1. ERMSAR 2012, Cologne March 21 – 23, 2012 GENERIC CONTAINMENT A first step towards bringing (European) containment simulations to a common level St. Kelm (JÜLICH), Ph. Broxtermann (RWTH), S.Krajewski (RWTH), H.-J. Allelein (RWTH, JÜLICH), G. Preusser (AREVA), M. Sangiorgi (ENEA), W. Klein-Hessling (GRS), I. Bakalov (GRS), A. Bleyer (IRSN), A. Bentaib (IRSN), I. Kljenak (JSI), M. Stempniewicz (NRG), J.R. Jonnet (NRG), P. Kostka (NUBIKI), S. Morandi (RSE), J. Burkhardt (RUB), L. Denk (UJV), Z. Parduba (UJV), S. Paci (UNIPI), A. Manfredini (UNIPI), A. Silde (VTT), J. Jancovic (VUJE), P. Juris (VUJE)

2. ERMSAR 2012, Cologne March 21 – 23, 2012 Outline Motivation and Methodology Generic Containment Definition Initial Benchmark Excercise run-0 Outlook to run-1 Summary 2

3. ERMSAR 2012, Cologne March 21 – 23, 2012 Background – OECD/NEA ISP47 Main outcome: strong ‘User-Impact’ in predictions of LP codes  Difficult to compare and rate single LP code predictions  recommendation to elaborate a ‘Generic Containment‘ including all important components allowing comparative analyses This Generic Containment is defined in the frame of SARNET-2 and applied: to compare and rate analyses performed with different lumped parameter codes as a basis for testing new model developments on a commonly available and accepted basis.

4. ERMSAR 2012, Cologne March 21 – 23, 2012 Code Benchmark Methodology Differences to other Benchmarks: No existing test setup, no experimental data Complex system rather than a well defined single compartment or separate effect:  Interaction of many physical models complicate identification of errors  different models require different assumptions & simplifications (‘user impact’) Full spectrum of variables available <> select right ones for comparison close to a well known system → rateable results (German PWR 1300MWE el ) commonly understood specification, transferable to the different codes Systematic, stepwise approach Needs for a Code-to-Code comparison:

5. ERMSAR 2012, Cologne March 21 – 23, 2012 Generic Containment - Roadmap 5 Get started!  Definition of Generic Containment  Basic test scenario Get started!  Definition of Generic Containment  Basic test scenario reduce user-impact reduce user-impact Basic common understanding  Increase scenario complexity Basic common understanding  Increase scenario complexity Enhanced common understanding:  Detailed comparison Enhanced common understanding:  Detailed comparison Well understood basis:  Apply to model testing (e.g. PAR-modelling)  Acceptance criteria Well understood basis:  Apply to model testing (e.g. PAR-modelling)  Acceptance criteria Understand deviations run-0 run-1run-2

6. ERMSAR 2012, Cologne March 21 – 23, 2012 Generic Containment - Definition 6 based on German 4-loop PWR with 1300 MW el : 2-compartment geometry 70.000 m³ inner steel shell U-tube SG

7. ERMSAR 2012, Cologne March 21 – 23, 2012 Specification - Clear Definitions (e.g. CV‘s) No description of a technical system, but of it‘s modeling Avoid missinterpretations and allow transfer to any other code

8. ERMSAR 2012, Cologne March 21 – 23, 2012 Initial Benchmark – run-0 14 European organizations, 10 different LP codes, 22 contributions Main objectives: – Prepraration and verification of inputs – Assessment of transferability between the codes  Transfer of Generic Containment nodalisation (specified data, assumptions)  Achieve a common understanding of the specified problem – By means of a first comparison of the containment thermal hydraulics  Flow pattern, histories of abs. pressure, CV temperature and humidity

9. ERMSAR 2012, Cologne March 21 – 23, 2012 Initial Benchmark – run-0 scenario - start of core melt: 00:41 h - melt relocation to lower plenum:03:06 h - failure of RPV:03:24 h run0 Break at the connection of the safety systems to the hot leg. Total loss of secondary heat removal and all active safety systems (comparable to GRS-A-2601,1998) Only thermal hydraulics (steam/air), no release of H2 or fission products Basic test scenario: simple to compare extendable to a more realistic / complex transient (run-1 & run-2) SB-LOCA, in-vessel phase until failure of the reactor pressure vessel (~3.2h)

10. ERMSAR 2012, Cologne March 21 – 23, 2012 Run-0 code comparison procedure Fundamental requirement: comparable flow pattern Comparison among all codes and aginst average and standard deviation: – Inside the tolerance band: certain probability of ‚correct‘ implementation of the specififcaiton – Outside the tolerance band: indication ot check & revise input Comparison in „code groups“: COCOSYS & ASTEC, MELCOR, OTHERS – Identify ‚user effect‘ 10

11. ERMSAR 2012, Cologne March 21 – 23, 2012 Initial Benchmark – run-0 very first results Misinterpretation of some input data, e.g.: Water/steam injection tables Treatment of drain junctions Need of clarification & additional input data for some models/codes Global comparison:  Wide range of abs. containment pressure Global comparison:  Wide range of abs. containment pressure

12. ERMSAR 2012, Cologne March 21 – 23, 2012 Initial Benchmark – run-0 open phase results Better agreement among the codes:  Common understanding achieved  Still large deviations need detailed analysis in run-1 Better agreement among the codes:  Common understanding achieved  Still large deviations need detailed analysis in run-1 First parametric studies identified some sensitive modelling options, e.g.: Treatment of water injection Heat structure modeling Impact of condensation models Time step management

13. ERMSAR 2012, Cologne March 21 – 23, 2012 Outlook to run-1 - start of core melt: 00:41 h - melt relocation to lower plenum:03:06 h - failure of RPV, MCCI:03:24 h run0 release of H 2 run1 release of H 2, CO, CO 2 - ingress of sump water to cavity t >13:37 h Same nodalisation Extended scenario, increased complexity (based on run-0): Additional energy source terms: fission product decay heat, system heat Main objectives: Blind phase: test predictive capability, provide basis for comparison Open phase: extended and detailed analysis of differences

14. ERMSAR 2012, Cologne March 21 – 23, 2012 Summary (on-going activity) 14 Aim: Establish commonly available and understood basis for – Comparing & rating LP code predictions – Testing new model developments – Definition of ‚acceptance criteria‘ for deviations among codes predictions Methodology: Reduce ‚user effect‘, detailed understanding of deviations – Problem definition based on German PWR (ratable results) – Systematic benchmark series with increasing complexity Achievements: – Common understanding allows comparison of models – Identification of sensible code/model options and (a few) code ‚inconsistencies‘ – Discussions are continued in user-groups (e.g. EMUG)

15. ERMSAR 2012, Cologne March 21 – 23, 2012 Thank you for your interest! 15 St. Kelm, H.-J. Allelein Ph. Broxtermann, S.Krajewski, G. Preusser M. Sangiorgi W. Klein-Hessling, I. Bakalov A. Bleyer, A. Bentaib, I. Kljenak, M. Stempniewicz, J.R. Jonnet, P. Kostka, S. Morandi J. Burkhardt L. Denk, Z. Parduba S. Paci, A. Manfredini A. Silde J. Jancovic, P. Juris