Overview on PANDA and ISP-42, T18 / / Aksan, 1 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 OVERVIEW ON THE PANDA TEST FACILITY AND ISP-42 PANDA TESTS DATA BASE Presented by Nusret Aksan Paul Scherrer Institut (PSI), 5232 Villigen PSI, Switzerland Tel , Fax , IAEA Course on Natural Circulation in Water-Cooled Nuclear Power Plants, International Centre for Theoretical Physics (ICTP), Trieste, Italy, 25th to 29 th, June 2007, Paper ID. T18

Overview on PANDA and ISP-42, T18 / / Aksan, 2 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 COURSE ROADMAP

Overview on PANDA and ISP-42, T18 / / Aksan, 3 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 ACKNOWLEDGEMENTS OECD Nuclear Energy Agency (NEA), Committee for the Safety of Nuclear Installations (CSNI) Research Funds of Swiss Electric Power Communities (VSE - PSEL ) Federal Department for Energy (BFE) Em. Prof. Dr. G. Yadigaroglu, ETH Zürich Dr. J. Dreier and PANDA Experimental Team Dr. D. Luebbesmeyer

Overview on PANDA and ISP-42, T18 / / Aksan, 4 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 OVERVIEW OF THE PRESENTATION PSI PERSPECTIVE FOR ISP-42 INTRODUCTION AND MAIN AIMS OF ISP-42 PANDA THE MAIN ISSUES AND PHENOMENA COVERED IN ISP-42 PANDA SHORT TEST OUTLINE AND TEST OVERVIEW OVERVIEW ON ISP-42 (PANDA) SUBMISSIONS SOME SELECTED RESULTS SOME SELECTED MAJOR CONCLUSIONS RELEVANCE OF THE ISP-42 FOR CURRENT AND FUTURE DEVELOPMENTS OF THE ALPHA PROJECT

Overview on PANDA and ISP-42, T18 / / Aksan, 5 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 The International Standard Problem 42 (ISP-42): PSI perspective in the context of the project ALPHA Project ALPHA: Thermal-hydraulic research for safety of current and advanced reactors: - Unique medium and large scale facilities for integral and separate effect tests - Model/code development, assessment and application ALPHA I and ALPHA II ( ): Projects including tests of passive cooling concepts and assessment of capabilities of codes for advanced reactors. Emerging issues: - Passive reactors: low pressure conditions, coupling between primary loop and containment, performance of passive cooling systems, etc. - Current and advanced reactors: 3-D phenomena (mixing/stratification) and their effect on system response, distribution of light gases in relation to severe accident scenario (hydrogen risk)  Propose an International Standard Problem on PANDA aiming at assessing capabilities of system, containment and CFD codes in relation to issues relevant for both advanced and current reactors.

Overview on PANDA and ISP-42, T18 / / Aksan, 6 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Relevance of the ISP-42 for current and future developments of the ALPHA project ►Advanced reactors: ISP-42 was a milestone for building confidence in system codes for simulating passive systems, and further enhance competence on – Gravity driven flows: contribute to address high priority industrial needs (EUROFASTNET and resulting projects in the 6th EU FWP); IAEA co-ordinated Research Programme. – Passive safety systems: perspective further work for innovative and evolutionary reactors (ESBWR, SWR1000, new projects in the 6th FWP, e.g., PASSION), as well as for new generation reactors (HPLWR, Gen. IV) Remaining issues in relation to severe accident scenarios require integral tests with a more complete and advanced instrumentation (5th EU FWP TEMPEST, ALPHA III ( )) ►Current and advanced reactors: ISP-42 revealed the potential of 3-D modelling approach, but also its difficulty Development/validation of 3-D codes: ISP-42 confirmed the need for new separate effect tests. A data base for basic flows in a multi-compartment geometry at large scale is required.  OECD-SETH Project (ALPHA IV, ) and perspective follow-ups ( ).

Overview on PANDA and ISP-42, T18 / / Aksan, 7 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Key Figures Vessel volumes: total 460 m³ Pool volumes: total 60 m³ Facility height: 25 m Operating Conditions: 10 barg / 180 oC Installed Power: 1.5 MW Modular Structure Six cylindrical vessels and four pools Two tower arrangement of the large vessels with large connection pipes Broad variety of vessel and pool interconnections Provides flexibility to easily adapt the facility for a variety of investigations Uniqueness Well suited for large-scale thermal-hydraulic tests, especially for containment multi-compartment and 3D effects Vessel dimensions approach those of actual LWR primary system components, allowing for specific tests at nearly full scale and large-scale separate-effects tests Extensive and accurate basic instrumentation Well insulated and characterised with respect to e.g. heat and line pressure losses Various controlled auxiliary systems for establishing proper test initial and boundary conditions

Overview on PANDA and ISP-42, T18 / / Aksan, 8 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 PANDA Experimental Facility: Vessels, Pools and System Lines

Overview on PANDA and ISP-42, T18 / / Aksan, 9 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 PANDA Experimental Facility PANDA Vessel and Pool Key Figures Cylindrical vessels (diameter/height) - Steam source/RPV:1.25 / 19.3 m - Upper large volumes/DW’s :4.00 / 7.8 m - Connection pipe diameter:1 m - Lower large volumes/WW’s:4.00 / 9.7 m - Upper connection pipe diameter:1.0 m - Lower connection pipe diameter:1.5 m - Medium size volume/GDCS:2.00 / 6.2 m 4 Pools (wide, length, height):1.5 / 2.0 / 5.0 m

Overview on PANDA and ISP-42, T18 / / Aksan, 10 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 PANDA Major Application Areas Large-scale containment cooling integral system tests Large-scale primary system component tests Large-scale containment multi-compartment and 3D separate-effects tests

Overview on PANDA and ISP-42, T18 / / Aksan, 11 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 PANDA Facility: Auxiliary Systems (I)  Mainly for Conditioning the Facility and also for Applying Specific Boundary Conditions During Tests: Air Supply System Controlled flow, connection to each vessel Max. flow: 29 g/s, ambient temperature Helium Supply System Controlled flow, connection to each vessel Max. flow: 50 g/s (limited by flowmeter), ambient temperature Demineralized Water Supply System Controlled flow, connections to RPV and auxiliary water system Max. flow: 2 kg/s, ambient temperature

Overview on PANDA and ISP-42, T18 / / Aksan, 12 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 PANDA Facility: Auxiliary Systems (cont’d: II) Auxiliary Water System Water recirculation system connectable to the top and bottom filling ports in all vessels and pools Cooling and heating (RPV as heat source) capability Controlled flow, Max. flow: 17 kg/s Auxiliary Steam System Controlled flow, connection to each vessel Max. flow: 680 g/s, up to 184 ˚C / 11 bar Vent System Connectable to any vessel Temperature or pressure controlled vent valve

Overview on PANDA and ISP-42, T18 / / Aksan, 13 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Earlier Investigations in PANDA (I) SBWR (Simplified Boiling Water Rector) Scaling 1:25 for volume, power, flow rates 1:1for height, time, pressure 10 integral system tests: - Concept demonstration - Asymmetric steam injection - Reduced condenser capacity - Isolation Condenser and Passive Containment Condenser system interaction - Vacuum Breaker leakage

Overview on PANDA and ISP-42, T18 / / Aksan, 14 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Earlier Investigations in PANDA (II) ESBWR (European SBWR) Scaling 1:40 for volume, power, flow rates 1:1for height, time, pressure 8 integral system tests – Extension of SBWR tests: - Low water level in PCC Pool - Deferred release of "trapped" air in DW - Severe accident scenario (H2 simulated with He)

Overview on PANDA and ISP-42, T18 / / Aksan, 15 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Earlier Investigations in PANDA (III) OECD/NEA International Standard Problem 42 (ISP-42) Scaling 1:40 for volume, power, flow rates 1:1for height, time, pressure Six well-defined sequential phases covering Many typical LWR and ALWR containment and primary system phenomena SWR-1000 Building Condenser Scaling 1:26for PCCS (except pool) 8:1for time (due to pool size) 6 integral system tests - Small, medium and large break LOCA scenarios - Severe accident scenarios (H2 simulated with He)

Overview on PANDA and ISP-42, T18 / / Aksan, 16 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Earlier Investigations in PANDA (IV) TEMPEST (5th EU FWP, related to ESBWR) - Influence of light non-condensable gases on integral system and PCC condenser behaviour - Drywell gas re-circulation system for accident mitigation and long-term containment depressurisation NACUSP (5th EU FWP) - Large-scale separate-effects low pressure natural circulation stability investigations in the RPV of PANDA

Overview on PANDA and ISP-42, T18 / / Aksan, 17 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 PANDA Facility

Overview on PANDA and ISP-42, T18 / / Aksan, 18 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 SBWR/ESBWRPANDA

Overview on PANDA and ISP-42, T18 / / Aksan, 19 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007

Overview on PANDA and ISP-42, T18 / / Aksan, 20 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 ESBWR PASSIVE SAFETY SYSTEMS

Overview on PANDA and ISP-42, T18 / / Aksan, 21 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 SWR1000Simulation inPANDA

Overview on PANDA and ISP-42, T18 / / Aksan, 22 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Natural Circulation and Stability of BWRs ( EU-5thFWP) NACUSP Configuration (Natural-circulation loop and condensation/cooling loop) for PANDA Facility Variation of Core Inlet Resistance Basic tests: BWR typical (k = 30) Few tests: Low value (k = 7) High value (k = 500) Variation of RPV Water Level Basic tests: BWR typical Few tests: Low level Pressure [bar] RPV Power [kW] Test Program Basic Tests

Overview on PANDA and ISP-42, T18 / / Aksan, 23 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 INTRODUCTION AND MAIN AIMS OF ISP-42 PANDA OECD/NEA-CSNI APPROVED A TEST IN THE PANDA FACILITY (DECEMBER 1997) AS ISP-42 PROPOSED ISP SCENARIO PRESENTED AND DISCUSSED WITH SOME REPRESENTATIVES FROM THE OECD COUNTRIES AT A PREPARATORY MEETING (MARCH 1998). RECOMMENDATIONS AND COMMENTS RECEIVED WERE CONSIDERED IN DEFINING THE ISP-TEST SCENARIO ISP-PANDA TEST PERFORMED ON 21/22 APRIL EXPERIMENTAL DATA LOCKED, SINCE THE FIRST PHASE IS CONDUCTED AS A "DOUBLE BLIND" OR "BLIND" EXERCISE MAIN AIMS OF ISP-42: ► GAINING INSIGHTS INTO PASSIVE HEAT REMOVAL SYSTEMS ► ASSESSING THE ABILITY OF THE MODELS IN CODES FOR THE PHYSICAL LOW-PRESSURE, LOW DRIVING FORCE PHENOMENA OF INTEREST ► TESTING AND ASSESSING CAPABILITIES OF INTERNATIONALLY USED THERMAL-HYDRAULICS COMPUTER CODES IN ANALYZING PASSIVE DECAY HEAT REMOVAL SYSTEMS, e.g., PRIMARY SYSTEM CODES, CONTAINMENT CODES (LUMPED PARAMETER, AS WELL AS 3D), CFD CODES, POSSIBLY SEVERE ACCIDENT CODES

Overview on PANDA and ISP-42, T18 / / Aksan, 24 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 THE MAIN ISSUES AND PHENOMENA COVERED IN ISP-42 PANDA TRANSIENT AND QUASI STEADY-STATE OPERATION OF A PASSIVE CONTAINMENT SYSTEM, INCLUDING OPERATION AT LOW POWER AND LOW PRESSURE UNDER NATURAL CIRCULATION CONDITIONS COUPLED PRIMARY SYSTEM AND CONTAINMENT BEHAVIOUR AND PHENOMENA BEHAVIOUR OF PASSIVE CONTAINMENT COOLERS (PCCs) MIXING AND STRATIFICATION OF LIGHT (HELIUM) AND/OR HEAVY (AIR) GASES WITH STEAM IN LARGE VOLUMES (3-D EFFECTS, STEAM JETS, AIR OR HELIUM RELEASE) MIXING AND STRATIFICATION IN LARGE WATER POOLS. MANY OF THE PHENOMENA COVERED ARE OF A GENERIC CHARACTER AND OF INTEREST TO LWR CONTAINMENTS (AND ALSO PRIMARY SYSTEMS) IN GENERAL

Overview on PANDA and ISP-42, T18 / / Aksan, 25 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 ISP-42 PANDA TEST OUTLINE TEST SCENARIO CONSISTS OF SIX PHASES WELL DEFINED BOUNDARY AND INITIAL CONDITIONS FOR EACH PHASE AND, RESTRICTING THE PHYSICAL PHENOMENA TAKING PLACE TO A REASONABLE NUMBER CALCULATIONS FOR EACH PHASE CAN BE STARTED AND PERFORMED INDEPENDENTLY PASSIVE CONTAINMENT COOLING SYSTEM IN OPERATION DURING THE FIVE DESIGN-BASIS-ACCIDENT-RELATED TEST PHASES SIXTH TEST PHASE SIMULATES A CORE OVERHEAT BY INJECTION OF HELIUM IN THE REACTOR PRESSURE VESSEL (NO CONTAINMENT HEAT REMOVAL SYSTEM IN OPERATION) TEST SCENARIO COVERS MANY TYPICAL LWR AND ALWR CONTAINMENT (AND PRIMARY SYSTEM) PHENOMENA

Overview on PANDA and ISP-42, T18 / / Aksan, 26 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 TEST OVERVIEW Phase A : Passive Containment Cooling System Start-Up Phase B : Gravity-Driven Cooling System Discharge Phase C : Long-Term Passive Decay Heat Removal Phase D : Overload at Pure-Steam Conditions Phase E : Release of Hidden Air Phase F : Release of Light Gas in Reactor Pressure Vessel

Overview on PANDA and ISP-42, T18 / / Aksan, 27 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 OVERVIEW ON ISP-42 (PANDA) SUBMISSIONS 49 "BLIND" PHASE CALCULATIONS RECEIVED FROM 10 ORGANIZATIONS (MARCH 2000) COMPUTER CODES USED FOR “BLIND” PHASE: RELAP5/Mod 3.2, CATHARE, SPECTRA, COCOSYS, RALOC, GOTHIC, CONTAIN, SPM 27 "OPEN" PHASE CALCULATIONS RECEIVED FROM 8 ORGANIZATIONS (FEBRUARY 2001) COMPUTER CODES USED FOR “OPEN” PHASE: RELAP5/Mod 3.2, CATHARE, SPECTRA, COCOSYS, RALOC, GOTHIC FINAL DRAFT REPORTS ON BOTH THE “BLIND” AND “OPEN” PHASE RESULTS (FEBRUARY 2002) REVIEW AND APPROVAL OF THE BOTH REPORTS BY OECD/NEA-CSNI AND ITS’ WORKING GROUPS (DURING 2002 – EARLY 2003)

Overview on PANDA and ISP-42, T18 / / Aksan, 28 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 SOME SELECTED RESULTS FOR PHASE A DRYWELL PRESSURE HISTORY, ISP-42 PHASE A LIQUID MASS INVENTORY IN REACTOR PRESSURE VESSEL (RPV), ISP-42 PHASE A AXIAL TEMPERATURE DISTRIBUTION IN WETWELL-1 AT 500 s and 4000 s, ISP-42 PHASE A “USER EFFECT” RELAP5 AND CATHARE

Overview on PANDA and ISP-42, T18 / / Aksan, 29 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 PHASE A: Passive Containment Cooling System Start-up

Overview on PANDA and ISP-42, T18 / / Aksan, 30 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Comparison of drywell pressure calculations (blind and open phases) with experimental data for Phase A of ISP-42

Overview on PANDA and ISP-42, T18 / / Aksan, 31 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Comparison of liquid mass inventory predictions (blind and open phases) with experimental data (Reactor Pressure Vessel) for Phase A of ISP-42

Overview on PANDA and ISP-42, T18 / / Aksan, 32 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Measured and Predicted axial temperature distribution in wetwell-1 at 500s for Phase A of ISP-42

Overview on PANDA and ISP-42, T18 / / Aksan, 33 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Measured and Predicted axial temperature distribution in wetwell-1 at 4000s for Phase A of ISP-42

Overview on PANDA and ISP-42, T18 / / Aksan, 34 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Drywell pressure RELAP 5/Mod3 and CATHARE code calculations compared to experimental data for Phase A of ISP-42

Overview on PANDA and ISP-42, T18 / / Aksan, 35 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 SOME SELECTED MAJOR CONCLUSIONS OBJECTIVES SET AT THE BEGINNING OF THIS ISP-42 ACTIVITY HAVE BEEN ACHIEVED, EVEN THOUGH VERY DEMANDING EFFORTS NEEDED FOR SUCH MULTIPLE EXERCISE WITH SIX DIFFERENT PHASES MOST IMPORTANT PARAMETER IN RELATION TO REACTOR SAFETY, THE CONTAINMENT PRESSURE HISTORY HAS BEEN CALCULATED SUFFICIENTLY CORRECT FOR MOST OF THE ISP-42 PARTICIPANTS FOR ALL SIX PHASES OF ISP-42 THE OVERALL BEST RESULTS WERE OBTAINED BY THE LUMPED PARAMETER CODE SPECTRA: ►ALTHOUGH SYSTEM CODES LIKE CATHARE OR RELAP5/Mod 3 WERE NOT DESIGNED TO CALCULATE TYPICAL CONTAINMENT PROBLEMS IN LOW PRESSURE ENVIRONMENTS IN THE PRESENCE OF LARGE AMOUNTS OF NONCONDENSIBLES, THEY PRODUCED ACCEPTABLE RESULTS. CONTAINMENT CODE COCOSYS ALSO PRODUCED GLOBALLY ACCEPTABLE RESULTS

Overview on PANDA and ISP-42, T18 / / Aksan, 36 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 SOME SELECTED MAJOR CONCLUSIONS (Continued) ►SOME CODES (LIKE GOTHIC) HAD PROBLEMS TO SIMULATE SPECIFIC EQUIPMENT (e.g., PCCs) AND NEEDED INTRODUCTION OF SOME TUNING OF “PHYSICAL” MODELS WITH THE KNOWLEDGE OF THE FACILITY BEHAVIOUR. THE RELAP5/Mod 3 AND CATHARE CODES HAVE HIGHER FLEXIBILITY TO SIMULATE SPECIAL COMPONENTS, IN THIS CASE, SPECIFICALLY THE MODELLING OF THE PCCs ►MOST OF THE MAJOR DEVIATIONS COULD BE ATTRIBUTED TO PROBLEMS WITH THE NODALISATION OR SIMPLY INPUT ERRORS RATHER THAN DEFICIENCIES OF THE SPECIFIC CODES. FOR EXAMPLE, IN THE CASE OF RELAP5 AND CATHARE, THE SAME CODE USED BY DIFFERENT ORGANIZATIONS PRODUCED QUITE DIFFERENT RESULTS (“USER EFFECT” AND ALSO DIFFERENT LEVEL OF EXPERIENCE OF THE CODE USERS). PSI RESULTS WERE VERY GOOD AND NO NEED FOR “OPEN” PHASE SUBMISSION IT WAS OBSERVED THAT MAJOR ATTENTION SHOULD BE GIVEN TO PROVIDE THE APPROPRIATE INPUT PARAMETERS, WHICH ARE USED IN THE ANALYSIS. AS AN EXAMPLE, USE OF LOSS COEFFICIENTS AND THEIR DISTRIBUTION, ESPECIALLY FOR LOW POWER, LOW PRESSURE TRANSIENTS AS IN ISP-42, IS A VERY IMPORTANT FACTOR. (COMPUTER CODE’S USER DISCIPLINE)

Overview on PANDA and ISP-42, T18 / / Aksan, 37 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 SOME SELECTED MAJOR CONCLUSIONS (Continued) FOR SIMPLE PHYSICAL SITUATIONS (HOMOGENEOUS CONDITIONS) LITTLE GAIN IN PREDICTIVE CAPABILTY IS ACHIEVED BY VERY DETAILED NODALIZATION OR USE OF 3-D MODELS AT THE COST OF VERY LARGE COMPUTATION TIME ► 3-D MODELS SUCH AS IN GOTHIC CODE INCLUDE RIGHT PHYSICAL REPRESENTATION OF PHENOMENA BUT NUMBER OF DIFFICULTIES CURRENTLY PREVENTS TO TAKE FULL ADVANTAGE OF THESE CAPABILITIES. CONSEQUENTLY, FURTHER ASSESSMENT OF 3-D MODELS AND ADVANCED MODELLING FEATURES (e.g., TURBULENCE) ARE NECESSARY, ESPECIALLY USING WELL-DEFINED SEPARATE EFFECTS TESTS ►THE USE OF CFD CODES STILL EXPLORATORY, AS THEY USUALLY LACK BUILT-IN PHYSICAL MODELS, INTERFACES (BOUNDARY CONDITIONS) WITH OTHER COMPONENTS ARE DIFFICULT TO SET, AND THEY OCCASIONALY SHOW PROBLEMS WITH RESPECT TO CONVERGENCE

Overview on PANDA and ISP-42, T18 / / Aksan, 38 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 SOME SELECTED MAJOR CONCLUSIONS (Continued) ►THE KNOWLEDGE GAINED IN ISP-42 AND OTHER PANDA TESTS INDICATED THE NEED TO IMPROVE AND UPGRADE SOME OF THE INSTRUMENTATION, e.g., IMPROVED MEASUREMENT OF INJECTED MEDIUM, IMPROVED MEASUREMENT OF LOCAL CONCENTRATION OF AIR, HELIUM AND STEAM IN THE GAS SPACES OF THE DIFFERENT PANDA COMPARTMENTS ►THE DATA SET PRODUCED FOR THE SIX PHASES OF THE ISP-42 PANDA TESTS WILL BE USED AS THE BASIS OF ASSESSMENT OF COMPUTER CODES IN RELATION TO THE PASSIVE CONTAINMENT COOLING SYSTEMS IN THE NEXT FUTURE, AT LEAST NEXT TEN YEARS. THESE DATA WILL BE AVAILABLE TO THE REQUESTING ORGANIZATIONS THROUGH NEA-DATA BANK AND EUROPEAN COMMUNITY PROJECT CERTA

Overview on PANDA and ISP-42, T18 / / Aksan, 39 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Current and Future Investigations in PANDA Facility OECD SETH ( ) - Large-scale investigation of gas mixing and distribution in multi- dimensional, multi-compartment geometries OECD SETH II ( ) - Resolving LWR containment key computational issues

Overview on PANDA and ISP-42, T18 / / Aksan, 40 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Gas Mixing and Stratification in LWR Containments (OECD-SETH Project) Objectives ►To perform PANDA tests to study mixing of steam, air and helium in containments under DBA and beyond DBA conditions and basic flow structures that drive mixing ►To provide data with high spatial resolution for validating codes with 3D capabilities in a key area related to accident analyses PANDA Configuration for Near Wall Plume/Jet Test Initial conditions: Air, 1.3 bar, 108 °C Vessel volume: 2 x 90 m3 5 m/s 140°C Measured Velocity Field with PIVPredicted Velocity Field with CFX-5 Measured Temperature Fields in DW1 95 sec after test start 1595 sec after test start

Overview on PANDA and ISP-42, T18 / / Aksan, 41 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 PANDA Application to Super Critical Water Reactor Investigation of SCWR passive systems behaviour in PANDA proposed:  Containment Cooling Condenser: Decay heat removal from containment  Emergency Condenser: Decay heat removal from RPV  Flooding System: Flooding of RPV Containment Cooling Condenser Emergency Condenser Safety relief valves Drywell Core flooding pool Suppression pool RPV Containment Cooling Condenser Drywell Suppression pool

Overview on PANDA and ISP-42, T18 / / Aksan, 42 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Some General Conclusions (I) PANDA provided relevant contributions: – Experimental investigations of LWR typical 3D phenomena in - multi-compartment confinements (containments) - pressure suppression pools – Large scale integral testing of passive cooling systems (SBWR, SWR1000, ESBWR): - performance under various accident conditions (including H2 release) - concept demonstrations – More than 100 tests performed up to now – Extensive high quality data bases for model development and code validation (ranging from LP codes to CFD codes) – Results published in various Journal Papers and several International Conferences

Overview on PANDA and ISP-42, T18 / / Aksan, 43 Laboratory for Thermal-Hydraulics Nuclear Energy and Safety Department IAEA-ICTP Natural Circulation Training Course, Trieste, Italy, June 2007 Some General Conclusions (II) Excellent resources available: - Unique facility PANDA - Operational, well maintained and proven test facility - Successfully used for integral containment system tests, component performance tests and generic investigations at large scale - Well equipped for measuring temperature, gas concentration and velocity fields - Sophisticated auxiliary systems ensure precise initial and boundary conditions - Potential for extension to many other areas of application - Highly qualified team - Many years of experience in performing complex experiments