fzk/irs-as w. hering, ch. homann1 forschungszentrum karlsruhe in der helmholtz-gemeinschaft 11th...

FZK/IRS-AS W. Hering, Ch. Homann 1

Forschungszentrum Karlsruhein der Helmholtz-Gemeinschaft

11th International QUENCH Workshop, Karlsruhe, Germany

W. Hering, Ch. HomannW. Hering, Ch. Homann

Forschungszentrum KarlsruheProgramme NUKLEAR

P.O. Box 3640, D-76021 Karlsruhe, Germany

11th International QUENCH Workshop, October 25-27 2004

Table of Contents Table of Contents

• Motivation and objectives• Imbedding of Q-11 into Reflood Database • Status of Q-11 preparation • Summary and conclusions

Pre-test calculations of QUENCH-11 Pre-test calculations of QUENCH-11 (Q-L2) using S/R5 and ASTEC (Q-L2) using S/R5 and ASTEC

Pre-test calculations of QUENCH-11 Pre-test calculations of QUENCH-11 (Q-L2) using S/R5 and ASTEC (Q-L2) using S/R5 and ASTEC




Motivation and objectives

• Open issues in SFD core refloodOpen issues in SFD core reflood

– Reduction in H2 uncertainty

– Perform a dry-out-reflood sequence test (Q-11)– Reflood with low capability systems (Q-11)– Assess risk of unintended core reflood (in case of LOOP)

• Pre-test work for QUENCH-11Pre-test work for QUENCH-11– Feasibility study (QWS-10)– Upgrade facility to meet requirements – First results of Q-11 pre-test experiments (Juri Stuckert)– Specification of step-by step approach to meet

requirements of QUENCH-11 (“Vorversuche”)




Data baseData base

– EU-Programs– FZK Experiments– IRSN Phebus– OECD/NEA– USNRC– Plant accidents– LUTCH

Reactor typeReactor type

– PWR– VVER– BWR

Imbedding of Imbedding of Q-11 into Reflood Q-11 into Reflood

DatabaseDatabase

Core damage state prior to refloodinitiation

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Data source 0 1 2 3 4 5 6 7 K K/s sec K g s*rod

%

CODEX 3/1 V 1420 / 1430 L 0,3 W 0,9 1

CODEX 3/2 V 1773 / 1916 L 0,6 W 0,9 <5

PARAMETR 1 V 1700 / ~1700 L ? Yes W 7 ?

PARAMETR 2 V B 1700 / ~2700 L ? No W 5 ?

QUENCH IBS05 P 1700 / 1750 L ? --- W 2,6 30

QUENCH-01 " 1830 / 1900 L 0,7 60 W 1,8 7 I

QUENCH-02 " 2470 / 2500 L " W 1,7 90

QUENCH-03 " Tiny 2450 / 2500 L " W 1,4 (85)

QUENCH-04 " 2110 / 2340 L " S 1,7 16 F

QUENCH-05 " Partial 2020 / 2270 L " S 1,7 7 G

Q-06 (ISP45) " 2060 / 2150 L " W 1,5 11 I/F

QUENCH-07 " B4C 2100 />2300 L " S 0,6 (68)

QUENCH-08 " Partial 2070 />2300 L " S 0,6 45 F

QUENCH-09 " B4C Tiny 2100 />2500 L " Yes S 1,8 87

QUENCH-10 (Q-L1) " 2180 / 2300 L " Air W 1,8 10 F

QUENCH-11 (Q-L2) " L 0.5 ? W 0.6 F

QUENCH-12 V t.b.d.

PBF SFD ST " ? / >2700 L 0.1 ? W 0,5 50

Phb SFD B9R2 " ? / 2150 L <0.2 Yes S S ?

CORA-12 " SIC ~2000 / 2300 L 1 --- W 1,4 ?

CORA-13 (ISP-31) " SIC Tiny ~2100 / 2500 L 1 --- W 1,4 48

CORA-17 B B4C ~2000 / 2300 L 1 Yes W 1,4 79

CORA-12 P SIC ? ? / >2400 L 2.2 --- W 130 75

TMI-2 P SIC ? / >2800 H 0.5 ? H 50-180 ~30 I

Paks (CTI) V 1600 / ? L 0.1 ? L W: ? ?




Accident Termination Released Hydrogen fraction A

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Flow rate (g/s*rod) 1 2 3 4 5 6 7 1 2 3 4 5 6 7

TMI-2: 50-180 (BPT) T T T T TLoft LP-FP2: 130 L L L ? ? L L ? ?very high (> 9.0) ? ? ? ? ? ? ?

All HP-SI + LP-SI ? ? ? ? ? ? ?high (2.0 - 9.0) P P ? ? ? P P ? ? ? ?

All LP-SI Q ? ? ? Q ? ? ? ?medium (1.0 - 2.0) C Q Q ? ? C Q Q ? ?

All HP-SI Q C C ? ? Q C C ? ?low ( 0.6... 1.0) Q Q ? ? ? Q Q ? ? ?

single HP-SI X Q ? ? ? ? X Q ? ? ? ?very low (< 0.7) ? Q-L2 ? ? ? ? ? ? ? ?

other ? ? ? ? ? ? ? ? ? ? ? ? ? ?Accident progression

Core damage state prior to refloodinitiation

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Q-L2 in the reflood map Q-L2 in the reflood map Experimental data base: Depending on Experimental data base: Depending on Reflood Mass Flow RateReflood Mass Flow Rate (RMFR) and (RMFR) and Core Damage State (CDS)Core Damage State (CDS)

Steam Steam starvedstarved(PARAMETR) (PARAMETR)

Q-11 Q-11 (Q-L2)(Q-L2)Q-11 Q-11 (Q-L2)(Q-L2)

Color codingA H2< 20%

B 20 < H2 < 50%

C H2 > 50%

Cat A & B

Cat B & C

Data sourcesC CORAQ QUENCHX CODEXP ParametrL LOFT LP-FP2T TMI-2




Step-by-step approach to QUENCH-11Step-by-step approach to QUENCH-11

Test objectives Test objectives - Extend QUENCH facility to low mass flow rate scenarios Extend QUENCH facility to low mass flow rate scenarios

(ceasing pumps or AMM)(ceasing pumps or AMM)

- Prepare facility for experiments with free water surfacePrepare facility for experiments with free water surface

- Investigate scenario with low steam availability Investigate scenario with low steam availability (app. 1g/s 0.04 g/rod*s)

Stepwise approachStepwise approach

- Component tests q11v1Component tests q11v1 - Guidance and control test q11v2 (T < 600 K)Guidance and control test q11v2 (T < 600 K)

qualification of input decks qualification of input decks

- Design basis reflood test q11v3 (T < 1400 K) Design basis reflood test q11v3 (T < 1400 K) extend database also for DBA codes extend database also for DBA codes update of input decks update of input decks

QUENCH-11 (Q-L2)QUENCH-11 (Q-L2)




Best simulation of reactor conditions

with Q-L2

ReactorReactor Consider real volumes

in the RPV: Contribution of downcomer: additional 80 to 120 % of the free core flow area

• Pre-test calculationsPre-test calculations– Pre-test experiments to

assess input decks

– Check independent control of: 1. evaporation rate and 2. bundle heat-up




Tools for pre-test calculations and Tools for pre-test calculations and post-test analysespost-test analyses

SCDAP/RELAP5 mod 3.2.irs:SCDAP/RELAP5 mod 3.2.irs:specially modified for out-of-pile facilities specially modified for out-of-pile facilities basic toolbasic tool

ASTEC V1.x (contribution to SARNET):ASTEC V1.x (contribution to SARNET): Check more possible test scenarios Check more possible test scenarios

(after qualification using S/R5) (after qualification using S/R5)

Parameter studies (fast running code)Parameter studies (fast running code)

Due to manpower restrictions: Due to manpower restrictions: Code validation focussed on DIVA (~ICARE2) Code validation focussed on DIVA (~ICARE2)




Pre-test Q-11v2

• Objectives:

Steam flow control with Auxiliary heater power

Control bundle heat-up

Response time of additional water inflow

Qualification of fluid measurement

Test low mass flow-rate reflood (< 0.7g/s*rod)




First post test analysis

• Draft findings:

Water ejected due to flashing even

Bundle voided z> 0.25 m

Temperature rise linearly until bundle power reduced

Not observed in experiment




Post-test Q-11v2

• Draft findings:

Boil-off rate larger: z > 0.5 m,smaller: z < 0.5 m

Bundle temperatures underestimated

Flashing observed (due to initial conditions)

Check initial conditions and heat losses to environment at “low” temperatures




Whole scenario

Pre-test calculationPre-test calculation(before Q-11v2):(before Q-11v2):

– Q-11v3 delivers50-60 µm oxide layer(reactor specific)

– Q-11v3 reflood phase simulates Accumulator driven core reflood

– Max temperatures: - Q-11v3: < 1350 K - Q-11 ~ 2600 K

Next steps:Next steps:

1. update input deck

2. Check sequence Q-11v3 and Q-11




Reasonable simulation of axial temperature profile during heat-up phase

Onset of final transient OK (t< 7000s)

Temperature peak prior / during reflood underestimated (like most of the codes in ISP-45)

ASTEC V1.2 in work

Validation: ASTEC results for ISP-45Validation: ASTEC results for ISP-45




ASTEC: draft

results for Quench-11

Comparable to S/R5 calculations

Deviations during cool-down are due to lacking reflood model in (ASTEC V1.1)

Much faster than S/R5

Shows Temperature evolution in the core as well as shroud insulation




Summary and conclusions (1)

Post test analysis identified unexpected deviations Post test analysis identified unexpected deviations in the S/R5 facility model: in the S/R5 facility model: not required before because experiments not required before because experiments

start at higher temperaturesstart at higher temperatures

Q-11v2 proved successfully step-by-step Q-11v2 proved successfully step-by-step approach to prepare Q-11approach to prepare Q-11

Free water level and steam mass flow rate Free water level and steam mass flow rate could be controlled, although predictions of pre-could be controlled, although predictions of pre-calculations differ from experiment calculations differ from experiment

QUENCH facility, originally not designed for a free water QUENCH facility, originally not designed for a free water level at lower end of the bundle is now able to simulate level at lower end of the bundle is now able to simulate that featurethat feature




Q-11v3 – Q11 pre-test calculations initiated Q-11v3 – Q11 pre-test calculations initiated using results of Q-11v2using results of Q-11v2

– Q-11 can be performed as proposed (QWS-10)– Database will be released to LACOMERA partners– Post-test analyses with ASTEC will be continued

with know-how from S/R5

SFD-Research focused on: SFD-Research focused on: SARNET: Validation of ASTEC V1.x by code to code

and code to data

Improvement and extension of the FZK reflood map

Detailed simulation with S/R5 to supply integral codes with reliable boundary conditions for Q-11

Summary and conclusions (2)

fzk/irs-as w. hering, ch. homann1 forschungszentrum karlsruhe in der helmholtz-gemeinschaft 11th...

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