31
Cur
rent
reg
ulat
ory
fram
ewor
k
4.
Is
Lea
k-B
efor
e-B
reak
acc
epte
d (o
r be
ing
cons
ider
ed)
in y
our
regu
lati
on?
If s
o, w
hat
are
the
cons
eque
nces
on
com
pone
nt
or p
ipin
g su
ppor
ts, s
yste
m a
naly
sis,
fuel
ass
embl
y, c
onta
inm
ent…
BE
LG
IUM
App
lica
tion
of L
eak-
Bef
ore-
Bre
ak h
as b
een
acce
pted
, but
lim
ited
to th
e re
acto
r co
olan
t pip
ing.
The
Lea
k-B
efor
e-B
reak
con
cept
w
as u
sed:
-
to ju
stif
y th
e re
acto
r pr
essu
re v
esse
l int
erna
ls u
nder
str
etch
-out
con
ditio
ns;
- to
rem
ove
som
e sn
ubbe
rs a
ttach
ed to
hea
vy c
ompo
nent
s of
the
reac
tor
cool
ant l
oops
(pr
imar
y pu
mps
, ste
am g
ener
ator
s);
- to
rem
ove
som
e re
stra
ints
on
the
reac
tor
cool
ant l
oops
; -
to m
odif
y th
e su
ppor
ts o
f so
me
heav
y co
mpo
nent
s (s
team
gen
erat
ors)
CA
NA
DA
LB
B is
not
nor
mal
ly c
onsi
dere
d fo
r L
LO
CA
in C
anad
a. L
BB
was
acc
epte
d as
a b
asis
for
not
inst
alli
ng p
ipe-
whi
p re
stra
ints
for
la
rge
diam
eter
pip
es i
n th
e ne
wes
t C
AN
DU
sta
tion
. In
thi
s ca
se, d
eter
min
isti
c L
LO
CA
ana
lysi
s w
as s
till
req
uire
d to
sho
w a
dequ
ate
fuel
coo
ling
and
inte
grity
of
cont
ainm
ent b
ound
ary.
L
BB
has
bee
n ac
cept
ed f
or c
erta
in m
ain
stea
m l
ine
brea
ks (
as p
art
of a
cos
t-be
nefi
t ar
gum
ent)
whe
re t
here
is
an e
xten
sive
pe
riod
ic in
spec
tion
prog
ram
, fra
ctur
e m
echa
nics
ana
lysi
s an
d le
ak d
etec
tion
.
SUJB
Saf
ety
Aut
hori
ty
It w
ill b
e ac
cept
ed in
fut
ure
CZ
EC
H
RE
PU
BL
IC
NR
I R
ez
Yes
. M
ain
cons
eque
nces
are
as
foll
ows:
SSE
and
LL
OC
A a
re n
ot c
oncu
rren
t ev
ents
, lo
wer
str
ess
stat
e of
all
rea
ctor
int
erna
ls
and
heav
y co
mpo
nent
sup
port
s (R
PV, M
CP,
SG
, PR
Z)
NE
A/C
SNI/
R(2
003)
16
32
FIN
LA
ND
LB
B i
s co
vere
d by
Gui
de Y
VL
3.5
: if
LB
B is
dem
onst
rate
d, p
ipe
whi
p re
stra
ints
may
be
elim
inat
ed, b
ut n
o re
duct
ion
in E
CC
S no
r co
ntai
nmen
t coo
ling
capa
city
is a
llow
ed.
IR
SN
- fo
r ex
isti
ng P
WR
, no
cons
ider
atio
n of
Lea
k-B
efor
e-B
reak
is a
ssum
ed.
- co
ncer
ning
EPR
, L
BB
cou
ld b
e ac
cept
ed i
f th
e de
sign
ers
prov
ide
an a
ccep
tabl
e de
mon
stra
tion
met
hodo
logy
(se
e po
ints
1
and
3 ab
ove)
FR
AN
CE
ED
F
SEP
TE
N
Not
for
the
mom
ent,
it's
unde
r re
-eva
luat
ion
proc
ess
insi
de th
e co
mpa
ny is
incl
uded
in th
e de
sign
bas
is o
f ne
w r
eact
ors
GE
RM
AN
Y
L
eak-
Bef
ore-
Bre
ak i
s ac
cept
ed o
n a
case
by
case
dec
isio
n if
cer
tain
req
uire
men
ts r
egar
ding
the
int
egri
ty o
f th
e pr
essu
re
boun
dary
are
ful
fille
d. T
he d
iffe
rent
asp
ects
are
dea
lt w
ith
in t
he R
SK g
uide
line
in c
hapt
er 2
1 w
hich
is
encl
osed
as
adde
nda
(See
at
tach
men
t).
JAP
AN
Yes
. Int
rodu
ctio
n of
an
LB
B c
once
pt is
acc
epte
d by
reg
ulat
ion
for
the
aust
enit
e st
ainl
ess
stee
l pip
es o
n th
e co
nsid
erat
ion
for
the
desi
gn t
o th
e in
tern
al g
ener
ated
mis
sile
res
ultin
g fr
om a
pip
ing
brea
k. C
onse
quen
tly,
the
des
ign
of p
ipin
g su
ppor
t st
ruct
ure
has
been
si
mpl
ifie
d fo
r th
e ne
wly
con
stru
cted
pla
nts;
Gen
kai-
4 an
d O
naga
wa-
3, a
nd f
or th
e ex
istin
g pl
ants
wit
h SG
rep
laci
ng; M
iham
a-1,
2 a
nd
3, T
akah
ama-
1and
2, O
i-1
and
2, G
enka
i-1
and
2, a
nd I
kata
-1 a
nd 2
. H
owev
er, a
pplic
atio
n of
the
LB
B c
once
pt to
con
tain
men
t des
ign
cond
ition
s, E
CC
S pe
rfor
man
ce e
valu
atio
n, e
xpos
ure
eval
uatio
n et
c. is
not
acc
epte
d ye
t.
ME
XIC
O
T
he le
ak b
efor
e br
eak
is n
ot c
onsi
dere
d in
the
pres
ent r
egul
atio
n. T
he te
chni
cal s
peci
fica
tion
mad
e re
fere
nce
to le
akag
e in
som
e co
mpo
nent
s or
sys
tem
and
est
ablis
h a
timin
g to
rep
air
it.
SLO
VA
K
RE
PU
BL
IC
Safe
ty
Aut
hori
ty
Lea
k-B
efor
e-B
reak
con
cept
is
impl
emen
ted
at a
ll Sl
ovak
ian
NPP
s. I
n sp
ecif
ic c
ases
the
im
plem
enta
tion
of L
BB
con
cept
has
be
en r
equi
red
by r
egul
ator
y de
cisi
on. F
or V
-1 N
PP in
the
deci
sion
No.
5/9
1 th
ere
wer
e e.
g. f
ollo
win
g re
quir
emen
ts:
- ba
sed
on r
egul
ator
y gu
idel
ines
to d
ecla
re th
e ac
cept
ibili
ty o
f L
eak-
Bef
ore-
Bre
ak c
once
pt,
- to
pro
ve th
at th
e oc
curr
ence
of
brea
k of
pip
elin
e of
ID
hig
her
than
100
mm
is le
ss th
an 1
0-5
per
year
- to
intr
oduc
e le
ak d
etec
tion
sys
tem
s, e
tc.
LB
B c
once
pt i
s ap
plie
d fo
r m
ain
cool
ant
lines
, su
rge
line
s an
d E
CC
S-to
-MC
L l
ines
. Fo
r m
ain
stea
m l
ines
the
int
egri
ty r
e-as
sess
men
t has
bee
n do
ne.
VU
JE
LB
B i
s co
nsid
ered
for
LB
LO
CA
in
Slov
ak N
PPs.
L
BB
con
cept
is
impl
emen
ted
for
RC
S pi
ping
with
the
dia
met
er >
200
mm
(R
CS
mai
n ci
rcul
atio
n li
ne, P
RZ
sur
ge li
ne, s
team
line
insi
de c
onfi
nem
ent)
.
NE
A/C
SNI/
R(2
003)
16
33
SPA
IN
Se
e an
swer
to q
uest
ion
1 SW
ED
EN
The
Lea
k-B
efor
e-B
reak
(L
BB
) co
ncep
t ha
s no
t ye
t be
en f
orm
ally
acc
epte
d by
SK
I. H
owev
er, o
ne o
f th
e lic
ense
es h
as a
ppli
ed
for
the
use
of L
BB
in
two
of t
heir
rea
ctor
s. L
BB
wil
l al
so b
e ad
dres
sed
in S
KI’
s ge
nera
l de
sign
reg
ulat
ions
tha
t no
w a
re b
eing
pr
epar
ed.
The
pro
pose
d ru
le i
n th
ese
regu
latio
ns s
tate
tha
t dy
nam
ic e
ffec
ts,
such
as
pipe
whi
ppin
g, m
issi
les,
ass
ocia
ted
with
po
stul
ated
pip
e ru
ptur
es m
ay b
e ex
clud
ed f
rom
the
desi
gn b
asis
if
- th
e pi
ping
sys
tem
is
desi
gned
so
that
the
con
ditio
ns f
or d
egra
datio
n as
a r
esul
t fr
om a
ny i
dent
ifia
ble
degr
adat
ion
mec
hani
sm
have
bee
n re
duce
d as
far
as
poss
ible
, and
- th
at a
ny f
law
s (d
efec
t, cr
ack)
that
des
pite
this
mea
sure
s ar
e in
itiat
ed p
erm
it ti
mel
y de
tect
ion
befo
re a
pip
e ru
ptur
e oc
cur.
- dy
nam
ic e
ffec
ts s
houl
d no
t com
plet
ely
fail
a sa
fety
fun
ctio
n or
the
cont
ainm
ent l
eak
tigh
tnes
s.
The
co
nsid
ered
pr
oced
ure
for
asse
ssin
g L
BB
ap
plic
atio
ns
will
in
clud
e co
nsid
erat
ion
aspe
cts
such
as
us
ed
mat
eria
l, en
viro
nmen
tal
cond
ition
s in
all
ope
ratio
nal
stat
es a
nd d
esig
n ba
ses
acci
dent
con
ditio
ns,
proc
edur
es f
or t
estin
g an
d in
-ser
vice
in
spec
tion,
equ
ipm
ent a
nd s
yste
ms
for
leak
det
ectio
n, e
tc.
Glo
bal
effe
cts
on c
onta
inm
ent
and
core
coo
ling
cap
acit
y w
ill
how
ever
stil
l be
ana
lyse
d w
ith t
he a
ssum
ptio
n of
a f
ailu
re o
f th
e la
rges
t pip
e co
nnec
ted
to th
e re
acto
r pr
essu
re v
esse
l.
SWIT
ZE
RL
AN
D
T
he L
eak-
Bef
ore-
Bre
ak c
once
pt i
s no
t m
enti
oned
in
the
regu
latio
ns,
but
it is
bei
ng c
onsi
dere
d up
on r
eque
st a
nd h
as b
een
acce
pted
for
one
PW
R p
lant
. The
con
sequ
ence
s w
ere
that
a 1
0% b
reak
of
a m
ain
cool
ant
pip
e br
eak
was
con
side
red
for
the
anal
ysis
of
com
pone
nts
(e.g
. th
e re
acto
r pr
essu
re v
esse
l su
p-po
rt s
truc
ture
) an
d pi
ping
sup
port
s an
d in
the
eva
luat
ion
of t
he m
echa
nica
l co
nseq
uenc
es o
f a
pipe
bre
ak o
n sa
fety
rel
evan
t sy
stem
s. A
lso,
Lea
k-B
efor
e-B
reak
has
bee
n ta
ken
into
acc
ount
in
the
prob
abili
stic
sa
fety
ana
lysi
s (P
SA)
of th
e pl
ant.
Lea
k-B
efor
e-B
reak
is u
nder
eva
luat
ion
for
a se
cond
PW
R.
U
NIT
ED
K
ING
DO
M
N
o, L
eak
Bef
ore-
Bre
ak is
not
con
side
red
as a
pri
mar
y sa
fety
arg
umen
t.
NE
A/C
SNI/
R(2
003)
16
34
USA
U
S N
RC
T
he u
se o
f le
ak-b
efor
e-br
eak
(LB
B)
anal
ysis
in
the
regu
lati
on i
s st
ipul
ated
in
Gen
eral
Des
ign
Cri
teri
a (G
DC
) 4
of A
ppen
dix
A
to P
art
50 o
f T
itle
10 o
f th
e C
ode
of F
eder
al R
egul
atio
ns (
10 C
FR 5
0).
GD
C 4
sta
tes,
"dy
nam
ic e
ffec
ts a
ssoc
iate
d w
ith p
ostu
late
d pi
pe r
uptu
res
in n
ucle
ar p
ower
uni
ts m
ay b
e ex
clud
ed f
rom
the
des
ign
basi
s w
hen
anal
yses
rev
iew
ed a
nd a
ppro
ved
by t
he
Com
mis
sion
dem
onst
rate
tha
t th
e pr
obab
ility
of
flui
d sy
stem
pip
ing
rupt
ure
is e
xtre
mel
y lo
w u
nder
con
diti
ons
cons
iste
nt w
ith t
he
desi
gn b
asis
for
the
pipi
ng."
So
far,
NR
C h
as a
ppro
ved
appl
icat
ions
of
the
LB
B m
etho
dolo
gy to
pri
mar
y co
olan
t loo
p, r
eact
or c
oola
nt
bypa
ss p
ipin
g, p
ress
uriz
er s
urge
, acc
umul
ator
, saf
ety
inje
ctio
n, a
nd r
esid
ual h
eat r
emov
al (
RH
R)
lines
. A
s a
cons
eque
nce
of th
e N
RC
ap
prov
als,
lic
ense
es h
ave
rem
oved
pip
e w
hip
rest
rain
ts a
nd j
et i
mpi
ngem
ent
barr
iers
fro
m a
num
ber
of s
yste
ms.
O
n th
e sy
stem
-an
alys
is s
ide,
lic
ense
es h
ave
also
bee
n pe
rmit
ted
to m
odif
y th
e lic
ensi
ng b
asis
for
the
ir f
acili
ties
by e
xclu
ding
fro
m c
onsi
dera
tion,
as
ymm
etri
c L
OC
A b
low
dow
n lo
ads
on r
eact
or p
rim
ary
cool
ant
syst
ems
and
dyna
mic
loa
ds o
n st
eam
gen
erat
or i
nter
nals
. H
owev
er,
the
NR
C h
as n
ot p
erm
itte
d th
e ex
clus
ion
of s
uch
dyna
mic
eff
ects
in d
eter
min
ing
the
desi
gn r
equi
rem
ents
for
em
erge
ncy
core
coo
ling
sy
stem
s (E
CC
S), e
nvir
onm
enta
l qua
lific
atio
n (E
Q)
of s
afet
y re
late
d el
ectr
ical
and
mec
hani
cal e
quip
men
t, an
d co
ntai
nmen
t.
NE
A/C
SNI/
R(2
003)
16
35
WO
G
Gen
eral
Des
ign
Cri
teri
on (
GD
C)
4 of
App
endi
x A
to 1
0CFR
50 a
llow
s th
e us
e le
ak-b
efor
e-br
eak
(LB
B)
to e
xclu
de th
e dy
nam
ic
effe
cts
of m
issi
les,
pip
e w
hipp
ing
and
disc
harg
ing
flui
ds a
ssoc
iate
d w
ith p
ostu
late
d pi
ping
fai
lure
s (L
OC
As)
on
stru
ctur
es,
syst
ems
and
com
pone
nts
impo
rtan
t to
safe
ty.
The
198
4 G
DC
4 r
ulem
akin
g ex
plic
itly
excl
uded
the
app
licat
ion
of L
BB
to
the
emer
genc
y co
re
cool
ing
syst
em (
EC
CS)
and
con
tain
men
t. R
ule
chan
ges
prop
osed
by
the
U.S
. nuc
lear
pow
er in
dust
ry w
ould
add
a p
rovi
sion
for
an
alte
rnat
e de
sign
bas
is b
reak
siz
e. N
o sp
ecif
ic
alte
rnat
e br
eak
size
is p
resc
ribe
d, n
or is
ther
e a
pres
crib
ed a
naly
tica
l met
hod
spec
ifie
d to
ana
lyze
the
even
t. T
he W
OG
is p
lann
ing
to
appl
y pr
obab
ilist
ic f
ract
ure
mec
hani
cs -
LB
B m
etho
ds to
sup
port
the
sele
ctio
n of
an
alte
rnat
e m
axim
um b
reak
siz
e.
RU
SSIA
Obs
erve
r G
idro
pres
s T
he L
BB
con
cept
is n
ot in
trod
uced
in th
e hi
gh-l
evel
saf
ety
stan
dard
s (l
ike
OPB
) bu
t acc
epte
d by
the
docu
men
t RD
95
1054
7-99
“G
uide
line
s on
LB
B s
afet
y co
ncep
t ap
plic
atio
n to
NPP
pip
elin
es”.
Thi
s do
cum
ent
is a
ppro
ved
by M
inat
om R
F an
d ag
reed
by
regu
lato
ry b
ody.
Acc
ordi
ng t
o th
is d
ocum
ent,
load
s in
duce
d by
mai
n pi
pelin
e br
eak
are
not
bein
g ta
ken
into
acc
ount
, th
e pi
pelin
e re
stra
ints
are
not
ins
talle
d, r
eact
or i
nter
nals
, fue
l as
sem
bly
and
in-c
onta
inm
ent
stru
ctur
es a
re d
esig
ned
to w
ithst
and
to b
reak
of
thos
e pi
pes
whe
re t
he L
BB
con
cept
is
not
appl
icab
le,
etc.
How
ever
, de
sign
bas
is f
or E
CC
S an
d co
ntai
nmen
t its
elf
are
kept
the
sam
e (i
.e.,
inst
anta
neou
s br
eak
of la
rges
t pri
mar
y pi
pe).
GA
N
LB
B i
s ac
cept
ed i
n re
gula
tion
and
is u
nder
im
plem
enta
tion
at N
PPs.
How
ever
it
does
not
cau
se c
hang
es o
f th
e re
gula
tory
re
quir
emen
ts a
pplie
d to
the
des
ign
of N
PP c
ompo
nent
s. A
t th
e sa
me
tim
e fo
r N
PPs
of t
he f
irst
gen
erat
ion
LB
B i
s co
nsid
ered
as
a m
easu
re a
ble
to c
ompe
nsat
e th
e in
cons
iste
ncy
betw
een
curr
ent
LO
CA
def
initi
on a
nd l
imit
ing
LO
CA
siz
e ac
cept
ed i
n th
e or
igin
al
desi
gn.
Slov
enia
Obs
erve
r Y
es.
It h
as b
een
acce
pted
onl
y fo
r th
e an
alys
is i
n co
nnec
tion
wit
h S/
G r
epla
cem
ent
and
pow
er u
prat
e of
the
NPP
. W
e di
dn't
allo
w a
ny p
ropo
sed
phys
ical
mod
ific
atio
n su
ch a
s sn
ubbe
r re
duct
ion
or p
ipe
whi
p re
stra
ins
(shi
ms)
rem
oval
. T
he n
umbe
r of
pip
ing
supp
orts
and
pip
e w
hip
rest
rain
s re
mai
ned
the
sam
e as
bef
ore
the
acce
ptan
ce o
f L
BB
. LB
B h
as b
een
appl
ied
to
the
Rea
ctor
Coo
lant
Loo
ps,
Surg
e L
ine,
RH
R L
ines
and
SI
Acc
umul
ator
Lin
es.
New
mec
hani
cal
anal
ysis
eli
min
atin
g th
e 11
lar
ge
prim
ary
loop
bre
aks
(> 6
inch
) fr
om th
e or
igin
al a
naly
sis
(Hyd
raul
ic F
orci
ng F
unct
ions
).
NE
A/C
SNI/
R(2
003)
16
36
Cur
rent
tech
nica
l fra
mew
ork
1.
Wha
t te
chni
cal
issu
es a
re c
urre
ntly
of
conc
erns
for
Str
uctu
res,
Sys
tem
s an
d C
ompo
nent
s (a
ssoc
iate
d w
ith
the
curr
ent
LO
CA
def
init
ion)
? (p
leas
e lis
t)
B
EL
GIU
M
C
onta
inm
ent l
eak-
tigh
tnes
s (i
n re
latio
n w
ith
the
sour
ce te
rm d
efin
ition
R
ecir
cula
tion
(sum
p cl
oggi
ng is
sue)
D
ynam
ic r
espo
nse
requ
este
d fo
r pr
essu
re s
enso
rs in
the
cont
ainm
ent
C
AN
AD
A
C
anad
a ha
s a
num
ber
of u
nres
olve
d te
chni
cal
conc
erns
ass
ocia
ted
wit
h L
LO
CA
. M
any
are
rela
ted
to t
he p
ositi
ve v
oid
coef
fici
ent o
f C
AN
DU
rea
ctor
s: m
agni
tude
of
void
rea
ctiv
ity e
rror
all
owan
ce, s
hutd
own
syst
em p
erfo
rman
ce, f
uel b
ehav
iour
in p
ower
pu
lse.
Som
e re
late
to
CA
ND
U s
peci
fic
feat
ures
: pr
essu
re t
ube
ballo
onin
g, m
oder
ator
as
a he
at s
ink.
Oth
ers
rela
te t
o ba
sic
ther
mal
-hy
drau
lics:
unc
erta
inty
in c
ore
void
ing
rate
, CH
F, p
ost d
ry-o
ut h
eat t
rans
fer.
CZ
EC
H
RE
PU
BL
IC
SUJB
Sa
fety
A
utho
rity
Fuel
inte
grit
y (a
lso
high
bur
n up
fue
l int
egri
ty),
PT
S, c
onta
imen
t int
egri
ty, b
ubbl
e co
nden
ser
inte
grity
(V
VE
R44
0/21
3)
N
RI
Rez
St
abili
ty o
f he
avy
com
pone
nts,
jet i
mpi
ngem
ent f
orce
s, d
esig
n an
d m
aint
enen
ce o
f E
CC
S, e
nvir
onm
enta
l gua
lific
atio
n of
I&
c,
EC
CS
sum
p sc
reen
blo
ckin
g ri
sk
F
INL
AN
D
T
here
are
no
maj
or c
once
rns
now
that
the
sum
p re
circ
ulat
ion
issu
e ha
s be
en r
esol
ved.
NE
A/C
SNI/
R(2
003)
16
37
IR
SN
Sum
p cl
oggi
ng i
s an
im
port
ant
issu
e, a
lthou
gh i
t do
es n
ot c
once
rn o
nly
larg
e L
OC
A, b
ut a
lso
inte
rmed
iate
and
in
som
e ca
ses
smal
l LO
CA
. Se
e th
e po
int 3
res
pons
e ab
ove
FR
AN
CE
ED
F
SEP
TE
N
- st
ruct
ures
and
com
pone
nts
conc
erne
d: R
PV,
SG d
ivid
ed p
late
, R
CP
flyw
heel
, su
ppor
t of
com
pone
nts
and
pipi
ng s
yste
ms,
an
d co
ntai
men
t pre
ssur
e -
all s
afet
y sy
stem
s -
fuel
G
ER
MA
NY
The
re a
re p
rese
ntly
no
open
tech
nica
l iss
ues
asso
ciat
ed w
ith
the
curr
ent L
OC
A d
efin
ition
, alth
ough
unc
erta
intie
s re
late
d to
the
frac
ture
mod
e of
bim
etal
lic w
elds
are
dif
ficu
lt to
trea
t.
JA
PA
N
A
n ex
tens
ive
argu
men
t on
the
LB
LO
CA
rel
ated
sub
ject
s ha
s no
t be
en s
tart
ed,
whi
le r
esol
utio
n an
d m
oder
niza
tion
of
mai
nten
ance
rul
es f
or S
SC a
re p
ursu
ed a
ctiv
ely
in J
apan
.
ME
XIC
O
Pl
ease
see
que
stio
n 3
of C
urre
nt R
egul
ator
y Fr
amew
ork
SL
OV
AK
R
EP
UB
LIC
Sa
fety
A
utho
rity
In
Slo
vaki
a, t
here
is
unde
r w
ay a
pro
gram
me
for
the
mod
erni
sati
on a
nd s
afet
y up
grad
ing
of
Boh
unic
e V
-2 N
PP.
The
mai
n ai
m o
f th
is p
rogr
amm
e, e
xpec
t of
mod
erni
satio
n is
als
o to
ful
ly im
plem
ent a
ll re
com
men
dati
ons
from
the
IAE
A d
ocum
ent N
o. I
AE
A-
EB
P-W
WE
R-0
3 –
Safe
ty I
ssue
s an
d T
heir
Ran
king
for
WW
ER
-440
Mod
el 2
13 N
ucle
ar P
ower
Pla
nts.
With
in t
his
prog
ram
me,
fo
llow
ing
task
s ar
e un
der
way
: -
anal
yses
of
all
grou
ps o
f in
itiat
ing
even
ts a
ccor
ding
to
the
IAE
A-E
BP
-WW
ER
-01
docu
men
t in
clud
ing
of a
ll L
OC
As
up t
o 2x
500
mm
wit
h re
spec
t the
mod
ific
atio
ns o
f sa
fety
sys
tem
s du
ring
rec
onst
ruct
ion
- qu
alif
icat
ion
of N
DT
sys
tem
s
For
V-1
NPP
ther
e ar
e un
der
way
acc
iden
t ana
lyse
s fo
llow
ing
from
the
aim
to u
se m
odif
ied
fuel
ass
embl
ies.
NE
A/C
SNI/
R(2
003)
16
38
VU
JE
Tec
hnic
al c
once
rns
asso
ciat
ed w
ith
LB
LO
CA
in
VU
JE T
rnav
a ar
e re
late
d to
fue
l be
havi
our,
ves
sel
inte
grity
and
her
met
ic
com
part
men
t int
egri
ty d
urin
g th
e L
OC
A a
ccid
ent.
a) A
naly
ses
of th
e fu
el r
od c
ladd
ing
stre
ss-s
trai
n be
havi
our
(with
min
imal
and
max
imal
the
rmal
pow
er),
det
erm
inat
ion
of t
he i
nter
nal
pres
sure
tim
e hi
stor
ies
and
loca
tion
of th
e cl
addi
ng a
xial
nod
e w
ith m
axim
al d
efor
mat
ion,
b)
Sta
tistic
al d
eter
min
atio
n of
the
num
ber
of r
uptu
red
rods
and
fue
l cha
nnel
blo
ckag
e in
the
anal
ysed
fue
l rod
s,
c) v
alid
atio
n of
mod
ellin
g of
ther
mal
mec
hani
cal f
uel b
ehav
iour
and
its
sim
ulat
ion
in th
e sy
stem
cod
es (
e.g.
RE
LA
P5),
d)
ves
sel i
nteg
rity
ana
lyse
s,
e) H
erm
etic
com
part
men
t int
egri
ty a
naly
ses.
NE
A/C
SNI/
R(2
003)
16
39
SPA
IN
(N
o an
swer
pro
vide
d)
SWE
DE
N
Fo
r th
e B
WR
with
inte
rnal
re-
circ
ulat
ion
pum
ps a
hyp
othe
tical
bre
ak s
ize
of 8
0 cm
2 has
bee
n ba
sis
for
the
licen
ce a
nd th
e de
sign
of
emer
genc
y co
re c
oolin
g sy
stem
. How
ever
, one
of
the
licen
sees
with
this
type
of
reac
tor
are
plan
ning
to r
emov
e th
e co
re
spri
nkli
ng p
art o
f th
e sy
stem
.
SWIT
ZE
RL
AN
D
-T
he b
ehav
iour
of
high
ly b
urnt
fue
l un
der
LO
CA
con
ditio
ns i
s no
t w
ell
know
n. B
y m
eans
of
expe
rim
ents
the
val
idity
of
the
pres
ent L
OC
A f
uel s
afet
y cr
iteri
a sh
ould
be
conf
irm
ed o
r ne
w c
rite
ria
shou
ld b
e es
tabl
ishe
d.
-One
pla
nt h
as r
eque
sted
tha
t a
10%
mai
n co
olan
t pi
pe b
reak
can
be
cons
ider
ed f
or t
he a
naly
sis
of t
he d
ynam
ic e
ffec
ts o
f a
LO
CA
on
the
fuel
ass
embl
ies
and
reac
tor
inte
rnal
s, if
Lea
k-B
efor
e-B
reak
is a
ccep
ted.
Thi
s re
ques
t is
still
und
er r
evie
w.
UN
ITE
D K
ING
DO
M
Non
e.
NE
A/C
SNI/
R(2
003)
16
40
USA
U
S N
RC
So
me
of th
e te
chni
cal i
ssue
s as
soci
ated
with
SSC
s in
clud
e:
- T
he e
mer
genc
y di
esel
gen
erat
or s
tart
tim
e fo
r L
BL
OC
A m
ay im
pose
unn
eces
sary
str
ess
and
oper
atio
nal l
imit
atio
ns.
- A
dver
se im
pact
on
reli
abili
ty/a
vail
abili
ty o
f E
DG
s -
Adv
erse
impa
ct o
n re
liab
ility
of
the
EC
CS
MO
Vs
- In
crea
sed
prob
abili
ty o
f in
adve
rten
t inj
ectio
n fr
om a
ccum
ulat
ors
- Fo
cus
on r
elia
bilit
y of
SSC
s th
at a
re r
isk
sign
ific
ant (
incl
udin
g m
itig
atio
n of
LO
CA
s at
shu
tdow
n)
Con
tain
men
t su
mp
debr
is g
ener
atio
n an
d su
mp
bloc
kage
. E
quip
men
t qu
alif
icat
ion
requ
irem
ents
.
WO
G
No
cont
rol
rod
inse
rtio
n fo
llow
ing
a L
BL
OC
A r
esul
ting
in h
ighe
r bo
ron
conc
entr
atio
ns /
Sw
itcho
ver
from
EC
CS
cold
leg
to
hot l
eg in
ject
ion
to a
ddre
ss b
oron
pre
cipi
tatio
n / C
onta
inm
ent s
ump
debr
is g
ener
atio
n an
d cl
oggi
ng o
f th
e su
mp
/ Fas
t die
sel g
ener
ator
st
arts
(10
sec
.) t
o m
itig
ate
the
LB
LO
CA
wit
h a
coin
cide
nt l
oss
of o
ff-s
ite
pow
er /
Con
tain
men
t de
sign
cha
nges
to
the
exis
ting
cont
ainm
ent
stru
ctur
al d
esig
n an
d lim
its
are
not
envi
sion
ed,
alth
ough
ben
efits
in
oper
atio
nal
mar
gin
are
expe
cted
. /
Equ
ipm
ent
qual
ific
atio
n -
othe
r br
eaks
tha
t w
ould
stil
l be
in
the
desi
gn b
asis
will
stil
l re
quir
e E
Q l
imit
s si
mil
ar t
o th
e ex
isti
ng l
imits
/
Ulti
mat
e he
at s
ink
requ
irem
ents
and
ass
ocia
ted
tem
pera
ture
lim
its
are
asso
ciat
ed w
ith t
he L
BL
OC
A /
The
con
tain
men
t le
akag
e ra
te t
est
pres
sure
Pa
is c
urre
ntly
bas
ed o
n th
e L
BL
OC
A r
esul
tant
pre
ssur
e. R
educ
ing
the
brea
k si
ze w
ould
red
uce
Pa f
or t
he c
onta
inm
ent
leak
age
rate
test
ing.
R
USS
IA
Obs
erve
r G
idro
pres
s E
ven
appl
ying
LB
B c
once
pt (
i.e.,
for
200-
300
mm
bre
aks
as t
he d
esig
n ba
sis
LO
CA
), a
sig
nifi
cant
num
ber
of s
uppo
rt-
cons
trai
nts
for
pipe
s, a
dditi
onal
sup
port
s fo
r eq
uipm
ent,
esse
ntia
l en
forc
emen
t of
in-
cont
ainm
ent
cons
truc
tions
are
stil
l ne
eded
. It
is
diff
icul
t to
sub
stan
tiate
the
equ
ipm
ent
stre
ngth
due
to
abse
nce
of t
he r
elev
ant
norm
ativ
e ba
sis,
and
the
refo
re t
he c
ostl
y ex
peri
men
tal
wor
ks a
re o
ften
nee
ded.
GA
N
•
Ins
uffi
cien
cy o
f pr
imar
y pi
pe s
uppo
rts
and
disp
lace
men
t lim
iter
s at
ope
rati
ng N
PP u
nits
•
C
logg
ing
of f
ilter
ing
grid
s in
the
cont
ainm
ent s
ump
•
inco
nsis
tenc
y be
twee
n cu
rren
t L
OC
A d
efin
ition
and
lim
iting
LO
CA
siz
e ac
cept
ed i
n th
e or
igin
al d
esig
n of
old
NPP
uni
ts
conc
erni
ng E
CC
S ca
paci
ty
Slov
enia
Obs
erve
r N
one
real
ly.
The
que
stio
n of
the
rmal
str
atif
icat
ion
(on
the
surg
e lin
e, n
orm
al a
nd a
ltern
ate
char
ging
che
ck v
alve
s, a
uxili
ary
spra
y lin
e, t
he R
HR
iso
latio
n va
lve
and
on t
he p
ress
uriz
er n
ozzl
e an
d pr
essu
rize
r sp
ray
nozz
le)
and
ther
mal
var
iatio
ns i
n ge
nera
l is
fo
llow
ed c
lose
ly, f
or th
is p
urpo
se a
lso
addi
tiona
l se
nsor
s ha
ve b
een
inst
alle
d at
thes
e li
nes.
Bes
ides
that
, the
sen
sitiv
ity
and
reli
abili
ty
of le
ak m
onit
orin
g sy
stem
cou
ld b
e im
prov
ed.
NE
A/C
SNI/
R(2
003)
16
41
Cur
rent
tech
nica
l fra
mew
ork
2.
W
hat
tech
nica
l is
sues
wou
ld b
e ne
eded
to
be a
ddre
ssed
by
Res
earc
hers
to
supp
ort
the
regu
lato
ry d
ecis
ion
proc
ess
to c
hang
e th
e cu
rren
t L
OC
A d
efin
itio
n?
B
EL
GIU
M
N
ot a
pplic
able
CA
NA
DA
Thi
s w
ould
dep
end
on th
e pr
opos
ed c
hang
es to
the
LL
OC
A d
efin
ition
.
T
o al
low
the
use
of th
e B
est E
stim
ate
Ana
lysi
s +
Unc
erta
inty
, mor
e in
form
atio
n w
ould
be
need
ed o
n se
nsiti
vity
to
impo
rtan
t var
iabl
es a
nd th
e ra
nge
of k
ey p
aram
eter
unc
erta
intie
s.
To
acce
pt L
BB
red
efin
ition
, the
n co
nsid
erab
le w
ork
wou
ld b
e ne
eded
to d
evel
op th
e in
spec
tion
prog
ram
s, f
ract
ure
mec
hani
cs a
nd le
ak d
etec
tion
part
s of
a L
BB
met
hodo
logy
and
ther
e w
ould
be
an o
ngoi
ng p
rogr
am o
f au
gmen
ted
peri
odic
in
spec
tions
.
T
o m
ove
to a
ris
k-in
form
ed d
ecis
ion-
mak
ing
regi
me,
cle
ar g
roun
d ru
les
are
need
ed f
or in
tegr
atin
g tr
aditi
onal
d
eter
min
isti
c, d
efen
ce-i
n-de
pth
desi
gn c
once
pts
wit
hin
a ri
sk-i
nfor
med
fra
mew
ork.
SUJB
Sa
fety
A
utho
rity
E
valu
atio
n of
LB
LO
CA
fre
quen
cy, L
BB
, use
bes
t est
imat
e co
mpu
ter
code
+un
cert
antie
s (
BE
met
hod)
C
ZE
CH
RE
PU
BL
IC
NR
I R
ez
Rec
ent o
pera
tion
al e
xper
ienc
es w
ith
larg
e di
amet
er p
ipin
g, q
ualif
ied
ISI,
pro
gres
s in
fra
ctur
e m
echa
nics
, pr
ogre
ss in
mon
itor
ing
syst
ems
FIN
LA
ND
All
asp
ects
of
nucl
ear
plan
t des
ign
whi
ch w
ere
base
d or
invo
lved
ass
umpt
ions
der
ived
fro
m th
e L
OC
A e
nvel
ope.
Se
e “C
urre
nt R
egul
ator
y Fr
amew
ork”
for
a s
hort
list
of
mos
t obv
ious
fac
tors
and
issu
es.
IRSN
R
ealis
tic L
OC
A f
requ
enci
es a
sses
smen
t is
an im
port
ant i
ssue
. F
RA
NC
E
ED
F S
EP
TE
N
– r
efre
shin
g al
l the
pro
babi
list
ic a
naly
sis
of le
ak a
nd b
reak
of
RC
S p
ipin
g, in
clud
ed a
ll th
e ex
istin
g
know
ledg
e of
deg
rada
tion
mec
hani
sm .
Pre-
wor
ksho
p su
rvey
– r
edef
inin
g th
e L
arge
-bre
ak L
oss-
of-c
oola
nt A
ccid
ent
GE
RM
AN
Y
T
here
are
no
plan
ts to
cha
nge
curr
ent L
OC
A d
efin
ition
s. S
ome
rese
arch
wor
k ha
s be
en p
erfo
rmed
in th
e pa
st
rega
rdin
g th
e re
qual
ific
atio
n of
old
er p
rim
ary
pres
sure
com
pone
nts
to th
e ba
sic
safe
ty s
tand
ard.
NE
A/C
SNI/
R(2
003)
16
42
JAP
AN
We
addr
ess
the
follo
win
g m
ajor
thre
e te
chni
cal i
ssue
s im
port
ant t
o co
nsid
er.
(1)
E
valu
atio
n of
LB
LO
CA
fre
quen
cy
a.
The
impr
ovem
ent o
f pr
ecis
ion
for
eval
uatio
n by
Pro
babi
listic
Fai
lure
Mec
hani
cs (
PFM
) w
ith o
pera
ting
expe
rien
ce
data
is in
disp
ensa
ble.
b. I
n co
nnec
tion
with
LB
B, e
valu
atio
n of
the
rel
iabi
lity
of i
nspe
ctio
n an
d de
tect
ion
is t
he b
igge
st p
robl
em a
nd i
t al
so
serv
es a
s an
im
port
ant
fact
or f
or t
he e
valu
atio
n by
PFM
. Bes
ides
, thi
s de
pend
s gr
eatly
on
hum
an a
nd a
n or
gani
zatio
n fa
ctor
as
an
exam
ple
of D
avis
-Bes
se e
vent
.
c. F
or t
he e
valu
atio
n of
occ
urre
nce
freq
uenc
y of
LB
- LO
CA
, w
e th
ink
it is
req
uire
d th
at t
he c
heck
of
taki
ng i
nto
cons
ider
atio
n al
l im
port
ant
LO
CA
gen
erat
ing
mec
hani
sms,
suc
h as
an
eart
hqua
ke a
nd p
lant
agi
ng,
by s
ynt h
etic
ana
lysi
s of
th
e ac
tual
eve
nt a
bout
the
leak
age
from
pre
ssur
e ve
ssel
or
pipi
ng, a
nd m
odel
ing
for
each
mec
hani
sm o
f L
OC
A g
ener
atio
n.
(2)
E
valu
atio
n of
max
imum
allo
wab
le p
ipe
brea
k si
ze
The
tec
hnic
al i
ssue
is
whe
ther
or
not
we
can
calc
ulat
e th
e ri
sk p
rofi
le w
ith s
uffi
cien
t pr
ecis
ion
alon
g w
ith t
he b
reak
siz
e of
L
B-L
OC
A w
hich
is o
ne o
f th
e D
BE
s. W
hen
the
brea
k si
ze is
alte
red,
the
plan
t des
ign
chan
ges
and
then
the
risk
may
larg
ely
chan
ge.
The
re m
ight
exi
st m
any
diff
icul
ties
to d
o it.
Fir
st,
we
mig
ht n
eed
to e
stab
lish
a ne
w D
BE
for
the
con
tain
men
t de
sign
whi
ch i
s la
rgel
y de
pend
ent o
n 20
0% L
B-L
OC
A a
t pre
sent
.
(3)
B
est e
stim
ate
eval
uatio
n m
etho
d an
d un
cert
aint
y In
the
eval
uatio
n an
alys
is o
f P
FM, s
ince
the
grea
test
load
to p
ipin
g is
con
side
red
to b
e an
ear
thqu
ake,
it is
ess
entia
lly th
ough
t th
at u
ncer
tain
ty i
s ve
ry l
arge
. If
the
unce
rtai
nty
of f
requ
ency
eva
luat
ion
is t
aken
int
o co
nsid
erat
ion,
in
para
llel
to t
he e
valu
atio
n of
fr
eque
ncy,
it
mig
ht b
e im
port
ant t
o co
nfir
m t
hat t
he r
isk
cont
ribu
tion
of L
OC
A e
xcee
ding
DB
E i
s sm
all.
In t
hat
case
, we
thin
k th
at
the
acci
dent
pro
gres
sion
ana
lysi
s w
hich
com
bine
d th
e be
st e
stim
ate
code
with
unc
erta
inty
ana
lysi
s an
d th
e kn
owle
dge
abou
t th
e co
olab
ility
for
dam
aged
rea
ctor
cor
e de
rive
d fr
om th
e se
vere
acc
iden
t res
earc
h is
impo
rtan
t.
ME
XIC
O
T
he P
roba
bilis
tic S
afet
y A
sses
smen
t , E
CC
S co
olin
g pe
rfor
man
ce a
re s
ome
issu
es to
be
cons
ider
ed in
cas
e of
cha
nge
in
the
defi
nitio
n of
LO
CA
.
SLO
VA
K R
EP
UB
LIC
Sa
fety
Aut
hori
ty
The
pre
cond
ition
for
a s
afe
oper
atio
n of
NPP
is th
e lo
ng te
rm a
ssur
ance
of
stru
ctur
al in
tegr
ity o
f co
mpo
nent
s.
The
refo
re w
e co
nsid
er f
ollo
win
g te
chni
cal i
ssue
s as
impo
rtan
t for
the
regu
lato
ry d
ecis
ion
mak
ing:
-
pre
cisi
ng a
nd v
alid
atio
n of
pro
cedu
res
for
the
inte
grity
and
life
time
asse
ssm
ent (
at p
rese
nt, e
.g. E
C P
roje
ct V
ER
LIF
E)
- pr
ecis
ing
of m
onito
ring
met
hods
for
the
agei
ng o
f st
ruct
ural
mat
eria
l of
prim
ary
circ
uit p
ipin
g
NE
A/C
SNI/
R(2
003)
16
43
V
UJE
Fi
rst
of a
ll, f
or t
he s
mal
l “n
ucle
ar”
coun
trie
s (S
lova
kia,
Cze
ch R
epub
lic, H
unga
ry, e
tc.)
, the
cha
nges
of
curr
ent
LO
CA
de
fini
tion
dep
end
on i
nter
natio
nal
coop
erat
ion.
Whe
n th
e pr
oces
s of
LB
LO
CA
red
efin
ing
is t
o be
sup
port
ed b
y O
EC
D
Nuc
lear
Ene
rgy
Age
ncy
as w
ell
as I
nter
natio
nal
Ato
mic
Ene
rgy
Age
ncy
the
Slo
vak
Nuc
lear
Reg
ulat
ory
Aut
hori
ty w
ould
lik
e at
tend
this
pro
cess
.
SPA
IN
N
ucle
ar f
uel p
erfo
rman
ce in
a L
OC
A (
incl
udin
g hi
gh b
urnu
p ef
fect
s)
SWE
DE
N
N
o an
swer
s pr
ovid
ed
SWIT
ZE
RL
AN
D
L
OC
A a
naly
ses
mus
t be
per
form
ed o
n a
cons
erva
tive
bas
is,
for
whi
ch t
he a
ppli
catio
n of
the
USN
RC
req
uire
men
ts
(10
CFR
§50
.46
and
App
endi
x K
) is
acc
epte
d al
thou
gh n
ot c
ompu
lsor
y. B
est-
esti
mat
e ca
lcul
atio
ns w
ith c
onse
rvat
ive
initi
al
and
boun
dary
con
ditio
ns o
r co
mpr
ehen
sive
unc
erta
inty
ana
lysi
s w
ould
sup
port
the
reg
ulat
ory
deci
sion
mak
ing
proc
ess
for
plan
ts w
ith s
mal
l saf
ety
mar
gins
.
UN
ITE
D K
ING
DO
M
E
lim
inat
ion
of f
ull
guill
otin
e br
eak
for
the
prim
ary
cool
ant
loop
pip
ewor
k w
ould
req
uire
a d
emon
stra
ble
leve
l of
st
ruct
ural
inte
grity
ana
lysi
s, o
r a
phys
ical
lim
itatio
n on
pip
e di
spla
cem
ent w
hich
wou
ld li
mit
the
disc
harg
e fl
ow a
rea,
i.e.
pla
nt
spec
ific
. N
o “r
esea
rch”
is r
equi
red.
USA
U
S N
RC
T
he f
ollo
win
g ar
e so
me
of t
he t
echn
ical
iss
ues
whi
ch n
eed
to b
e ad
dres
sed
by r
esea
rche
rs t
o su
ppor
t th
e re
gula
tory
de
cisi
on m
akin
g pr
oces
s to
cha
nge
the
curr
ent L
OC
A d
efin
ition
.
• D
eter
min
atio
n of
th
e sm
all-
brea
k,
med
ium
-bre
ak,
and
larg
e-br
eak
LO
CA
fr
eque
ncy
dist
ribu
tions
an
d fa
ilure
m
echa
nism
s w
hich
ref
lect
pot
entia
l cha
nges
in th
e ex
pect
ed L
OC
A f
requ
enci
es a
nd c
onse
quen
ces
• D
eter
min
atio
n of
the
rel
atio
nshi
p be
twee
n br
eak
size
and
exp
ecte
d ev
ent
freq
uenc
y fo
r la
rge
prim
ary
syst
em p
ipes
(>
15
0 m
m d
iam
eter
) to
ass
ess
the
feas
ibili
ty o
f re
defi
ning
the
desi
gn b
reak
siz
e.
• D
evel
opm
ent
of t
he b
reak
siz
e fr
eque
ncy
spec
trum
for
LB
LO
CA
s co
nsid
erin
g PR
A q
ualit
y an
d re
sults
to
deve
lop
suita
ble
gene
ric
and/
or p
lant
spe
cifi
c ap
proa
ches
whi
ch s
houl
d be
the
basi
s fo
r an
y ru
le c
hang
e.
• D
eter
min
atio
n th
at th
e pl
ant c
an d
eal w
ith
cert
ain
even
ts th
at w
ere
not a
ddre
ssed
pre
viou
sly
in th
e de
sign
bas
is b
ecau
se
they
wer
e bo
unde
d by
the
LB
LO
CA
. E
xam
ples
of
such
eve
nts
incl
ude
sour
ces
of L
OC
As
othe
r th
an p
ipe
brea
ks (
e.g.
,
NE
A/C
SNI/
R(2
003)
16
44
stea
m m
anw
ay f
ailu
re).
• Se
e It
em 3
b of
Con
side
ratio
n fo
r th
e fu
ture
for
dis
cuss
ions
of
anal
ytic
al t
ools
and
mod
els
whi
ch m
ay r
equi
re
deve
lopm
ent
WO
G
LB
LO
CA
initi
atin
g ev
ent f
requ
enci
es
Prob
abili
stic
fra
ctur
e m
echa
nics
(PF
M)
to s
uppo
rt b
oth
freq
uenc
y an
d br
eak
size
det
erm
inat
ion.
RU
SSIA
Obs
erve
r G
idro
pres
s O
ne o
f th
e m
ost
impo
rtan
t pr
oble
ms
is t
o pr
ove
very
low
pro
babi
lity
of l
arge
pip
elin
e br
eak.
Alth
ough
the
LB
B i
s su
bsta
ntia
ted
by d
esig
ner
and
acce
pted
by
regu
lato
ry b
ody,
the
pro
babi
list
ic a
naly
ses
have
dis
play
ed s
mal
l bu
t no
t ne
glig
ible
pr
obab
ility
of
larg
e-sc
ale
rupt
ure
of a
lar
ge s
ize
pipe
. A
s th
e ne
ares
t ta
sk,
it w
ould
be
usef
ul t
o de
velo
p an
d ag
ree
wit
h th
e re
gula
tor
the
met
hod
that
wou
ld a
llow
to li
mit
the
num
ber
of a
ssum
ed lo
cati
ons
for
pipe
bre
aks
(to
defi
ne th
e po
ints
whe
re th
e pr
otec
tive
mea
sure
s ar
e re
ally
nee
ded)
. A
s th
e lo
ng-t
erm
tas
k, t
he s
ubst
antia
tion
and
impl
emen
tatio
n of
LB
B c
once
pt f
or
smal
ler
pipe
s (a
t lea
st, u
p to
150
mm
) w
ould
be
extr
emel
y us
eful
.
GA
N
No
answ
ers
prov
ided
Slov
enia
Obs
erve
r
The
rel
evan
t one
s. E
.g.:
New
EC
CS
desi
gn c
rite
ria,
…
45
Con
side
ratio
n fo
r th
e fu
ture
1
.
A
re y
ou c
onsi
deri
ng c
hang
es in
you
r re
gula
tion
? F
or o
pera
ting
pla
nts?
For
fut
ure
plan
ts?
BE
LG
IUM
No.
C
AN
AD
A
T
he C
anad
ian
regu
lato
r ha
s no
cur
rent
pla
ns to
rem
ove
LL
OC
A f
rom
the
desi
gn b
asis
set
of
acci
dent
s, e
ither
for
cur
rent
or
futu
re r
eact
ors.
How
ever
, the
reg
ulat
or is
inve
stig
atin
g w
ays
to d
evel
op a
mor
e ba
lanc
ed a
ppro
ach
to L
LO
CA
, inc
ludi
ng u
sing
ris
k in
sigh
ts.
Lic
ense
es a
re p
ropo
sing
bes
t est
imat
e an
alys
is p
lus
unce
rtai
nty
met
hodo
logy
. Reg
ulat
or d
oes
not d
icta
te a
n an
alys
is
met
hodo
logy
but
will
eva
luat
e th
e lic
ense
e’s
prop
osal
s, a
ccep
ting
them
if th
ey d
emon
stra
te s
afet
y ta
rget
s ar
e m
et w
ith
suff
icie
nt
conf
iden
ce. T
he p
ositi
on is
the
sam
e fo
r op
erat
ing
and
futu
re p
lant
s.
The
Can
adia
n in
dust
ry is
con
side
ring
pro
posi
ng c
hang
es w
hich
wou
ld b
e al
igne
d w
ith
mov
emen
t tow
ards
a r
isk-
info
rmed
de
cisi
on m
akin
g re
gim
e. S
uch
prop
osed
cha
nges
will
then
initi
ate
disc
ussi
ons
wit
h th
e re
gula
tor.
C
ZE
CH
R
EP
UB
LIC
SU
JB
Safe
ty
Aut
hori
ty
No.
N
RI
Rez
N
o an
swer
s pr
ovid
ed
FIN
LA
ND
No.
IR
SN
- Fo
r op
erat
ing
plan
ts:
in th
e fr
amew
ork
of p
erio
dic
safe
ty r
eass
essm
ent,
ED
F ha
s re
cent
ly p
rese
nted
a p
ropo
sal
for
chan
ging
th
e L
LO
CA
def
initi
on,
but
due
to a
lac
k of
met
hodo
logy
whi
ch c
ould
be
used
for
the
cor
resp
ondi
ng d
emon
stra
tion,
the
pr
opos
al w
as n
ot a
ccep
ted
by th
e Sa
fety
Aut
hori
ty.
- St
atus
of
EPR
: See
the
poin
t 1 r
espo
nse
abov
e
FR
AN
CE
ED
F
SEP
TE
N
- fo
r op
erat
ing
plan
t, in
tern
al r
evie
w is
und
er p
rogr
ess
- fo
r fu
ture
pla
nts
incl
uded
as
desi
gn b
asis
and
no
LB
LO
CA
in th
e de
sign
tran
sien
t lis
t
GE
RM
AN
Y
T
here
are
no
cons
ider
atio
ns to
cha
nge
the
regu
latio
ns.
JAP
AN
Sinc
e w
e ar
e no
t re
gula
tors
, w
e ca
nnot
ans
wer
thi
s qu
estio
n. H
owev
er,
the
dem
and
for
ratio
nali
zing
saf
ety
eval
uatio
n is
in
crea
sing
in J
apan
: suc
h as
an
appl
icat
ion
of R
IR, s
afet
y go
al, a
nd p
erfo
rman
ce in
dica
tors
.
NE
A/C
SNI/
R(2
003)
16
46
ME
XIC
O
U
p to
dat
e th
ere
is n
ot a
ny c
onsi
dera
tion
to c
hang
e th
e ac
tual
reg
ulat
ion
SLO
VA
K
RE
PU
BL
IC
Safe
ty
Aut
hori
ty
At
pres
ent
we
do n
ot c
onsi
der
any
chan
ges
in r
egul
atio
n re
late
d to
LB
LO
CA
def
initi
on.
But
in
case
tha
t th
ere
are
enou
gh
evid
ence
s fo
r th
e L
B L
OC
A r
e-de
fini
tion
, th
e de
fini
tion
of l
imit
ing
brea
k si
ze i
n th
e cu
rren
t le
gisl
atio
n co
uld
be c
hang
ed f
or b
oth,
op
erat
ing
and
futu
re p
lant
s.
VU
JE
No.
SP
AIN
We
curr
ently
fol
low
the
regu
lati
on o
f ou
r ve
ndor
s (U
SA a
nd G
erm
any)
SW
ED
EN
As
men
tion
ed i
n th
e an
swer
to
ques
tion
no. 1
and
3 S
KI
is p
repa
ring
gen
eral
des
ign
regu
latio
ns, w
hich
will
app
licab
le t
o al
l pr
esen
tly o
pera
tion
nucl
ear
pow
er p
lant
s in
Sw
eden
. T
he m
ain
purp
ose
of i
ssui
ng t
hese
new
reg
ulat
ions
is
to s
tren
gthe
ning
the
de
fenc
e-in
dep
th, p
artic
ular
for
the
olde
r re
acto
rs b
y re
quir
e m
ore
use
of r
edun
danc
y an
d di
vers
ity
of s
afet
y sy
stem
s.
No
futu
re p
lant
s ar
e pr
esen
tly c
onsi
dere
d in
Sw
eden
. SW
ITZ
ER
LA
ND
No
chan
ge t
o th
e L
OC
A b
reak
siz
e de
fini
tion
is f
ores
een
at t
he p
rese
nt t
ime
and
no c
orre
spon
ding
app
licat
ion
has
been
su
bmit
ted
by th
e ow
ners
of
the
nucl
ear
pow
er p
lant
s.
UN
ITE
D K
ING
DO
M
No.
USA
U
S N
RC
C
hang
es a
re c
urre
ntly
bei
ng c
onsi
dere
d in
the
reg
ulat
ion
(10
CFR
50.
46)
for
oper
atin
g pl
ants
. I
t is
int
ende
d th
at a
ny
rule
mak
ing
asso
ciat
ed w
ith t
he p
ropo
sed
chan
ges
will
be
a vo
lunt
ary
alte
rnat
ive
to t
he c
urre
nt r
ules
. T
he N
RC
sta
ff i
s de
velo
ping
a
“fra
mew
ork”
for
the
futu
re p
lant
s. T
he s
taff
exp
ects
to f
ollo
w th
e si
mil
ar a
ppro
ach
as th
at ta
ken
for
this
initi
ativ
e.
WO
G
The
pet
ition
for
rul
e m
akin
g su
bmit
ted
by t
he N
EI
coul
d be
app
lied
to e
ither
ope
rati
ng p
lant
s or
fut
ure
plan
ts. T
he p
ropo
sed
chan
ge is
sim
ply
wor
ded
and
prov
ides
for
an
opti
onal
alte
rnat
e br
eak
size
that
wou
ld h
ave
to b
e ap
prov
ed b
y th
e N
RC
. The
pro
pose
d ru
le w
ould
not
pre
scri
be t
he b
reak
siz
e.
Add
ition
al r
isk-
info
rmed
cri
teri
a ar
e be
ing
cons
ider
ed f
or i
nclu
sion
in
the
prop
osed
rul
e th
at
wou
ld g
ive
the
NR
C a
sta
ndar
d fo
r ac
cept
ance
bas
ed o
n L
OC
A c
ontr
ibut
ion
to r
isk.
The
re i
s no
tec
hnic
al r
easo
n th
at t
he s
ame
set
of
crite
ria
cann
ot b
e ap
plie
d to
exi
stin
g an
d ne
w p
lant
s.
RU
SSIA
Obs
erve
r G
idro
pres
s Si
nce
the
curr
ent s
afet
y st
anda
rds
cont
ain
no d
irec
t ind
icat
ion
on th
e m
axim
um s
ize
of th
e de
sign
bas
is L
OC
A, t
he c
hang
es (
to
decr
ease
the
desi
gn b
asis
LO
CA
siz
e) a
re n
ot e
xpec
ted.
NE
A/C
SNI/
R(2
003)
16
47
G
AN
A
t the
mom
ent t
here
is n
o pl
ans
to c
hang
e th
e re
gula
tion
in v
iew
of
limit
ing
LO
CA
def
initi
on.
Slov
enia
Obs
erve
r N
ot r
egar
ding
des
ign
basi
s.
For
oper
atin
g pl
ants
? N
ot a
t the
mom
ent.
For
futu
re p
lant
s? N
/A.
48
Con
side
ratio
n fo
r th
e fu
ture
2.
W
hat w
ould
be
the
ince
ntiv
es?
Fro
m t
he r
egul
ator
y vi
ewpo
int?
Fro
m t
he I
ndus
try
view
poin
t?
BE
LG
IUM
Not
app
licab
le
CA
NA
DA
Can
adia
n re
gula
tor
sees
som
e in
cent
ive
to r
emov
e so
me
LL
OC
A b
reak
s fr
om d
esig
n ba
sis:
-
conc
entr
ate
revi
ew e
ffor
t on
mor
e ri
sk-s
igni
fica
nt e
vent
s -
refo
cus
rese
arch
eff
ort
- re
duce
dos
es to
wor
kers
(if
gai
n fr
om r
educ
ed te
stin
g is
gre
ater
than
incr
ease
fro
m in
spec
tion)
.
Indu
stry
cou
ld g
ain
from
the
abov
e an
d al
so:
- re
laxa
tion
of o
pera
ting
res
tric
tions
-
rem
oval
of
pow
er r
estr
ictio
ns
- be
tter
util
izat
ion
of r
esou
rces
on
high
er im
port
ance
saf
ety
issu
es.
SUJB
Sa
fety
A
utho
rity
N/A
C
ZE
CH
R
EP
UB
LIC
NR
I R
ez
From
the
Indu
stry
vie
wpo
int c
ost s
avin
g F
INL
AN
D
T
here
are
non
e fr
om e
ithe
r si
de.
IRSN
-
for
the
regu
lato
ry :
LB
B c
ould
lead
to a
n im
prov
emen
t of
leak
det
ectio
n sy
stem
s.
-for
the
ind
ustr
y :
less
con
stra
ints
for
mai
nten
ance
of
whi
p re
stra
ints
and
for
ope
ratio
n ev
olut
ions
(fu
el c
ycle
, po
wer
ch
ange
s….)
.
FR
AN
CE
ED
F S
EP
TE
N
No
answ
ers
prov
ided
G
ER
MA
NY
No
answ
ers
prov
ided
JA
PA
N
W
e th
ink
that
it
is a
com
mon
rec
ogni
tion
of t
he i
ndus
try
and
regu
lato
r to
rem
ove
unne
cess
ary
cons
erva
tive
s. T
he b
est
use
of
safe
ty m
argi
n w
ill b
e al
so a
noth
er in
cent
ive.
NE
A/C
SNI/
R(2
003)
16
49
ME
XIC
O
N
/A
SLO
VA
K
RE
PU
BL
IC
Safe
ty
Aut
hori
ty
As
the
mai
n pr
econ
ditio
n fo
r th
e L
B L
OC
A r
e-de
fini
tion
fro
m t
he r
egul
ator
y po
int
of v
iew
we
cons
ider
to
perf
orm
the
re-
clas
sifi
catio
n of
initi
atin
g ev
ents
acc
ordi
ng to
the
prob
abili
ty o
f th
eirs
occ
urre
nce.
V
UJE
T
o ch
ange
the
curr
ent L
B L
OC
A d
efin
ition
sho
uld
be b
ased
on
risk
ana
lyse
s fo
r ne
w g
ener
atio
n of
NPP
s.
SPA
IN
B
ette
r kn
owle
dge
of t
he L
OC
A c
once
rns.
In
Indu
stry
: ec
onom
ic r
easo
ns, d
raw
ing
mor
e re
sour
ces
to s
afet
y. R
egul
ator
y bo
dy:
mor
e re
sour
ces
to o
ther
saf
ety
issu
es.
SWE
DE
N
Se
e an
swer
to q
uest
ion
no. 1
abo
ve
SWIT
ZE
RL
AN
D
N
ot a
pplic
able
.
UN
ITE
D K
ING
DO
M
Non
e
USA
U
S N
RC
R
egul
ator
y vi
ewpo
int:
T
he C
omm
issi
on, i
n its
pol
icy
stat
emen
t on
PR
A (
Fede
ral
Reg
iste
r, V
ol. 6
0, N
o. 1
58, A
ugus
t 16
, 199
5, p
. 426
22)
has
stat
ed
that
: “T
he u
se o
f P
RA
tec
hnol
ogy
shou
ld b
e in
crea
sed
in a
ll r
egul
ator
y m
atte
rs to
the
ext
ent s
uppo
rted
by
the
stat
e-of
-the
- art
in
PRA
m
etho
ds a
nd d
ata
and
in a
man
ner
that
com
plem
ents
the
NR
C’s
trad
ition
al d
efen
se-i
n-de
pth
philo
soph
y.”
The
Com
mis
sion
, in
orde
r to
mov
e fo
rwar
d to
im
plem
ent
the
polic
y st
atem
ent,
in a
Whi
te P
aper
on
Ris
k-In
form
ed a
nd P
erfo
rman
ce- B
ased
Reg
ulat
ion
(Sta
ff
Req
uire
men
ts -
SE
CY
-98-
144,
Mar
ch 1
, 199
9), h
as d
efin
ed, i
n pa
rt, “
Ris
k-In
form
ed A
ppro
ach”
as:
“A
“ri
sk- i
nfor
med
” ap
proa
ch t
o re
gula
tory
dec
isio
n-m
akin
g re
pres
ents
a p
hilo
soph
y w
here
by r
isk
insi
ghts
are
con
side
red
toge
ther
wit
h ot
her
fact
ors
to e
stab
lish
requ
irem
ents
that
bet
ter
focu
s li
cens
ee a
nd r
egul
ator
y at
tent
ion
on d
esig
n an
d op
erat
iona
l iss
ues
com
men
sura
te w
ith
thei
r im
port
ance
to
pub
lic h
ealth
and
saf
ety.
” W
ith t
he a
bove
ove
r-ar
chin
g pr
inci
ples
, co
nsid
erat
ion
of t
he f
ollo
win
g fa
ctor
s, a
nd i
nput
fro
m t
he s
take
hol d
ers
prov
ide
ince
ntiv
e fo
r co
nsid
erin
g re
quir
emen
ts f
or th
e an
alys
is o
f de
sign
bas
is L
OC
As,
and
som
e of
the
asso
ciat
ed r
equi
rem
ents
as
cand
idat
es
for
risk
-inf
orm
ed r
egul
atio
n. T
he f
acto
rs in
clud
e:
•
T
he d
esig
n ba
sis
LO
CA
and
req
uire
men
ts w
ere
esta
blis
hed
in th
e ni
nete
en-s
ixtie
s w
ith v
ery
little
ope
ratin
g ex
peri
ence
. Sin
ce
th
en, t
here
has
bee
n se
vera
l tho
usan
d ye
ars
of c
olle
ctiv
e op
erat
iona
l exp
erie
nce,
wit
h no
occ
urre
nce
of a
larg
e-br
eak
LO
CA
.
NE
A/C
SNI/
R(2
003)
16
50
•
Ris
k as
sess
men
ts s
how
that
LB
LO
CA
s ar
e no
t maj
or c
ontr
ibut
ors
to r
isk.
•
T
here
has
als
o be
en e
xten
sive
res
earc
h in
clud
ing
rese
arch
in f
uel b
ehav
ior
and
seve
re a
ccid
ents
whi
ch a
llow
us
to c
ondu
ct
mor
e re
alis
tic a
naly
sis
and
eval
uatio
n of
mar
gins
.
•
Bot
h th
e ut
ility
and
reg
ulat
ors
devo
te s
igni
fica
nt r
esou
rces
to a
ssur
e th
at a
ll of
the
requ
irem
ents
res
ultin
g fr
om th
e D
EG
B a
re
met
. The
oth
er s
peci
fic
fact
ors
(e.g
., im
prov
ed r
elia
bilit
y of
ED
Gs
and
fast
-ope
rati
ng v
alve
s w
hose
ope
ratin
g ti
mes
are
der
ived
fr
om L
BL
OC
A a
naly
sis)
whi
ch r
esul
t in
safe
ty e
nhan
cem
ents
, ope
ratio
nal f
lexi
bilit
y, a
nd o
ther
ben
efits
are
dis
cuss
ed in
var
ious
par
ts
of th
is s
urve
y.
In s
umm
ary,
the
reg
ulat
ory
ince
ntiv
e is
bet
ter
focu
s of
bot
h th
e lic
ense
e an
d th
e re
gula
tor
on m
ore
safe
ty s
igni
fica
nt in
itiat
ors
wit
h re
duct
ion
of u
nnec
essa
ry b
urde
n.
Indu
stry
vie
wpo
int
The
inc
entiv
es f
rom
the
ind
ustr
y vi
ewpo
int
are
num
erou
s. T
he W
estin
ghou
se O
wne
rs G
roup
(W
OG
) an
ticip
ates
tha
t ec
onom
ic b
enef
its w
ill a
ccru
e fr
om p
oten
tial
pow
er u
prat
es,
rela
xatio
n of
DG
sta
rt t
imes
, in
crea
ses
in p
eaki
ng f
acto
rs,
redu
ced
anal
ysis
cos
ts,
etc.
The
Boi
ling
Wat
er R
eact
or O
wne
rs G
roup
(B
WR
OG
) ex
pect
s to
red
uce
cost
s as
soci
ated
with
tes
ting
(e.g
., in
tegr
ated
saf
ety
inje
ctio
n/lo
ss o
f of
fsite
pow
er t
est,
DG
loa
d sh
ed a
nd l
ogic
tes
t, M
OV
str
oke
test
s),
mai
nten
ance
(e.
g.,
DG
ov
erha
uls,
MO
V a
ctua
tor
set-
up a
nd r
etes
ts),
des
ign
(e.g
., D
G l
oad
sequ
enci
ng,
MO
V a
ctua
tor
repl
acem
ents
/sei
smic
con
cern
s),
and
oper
atio
n (e
.g.,
exte
nsio
n of
DG
and
MO
V a
llow
ed o
utag
e ti
mes
).
See
addi
tiona
l tab
ular
info
rmat
ion
in I
tem
4.
NE
A/C
SNI/
R(2
003)
16
51
WO
G
The
saf
ety
bene
fit
is i
n te
rms
of f
ocus
ing
reso
urce
s in
are
as o
f gr
eate
r ri
sk s
igni
fica
nce,
suc
h as
SB
LO
CA
, an
d th
e po
tent
ial
for
incr
ease
d re
liabi
lity
and
avai
labi
lity
due
to m
ore
real
istic
sur
veill
ance
req
uire
men
ts a
nd f
ewer
ope
rati
onal
res
tric
tion
s. T
here
is
also
a s
afet
y be
nefi
t in
the
are
a of
op
erat
or t
rain
ing
and
post
acc
iden
t op
erat
or a
ctio
ns, f
or e
xam
ple
elim
inat
ing
the
requ
irem
ent
for
hot l
eg s
wit
chov
er. T
here
are
add
ition
al s
afet
y be
nefi
ts f
rom
pla
nt c
hang
es th
at c
ould
res
ult f
rom
the
revi
sed
regu
latio
n. F
or e
xam
ple,
E
CC
S fl
ow c
ould
be
bala
nced
to
bette
r m
itig
ate
the
mor
e pr
obab
le s
mal
l br
eak
LO
CA
. The
saf
ety
mar
gin
is m
aint
aine
d by
the
Ris
k-In
form
ed a
ppro
ach,
whi
ch u
tiliz
es th
e D
efen
se-I
n-D
epth
phi
loso
phy
that
und
erlie
s th
e sa
fety
reg
ulat
ions
(SE
CY
-98-
300)
. By
util
izin
g ri
sk in
sigh
ts, r
esou
rces
can
be
dire
cted
to a
reas
of
grea
ter
risk
sig
nifi
canc
e, p
rovi
ding
an
incr
ease
in o
vera
ll p
lant
saf
ety.
The
fun
dam
enta
l des
ign
basi
s co
ncep
t is
not e
limin
ated
by
rede
fini
ng th
e L
BL
OC
A. T
he d
efin
ition
of
LO
CA
is b
eing
rev
ised
co
nsis
tent
with
ope
ratin
g ex
peri
ence
and
cur
rent
tec
hnol
ogie
s.
The
re w
ould
be
a ne
t in
crea
se i
n pl
ant
safe
ty d
ue t
o re
alis
tic
equi
pmen
t te
stin
g re
quir
emen
ts a
nd i
ncre
ased
rel
iabi
lity,
and
the
foc
usin
g of
res
ourc
es i
n m
ore
risk
sig
nifi
cant
are
as,
such
as
SBL
OC
A.
The
exi
stin
g de
sign
bas
is L
BL
OC
A r
egul
atio
n al
so i
mpo
ses
an a
rtif
icia
l re
stra
int
on f
utur
e de
velo
pmen
t. T
he c
urre
nt s
tate
of
know
ledg
e, te
chno
logy
, ana
lyti
cal t
echn
ique
s, a
nd o
pera
ting
expe
rien
ce p
rovi
de a
bas
is f
or r
egul
ator
y ch
ange
. G
idro
pres
s P
roba
bly,
the
only
ince
ntiv
e w
ould
be
the
plan
t eco
nom
ics.
The
refo
re it
is d
iffi
cult
to e
xpec
t tha
t reg
ulat
ory
body
wil
l ini
tiate
th
e ch
ange
s w
ith r
espe
ct to
des
ign
basi
s L
OC
A d
ecre
asin
g.
As
for
the
indu
stry
, VV
ER
NPP
des
igne
rs tr
y to
dec
reas
e th
e co
sts
incu
rred
by
curr
ent s
ize
of d
esig
n L
OC
A b
y ap
plyi
ng n
ew
conf
igur
atio
ns o
f th
e re
leva
nt s
afet
y sy
stem
s (i
mpl
emen
tati
on o
f pa
ssiv
e fe
atur
es, a
ssig
nmen
t of
norm
al a
nd s
afet
y fu
ncti
ons
to o
ne
syst
em, c
ombi
nati
on o
f lo
w-
and
high
pre
ssur
e sa
fety
inje
ctio
n, e
tc).
Pr
obab
ly, t
he u
tility
initi
ativ
es w
ould
be
the
mos
t eff
ectiv
e fo
r re
-con
side
rati
on o
f de
sign
LO
CA
siz
e (s
ince
the
insp
ectio
n an
d m
aint
enan
ce o
f sa
fety
sys
tem
s m
ay e
ssen
tiall
y ef
fect
to th
e ca
pita
l inv
estm
ents
and
gen
erat
ion
cost
s). H
owev
er, t
here
are
no
such
in
dica
tion
s ev
en in
the
rece
nt r
elev
ant d
ocum
ents
(li
ke E
UR
D).
RU
SSIA
Obs
erve
r
GA
N
N/A
Slov
enia
Obs
erve
r Fr
om th
e re
gula
tory
vie
wpo
int?
Non
e Fr
om th
e In
dust
ry v
iew
poin
t? N
othi
ng a
t the
mom
ent.
Dos
e an
d co
st s
avin
gs a
fter
pos
sibl
e sn
ubbe
r re
duct
ion
prog
ram
me.
52
Con
side
ratio
n fo
r th
e fu
ture
3.
If
you
are
con
side
ring
rep
laci
ng l
arge
bre
ak L
OC
A b
y a
smal
ler
brea
k si
ze w
ithi
n th
e de
sign
bas
is,
som
e de
gree
of
core
da
mag
e, s
hort
of
core
mel
t res
ultin
g in
ves
sel f
ailu
re, m
ay b
e ex
pect
ed if
a la
rge
brea
k L
OC
A a
ctua
lly o
ccur
red.
3.
a
How
wou
ld y
ou e
stab
lish
perf
orm
ance
req
uire
men
ts f
or t
he e
mer
genc
y co
olin
g sy
stem
s in
ord
er t
o pr
ovid
e so
me
assu
ranc
e th
at d
amag
e fo
llow
ing
a la
rge
brea
k L
OC
As
can
still
be
mit
igat
ed b
efor
e ve
ssel
fai
lure
? W
hat
is t
he t
echn
ical
bas
is?
BE
LG
IUM
N/A
CA
NA
DA
Can
ada
is n
ot c
onsi
deri
ng r
epla
cing
LL
OC
A.
CZ
EC
H
RE
PU
BL
IC
SUJB
Sa
fety
A
utho
rity
Cze
ch R
epub
lic is
not
con
side
ring
rep
laci
ng L
BL
OC
A. T
he la
rges
t or
lim
iting
bre
ak s
ize
assu
med
as
desi
gn b
asis
(L
OC
A)
is
doub
le E
nded
Gui
llotin
e L
B L
OC
A
(2x5
00 f
or V
VE
R 4
40/2
13 o
r 2x
850
for
VV
ER
100
0) .
All
spec
trum
of
LO
CA
Ana
lyse
s ar
e re
quir
ed f
or S
afet
y A
naly
sis.
N
RI
Rez
O
ptim
ize
pass
ive
EC
CS
FIN
LA
ND
Can
not
answ
er;
too
sens
itive
dep
ende
nce
on d
esir
ed c
onfi
denc
e le
vel
for
the
“som
e as
sura
nce”
and
als
o m
eani
ng o
f “m
itig
atio
n”. P
erfo
rman
ce r
equi
rem
ents
in te
rms
of r
elea
se li
mit
s et
c ca
n be
set
larg
ely
inde
pend
ent o
f te
chni
cal b
asis
. Tec
hnic
al b
asis
is
poo
rer
than
“ge
neri
c” s
ever
e ac
cide
nt k
now
ledg
e ba
se (
whi
ch h
as f
ocus
ed o
n la
ter
phas
es w
here
sta
te-o
f-th
e-ar
t is
now
muc
h m
ore
mat
ure
than
the
earl
y tr
ansi
ent p
hase
s, b
etw
een
beyo
nd-1
200°
C P
CT
s an
d co
re c
olla
pse)
.
IRSN
Fo
r th
e ex
istin
g pl
ants
, the
re i
s no
dec
isio
n fo
r re
plac
ing
LL
OC
A b
y a
smal
ler
brea
k si
ze. F
or t
he E
PR p
roje
ct, i
f la
rge
brea
k L
OC
A i
s re
plac
ed b
y a
smal
ler
brea
k si
ze w
ithi
n th
e de
sign
bas
is,
no s
afet
y ob
ject
ives
hav
e be
en y
et d
iscu
ssed
con
cern
ing
larg
e br
eak.
FR
AN
CE
ED
F
SEP
TE
N
- C
an w
e as
sure
saf
ety
inje
ctio
n in
RPV
und
er L
OC
A c
ondi
tion
with
out
LO
CA
in t
he d
esig
n tr
ansi
ent l
ist?
Not
sur
e, it
has
to
be a
naly
zed
GE
RM
AN
Y
A
t the
leve
l of
PSA
a la
rge
brea
k L
OC
A a
s an
initi
atin
g ev
ent i
s tr
eate
d in
the
sam
e w
ay a
s a
failu
re o
f la
rge
com
pone
nts.
Thi
s is
bas
ed o
n in
tegr
ity
anal
ysis
bei
ng p
erfo
rmed
acc
ordi
ng t
o th
e st
ate
of t
he a
rt. A
s fa
r as
str
uctu
ral
relia
bilit
y m
odel
s ar
e ap
plie
d th
e va
lida
tion
of
such
cod
es a
re n
ot s
atis
fact
ory
up to
now
for
bot
h ty
pes
of c
ompo
nent
s, p
ipin
gs a
s w
ell a
s ve
ssel
s.
NE
A/C
SNI/
R(2
003)
16
53
JAP
AN
(1)
We
thin
k th
at t
he L
B- L
OC
A s
houl
d be
reg
arde
d as
res
idua
l ri
sk i
f th
e oc
curr
ence
fre
quen
cy c
onfi
rmed
to
be s
uffi
cien
tly
low
with
tech
nica
l bas
is. T
his
mig
ht b
e th
e sa
me
reas
on a
s w
hy R
V b
otto
m f
ailu
re is
not
con
side
red
in th
e E
CC
S de
sign
bas
is.
(2)
It i
s no
t ra
tiona
l to
equ
ip w
ith t
oo m
uch
safe
ty s
yste
m f
or t
he e
vent
with
ver
y lo
w o
ccur
renc
e fr
eque
ncy.
If
a fu
rthe
r ra
tiona
lizat
ion
is s
ough
t fo
r m
itig
atio
n po
tent
ial
agai
nst
an L
B L
OC
A,
appl
icat
ion
of t
he s
ate-
of -
the-
art
know
ledg
e ab
out
IVR
and
be
st u
se o
f m
itig
atio
n m
easu
res
such
as
mit
igat
ion
acci
dent
man
agem
ent w
ill b
e of
val
ue.
ME
XIC
O
T
he e
mer
genc
y co
re c
ooli
ng s
yste
m (
EC
CS)
mus
t be
des
igne
d in
acc
orda
nce
with
and
acc
epta
ble
eval
uatio
n m
odel
and
mus
t be
cal
cula
ted
for
a nu
mbe
r of
pos
tula
ted
loss
-of-
cool
ant a
ccid
ent o
f di
ffer
ent s
izes
, loc
atio
ns a
nd o
ther
pro
pert
ies
suff
icie
nt to
pro
vide
as
sura
nce
that
the
mos
t se
vere
pos
tula
ted
loss
-of-
cool
ant
acci
dent
are
cal
cula
ted.
The
mod
el m
ust
to i
nclu
ded
suff
icie
nt s
uppo
rtin
g ju
stif
icat
ion
to s
how
tha
t th
e an
alyt
ical
tec
hniq
ue r
eali
stic
ally
des
crib
es t
he b
ehav
ior
of t
he r
eact
or s
yste
m d
urin
g lo
ss-o
f-co
olan
t ac
cide
nt. T
he u
ncer
tain
ty in
the
calc
ulat
ed r
esul
ts m
ust b
e es
tim
ated
. SL
OV
AK
R
EP
UB
LIC
Sa
fety
A
utho
rity
A
t pr
esen
t, th
erm
al-h
ydra
ulic
ana
lysi
s do
ne f
or a
ll L
OC
A s
izes
(up
to
2x50
0 m
m)
show
ed t
hat
even
in
the
case
of
a si
ngle
fa
ilure
of
EC
CS
thes
e tr
ansi
ents
do
not l
ead
to th
e co
re d
amag
e or
to th
e re
acto
r p
ress
ure
vess
el f
ailu
re.
VU
JE
N/A
SP
AIN
The
trea
tmen
t sho
uld
follo
w th
e sa
me
path
as
othe
r sc
enar
ios
like
this
, mai
nly
thos
e of
leve
l 2 P
SA. T
he a
ccep
tanc
e cr
iteri
a of
th
e fr
eque
ncy
of e
xcee
danc
e of
dam
age
to t
he v
esse
l an
d/or
con
tain
men
t sh
ould
be
mor
e pr
ecis
e. T
he e
nvel
opin
g ch
arac
ter
of
SBL
OC
A r
elat
ive
to L
BL
OC
A s
houl
d be
exp
lore
d in
det
ail,
revi
ewin
g al
l th
e as
pect
s of
des
ign
incl
udin
g co
ntai
nmen
t an
d ra
diol
ogic
al p
rote
ctio
n co
ncer
ns.
SWE
DE
N
N
o an
swer
s pr
ovid
ed
SWIT
ZE
RL
AN
D
N
o co
rres
pond
ing
cons
ider
atio
ns h
ave
been
per
form
ed a
t HSK
. U
NIT
ED
KIN
GD
OM
N
/A
USA
U
S N
RC
T
he d
esig
n cr
iter
ion
for
the
EC
CS
(i.e
., ha
rdw
a re)
is
expe
cted
to
still
be
base
d on
the
bre
ak o
f th
e la
rges
t pi
pe,
but
the
anci
llary
req
uire
men
ts (
e.g.
, te
chni
cal
spec
ific
atio
ns f
or s
afet
y in
ject
ion
flow
rat
es a
nd i
nspe
ctio
n fr
eque
ncie
s fo
r ac
cum
ulat
or
cond
ition
) w
ill b
e su
bjec
t to
ris
k-in
form
ed m
odif
icat
ion.
Tha
t is
, th
e E
CC
S w
ill m
aint
ain
its m
itiga
tion
fun
ctio
n fo
r al
l br
eak-
size
L
OC
As.
The
red
efin
ition
wou
ld a
lso
prov
ide
mor
e op
erat
iona
l fl
exib
ility
by
allo
win
g po
wer
upr
ates
, hi
gher
pea
king
fac
tors
and
as
sem
bly
disc
harg
e bu
rn-u
p.
In a
dditi
on, t
he 1
0 C
FR 5
0.46
acc
epta
nce
crite
ria
are
bein
g re
-exa
min
ed a
long
with
a r
e-de
fini
tion
of th
e m
axim
um b
reak
siz
e.
A v
olun
tary
alt
erna
tive
to th
e ex
istin
g cr
iteri
a is
und
er c
onsi
dera
tion
that
wou
ld m
aint
ain
the
requ
irem
ent f
or c
oola
ble
geom
etry
whi
le
NE
A/C
SNI/
R(2
003)
16
54
mak
ing
spec
ific
req
uire
men
ts f
or f
uel a
nd f
uel c
ladd
ing
perf
orm
ance
bas
ed.
WO
G
The
re m
ay b
e a
brea
k si
ze t
hres
hold
tha
t ca
n be
ack
now
ledg
ed a
s co
mpa
rabl
e to
ves
sel
fail
ure
in p
roba
bilit
y. T
he d
oubl
e-en
ded
brea
k of
the
larg
est R
CS
pipe
is li
kely
to f
all i
n th
is c
ateg
ory.
Thi
s sp
ectr
um o
f es
sent
iall
y in
cred
ible
bre
aks
coul
d be
add
ress
ed
in s
ever
e ac
cide
nt m
anag
emen
t as
a b
eyon
d-de
sign
-bas
is e
vent
. Rev
ised
PSA
suc
cess
cri
teri
a w
ould
be
esta
blis
hed
and
the
capa
bilit
y to
mit
igat
e th
e L
BL
OC
A a
s a
seve
re a
ccid
ent w
ould
be
reta
ined
.
Gid
ropr
ess
The
TM
I ca
se h
as p
rove
d th
at th
e in
-ves
sel r
eten
tion
of th
e es
sent
ially
dam
aged
cor
e is
pos
sibl
e by
inje
ctio
n of
wat
er. E
ven
if
the
EC
CS
will
be
desi
gned
for
sm
alle
r L
OC
A s
ize
(e.g
., fo
r 20
0 m
m b
reak
), i
t w
ill e
nsur
e t h
e (a
lrea
dy d
amag
ed)
core
coo
labi
lity
in
the
mid
- an
d lo
ng-t
erm
per
iods
of
LB
LO
CA
. The
cal
cula
ted
core
dam
age
duri
ng s
hort
-ter
m is
exp
ecte
d to
be
lim
ited
(si
nce
LB
LO
CA
be
com
es b
eyon
d-D
BA
, we
wil
l ap
ply
the
real
istic
app
roac
h in
stea
d of
con
serv
ativ
e de
term
i nis
tic a
naly
sis)
. So,
the
exi
stin
g te
chni
cal
basi
s w
ould
be
suff
icie
nt to
pre
vent
ves
sel f
ailu
re (
if s
uch
a re
quir
emen
t will
acc
ompa
ny th
e re
-def
initi
on o
f de
sign
LO
CA
).
RU
SSIA
Obs
erve
r
GA
N
N/A
Slov
enia
Obs
erve
r
N/A
NE
A/C
SNI/
R(2
003)
16
55
Con
side
ratio
n fo
r th
e fu
ture
3.
I
f yo
u ar
e co
nsid
erin
g re
plac
ing
larg
e br
eak
LO
CA
by
a sm
alle
r br
eak
size
wit
hin
the
desi
gn b
asis
, som
e de
gree
of
core
da
mag
e, s
hort
of
core
mel
t res
ultin
g in
ves
sel f
ailu
re, m
ay b
e ex
pect
ed if
a la
rge
brea
k L
OC
A a
ctua
lly o
ccur
red.
3.b
Are
cur
rent
ly a
vaila
ble
com
pute
r co
des
and
mod
els
adeq
uate
for
the
req
uire
d an
alys
es o
r ne
w t
ools
will
hav
e to
be
dev
elop
ed?
BE
LG
IUM
N/A
C
AN
AD
A
C
anad
a is
not
con
side
ring
rep
laci
ng L
LO
CA
. SU
JB
Safe
ty
Aut
hori
ty
N/A
C
ZE
CH
R
EP
UB
LIC
NR
I R
ez
No
answ
ers
prov
ided
F
INL
AN
D
C
anno
t ans
wer
– d
epen
ds to
o m
uch
on th
e am
biti
on le
vel b
ased
on
prev
ious
que
stio
n.
IRSN
Se
e 3a
F
RA
NC
E
ED
F
SEP
TE
N
- Pa
rtia
lly y
es f
or m
echa
nica
l asp
ect;
I d
on't
know
for
TH
asp
ects
GE
RM
AN
Y
A
t th
e le
vel
of P
SA a
lar
ge b
reak
LO
CA
as
an i
niti
atin
g ev
ent
is t
reat
ed i
n th
e sa
me
way
as
a fa
ilure
of
larg
e co
mpo
nent
s. T
his
is b
ased
on
inte
grity
ana
lysi
s be
ing
perf
orm
ed a
ccor
ding
to th
e st
ate
of th
e ar
t. A
s fa
r as
str
uctu
ral r
elia
bilit
y m
odel
s ar
e ap
plie
d th
e va
lidat
ion
of s
uch
code
s ar
e no
t sat
isfa
ctor
y up
to n
ow f
or b
oth
type
s of
com
pone
nts,
pip
ings
as
wel
l as
vess
els.
NE
A/C
SNI/
R(2
003)
16
56
JAP
AN
(1)
Yes
. We
thin
k th
at th
e cu
rren
t too
l is
adeq
uate
for
the
anal
ysis
of
the
proc
ess
at th
e in
itial
pha
se o
f th
e co
re d
amag
e,
how
ever
, not
suf
fici
ent f
or th
e pr
oces
s in
late
pha
se c
ore
dam
age.
(2)
How
ever
, w
e do
not
thi
nk i
t im
port
ant
to d
evel
op f
urth
er t
he c
ode
wit
h de
taile
d m
odel
ling.
Rat
her
we
shou
ld
cons
ider
the
app
roac
h of
re-
defi
ning
the
con
diti
ons
that
can
mai
ntai
n re
acto
r co
re c
oolin
g by
the
use
of
exis
ting
code
s an
d ex
peri
men
tal d
ata.
(3)
In s
truc
ture
rel
atio
n, c
alcu
latio
n co
des
whi
ch e
valu
ate
pipi
ng (
also
inc
ludi
ng R
PV)
relia
bilit
y sh
ould
be
impr
oved
. Fo
r ex
ampl
e, w
e re
gard
the
failu
re m
odes
(ra
tche
ting,
etc
.) w
hich
can
not b
e tr
eate
d by
the
sim
ple
frac
ture
mec
hani
cs, t
he la
test
ag
ing
phen
omen
on (
not
only
IG
SCC
but
PW
SCC
), w
all
thin
ning
due
to
flaw
ass
iste
d co
rros
ion,
the
fai
lure
cri
teri
a by
the
ea
rthq
uake
, etc
. sho
uld
be ta
ken
into
con
side
rati
on in
the
code
dev
elop
men
t. M
EX
ICO
The
cur
rent
ly c
ompu
ter
code
s av
aila
ble
in t
he n
ucle
ar i
ndus
try
are
cons
ider
ed a
dequ
ate
to s
imul
ated
dif
fere
nt b
reak
s L
OC
A.
How
ever
in
case
of
evol
utio
n of
the
acc
iden
t to
cor
e da
mag
e, t
he e
xper
imen
ts i
n th
is f
ield
hav
e be
en s
how
tha
t th
e m
odel
s of
the
com
pute
r co
des
need
to b
e im
prov
e. T
he p
rope
rtie
s of
the
mat
eria
l und
er h
igh
tem
pera
ture
s co
nditi
on, h
ydro
gen
prod
uctio
n, c
ore
degr
adat
ion,
coo
labi
lity
of th
e de
bris
, are
som
e to
pics
that
sho
uld
be in
vest
igat
ed.
SLO
VA
K
RE
PU
BL
IC
Safe
ty
Aut
hori
ty
At
pres
ent,
for
the
ther
mal
-hyd
raul
ic a
naly
sis
the
RE
LA
P 5
code
is
used
and
for
the
rea
ctor
pre
ssur
e ve
ssel
int
egri
ty
asse
ssm
ent t
he A
DIN
A c
ode
is u
sed.
V
UJE
N
/A
SPA
IN
C
odes
and
mod
els
seem
to b
e ev
olvi
ng in
the
righ
t dir
ectio
n SW
ED
EN
No
answ
ers
prov
ided
SW
ITZ
ER
LA
ND
Not
app
licab
le. H
SK h
as n
ot p
erfo
rmed
any
cor
resp
ondi
ng c
ode
eval
uatio
ns.
UN
ITE
D K
ING
DO
M
N/A
NE
A/C
SNI/
R(2
003)
16
57
USA
U
S N
RC
C
urre
ntly
ava
ilabl
e co
des
shou
ld b
e ca
pabl
e of
han
dlin
g ne
w L
BL
OC
A d
efin
ition
. H
owev
er,
new
ass
essm
ent
and
revi
ew w
ill b
e ne
cess
ary
as a
pplic
ants
mod
ify
plan
t ope
rati
ng c
ondi
tions
to ta
ke a
dvan
tage
of
the
prop
osed
cha
nge.
Cod
es m
ay
be u
sed
outs
ide
of th
eir
appr
oved
ran
ge o
f ap
plic
abili
ty.
Bec
ause
the
lar
ge b
reak
LO
CA
ana
lysi
s ha
s ha
d su
ch a
dom
inan
t im
pact
on
plan
t op
erat
ing
cond
ition
s, m
uch
of t
he
prio
r ex
peri
men
tal
rese
arch
has
bee
n di
rect
ed a
t un
ders
tand
ing
larg
e br
eak
LO
CA
phe
nom
ena
and
in d
emon
stra
ting
safe
ty
mar
gins
for
rea
ctor
sys
tem
s su
bjec
t to
a la
rge
LO
CA
. T
est r
esul
ts o
btai
ned
from
maj
or in
tegr
al te
st f
acili
ties
unde
r sm
all b
reak
L
OC
A c
ondi
tions
may
not
be
repr
esen
tativ
e of
the
exp
ecte
d tr
ansi
ents
in
reac
tor
syst
ems
that
hav
e be
en s
igni
fica
ntly
upr
ated
an
d as
sum
e m
ore
real
istic
saf
ety
inje
ctio
n fl
ow r
ates
. Thu
s, t
he e
xist
ing
expe
rim
enta
l da
taba
se f
or s
mal
ler
brea
k si
zes
at n
ew
plan
t ope
rati
ng c
ondi
tion
s w
ill n
eed
to b
e re
-exa
min
ed.
Impr
ovem
ent
in
PRA
m
odel
s m
ay
be
need
ed
to
inco
rpor
ate
pass
ive
syst
em
fail
ure
mod
es.
Im
prov
emen
ts
to
prob
abili
stic
fra
ctur
e m
echa
nics
cod
es a
re n
eede
d to
mod
el r
ecen
t de
grad
atio
n m
echa
nism
s to
est
imat
e fa
ilure
fre
quen
cies
and
br
eak
size
s fo
r pi
ping
sys
tem
s.
Sim
ilar
ly,
mod
els
are
need
ed t
o es
timat
e fr
eque
ncie
s an
d br
eak
size
s fo
r no
n-pi
pe f
ailu
re
LO
CA
s.
WO
G
It is
env
isio
ned
that
cur
rent
ly a
vail
able
cod
es a
nd m
odel
s w
ould
be
used
to a
naly
ze th
e L
BL
OC
A a
s a
seve
re a
ccid
ent.
RU
SSIA
Obs
erve
r G
idro
pres
s Y
es,
avai
labl
e co
des
(lik
e R
EL
AP/
SCD
AP,
ME
LC
OR
, si
mil
ar R
ussi
an c
odes
) ar
e as
who
le a
pplic
able
for
suc
h an
alys
es.
Prob
ably
, li
mite
d ch
ange
s w
ould
be
need
ed (
e.g.
, de
velo
pmen
t an
d va
lidat
ion
of m
ore
accu
rate
mod
els
for
core
de
bris
ref
lood
ing
or c
oriu
m-v
esse
l int
erac
tion
).
GA
N
N/A
Slov
enia
Obs
erve
r N
/A
NE
A/C
SNI/
R(2
003)
16
58
Oth
er is
sues
Wha
t ot
her
issu
es c
once
rnin
g L
OC
A d
o yo
u fe
el s
houl
d be
dis
cuss
ed d
urin
g th
e w
orks
hop?
B
EL
GIU
M
R
edef
inin
g th
e L
OC
A i
s no
t ju
st a
mat
ter
of s
ome
prob
abili
stic
cal
cula
tions
tog
ethe
r w
ith
som
e br
eak
prec
lusi
on c
onsi
dera
tions
. A
bro
ad d
iscu
ssio
n on
all
safe
ty i
mpl
icat
ions
, w
ith a
def
ense
-in-
dept
h ap
proa
ch,
is n
eede
d.
We
expe
ct th
at th
e w
orks
hop
will
all
ow th
e re
leva
nt to
pics
to b
e id
entif
ied
and
put i
n pe
rspe
ctiv
e.
CA
NA
DA
Can
ada
does
not
wis
h to
add
oth
er is
sues
to th
e ag
enda
. SU
JB
Safe
ty
Aut
hori
ty
N/A
C
ZE
CH
R
EP
UB
LIC
NR
I R
ez
No
Bre
ak Z
ones
FIN
LA
ND
Ade
quat
e re
fere
nce
to s
ump
/ su
ctio
n st
rain
er p
erfo
rman
ce i
ssue
s (a
nd r
elat
ed o
ngoi
ng w
ork
such
as
the
fort
hcom
ing
NE
A W
orks
hop
on t
he i
ssue
s) s
houl
d be
mad
e. T
his
is a
n ex
ampl
e w
here
muc
h m
ore
(als
o re
gula
tory
) at
tent
ion
is n
eede
d to
att
ain
a co
nsis
tent
set
of
safe
ty r
equi
rem
ents
(co
nsis
tenc
y be
twee
n re
quir
emen
ts o
n de
sign
, de
mon
stra
tion
, ope
rati
onal
sur
veill
ance
, mai
nten
ance
, etc
).
IRSN
-
issu
es c
once
rnin
g L
OC
A s
tudi
es m
etho
dolo
gy (
assu
mpt
ions
, bou
ndar
y co
nditi
ons,
cod
es m
odel
s, c
rite
ria…
).
- ge
nera
lly
spea
king
: wha
t cou
ld b
e th
e co
nseq
uenc
es f
or s
afet
y (n
egat
ive
and/
or p
ositi
ve).
F
RA
NC
E
ED
F
SEP
TE
N
- ju
stif
icat
ion
of L
BB
wit
h di
ffer
ent t
ype
of p
ossi
ble
degr
adat
ion
mec
hani
sms
for
40 o
r 60
yea
rs o
f op
erat
ion
- le
ak d
etec
tion
capa
bilit
y re
quir
emen
ts
- R
I-IS
I re
sults
and
rea
listic
IS
I pr
ogra
m
GE
RM
AN
Y
N
o an
swer
s pr
ovid
ed
JAP
AN
App
roac
hes
prac
ticab
le t
o re
solv
e th
e is
sues
; ro
les
o f r
egul
ator
, re
sear
cher
s an
d th
e in
dust
ry.
Suc
h is
sues
as
avai
labi
lity
of p
lant
per
form
ance
dat
a ar
e of
int
erfa
cing
con
cern
s. A
lso
poss
ible
adv
erse
eff
ects
on
oper
atio
n or
m
aint
enan
ce o
rigi
nate
d fr
om c
urre
nt L
B-L
OC
A a
ssum
ptio
ns, o
r ad
equa
te r
esou
rce
dist
ribu
tion
to
enha
nce
safe
ty f
rom
th
e ri
sk p
ersp
ectiv
es.
NE
A/C
SNI/
R(2
003)
16
59
ME
XIC
O
N
/A
SLO
VA
K
RE
PU
BL
IC
Safe
ty
Aut
hori
ty
Lon
g te
rm s
truc
tura
l int
egri
ty o
f pr
imar
y ci
rcui
t pip
ing.
VU
JE
Slov
akia
doe
s no
t wis
h to
add
oth
er is
sues
to th
e ag
enda
.
SPA
IN
R
isk-
info
rmed
reg
ulat
ion
/ C
onse
quen
ces
or r
emov
ing
LB
LO
CA
fro
m d
esig
n ba
sis
enve
lope
/ B
est-
estim
ate
LO
CA
ana
lyse
s / A
dvan
ced
desi
gns
conc
erns
, and
fee
dbac
k to
our
cur
rent
tech
nolo
gy.
SWE
DE
N
N
o an
swer
s pr
ovid
ed
SWIT
ZE
RL
AN
D
E
valu
atio
n of
the
fre
quen
cy o
f a
larg
e br
eak
LO
CA
and
eve
n of
an
exce
ssiv
e L
OC
A (
brea
k of
the
rea
ctor
pr
essu
re v
esse
l).
UN
ITE
D K
ING
DO
M
If a
ppro
pria
te, H
igh
burn
up
fuel
beh
avio
ur u
nder
LO
CA
s co
nditi
ons.
USA
U
S N
RC
“R
ealis
tic”
oper
ator
res
pons
e as
sum
ptio
ns.
Con
trib
utio
n of
non
-pip
e-br
eak
LO
CA
s.
PRA
Qua
lity
and
com
plet
enes
s E
lem
ents
of
the
new
req
uire
men
t (a
ris
k-in
form
ed a
lter
nativ
e to
the
max
imum
LO
CA
bre
ak s
ize)
inc
ludi
ng
conf
igur
atio
n co
ntro
l dur
ing
all m
odes
of
oper
atio
ns.
WO
G
Poss
ible
pilo
t sub
mit
tals
to d
emon
stra
te th
e fe
asib
ility
of
the
rule
cha
nge
RU
SSIA
O
bser
ver
Gid
ropr
ess
Wha
t w
ould
be
th
e “m
echa
nist
ical
” ba
sis
to
assi
gn
the
scal
e (s
ize)
of
de
sign
L
OC
A
(i.e
., w
hat
proc
esse
s/ph
enom
ena
in t
he R
CS
pres
sure
bou
ndar
y m
ight
lea
d to
sud
den
leak
of
esse
ntia
l si
ze a
nd h
ow t
o ca
lcul
ate
thos
e pr
oces
ses/
phen
omen
a)?
Or
the
desi
gn L
OC
A s
ize
is s
olel
y an
adm
inis
trat
ive
deci
sion
?
GA
N
N/A
Slov
enia
Obs
erve
r N
o Su
gges
tions
.
NE
A/C
SNI/
R(2
003)
16
60
App
endi
x 1
In
form
atio
n pr
ovid
ed b
y th
e U
SNR
C to
com
plem
ent t
he a
nsw
er o
n qu
estio
n fu
ture
2
Con
side
ratio
n fo
r th
e fu
ture
2. W
hat w
ould
be
the
ince
ntiv
es?
Fro
m th
e re
gula
tory
vie
wpo
int?
Fro
m t
he I
ndus
try
view
poin
t?
Indu
stry
vie
wpo
int
The
fol
low
ing
list i
s fr
om a
n in
dust
ry le
tter
to N
RC
Item
Sa
fety
Ben
efit
a)
Acc
umul
ator
1)
Dec
reas
e th
e nu
mbe
r of
acc
umul
ator
s re
quir
ed t
o be
op
erab
le
2)
Para
met
ers
(bor
on
conc
entr
atio
n,
wat
er
volu
me,
co
ver
pres
sure
) -
rela
x ac
cept
able
par
amet
er r
ange
. 3)
Inc
reas
e A
OT
s
Red
uced
ch
ance
fo
r in
adve
rten
t in
ject
ion
from
ac
cum
ulat
or.
(Not
ver
y lik
ely,
but
mor
e pr
obab
le t
han
a L
BL
OC
A)
Rev
isio
n of
T
ech.
Sp
ecs.
sh
utdo
wn
requ
irem
ents
as
soci
ated
with
acc
umul
ator
s w
ould
red
uce
likel
ihoo
d of
fo
rced
shu
tdow
n an
d re
sulti
ng t
herm
al c
ycle
on
plan
t. M
ore
real
istic
Tec
h. S
pecs
eas
es o
pera
tiona
l bu
rden
s en
ablin
g op
erat
ors
to b
ette
r fo
cus
on s
afet
y si
gnif
ican
t ac
tivit
ies
Red
uces
the
pot
entia
l fo
r un
nece
ssar
y pl
ant
shut
dow
ns
and
redu
ces
the
num
ber
of
oper
atio
nal
and
ther
mal
tr
ansi
ents
W
ider
ac
cum
ulat
or
para
met
er
band
s w
ould
re
duce
pe
riod
ic a
djus
tmen
ts a
nd t
hus
the
chan
ces
for
EC
CS
valv
e m
isal
ignm
ent
NE
A/C
SNI/
R(2
003)
16
61
b) D
iese
l G
ener
ator
Sta
rt T
ime
Incr
ease
(E
xpan
d to
all
EC
CS
resp
onse
tim
es.)
req
uire
men
ts.
Red
uced
wea
r an
d te
ar o
n di
esel
fro
m m
ore
reas
onab
le
test
ing
Incr
ease
d di
esel
rel
iabi
lity
- le
ss n
eed
for
inva
sive
tr
oubl
esho
otin
g.
Red
uces
the
pot
enti
al f
or m
aint
enan
ce e
rror
s w
hich
cou
ld
resu
lt
in
chal
leng
es
to
the
plan
t's
safe
ty
syst
ems
by
redu
cing
th
e fr
eque
ncy
of
mai
nten
ance
an
d in
spec
tion
ac
tivit
ies.
c)
Die
sel G
ener
ator
Loa
ding
tim
es
Rel
axed
die
sel
load
ing
tim
es d
urin
g an
acc
iden
t re
spon
se
wou
ld e
nhan
ce d
iese
l rel
iabi
lity.
d) C
ore
Peak
ing
Fact
or I
ncre
ases
(FQ
or
Fdel
taH
) W
ider
pea
king
fac
tor
band
s w
ould
res
ult
in l
ess
oper
ator
re
acti
vity
m
anip
ulat
ions
an
d po
tent
ially
le
ss
adve
rse
excu
rsio
ns
NE
A/C
SNI/
R(2
003)
16
62
e) C
onta
inm
ent D
esig
n C
alcu
latio
ns
1) L
ower
Pea
k Pr
essu
re in
Ana
lysi
s
Man
y pl
ants
ar
e lim
ited
by
SL
B,
but
Pa
coul
d be
lo
wer
ed s
ince
it is
dri
ven
by L
OC
A o
nly.
2)
Eva
luat
e el
imin
atio
n of
sub
-com
part
men
t an
alys
es
wit
h th
e sm
alle
r cr
edib
le m
axim
um L
OC
A s
ize.
Wor
ker
safe
ty b
enef
it f
rom
per
form
ing
leak
rat
e te
sts
at
low
er p
ress
ure.
f) M
odif
y Sp
ray
Syst
em
1) R
educ
e th
e re
quir
ed f
low
rat
e of
the
spr
ays,
and
/or
rela
x su
rvei
llanc
e re
quir
emen
ts.
Due
to
defe
nse
in d
epth
con
cern
s, r
educ
ing
the
num
ber
of s
pray
s w
ill n
ot b
e pu
rsue
d.
Eli
min
atio
n of
TS
shut
dow
n re
quir
emen
t as
soci
ated
with
C
S w
ould
re
duce
lik
elih
ood
of f
orce
d sh
utdo
wn
and
asso
ciat
ed t
herm
al c
ycle
on
plan
t. (A
lso
see
item
(a)
ab
ove)
NE
A/C
SNI/
R(2
003)
16
63
g) M
odif
y Fa
n C
oole
r re
quir
emen
ts.
Red
uce
the
num
ber
or
incr
ease
th
e A
OT
. C
onsi
der
relo
cati
ng to
the
Tec
hnic
al R
equi
rem
ents
Man
ual.
See
item
s (a
) an
d (b
) ab
ove
h) U
ltim
ate
Hea
t Sin
k -
Rel
ax R
equi
rem
ents
. M
axim
um
post
-LO
CA
he
at
load
s oc
cur
duri
ng
the
inje
ctio
n ph
ase
for
plan
ts
with
sa
fety
- rel
ated
co
ntai
nmen
t ai
r re
circ
ulat
ion
cool
ers,
or
at t
he t
ime
of
sum
p re
circ
ulat
ion
switc
hove
r fo
r pl
ants
w
ithou
t co
ntai
nmen
t air
rec
ircu
latio
n co
oler
s.
Incr
ease
in
oper
atio
nal
mar
gins
red
uce
the
like
lihoo
d of
un
nece
ssar
y pl
ant
shut
dow
ns.
(see
(a
) an
d (b
) ab
ove)
i) P
ower
Upr
ates
j) E
CC
S Fl
ow I
ssue
s 1)
Cha
nge
Flow
bal
anci
ng r
equi
rem
ents
2)
Dec
reas
e sy
stem
res
ista
nce
if L
BL
OC
A r
unou
t is
no
long
er a
cre
dibl
e co
ncer
n 3)
For
thr
ee t
rain
sys
tem
s, e
lim
inat
e th
e ne
ed f
or s
ome
EC
CS
pum
ps
4) R
educ
es s
ensi
tivit
y to
pum
p de
grad
atio
n
Incr
ease
s E
CC
S ef
fect
iven
ess
for
mor
e pr
obab
le
even
ts.
Red
uces
ope
rato
r bu
rden
by
enha
ncin
g fo
cus
on m
ore
prob
able
eve
nts
Sim
plif
ies
conf
igur
atio
n m
anag
emen
t
NE
A/C
SNI/
R(2
003)
16
64
k) O
pera
tor
Act
ion
Tim
e fo
r R
WST
Sw
itch
over
Rev
iew
the
ope
rato
r-tr
aini
ng p
rogr
am t
o de
term
ine
if
too
muc
h em
phas
is is
pla
ced
on th
e L
BL
OC
A.
Red
uced
op
erat
or
burd
en.
Ope
rato
r ac
tions
ca
n be
im
prov
ed
by
bett
er
sequ
enci
ng
of
oper
ator
ac
tion
s co
nsis
tent
with
saf
ety-
sign
ific
ant o
pera
tion
al n
eeds
and
sc
enar
io p
rogr
essi
ons
NO
TE
: doe
s no
t app
ly to
all
desi
gns,
som
e de
sign
s an
d pl
ants
hav
e au
tom
atic
sw
itcho
ver
to r
ecir
cula
tion
l) R
esol
utio
n of
Sum
p D
ebri
s Is
sues
(sho
w th
at le
ss (
or n
o) d
ebri
s is
cre
ated
with
the
revi
sed
LO
CA
bre
ak s
ize
to b
e an
alyz
ed)
Red
uce
wor
ker
expo
sure
. A
LA
RA
: Po
tent
ial
for
avoi
ding
oc
cup a
tiona
l do
se
from
m
odif
icat
ions
th
at
coul
d re
sult
from
the
sum
p de
bris
res
olut
ion.
m)
Res
olut
ion
of G
L 8
9-10
MO
V I
ssue
s
(cha
nge
MO
V te
st r
equi
rem
ents
incl
udin
g cl
osur
e tim
es
and
mot
ive
forc
es I
val
ve d
elta
pre
ssur
e)
May
be
a sp
ecia
l tr
eatm
ent
requ
irem
ent.
Not
e th
at t
his
rule
cha
nge
is n
ot r
equi
red
to r
isk
info
rm M
OV
test
ing.
Red
uce
wor
ker
expo
sure
. A
LA
RA
be
nefi
ts
from
re
duce
d te
stin
g sc
ope.
M
ore
relia
ble
valv
es
if
set
for
mor
e re
alis
tic
requ
irem
ents
.
n)
Res
olut
ion
of C
onta
inm
ent P
urge
Val
ve I
ssue
s R
elax
min
i pur
ge v
alve
clo
sure
tim
es a
nd le
akag
e ra
tes.
o) R
educ
e R
WST
Bor
on c
once
ntra
tion
Impr
oved
m
ater
ial
relia
bilit
y an
d re
duce
s op
erat
or
actio
n re
quir
emen
ts
p) I
mpr
oved
Fue
l Des
ign
Issu
es
Con
side
r re
duci
ng
boro
n an
d bu
rnab
le
pois
on
requ
irem
ents
, and
low
erin
g en
rich
men
ts.
NE
A/C
SNI/
R(2
003)
16
65
q)
Con
tain
men
t EQ
Tem
pera
ture
Pro
file
Rel
axat
ion
In
crea
sed
oper
atio
nal
mar
gins
red
uce
the
pote
ntia
l fo
r un
nece
ssar
y ou
tage
s.
NE
A/C
SNI/
R(2
003)
16
66
App
endi
x II
Info
rmat
ion
prov
ided
by
GR
S (G
erm
any)
to c
ompl
emen
t th
e an
swer
to
ques
tion
"C
urre
nt R
egul
ator
y F
ram
ewor
k 4"
RSK
Gui
delin
es w
ill b
e ad
ded
late
r T
RA
NSL
AT
ION
S-SA
FE
TY
CO
DE
S A
ND
GU
IDE
S A
men
dmen
ts to
Edi
tion
5/8
2 C
onte
nts
R
evis
ed S
ec. 2
1 of
the
RSK
Gui
delin
es f
or P
ress
uriz
ed W
ater
Rea
ctor
s, 3
rd E
ditio
n, O
ctob
er 1
4, 1
981
Ube
rarb
eite
tes
Kap
. 21
der
RSK
Lei
tlini
en f
iir D
ruck
was
serr
eakt
oren
3. A
usga
be, 1
4 O
ktob
er 1
981
Sec.
21
of t
he R
SK G
uide
lines
for
Pre
ssur
ized
Wat
er R
eact
ors
has
been
rev
ised
as
publ
ishe
d by
the
Ger
man
Fed
eral
Min
iste
r of
the
Inte
rior
in
the
Bun
desa
nzei
ger
No.
106
on
June
l0, 1
983
and
No.
104
on
June
5, 1
984
If th
ere
are
any
inte
rpre
tatio
n di
ffic
ultie
s, th
e G
erm
an o
rigi
nal a
s pu
blis
hed
is d
efin
ite.
21
Post
ulat
ed L
eaks
and
Bre
aks
21.1
Po
stul
ated
Lea
k C
ross
Sec
tions
in th
e M
ain
Coo
lant
Pip
e In
clud
ing
Aus
teni
tic C
onne
ctio
n Pi
pes
(Ste
el 1
.455
0) o
f D
iam
eter
> 2
00 m
m a
nd in
th
e R
eact
or P
ress
ure
Ves
sel.
(1)
Rea
ctio
n an
d je
t for
ces
actin
g on
pip
es, c
ompo
nent
s, c
ompo
nent
inte
rnal
s, a
nd b
uild
ings
.
NE
A/C
SNI/
R(2
003)
16
67
1*
Con
cern
ing
the
load
ass
umpt
ion
for
reac
tion
and
jet f
orce
s on
pip
es, c
ompo
nent
s, a
nd s
truc
ture
s a
leak
wit
h a
cros
s se
ctio
n of
0,l
F (F
= o
pen
cros
s se
ctio
n) a
nd s
tatic
out
flow
sha
ll be
pos
tula
ted
for
diff
eren
t br
eak
posi
tions
. A
s lo
ad a
ssum
ptio
n fo
r th
e re
acto
r pr
essu
re v
esse
l in
tern
als
a sp
onta
neou
sly
open
ing
leak
(li
near
ope
ning
beh
avio
ur,
open
ing
tim
e 15
ms)
wit
h a
cros
s se
ctio
n of
0,l
F in
the
mai
n co
olan
t pi
pes
shal
l be
po
stul
ated
for
dif
fere
nt b
reak
pos
ition
s.
2.
In o
rder
to
cope
with
the
con
sequ
ence
s (p
ress
ure
incr
ease
in
the
reac
tor
pit,
rele
ase-
pres
sure
-wav
e ac
ting
on
the
reac
tor
pres
sure
ves
sel
inte
rnal
s) o
f a
post
ulat
ed l
eak
wit
h a
cros
s se
ctio
n of
0,l
F be
twee
n th
e re
acto
r pr
essu
re v
esse
l an
d th
e bi
olog
ical
shi
eld,
mea
sure
s sh
all
be t
aken
, e.
g. d
oubl
e pi
pes
in th
e ar
ea o
f th
e m
ain
cool
ant p
ipe
pene
trat
ions
thro
ugh
the
biol
ogic
al s
hiel
d.
(2)
Pr
esum
ptio
ns f
or th
e de
sign
and
the
safe
ty d
emon
stra
tion
of th
e em
erge
ncy
core
coo
ling
syst
ems,
the
con
tain
men
t ve
ssel
and
its
inte
rnal
s as
w
ell a
s th
e su
ppor
ts o
f th
e re
acto
r co
olan
t sys
tem
com
pone
nts.
For
the
desi
gn a
nd e
xam
inat
ion
by c
alcu
latio
n th
e fo
llow
ing
post
ulat
es a
re r
elev
ant:
1.
The
ana
lysi
s of
the
em
erge
ncy
core
coo
ling
effi
cien
cy (
refe
renc
e to
Sec
., 22
.1.1
) sh
all
be b
ased
on
leak
cro
ss s
ectio
ns i
n th
e m
ain
cool
ant
pipe
s up
to 2
F. T
he e
mer
genc
y co
re c
ooli
ng s
yste
ms
shal
l be
desi
gned
acc
ordi
ngly
.
2.
The
det
erm
inat
ion
of t
he c
onta
inm
ent
vess
el d
esig
n pr
essu
re a
s w
ell
as t
he d
eter
min
atio
n of
pre
ssur
e di
ffer
ence
s in
side
the
con
tain
men
t ve
ssel
sha
ll be
bas
ed o
n le
ak c
ross
sec
tion
up to
2 F
. T
he d
eter
min
atio
n of
des
ign
pres
sure
and
des
ign
tem
pera
ture
for
inc
iden
t re
sist
ant
elec
tric
al e
quip
men
t sh
all
be b
ased
on
leak
cro
ss s
ecti
on o
f 2
F as
wel
l. 3.
Fo
r th
e de
mon
stra
tion
of s
tabi
lity
of t
he c
ompo
nent
s re
acto
r pr
essu
re v
esse
l, st
eam
gen
erat
ors,
mai
n co
olan
t pu
mps
, an
d pr
essu
rize
r th
e fo
llow
ing
assu
mpt
ions
sha
ll be
mad
e:
The
sta
bilit
y of
the
com
pone
nts
shal
l be
assu
red
for
a st
atic
for
ce P
ax
mag
nitu
de:
Pax
=p
x F
x S
P
= n
omin
al o
pera
ting
pres
sure
F =
ope
n cr
oss
sect
ion
S =
2 (
safe
ty m
argi
n)
*
Not
e: T
his
defi
nitio
n is
rel
evan
t for
the
desi
gn r
equi
rem
ents
in S
ec.
3.3
(1)
Rea
ctor
pre
ssur
e ve
ssel
inte
rnal
s 5.
1 (5
) C
onta
inm
ent v
esse
l int
erna
ls
5.2
(l),
(5)
Ele
ctri
cal e
quip
men
t ins
ide
the
cont
ainm
ent v
esse
l
NE
A/C
SNI/
R(2
003)
16
68
or
igin
mid
dle
line
of th
e pi
pe c
ross
sec
tion
in th
e ar
ea o
f th
e no
zzle
of
for
ce:
circ
umfe
rent
ial w
eld
mid
dle
line
of th
e no
zzle
act
ing
dire
ctio
n
of
for
ce:
tow
ards
the
com
pone
nt
T
his
forc
e ac
ts o
nly
on o
ne n
ozzl
e at
a ti
me.
The
sta
bilit
y sh
all b
e de
mon
stra
ted
for
each
noz
zle
sepa
rate
ly.
Not
e: w
ith
resp
ect t
o th
e st
eam
gen
erat
or th
e st
abili
ty s
hall
be a
ssur
ed f
or th
e co
nnec
tion
to th
e se
cond
ary
circ
uit i
n th
e sa
me
way
. (3
)
Det
erm
inis
tic p
ostu
late
d le
ak c
ross
sec
tion
in th
e re
acto
r pr
essu
re v
esse
l 1.
In
vie
w o
f th
e re
stra
ints
of
the
reac
tor
pres
sure
ves
sel,
the
stre
sses
act
ing
on t
he r
eact
or p
ress
ure
vess
el i
nter
nals
and
the
des
ign
of t
he
emer
genc
y co
re c
oolin
g sy
stem
, a
leak
of
abou
t 20
cm
2 (g
eom
etri
c cr
oss
sect
ion:
cir
cula
r) s
hall
als
o be
pos
tula
ted
belo
w,
the
reac
tor
core
up
per
edge
. Pr
ior
defe
cts
of t
he r
eact
or p
ress
ure
vess
el w
hich
mig
ht l
ead
to a
lea
k si
ze o
f m
ore
than
20
cm2 s
hall
be d
etec
tabl
e in
tim
e by
m
eans
of
suit
able
mon
itor
ing
mea
sure
s.
2.
The
des
ign
shal
l al
so b
e ba
sed
on t
he c
onse
quen
ces
of t
he s
udde
n br
eak
of a
con
trol
ass
embl
y no
zzle
inv
olvi
ng t
he m
axim
um p
ossi
ble
leak
cr
oss
sect
ion
as w
ell a
s th
e po
stul
ated
leak
s in
the
reac
tor
pres
sure
ves
sel.
(4)
Pre
ssur
e ba
rrie
r of
the
low
-pre
ssur
e sy
stem
tow
ards
the
high
-pre
ssur
e sy
stem
.
Pro
visi
ons
shal
l be
mad
e ag
ains
t pr
essu
rizi
ng o
f th
e lo
w-p
ress
ure
syst
em a
s a
resu
lt of
a f
ailu
re o
f th
e pr
essu
re b
arri
er t
owar
ds t
he h
igh-
pres
sure
sys
tem
. (pr
essu
re-r
etai
ning
bou
ndar
y) (
e.g.
rec
urre
nt te
sts
of v
alve
fun
ctio
ns, m
easu
rem
ents
of
the
pres
sure
bet
wee
n tw
o su
cces
sive
val
ves
and
the
indi
catio
n of
leak
s in
the
cont
rol r
oom
).
21.2
Po
stul
ated
Lea
ks a
nd B
reak
s in
the
Mai
n St
eam
and
/ or
Feed
wat
er P
ipe
(1)
Fo
r th
e m
ain
stea
m a
nd f
eedw
ater
pip
es b
etw
een
stea
m g
ener
ator
and
val
ve s
tatio
n ou
tsid
e th
e co
ntai
nmen
t ve
ssel
, le
aks
resu
lting
fro
m
subc
ritic
al c
rack
s ar
e po
stul
ated
. The
se c
an e
ither
be
dete
rmin
ed o
n th
e ba
sis
of f
ract
ure
mec
hani
cs o
r ar
e lim
ited
to 0
,l F.
NE
A/C
SNI/
R(2
003)
16
69
With
reg
ard
to t
he l
oad
assu
mpt
ions
for
the
rea
ctio
n an
d je
t fo
rces
act
ing
on t
he m
ain
stea
m a
nd f
eedw
ater
pip
es i
n th
e ar
ea b
etw
een
stea
m
gene
rato
r an
d fi
rst
isol
atin
g va
lve
outs
ide
the
cont
ainm
ent
vess
el,
an 0
,l F
leak
ope
ning
("F
" =
ope
n cr
oss-
sect
ion
of t
he p
ipe)
and
sta
tic
outf
low
sh
all b
e po
stul
ated
to c
over
all
poss
ibili
ties.
(2
)
With
reg
ard
to d
ynam
ic l
oads
, in
com
ing
rele
ase-
pres
sure
-wav
es e
ithe
r re
sulti
ng f
rom
bre
aks
in p
ipe
area
s lo
cate
d be
hind
the
fir
st i
sola
ting
valv
e ou
tsid
e th
e co
ntai
nmen
t ve
ssel
, or
pos
tula
ted
as a
res
ult
of e
xter
nal
impa
cts,
sha
ll be
app
lied
and
used
as
a de
sign
bas
is.
For
this
pu
rpos
e, a
cir
cum
fere
ntia
l rup
ture
hav
ing
a li
near
ope
ning
beh
avio
r an
d an
ope
ning
tim
e of
15
mse
c is
pos
tula
ted
as in
put f
or th
e ca
lcul
atio
n.
Usi
ng th
is a
ssum
ptio
n, a
naly
ses
of d
ynam
ic lo
ads
resu
lting
fro
m s
ubcr
itica
l cra
cks
are
not n
eces
sary
. (3
)
As
far
as th
e st
abili
ty o
f th
e st
eam
gen
erat
or is
con
cern
ed, t
he f
ollo
win
g fo
rmal
ass
umpt
ions
sha
ll be
mad
e w
ith
a vi
ew to
the
conn
ectio
n of
th
e se
cond
ary
cir
cuit
(cf.
Sec
. 21-
l (2)
3.)
:
The
sta
bilit
y of
the
stea
m g
ener
ator
has
to b
e as
sure
d fo
r th
e st
atic
equ
ival
ent f
orce
Pax
in a
dditi
on to
its
dead
wei
ght.
M
agni
tude
:
Pax
=2
x p
x F
P =
nom
inal
ope
ratin
g pr
essu
re
:
F =
ope
n cr
oss
sect
ion
or
igin
of
forc
e:
mid
dle
of p
ipe
cros
s se
ctio
n in
the
area
of
the
firs
t con
nect
ing
wel
d di
rect
ion
of f
orce
m
iddl
e lin
e of
the
nozz
le a
ctin
g to
war
ds
forc
e
th
e co
mpo
nent
Thi
s fo
rce
only
act
s on
one
noz
zle
at a
tim
e. S
tabi
lity
shal
l be
dem
onst
rate
d fo
r ea
ch n
ozzl
e se
para
tely
. (4
) T
he l
oads
act
ing
on t
he s
team
gen
erat
or h
eati
ng t
ubes
due
to
the
stat
ic a
nd t
rans
ient
str
esse
s (p
ress
ure
wav
es,
flow
for
ces,
sta
tic p
ress
ure
diff
eren
ces
over
the
ste
am g
ener
ator
hea
ting
tube
s) i
n th
e ca
se o
f a
mai
n st
eam
or
feed
wat
er p
ipe
brea
k or
the
non
-clo
sure
of
a sa
fety
val
ve
on th
e se
cond
ary
side
, sha
ll be
det
erm
ined
. It s
hall
be
dem
onst
rate
d th
at th
e st
eam
gen
erat
or h
eatin
g tu
bes
cope
wit
h th
ese
stre
sses
.
How
ever
, as
a m
atte
r of
pri
ncip
le, w
hen
carr
ying
out
an
inci
dent
ana
lysi
s fo
r a
mai
n st
eam
pip
e br
eak,
the
fai
lure
of
a fe
w s
team
gen
erat
or
heat
ing
tube
s sh
all
be p
ostu
late
d as
an
addi
tion
al f
ailu
re o
ccur
ring
acc
iden
tally
and
not
as
a re
sult
of
the
mai
n st
eam
pip
e br
eak.
Thi
s fa
ilure
sha
ll be
take
n in
to a
ccou
nt b
y po
stul
atin
g, a
s an
env
elop
e, th
e co
mpl
ete
rupt
ure
(2F)
of
a st
eam
gen
erat
or h
eatin
g tu
be in
the
stea
m g
ener
ator
con
cern
ed.
NE
A/C
SNI/
R(2
003)
16
70
In s
uch
a ca
se, a
sin
gle
failu
re a
t som
e ot
her
loca
tion
need
no
long
er b
e po
stul
ated
in th
is in
cide
nt a
naly
sis.
In
the
cas
e of
a m
ain
stea
m p
ipe
brea
k ou
tsid
e th
e ou
ter
isol
atin
g va
lve
and
acco
mpa
nied
by
an a
ddit
iona
l si
ngle
fai
lure
ref
erre
d to
as
"non
-cl
osur
e of
the
iso
latin
g va
lve"
, a
stea
m g
ener
ator
hea
ting
tube
fai
lure
nee
d no
t be
pos
tula
ted
if t
he a
fore
men
tion
ed l
oad
dem
onst
rati
on h
ad a
po
siti
ve r
esul
t. In
the
case
of
a fe
edw
ater
pip
e br
eak,
a s
team
gen
erat
or h
eatin
g tu
be f
ailu
re n
eed
not b
e po
stul
ated
. If
sub
criti
cal
crac
ks s
uch
as r
efer
red
to i
n (1
) ab
ove,
or
a ru
ptur
e of
a s
mal
l pi
pe, a
re p
ostu
late
d, n
o ad
diti
onal
ste
am g
ener
ator
hea
ting
tube
fa
ilure
is s
uper
impo
sed.
(5
)
The
eff
ects
of
a m
ain
stea
m p
ipe
brea
k an
d of
a c
old
wat
er t
rans
ient
on
the
reac
tivit
y be
havi
or a
nd o
n pr
essu
re a
nd t
empe
ratu
re
chan
ges
insi
de th
e re
acto
r, a
s w
ell a
s th
e re
sulti
ng s
tres
ses
acti
ng o
n th
e re
acto
r pr
essu
re v
esse
l and
its
inte
rnal
s, m
ust b
e co
ped
with
.
NE
A/C
SNI/
R(2
003)
16
71
App
endi
x II
I
Info
rmat
ion
prov
ided
by
STU
K (F
inla
nd)
LB
B A
ND
FA
ILU
RE
FR
EQ
UE
NC
Y R
EQ
UIR
EM
EN
TS
IN T
HE
FIN
NIS
H G
UID
EL
INE
YV
L 3
.5:
"ASS
UR
ING
T
HE
ST
RE
NG
TH
OF
NU
CL
EA
R P
OW
ER
PL
AN
T P
RE
SSU
RE
EQ
UIP
ME
NT
ST
UK
has
issu
ed th
e gu
idel
ine
YV
L 3
.5 o
n 5.
4.20
02. I
t app
lies
to n
ew N
PPs
whi
le th
e en
forc
emen
t to
exis
ting
plan
ts is
stil
l pen
ding
. Se
ctio
n 2.
2 st
ipul
ates
the
stre
ngth
-rel
ated
doc
umen
ts to
be
subm
itte
d in
con
junc
tion
wit
h th
e ap
plic
atio
n fo
r a
cons
truc
tion
licen
se o
f a
NPP
. A
mon
g th
em i
s a
docu
men
t en
title
d “P
rinc
iple
s of
ass
urin
g th
e st
reng
th”
whi
ch s
hall
clar
ify
1) t
he p
rim
ary
circ
uit
and
cont
ainm
ent
cons
truc
tion
pr
inci
ples
to
elim
inat
e th
e an
ticip
ated
fai
lure
mec
hani
sms;
2)
the
prov
isio
n ag
ains
t pi
pe b
reak
s. A
n un
offi
cial
Eng
lish
vers
ion
of t
he l
atte
r re
quir
emen
ts is
giv
en b
elow
.
Pro
visi
on a
gain
st P
ipe
Bre
aks
(par
a. 2
.2.2
)
The
des
ign
of a
nuc
lear
pow
er p
lant
sha
ll m
ake
prov
isio
n ag
ains
t com
plet
e, in
stan
tane
ous
brea
ks o
f lar
ge p
ipin
g w
ith
rega
rd to
•
loss
of c
oola
nt a
nd o
verp
ress
uriz
atio
n of
con
tain
men
t •
reac
tor
pres
sure
ves
sel a
nd r
eact
or c
ore
supp
ort l
oadi
ngs
• pr
imar
y ci
rcui
t pum
p lo
adin
gs
• P
WR
ste
am g
ener
ator
sup
port
and
tub
e bu
ndle
loa
ding
s an
d ot
her
glob
al s
afet
y im
plic
atio
ns s
uch
as f
lood
ing,
ris
e of
hum
idit
y an
d te
mpe
ratu
re, a
nd im
puri
ties
ent
erin
g th
e em
erge
ncy
cool
ant.
Pip
e w
hips
, mis
sile
s an
d je
t im
ping
emen
t fo
llow
ing
a pi
pe b
reak
sha
ll n
ot c
ause
suc
h da
mag
e an
d le
akag
es o
f ot
her
com
pone
nts
that
wou
ld
chal
leng
e th
e su
cces
s of
con
sequ
entl
y ne
eded
saf
ety
func
tion
s su
ch a
s re
acto
r tr
ip,
emer
genc
y co
olin
g, r
esid
ual
heat
rem
oval
and
con
tain
men
t is
olat
ion.
T
he v
ital
com
pone
nts
shal
l be
loc
ated
at
suff
icie
nt d
ista
nce
wit
h re
spec
t to
hig
h-en
ergy
pip
ing,
and
str
uctu
ral
depa
rtm
entin
g sh
all
be
arra
nged
for
mut
ual s
epar
atio
n of
saf
ety
syst
ems
assu
ring
eac
h ot
her
and
of r
edun
dant
par
ts o
f saf
ety
syst
ems.
Whi
p re
stra
ints
and
jet i
mpi
ngem
ent
shie
lds,
com
plyi
ng w
ith
the
guid
ance
of [
2], s
hall
be
prim
aril
y pr
ovid
ed to
pre
vent
impa
ct lo
ads
aris
ing
from
bre
aks
of m
ost s
tres
sed
pipe
por
tion
s.
NE
A/C
SNI/
R(2
003)
16
72
In th
e ev
ent t
hat p
rim
ary
circ
uit p
ipin
g w
ere
not t
o be
pro
vide
d w
ith
whi
p re
stra
ints
and
jet i
mpi
ngem
ent s
hiel
ds, a
n au
thor
izat
ion
for
such
a
plan
has
to
be r
ecei
ved
from
ST
UK
whi
le a
pply
ing
the
cons
truc
tion
lic
ence
. T
he p
lan
shal
l sp
ecif
y th
e af
fect
ed s
yste
ms
and
part
s of
sys
tem
s, a
s w
ell a
s th
e se
para
tion
pri
ncip
le im
plem
enta
tion
for
each
. P
rese
nted
in
the
plan
sha
ll a
lso
be t
he e
xper
imen
tal
resu
lts,
val
idat
ed a
naly
ses
and
com
para
ble
oper
atin
g ex
peri
ence
s pr
ovid
ing
the
just
ific
atio
n.
Pro
babi
list
ic a
sses
smen
ts m
ay b
e pr
esen
ted
usin
g th
e m
etho
dolo
gy p
resc
ribe
d in
par
agra
ph 2
.3.3
. T
his
evid
ence
sha
ll d
emon
stra
te
that
the
pipi
ng a
nd th
eir
fitti
ngs,
wit
h re
gard
to th
e di
men
sion
ing,
mat
eria
ls, f
abri
cati
on, q
uali
ty a
ssur
ance
, loa
ding
s an
d en
viro
nmen
tal c
ondi
tion
s,
rend
er d
evel
opm
ent
of c
rack
siz
es c
onst
itut
ing
a th
reat
of
brea
k ve
ry u
nlik
ely.
T
he s
ched
uled
in-
serv
ice
insp
ecti
on a
nd c
ondi
tion
mon
itor
ing
prog
ram
mes
, as
wel
l as
leak
age
mon
itor
ing,
sha
ll fa
cili
tate
cra
ck d
etec
tion
and
the
nece
ssar
y ac
tion
s lo
ng b
efor
e at
tain
ing
a ha
zard
ous
crac
k si
ze
(lea
k-be
fore
-bre
ak p
rinc
iple
, L
BB
).
The
can
dida
te p
ipin
g m
ay n
ot b
e pr
one
to u
npre
dict
able
exc
essi
ve l
oadi
ng s
itua
tion
s an
d de
grad
atio
n m
echa
nism
s su
ch a
s w
ater
ham
mer
and
cor
rosi
on p
heno
men
a.
The
ana
lyse
s pe
rtai
ning
to
the
desi
gn-b
asis
pip
e br
eaks
and
the
ir m
echa
nica
l co
nseq
uenc
es s
hall
be
subm
itte
d as
par
t of
the
str
engt
h an
alys
is r
epor
t of
the
par
ticu
lar
pipi
ng c
ompo
nent
. A
s re
gard
s th
e sy
stem
s an
d pa
rts
of s
yste
ms
not
supp
lied
wit
h de
vice
s to
pre
vent
dyn
amic
ef
fect
s of
pip
e br
eaks
, th
e L
BB
pri
ncip
le s
hall
be
veri
fied
by
anal
ysis
. T
he a
naly
sis
may
fol
low
the
pro
cedu
res
pres
ente
d in
[3]
and
[4]
. T
he
frac
ture
mec
hani
cs s
tabi
lity
eva
luat
ion
for
the
post
ulat
ed b
reak
loc
atio
ns s
hall
be
base
d on
the
loca
lly
mos
t str
essi
ng s
ervi
ce c
ondi
tion
s, i
nclu
ding
th
e de
sign
-bas
is e
arth
quak
e ad
dres
sed
in th
e gu
idel
ine
YV
L 2.
6.
Se
ctio
n 2.
3 st
ipul
ates
the
str
engt
h-re
late
d do
cum
ents
to
be s
ubm
itted
in
conj
unct
ion
wit
h th
e ap
plic
atio
n fo
r th
e op
erat
ion
licen
ce o
f a
NPP
. A
mon
g th
em i
s a
docu
men
t ad
dres
sing
the
“L
eak
and
brea
k pr
obab
ilitie
s” r
elev
ant
to th
e as
sum
ed i
nitia
ting
even
ts.
An
unof
fici
al E
ngli
sh v
ersi
on
of th
ese
requ
irem
ents
is g
iven
bel
ow.
Lea
k an
d B
reak
Pro
babi
litie
s (p
ara.
2.3
.3)
The
nuc
lear
pow
er p
lant
des
ign
and
safe
ty a
naly
ses
shal
l ac
coun
t fo
r th
e st
reng
th-r
elat
ed u
ncer
tain
ties
of
the
mai
n pr
essu
re b
ound
ary
com
pone
nts.
The
ris
ks d
ue t
o fa
ilur
es a
nd f
ollo
win
g ac
cide
nt s
eque
nces
sha
ll n
ot e
xcee
d th
e pr
obab
ilis
tic
safe
ty a
naly
sis
goal
s la
id d
own
in t
he
guid
elin
e Y
VL
2.8
. T
he r
equi
rem
ents
rel
atin
g to
pro
babi
list
ic n
ondu
ctil
e fa
ilur
e an
alys
is o
f th
e re
acto
r pr
essu
re v
esse
l ar
e gi
ven
in p
arag
raph
3.
3.7.
NE
A/C
SNI/
R(2
003)
16
73
T
he s
ubm
itte
d ev
alua
tion
of
the
initi
atin
g ev
ent
freq
uenc
ies
shal
l ca
tego
rise
the
pre
ssur
e eq
uipm
ent
leak
s an
d br
eaks
acc
ordi
ng t
o th
eir
loca
tion
, ty
pe a
nd c
ross
-sec
tion
al l
eak
area
. A
com
plet
e lo
ss o
f pr
essu
re b
eari
ng c
apab
ilit
y of
the
ves
sel
or p
art
of i
t, w
here
the
lea
k is
ac
com
pani
ed w
ith
the
dyna
mic
eff
ects
dis
cuss
ed in
par
agra
ph 2
.2.2
, sha
ll b
e tr
eate
d as
a b
reak
. Fai
lure
s of
sin
gle
pass
ive
or a
ctiv
e pa
rts
like
hea
t ex
chan
ger
tube
s, f
lang
ed c
onne
ctio
ns a
nd g
aske
ts a
s w
ell
as l
eaks
and
bre
aks
due
to m
alfu
ncti
ons,
ope
rati
ng e
rror
s an
d m
aint
enan
ce e
rror
s sh
all
be ta
ken
into
acc
ount
. T
he f
requ
ency
est
imat
es s
hall
mak
e to
an
adeq
uate
ext
ent
use
of s
tati
stic
s fr
om c
ompa
rabl
e fa
cili
ties
, co
rrel
atio
ns b
etw
een
vari
ous
degr
ees
of le
aks
and
brea
ks a
s w
ell a
s pr
obab
ilis
tic
frac
ture
mec
hani
cs a
naly
ses.
The
frac
ture
mec
hani
cs a
naly
ses
shal
l be
base
d on
phy
sica
l mod
els
of th
e de
grad
atio
n m
echa
nism
evo
luti
on (
fati
gue,
cor
rosi
on a
nd a
gein
g ph
enom
ena)
. O
ther
fact
ors
to b
e co
nsid
ered
are
: •
load
ing
and
defe
ct s
ize
vari
abil
ity
• cr
ack
grow
th r
ate
in r
elat
ion
to th
e in
spec
tion
inte
rval
•
in-s
ervi
ce in
spec
tion
and
leak
mon
itor
ing
effe
ctiv
enes
s •
the
fail
ure
mod
e an
d th
e go
vern
ing
stre
ngth
and
toug
hnes
s pr
oper
ties
.
Dur
ing
the
oper
atio
n, a
com
pone
nt r
elia
bili
ty d
atab
ase,
mai
ntai
ned
in c
ompl
ianc
e w
ith
the
guid
elin
e Y
VL
2.8
, sh
all
be u
pdat
ed w
ith
obse
rved
leak
s an
d br
eaks
and
def
ect i
ndic
atio
ns, a
s w
ell a
s w
ith
thei
r ca
uses
and
mea
ns o
f det
ecti
on.
T
he r
efer
ence
s us
ed in
thes
e se
ctio
ns a
re:
2.
Det
erm
inat
ion
of R
uptu
re L
ocat
ions
and
Dyn
amic
Eff
ects
Ass
ocia
ted
wit
h th
e P
ostu
late
d R
uptu
re o
f P
ipin
g, S
tand
ard
Rev
iew
Pla
n 3.
6.2,
R
ev. 1
, U.S
. Nuc
lear
Reg
ulat
ory
Com
mis
sion
, 198
1.
3.
Lea
k-B
efor
e-B
reak
Eva
luat
ion
Proc
edur
es, S
tand
ard
Rev
iew
Pla
n 3.
6.3,
U.S
. Nuc
lear
Reg
ulat
ory
Com
mis
sion
, Fed
eral
Reg
iste
r, V
ol. 5
2 N
o.
167,
Aug
. 28,
198
7.
4.
Lea
k-B
efor
e-B
reak
Eva
luat
ion
Proc
edur
es f
or P
ipin
g C
ompo
nent
s, K
. Iko
nen
et a
l., S
TU
K-Y
TO
-TR
83,
Hel
sink
i, 19
95.