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ÚJV Řež, a. s.
Energoprojekt Praha division
Design implementation of Stress-test measures on Czech and Slovak NPPs
11/2013
After Fukushima activities – CZ and SK NPPs
This presentation focuses design activities on
CZ NPPs (Temelin12, Dukovany1234)
SK NPP MO 34 (still under construction)
The result of stress test analyses (~National reports) quite well defined needed actions and improvement of safety functions.
Technical solution of safety measures was defined very generally (no feasifibility studies performed), accenting these main aspects:
High withstand level against more severe extreme external events (combinations)
All Units on site can be affected
Reactor and SFP can be affected simultaneously
Various modes of the Unit considered (power operation, refueling,….)
Added safety measures should be diverse/independent on existing systems
Mobile equipment strongly preferred
Big press on short deadlines (conceptual design, detailed design, commissioning)
2
3
Example of original technical ideas
TB30
2x500m3
TX
3x500m3
GA201,500m3
TX10,20,30
PG2 PG3 PG4
TQ22
TQ30
TM
TG11,12,13
M 140kW
alternativně
III.kat.NZN
M
III.kat.NZN
880kW
I.kat.ZN
CV02
(CW02)
CV03
(CW03)
TQ14(24),
TL, UV
40kW
nová zařízení/potrubní trasy – technologie
flexibilní propoje
nová zařízení elektro
Diverse Makeup System
(Reactor / SFP / Sump)
Diverse EFW System
140kW
SBO DG
4
Before Fukushima status of NPPs
(example of MO34)
External AAC (Grid) not
available for several days
– SEISMICITY,…
Interconnections 6kV
cannot be used because
ALL UNITS
are affected by the
EVENT
Functionality for SA with
just SINGLE common DG is
under question (for min.
3days, after seismicity ???)
The SBO „After Fukushima“
is not solved !!
5
Design considerations
Design environment
CZ legislation does not cover DEC (SBO, SA) ( ̶ )
CZ NPPs are in operation ( ̶ )
SK legislation includes requirements on DEC (SBO, SA) (+)
SK NPP MO34 is under construction – Basic desig level still opened (+)
Diversity and independence of new safety measures
New equipment is only partly diverse. No time for technical development of new robust principles.
Independence / separation resolved quite well (because it is standard design principle in NPPs)
6
Design considerations
Targeting of safety measures
It is difficult to forecast the type of disaster in Central Europe. New safety measures
are therefore focused on improvement of essential safety principles of NPPs
More robust Defence in Depth (in all DID levels, main accent to level DID 4 – IAEA system)
Additional safety functions for DEC
DID
sublevel
Purpose Description Note CZ SK (MO34)
4.1 A SA
prevention
SBO single unit, other unit in
DBC, external AAC
Designed before
Fukushima
4.1 B SBO single unit, other unit in
DBC, internal AAC
4.1 C SBO ALL units, internal AAC,
with UHS
New after Fukushima
4.1 D SBO ALL units, internal AAC,
without UHS
4.2 A SA
mitigation
SA single unit,
other unit in DBC
Designed before
Fukushima
4.2 B SA single unit,
other unit in SBO
New after Fukushima
4.2 C SA ALL units,
after SBO development
7
Mobile or stable equipment?
Feature (vlastnost) Mobile Stable
Protection against event
-On site (close)
-On site (distant)
By transport
Bunker
Bunker
By distance
Bunker
Bunker
Transport Expected problems (mainly with
heavy, powerfull equipment)
N/A – stable equipment
Connection (připojení) Where? How? Who?
(difficult in real disaster situation)
Permanently
connected, prepared
Start of function
(Náběh funkce)
After connection, with large
time delay
Fast (minutes),
automatic
Voltage and Power
(Napětí a výkon)
LV (400V) close to consumers
Low power - (sensitive on
behavior of consumers and failures
in distribution)
MV (6kV) – protection by
distance possible
High power – non
sensitive, tolerates
mistakes, transients
Compatibility with EEPS
Kompatibilita s SZN
Incompatible (selectivity
corrupted)
Compatible (selectivity
is kept)
Testing – for functionality in
real disaster situation
Testovatelnost – pro
funkčnost v reálné situaci
Test of transport, connection …
impossible (simulation will be
demanding for operation staff –
military skill needed)
Regular periodical
tests possible (similar
as for design EEPS)
8
Design considerations
Location of stable equipment
SZN 1
SZN 2
SZN 3
Blok č. 2
R
Strojovna
Výměn. stanice
2GX
2GW
2GV
1GX
1GW
7GK
7GJ
1GV
BJ CJ
BK CK
DGS
SZN 4, 5
Strojovna
Výměn. stanice Rozv.
normál. napá-jení
Blok č. 1
BJ CJ
BK CK
Rozv. normál. napá-jení
DGS DGS
NPP Temelin: Layout scheme of EEPS and AAC grid
R R
9
Design considerations
Location of stable equipment
AAC DG 1 AAC DG 2
SZN 1
SZN 2
SZN 3
Blok č. 2
R
Strojovna
Výměn. stanice
2GX
2GW
2GV
1GX
1GW
7GK
7GJ
1GV
BJ CJ
BK CK
DGS
SZN 4, 5
R
Strojovna
Výměn. stanice Rozv.
normál. napá-jení
Blok č. 1
BJ CJ
BK CK
Rozv. normál. napá-jení
DGS DGS
NPP Temelin: Layout scheme of EEPS and AAC grid
10
Design considerations
Common features of stress tests safety measures-1
NPPs will have following significantly improved safety features after
design and implementation of stress test measures:
Increased robustness of DID (further independent sublevels in relation to
every detected “cliff edge” effects).
Wider scope of NPP accident operating modes and accident scenarios
addressed. DEC considered even at all Units on site.
Previous safety measures and procedures sufficient for coping with less
difficult events are usually preserved
New safety measures must not decrease performance of design basis
safety functions
11
Design considerations
Common features of stress tests safety measures-2
Minimization of the need of human intervention during the first phases of accident
scenarios declared in some cases is not realistic. Particularly due to effort for more
economical design significant scope of direct human actions is needed.
Higher preference is given to “passive” or manually operated systems (i.e. storages
of coolant, longer battery autonomy time, battery supplied or manual actuations,
etc.)
Emphasis was given to keep the plant in “safe” conditions within 72 hours from the
accident onset, also with the support of in-site contributions. Later is assumed
effective external help and repair of some portion of DBC systems.
The combination of mobile and stable means is used. Hardened stable means are
more essential, mobile more backup. Use depends on the event and scenario of
solution. Flexibility is accented.
Design solution enables fulfillment of safety functions even upon failures of
equipment. The principle of functional groups (FSK) is used. Preventive measures
(coping with SBO) have higher ability to cope with failures. For SA mitigation
measures is this ability at least partial.
12
Mochovce 3,4 – „stress test measures“
SAXSNAXS
DGDGDG
EE
PS
1
EE
PS
2
EE
PS
3DG DG DG
EE
PS
1
EE
PS
2
EE
PS
3DG
Common DG
SBO sectionK L M KLM
G
H
DG
mDG mDG
X XX X X
Supply selected LV part
DG
X
3BMH55
M
ESW
G
H
X X
M ESW
Supply selected LV part
EMO12
EMO12affected by SBOX
XX XX
Contacts
Addressa: Vyskočilova 3/741, 140 21 Praha 4
Jan Anděl
Tel.: +420 241 006 910
E-mail: [email protected]
Web: www.ujv.cz
© 2013 ÚJV Řež, a. s.
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