ciau method for uncertainty evaluation · 5 general frame of uncertainty evaluation historical...
TRANSCRIPT
DIPARTIMENTO DI INGEGNERIA MECCANICA, NUCLEARE E DELLA PRODUZIONE
UNIVERSITA' DI PISA 56100 PISA -ITALY
Tel +39-050-8366-53 Fax +39-050-8366-65
E-mail [email protected]
CIAU METHOD FOR UNCERTAINTY EVALUATION
F. D’Auria
OECD/NEA/CSNI - Wgama “Exploratory meeting of experts on BE calculations and uncertainty analysis”
Aix-en-Provence (France) – May 13-14, 2002
2
CONTENT
a) General frame of Uncertainty Evaluation - needs for uncertainty - historical remarks
b) Flow diagram of UMAE c) CIAU definition & needs d) The idea at the basis of CIAU e) CIAU diagram f) CIAU application & developments
- “Bifurcation” study - Licensing process of the Angra-2 NPP LBLOCA (an outline) - BE analysis of Kozloduy-3 NPP LBLOCA (an outline)
3
GENERAL FRAME OF UNCERTAINTY
EVALUATION
Needs for Uncertainty p1/2
CONSISTENT APPLICATION OF A THERMOHYDRAULIC SYSTEM CODE
CODE DEVELOPMENT & IMPROVEMENT (1)
CODE ASSESSMENT (4)
CODE USE (NPP) (5)
UNCERTAINTY EVALUATION
(6)
EXPERIMENTAL DATA (2)
PROCEDURES FOR
CODE USE (3)
PART I – UMAE
4
GENERAL FRAME OF UNCERTAINTY EVALUATION
Needs for Uncertainty p2/2
The predictions of the system codes are not exact but remain uncertain. Reasons are:
− the assessment process depends upon data almost always measured in small scaled facilities and not in the full power reactors;
− the models and the solution methods in the codes are approximate: in some cases, fundamental laws of the physics are not considered.
Consequently, the results of the code calculations may not be applicable to give ‘exact’ information on the behaviour of a Nuclear Power Plant during postulated accident scenarios. Therefore, best estimate predictions of nuclear power plant scenarios must be supplemented by proper uncertainty evaluations in order to be meaningful.
PART I – UMAE
5
GENERAL FRAME OF UNCERTAINTY EVALUATION
Historical Remarks YEAR ACTIVITY REF. (*)
1980-1982 Scaling analysis for the design of the PIPER-ONE BWR simulator 6 1982 Proposal for design criteria for PIPER-ONE 7 1985 Analysis of SBLOCAs in PWR on the basis of ‘similar’ tests 10
“ Proposal for criteria for accuracy quantification 11 1987 (1) Publication of OECD/CSNI ITF-CCVM 12a & 12b
1988 Proposal of criteria for planning ‘Counterpart’ tests (CT) 13 1989 Issue of US NRC Compendium on ECCS Research 16
“ Issue of OECD/CSNI SOAR onTECC 15 “ ‘Use’ of CT data related to BWRs 14
1989-1992 Papers dealing with the basis of the UMAE uncertainty methodology 14, 17, 18 1990 Publication of CSAU 22 “ (6) Studies on user effect, bringing to a CSNI publication in 1992 19
“ Proposal for the FFTBM for accuracy quantification 20 “ Analysis of Natural Circulation in PWR on the basis of ‘similar’ tests 21
1991 (2) Proposal for a methodology for independent assessment of codes 4 & 23 1992 Analysis of LOFW in PWR on the basis of similar tests 24
“ Proposal for a procedure for nodalisation qualification 25 1993 Simplified flow-sheet of UMAE and differences with respect to CSAU 26
“ Analysis of SBLOCA in PWR on the basis of performed CT (4) “ Application of UMAE to a SBLOCA in Krsko PWR 27 “ Publication of OECD/CSNI SETF-CCVM 28
1994 Completion of the 2D-3D Research Program and planning of TRAM 29 1995 Issue of UMAE-ET (to account for ‘unrecoverable’ code errors) 30 & 31 “ (2) Comparison between features of uncertainty methodologies (4) 1996 Issue of UMAE-SETF (to exploit SETF data) 32
“ Publication of OECD/CSNI on Lesson Learned from SBLOCA ISP 39 (5) “ (3) Proposal for a procedure for code user training, see also (6) 33 1997 Application of UMAE utilising Relap5/mod2 and Cathare 2v1.3 codes 5
“ Application of UMAE to Angra-1 PWR 34 “ Proposal for the CIAU (idea at the basis of the method) 35
1998 Publication of OECD/CSNI UMS report 2 1997-1999 Execution of different Kv scaled calculations (4)
1999 Demonstration of feasibility of CIAU and preliminary results (4) 2000 Publication of IAEA Guidelines for Accident Analysis – Draft – (4)
“ Bifurcation analysis and CIAU matrix enlargement (4) 2001 Application of CIAU to Angra-2 and Kozloduy-3 NPP LBLOCA (4) 2002 Development of uncertainty for 3-D neutronics/thermalhydraulics coupled codes
(*) list of references in the paper presented at UIT National Conf. 1998 (1) updated in 1996 (2) updated in 1998 (3) updated in 1998 and finalised in 1999 (4) papers and reports available (not part of the same list) (5) the report related to all ISP issued in 1998
The CSNI report on User Effects has been extended in 1999 to cover countermeasures suitable for reducing user effects
PART I – UMAE
6
FLOW DIAGRAM OF UMAE
General qualification
processCode
Plant nodalization
Plant calculation
ITF nodalizations
Specific experimental data
ITF calculations
Accuracy quantification (°)
Accuracy extrapolation (°)
Nodalization and user qualification
Generic experimental
data
Demonstration of similarity (°) (Phenomena (Scaling laws)
ASM calculation
Uncertainty
ba
i
h
j
GI FG
gc
d
e
f
l
LN (°)
n
YES
FG
k
(°) Special methodology developed
(Phenomena analysis) (Scaling laws)
Stop of the process
NO
NO
PART I – UMAE
7
CIAU DEFINITION & NEEDS
CIAU = Code with capability of Internal Assessment of Uncertainty • RELAP5 IS THE CODE • UMAE IS THE COUPLED UNCERTAINTY METHODOLOGY THE WORDS ‘INTERNAL ASSESSMENT OF UNCERTAINTY’ CAME OUT AS A
NEED FOR THE SCIENTIFIC COMMUNITY DURING THE OECD/CSNI “ANNAPOLIS MEETING” ORGANISED BY US NRC AND HELD IN ANNAPOLIS
(MD) IN NOVEMBER 1996
NEEDS A) CODE RESULTS ARE AFFECTED BY USER CHOICES. THE USER OF
UNCERTAINTY METHODS MAY ALSO HEAVILY AFFECT RESULTS PREDICTED BY UNCERTAINTY METHODS. THE COMBINATION OF THE TWO EFFECTS MAY BE NOT TOLERABLE.
B) THE APPLICATION OF ANY UNCERTAINTY METHOD MAY REQUIRE
EXPERTISE AND/OR RESOURCES NOT EASILY AVAILABLE. C) THE UNCERTAINTY MUST BE A CHARACTERISTIC OF THE CODE
QUALITY OR OF THE QUALIFICATION LEVEL.
PART I I – CIAU
8
CIAU DEFINITION & NEEDS
PART I I – CIAU
9
THE IDEA AT THE BASIS OF CIAU REFERENCE SYSTEMS THE CLASS OF LWRs. THE FOLLOWING REACTORS BELONG TO THE CLASS: • BWR - ALL THE TYPES (JET PUMPS OR INTERNAL RECIRCULATION MCP
OR EXTERNAL LOOPS); • PWR EQUIPPED WITH UT-SG; • PWR EQUIPPED WITH OT-SG; • WWER EQUIPPED WITH HO-SG. EXTENSION OF THE METHODOLOGY CAN BE ENVISAGED TO COVER: • CANDU, • NEW GENERATION REACTORS EQUIPPED WITH PASSIVE ECC (AP-600,
SBWR, ETC.). REFERENCE SCENARIOS • ANY TRANSIENT SCENARIO ASSUMED FOR THE REFERENCE
SYSTEM.
- SITUATIONS WITHIN-DBA AND BEYOND-DBA ARE CONCERNED
- THE BOUNDARIES OF VALIDITY FOR THE ADOPTED CODE-NODALISATION AND FOR THE ADOPTED UNCERTAINTY METHODOLOGY ARE NOT OVERPASSED.
PART I I – CIAU
10
THE IDEA AT THE BASIS OF CIAU
THE IDEA
“THE STATUS APPROACH” FOR NUCLEAR PLANT TRANSIENT SCENARIOS: 1) ANY TRANSIENT SCENARIO ASSUMED IN THE REFERENCE
SYSTEMS CAN BE CHARACTERIZED BY THE TIME AND BY A LIMITED NUMBER OF VARIABLES. THE BOUNDARIES OF VARIATION FOR THOSE VARIABLES AND THE TIME ARE IDENTIFIED.
2) THE RANGES OF VARIATION FOR THOSE VARIABLES AND THE
TRANSIENT TIME ARE SUBDIVIDED INTO INTERVALS. HYPERCUBES RESULT FROM THE COMBINATION OF VARIABLES INTERVALS.
3) THE NPP STATUS IS FORMED BY THE COMBINATION OF ONE
HYPERCUBE AND ONE TIME INTERVAL. 4) IT IS ASSUMED THAT UNCERTAINTY CAN BE ASSOCIATED TO
ANY NPP STATUS.
PART I I – CIAU
11
THE IDEA AT THE BASIS OF CIAU
THE ORIGIN OF THE IDEA
• THE NPP STATUS APPROACH FOR ACCIDENT
MANAGEMENT AND FOR EOP OPTIMISATION:
- ALREADY DISCUSSED IN A SPECIALISTS MEETING HAD IN PISA IN JUNE 1985 AS AN ALTERNATIVE TO THE EVENT APPROACH,
- CONSIDERED IN THE “CATALOGUE OF GENERIC PLANT
STATES…” ISSUED BY OECD/CSNI IN NOVEMBER 1996. • THE LOOK-UP TABLES FOR THE EVALUATION OF THE
CRITICAL HEAT FLUX (CHF) PROPOSED BY D.C. GROENEVELD AND P. KIRILLOV.
PART I I – CIAU
12
THE IDEA AT THE BASIS OF CIAU
PART I I – CIAU
13
CIAU DIAGRAM
Qual. ITF and SETF data Qual.
Calc. Results
Transient evolution and status approach
CIAU development
Data documentation for each status
Quantitative accuracy Qualitative accuracy
Time accuracy Needed variables
selection
Quantity Accuracy Matrix
Time Accuracy Vector
Scenario independence
check
Transient types and Hypercubes number
Uncertainty calculation
Quantity Uncertainty Matrix Time Uncertainty Vector
CIAU
CIAU application ASM
transient result
Possible stop of the process
Transient status characterization
Quantity Uncertainty Time Uncertainty
Scenario Uncertainty
a b
e
c
d
f g
h
i
l
m n
o
p q
r t s
u
YES
NO
UMAE specific
14
CIAU STATUS
Set of tests for QUM+TUV No. 2, part 1
PART I I – CIAU
15
CIAU STATUS
Set of tests for QUM+TUV No. 2, part 2
PART I I – CIAU
16
CIAU QUALIFICATION
‘EXTERNAL’ QUALIFICATION *** DEMONSTRATION ***
THE CIAU CAN BE APPLIED FOR CALCULATING ITF OR NPP TRANSIENTS DIFFERENT FROM THOSE THAT ORIGINATED THE QUM+TUV (THIS CONDITION IS NOT MET IN THE REPORTED EXAMPLE). IN THESE CASES IT MUST BE SHOWN THAT: THE UNCERTAINTY BANDS ENVELOPE THE EXPERIMENTAL DATA.
0
2
4
6
8
10
12
14
16
18
20
0 200 400 600 800 1000 1200
Time (s)
Pres
sure
(MPa
)
Upper Uncertainty Bound
Lower Uncertainty Bound
ExpCalc
Fig. 2 - Application of the CIAU to the UMS: uncertainty bands in predicting primary system pressure.
PART I I – CIAU
17
CIAU QUALIFICATION
‘EXTERNAL’ QUALIFICATION *** DEMONSTRATION ***
0
20
40
60
80
100
120
0 200 400 600 800 1000 1200
Time (s)
Mas
s (%
)
Upper Uncertainty Bound
Lower Uncertainty Bound
Exp
Calc
Fig. 3 - Application of the CIAU to the UMS: uncertainty bands in predicting primary system mass inventory.
400
450
500
550
600
650
700
750
0 200 400 600 800 1000 1200
Time (s)
Tem
pera
ture
(K) Upper Uncertainty Bound
Lower Uncertainty Bound
Calc
Exp
Fig. 4 - Application of the CIAU to the UMS: uncertainty bands in predicting rod surface temperature at 2/3 core height.
PART I I – CIAU
18
CIAU APPLICATION & DEVELOPMENTS “Bifurcation” study
Bifurcations can be originated by: • the actuation or lack of actuation of a system (e.g.
pressurizer relief valves) • the occurrence of a physical phenomenon characterized by
a threshold (typically, the dryout). Type one and type two bifurcations, (or system and phenomenon connected bifurcations) are distinguished.
Scenarios can be imagined where bifurcations bring the transient evolution far from the best-estimate deterministic prediction, thus invalidating the connected uncertainty evaluation. Therefore, a bifurcation analysis is necessary.
Starting points for the bifurcation analysis are: A) the identification of type one and of type two
bifurcations B) the knowledge of the uncertainty characterizing the
parameters which affect the bifurcation.
PART I I – CIAU
19
CIAU APPLICATION & DEVELOPMENTS “Bifurcation” study - plan
No. EVENT ID. STATUS EVENT TIME (s)
A Test start NA 0. B Scram # 13. C MSL valves operation (closure, opening) # 13. D MFW operation (closure, opening) # 13. E Pumps trip and coast down limits #* 13.-280. F Blow down in saturation condition NC 50. G Pressurizer PORV actuation (start and end of
cycling) NO -
H Steam generators SRV operation (as above) #* 25.-135. I ECCS (Accumulators, LPIS, HPIS) start and end
of liquid delivery #*+ 335.
L Dry out occurrence (at 2/3 of the active fuel height)
NC 300.
M PCT event (at 2/3 of the active fuel height) NC 310. N Rewetting occurrence (at 2/3 of the active fuel
height) NC 420.
O Actuation of relevant ESF (PRZ heaters, CVCS, RHR, etc.)
NO -
P Neutron power peaks in case of ATWS NO - Q Test end NA 900. NA: Not Applicable NO: Not Occurring NC: Not Considered * Only the event start + Accumulator # The event is considered as source of potential bifurcation
Tab. 2 - List of events utilized for identifying comparable time spans and timing of events in the reference calculation. The same events are sources of potential
bifurcations.
PART I I – CIAU
20
CIAU APPLICATION & DEVELOPMENTS “Bifurcation” study - plan
Time
Pres
sure
Upper Uncertainty Bound
Lower Uncertainty Bound
Primary Side Pressure (Nominal Calculation )
1a 1b
PSCRAM
Fig. 5 - Planning of bifurcation studies. Bifurcation calculations 1a and 1b are originated by the events B, C, D, E in Tab. 2.
Time
Prim
ary
Side
Pre
ssur
e
Seco
ndar
y Si
de P
ress
ure
Primary Side Pressure (Nominal Calculation)
2a
2b
2c 2d
Secondary Side Pressure (Nominal Calculation)
SRV Pressure Set
Lower Uncertainty Bound
Upper Uncertainty Bound
SRV Actuation Time
Fig. 6 - Planning of bifurcation studies. Bifurcation calculations 2a, 2b, 2c and 2d are originated by the event H in Tab. 2.
PART I I – CIAU
21
CIAU APPLICATION & DEVELOPMENTS “Bifurcation” study - plan
Time
Pres
sure
Lower Uncertainty Bound
Primary Side Pressure (Nominal Calculation)Time Error
Upper Uncertainty Bound
3a
3b
3c
Accumulators Pressure
Fig. 7 - Planning of bifurcation studies. Bifurcation calculations 3a, 3b and 3c originated by event I in Tab. 2.
PART I I – CIAU
22
CIAU APPLICATION & DEVELOPMENTS “Bifurcation” study -plan
No. ID.+ Reference Events (Tab. 2)
Bifurcation Initial Status (BIS)
Way to reach the BIS
Notes from the Calculated Database
Dryout at level ‘9’
(time/PCT) s/K
0 LS00 - - - Reference Calculation AR = 3.97e-4
130./570.*
1 1a LS1A
B,C,D,E PPRZ = PSCRAM at 5
s
Additional break (AR = 3.5e-3) in the period
0-5 s.
A new dryout condition (loop seal controlled) occurs.
160./710.
2 1b LS1B
B,C,D,E PPRZ = PSCRAM at
45 s
Additional break (AR = 5.0e-5) in the period 0-45 s. Original break
opening at 45 s.
- 130./690.
3 2a LS2A
H PPRZ = 15 Mpa at tSRV
Additional break (AR = 1.0e-5) in the period 0-tSRV. Original break
opening at tSRV.
- 135./674.
4 2b LS2B
H PPRZ = 6 Mpa at
tSRV
Additional break (AR = 5.0e-3) in the period
0-tSRV.
Early DNB (50 s) and accumulator actuation (120 s).
Extended DNB.
350./1540.
5 2c LS2C
H PSG = PSRV at 10 s
Early MSIV closure to achieve tSRV =10 s.
The achieved value for tSRV is 20 s (MSIV closure at t=1 s).
140./695.
6 2d LS2D
H PSG = PSRV at 70 s
Delayed MSIV closure to achieve tSRV
=70 s.
The achieved value for tSRV is 100 s (MSIV closure at t=60 s).
130./680.
7 3a LS3A
I PPRZ = PACC at 320 s
Additional break (AR = 3.0e-5) in the period
0-320 s.
Accumulator actuation achieved at 310 s.
115./705.
8 3b LS3B
I PPRZ = PACC at 600 s
Additional break (AR = 2.2e-4) in the period 0-600s. Original break
opening at 600 s.
Accumulator actuation achieved at 604 s.
200./734.
9 3c LS3C
I tACC=tNOM + ∆tACC
Delayed actuation of accumulators. Delay ∆tACC derived from
Fig. 7.
Dryout occurring at all core levels.
280./950.
Tab. 3 – Performed ‘bifurcation calculations’
PART I I – CIAU
23
CIAU APPLICATION & DEVELOPMENTS “Bifurcation” study - results
0 200. 400. 600. 800. 1000. 1200.Time (s)
0
2.5
5.0
7.5
10.0
12.5
15.0
17.5
20.0
22.5
Pres
sure
(MPa
)
WinGraf 3.2 - 02-12-2000
XXX 00 upper uncertainty limitX
X
X
X X XX X
X XX
XX X
XX X X X X
YYY 00 lower uncertainty limit
Y
Y YY Y
YY
YY Y
Y Y Y Y Y Y Y Y Y Y
ZZZ 00
Z
ZZ Z Z Z
ZZ
ZZ
ZZ
Z Z Z Z Z Z Z Z
VVV 3C
VVVVVVVVVVVVVVVVVVV
JJJ 3B
JJJJJJJJJJJJJJJJJJ
HHH 3A
H H H H H H H H H H H H H H H H H H H
### 2D
##
##
##
## # # # # # # # # # # #
OOO 2C
OOOO
OO
OO
O O O O O O O O O O O
AAA 2B
AA
AA A A A A A A A A A A A A A A
BBB 2AB B B
BB
BB
BB B B B B B B B B B
CCC 1BC C
CC
CC
CC C C C C C C C C C C
DDD 1AD DD
DD
DD
D D D D D D D D D D D
Fig. 8 – Results of the bifurcation calculations: primary system pressure.
-100.0 0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 900.0Time (s)
0
1000
2000
3000
4000
5000
6000
7000
Mas
s (k
g)
WinGraf 3.2 - 02-12-2000
XXX ls03 cntrlvar34X
X
X
XX
XX X X X X X X X X X X X X X
YYY ls1a cntrlvar34Y
Y
YY
YY Y Y Y Y Y Y Y Y Y
Y Y Y Y Y
ZZZ ls1b cntrlvar34
ZZ
Z
Z
ZZ
Z Z Z Z Z Z Z Z Z ZZ Z Z Z
VVV ls2a cntrlvar34
V
V
V
VV
V V V V V V V V V V V V V V V
JJJ ls2b cntrlvar34
J
J J J J J J J J J J J J J J J J J J J
HHH ls2c cntrlvar34
H
H
H
HH H H H H H
H H H H HH
HH H H
### ls2d cntrlvar34
#
#
#
## # # # # # # # # # #
##
# #
OOO ls3a cntrlvar34
O
O
OO
OO O O O O O O O O O O O O O O
AAA ls3b cntrlvar34
A
A
A
A
A A A A A A A A A A A A A A AA
BBB ls3c cntrlvar34
B
B
BB
BB B B B B B
BB
BB
B B B B B
Fig. 9 – Results of the bifurcation calculations: primary system mass inventory.
PART I I – CIAU
24
CIAU APPLICATION & DEVELOPMENTS “Bifurcation” study – results
-100.0 0 100.0 200.0 300.0 400.0 500.0 600.0 700.0 800.0 900.0Time (s)
400
600
800
1000
1200
1400
1600
Tem
pera
ture
(K)
WinGraf 3.2 - 02-12-2000
XXX ls03 httemp902000910
X X X X X X X X
X X
X X X X X X X X X X
YYY ls1a httemp902000910
YY Y Y Y Y Y
YY
Y Y Y Y Y Y Y Y Y Y Y
ZZZ ls1b httemp902000910
Z Z Z Z Z Z Z Z
ZZ
Z Z Z Z Z Z Z Z Z Z
VVV ls2a httemp902000910
V V V V V V V VV
V
V V V V V V V V V V
JJJ ls2b httemp902000910
J J
J
JJ
JJ
J
J
J
J J J J J J J J J J
HHH ls2c httemp902000910
H H H H H H H H H H
H H
H H H H H H H H
### ls2d httemp902000910
# # # # # # # # # #
#
# # # # # # # #
OOO ls3a httemp902000910
O O O O O OO
OO
O O O O O O O O O O O
AAA ls3b httemp902000910
A A A A A A A A A A AA
AA
A
A A A A A
BBB ls3c httemp902000910
B B B B B BB
B
B
B
BB
B B B B B B B B
Fig. 10 – Results of the bifurcation calculations: rod surface temperatures at 2/3
core height.
0
2
4
6
8
10
12
14
16
18
20
0 200 400 600 800 1000 1200
Time (s)
Pres
sure
(MPa
)
3b sup
3a sup
3b inf
3a inf
3b
3a
Upper Uncertainty Bound
Lower Uncertainty Bound
UP Pressure (Nominal Calculation)
Fig. 11 – ‘Tree’ of uncertainty bands resulting from the bifurcation study: primary system pressure.
PART I I – CIAU
25
CIAU APPLICATION & DEVELOPMENTS Licensing process of the Angra-2 NPP LBLOCA
(an outline)
Angra-2 is a 3765 MWth Siemens (Framatome-ANP) NPP – four loop PWR. LBLOCA DEGB DBA licensing analysis in the FSAR was submitted by the applicant to the regulatory authority based on BE+Uncertainty calculation. Independent evaluation of uncertainty was performed by CIAU to support the licensing authority. CIAU application ‘supported’ by extensive sensitivity study (> 150 code runs). PCT related results shown below.
PART I I – CIAU
26
CIAU APPLICATION & DEVELOPMENTS
BE analysis of Kozloduy-3 NPP LBLOCA (an outline)
Kozloduy-3 is a WWER-440/213, Gidropress – six loop reactor. LBLOCA, ‘200 mm break’ was requested by the NPP to support license renewal activity. Evaluation of uncertainty was performed by CIAU. Related to PCT, it was shown that Cathare predictions are bounded by the uncertainty bands predicted by the Relap5 BE analysis. PCT time trends reported below.
PART I I – CIAU
0
200
400
600
800
1000
1200
1400
1600
0 200 400 600 800 10 00 1 200
Time (s )
Tem
pera
ture
(K
) Relap5 "reference"
Cathare CIAU upper band
27
CONCLUSIONS
1. CIAU CONSTITUTES A TOOL ORIGINATED BY THE COMBINATION OF A QUALIFIED BEST ESTIMATE CODE AND A SUITABLE UNCERTAINTY METHODOLOGY. “CONTINUOUS” ERROR BANDS ARE OBTAINED.
2. THE IDEA AT THE BASIS OF CIAU DERIVES FROM THE “NPP
STATUS” APPROACH: HYPERCUBES AND TIME INTERVALS HAVE BEEN DEFINED THAT ARE “FILLED” BY UNCERTAINTY DATA.
3. RELAP5/MOD3.2 SYSTEM CODE AND UMAE UNCERTAINTY
METHODOLOGY HAVE BEEN COUPLED. UNCERTAINTY COMES FROM THE ‘EXTRAPOLATION OF ACCURACY’.
4. FOUR SETS OF QUM+TUV (QUANTITY UNCERTAINTY
MATRICES AND TIME UNCERTAINTY VECTORS) HAVE BEEN DEFINED.
5. RECENT ACHIEVEMENTS:
• ‘EXTERNAL’ QUALIFICATION (DATA OTHER THAN THOSE
DISCUSSED); • CONSIDERATION OF BIFURCATION: ‘TREE’ OF UNCERTAINTY
BANDS; • ‘AUTOMATISATION’ (METHOD AVAILABLE UNDER WINDOWS) • APPLICATION TO ANGRA-2 (LICENSING, LBLOCA DEGB-DBA)
AND KOZLODUY-3 NPP (LBLOCA ‘200 MM’ BREAK).
6. PLANNED DEVELOPMENTS:
• COUPLED 3-D NEUTRONICS-THERMALHYDRAULIC ANALYSES; • DATABASE EXPANSION.
PART I I – CIAU