FZK/IRS-AS W. Hering, Ch. Homann1 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany W. Hering, Ch. Homann W. Hering, Ch. Homann Forschungszentrum Karlsruhe Programme NUKLEAR P.O. Box 3640, D Karlsruhe, Germany 11th International QUENCH Workshop, October 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 (Q-L2) using S/R5 and ASTEC

FZK/IRS-AS W. Hering, Ch. Homann2 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany Motivation and objectives Open issues in SFD core refloodOpen issues in SFD core reflood – –Reduction in H 2 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”)

FZK/IRS-AS W. Hering, Ch. Homann3 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany  Data base – –EU-Programs – –FZK Experiments – –IRSN Phebus – –OECD/NEA – –USNRC – –Plant accidents – –LUTCH  Reactor type – –PWR – –VVER – –BWR Imbedding of Q-11 into Reflood Database

FZK/IRS-AS W. Hering, Ch. Homann4 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany Q-L2 in the reflood map Experimental data base: Depending on Reflood Mass Flow Rate (RMFR) and Core Damage State (CDS) Steam starved (PARAMETR) Q-11 (Q-L2)

FZK/IRS-AS W. Hering, Ch. Homann5 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany Step-by-step approach to QUENCH-11  Test objectives -Extend QUENCH facility to low mass flow rate scenarios (ceasing pumps or AMM) -Prepare 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 approach - Component tests q11v1 - Component tests q11v1 - Guidance and control test q11v2 (T < 600 K)   qualification of input decks - Design basis reflood test q11v3 (T < 1400 K)   extend database also for DBA codes  update of input decks  QUENCH-11 (Q-L2)

FZK/IRS-AS W. Hering, Ch. Homann6 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany Best simulation of reactor conditions with Q-L2  Reactor  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

FZK/IRS-AS W. Hering, Ch. Homann7 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany Tools for pre-test calculations and post-test analyses  SCDAP/RELAP5 mod 3.2.irs: specially modified for out-of-pile facilities  basic tool  ASTEC V1.x (contribution to SARNET):  Check more possible test scenarios (after qualification using S/R5)  Parameter studies (fast running code)  Due to manpower restrictions: Code validation focussed on DIVA (~ICARE2)

FZK/IRS-AS W. Hering, Ch. Homann8 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany 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)

FZK/IRS-AS W. Hering, Ch. Homann9 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany 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

FZK/IRS-AS W. Hering, Ch. Homann10 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany 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

FZK/IRS-AS W. Hering, Ch. Homann11 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany Whole scenario Pre-test calculation (before Q-11v2): – –Q-11v3 delivers 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: 1. 1.update input deck 2. 2.Check sequence Q-11v3 and Q-11

FZK/IRS-AS W. Hering, Ch. Homann12 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany   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-45

FZK/IRS-AS W. Hering, Ch. Homann13 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany 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

FZK/IRS-AS W. Hering, Ch. Homann14 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany Summary and conclusions (1)  Post test analysis identified unexpected deviations in the S/R5 facility model:  not required before because experiments start at higher temperatures  Q-11v2 proved successfully step-by-step approach to prepare Q-11  Free water level and steam mass flow rate could be controlled, although predictions of pre- calculations differ from experiment  Free water level and steam mass flow rate could be controlled, although predictions of pre- calculations differ from experiment  QUENCH facility, originally not designed for a free water level at lower end of the bundle is now able to simulate that feature

FZK/IRS-AS W. Hering, Ch. Homann15 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany  Q-11v3 – Q11 pre-test calculations initiated using 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:   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. Homann16 Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft 11th International QUENCH Workshop, Karlsruhe, Germany