ESA Enhancement of Safety Evaluation tools

Transcription

1 ESA Enhancement of Safety Evaluation tools SAFIR2014 Interim seminar, Hanasaari, Ismo Karppinen, Seppo Hillberg, Pasi Inkinen, Jarno Kolehmainen, Joona Kurki, Ari Silde, Risto Huhtanen VTT Technical Research Centre of Finland

2 2 Objectives of the project To develop and validate calculation methods for safety evaluation of nuclear power plants To prepared to analyse new plant concepts with passive safety systems (OL4, Hanhikivi 1) Train new thermal hydraulic code users and educate young experts

3 3 1 Validation of system codes APROS TRACE Tasks 2 Validation of containment analysis methods Lumped parameter, APROS Containment CDF, Fluent 3 International co-operation OECD/NEA research programs ROSA, PKL, SETH, HYMERERS OECD Working Group on the Analysis and Management of Accidents (WGAMA) USNRC Code Applications and Maintenance Program (CAMP) NORTHNET RoadMap 3

4 4 System code applications Steam Line 2 Feedwater Steam Line 1 Feedwater APROS and TRACE validation PWR PACTEL benchmark Steam Line A Steam Line B Steam Generator 2 Pressurizer Surge Line Hot Leg 2 Cold Leg 2 Break Core Pressure Vessel Hot Leg 1 Cold Leg 1 Downcomer Steam Generator 1 Steam Generator A Pressurizer Steam Generator B ROSA2 Test 3 and Test 7 Feedwater Accumulator Accumulator Feedwater Surge Line ROCOM mixing experiments Primary Loop A Core Primary Loop B Pressure Vessel PANDA Isolation Condenser NOKO emergency condenser (Kerena) ISP-50 (ATLAS/APR-1400) ABWR model based on public information (diploma work)

5 5 APROS validation with PACTEL experiments VVER PACTEL experiment NCg1, NCg3, NCg2-04, -05 SG behavior when air or helium is injected in the primary circuit (only one loop in operation) Reduced water inventory (~50%) Boiler-condenser operation mode

6 6 PACTEL steam generator and APROS model Steam was condensing in the SG Non-condensable gas was injected in hot leg, just below the steam generator

7 7 NCg4-02 experiment Helium injection in steps Reduction of heat transfer results in increased pressure and temperature Heat transfer degradation was well reproduced with APROS Serves also as validation case for equivalent condensers

8 8 Containment modelling Validation cases AB-CHIM SARNET containment benchmark with PAR AB-UP1 AB-UP2 AB-SUMP PANDA PCC GEKO building condenser PANDA containment cooler experiments SARNET spray benchmark THAI stratification/mixing experiment Pressure meter Nozzle Computer z-axis translation Spray Analyser 1 Analyser 2 Filter Laser Measurement point Receiver y-axis translation Pool x-axis translation Main Pump

9 9 THAI TH24 gas stratification benchmark THAI facility in Easchborn in Germany (Becker Technologies GmbH) Height 9.2 m, diameter 3.2 m Cooled wall Test TH24 Dissolution of Steam Stratification by Natural Convection Controlled wall temperature Natural circulation Heated wall

10 10 APROS APROS and Fluent models THAI facility Fluent 144-cell model, 350 gas flow paths 28 vertical (axial) cell elevations 5 horizontal cells on each elevation Dedicated 8 cell nodalization for steam injection zone Mesh with cells k-ε turbulence model

11 11 Steaminjection phase Steam concentration profile t = 500 s Blind simulation results (TH24) steam concentration profiles Steam mass flow Concentration [%] Test APROS Fluent Height [m] Steam concentration profile t = 1000 s Eruption of stratification Steam concentration profile t = 2000 s Concentration [%] Test APROS Fluent Concentration [%] Test APROS Fluent Height [m] Height [m]

12 12 APROS LP simulation results steam concentration animation

13 13 Conclusions of THAI simulations Both codes predicted stratification and mixing quite well Parallel use of a lumped parameter code and CFD analysis was found useful Post test calculation are still going on (some discrepancy in specified initial and boundary conditions) APROS: To simulate the stratification and the dissolution of the steam (and light gas) cloud, a proper nodalisation is necessary: nodalizations should be detailed enough both in vertical and horizontal directions dedicated nodalization for the plume zone to improve the modeling of bouncy driven flow, is recommended Fluent: Stratification in the vessel was well predicted, but the stability of density layer may even be too strong. The used k-ε turbulence model has got buoyancy effects for turbulence (for stable stratification).

14 14 CONCLUSIONS System codes APROS and TRACE validated with both separate effects and integral experiments Special interest has been paid on passive safety systems of the new plant concepts Containment analysis methods Both APROS Containment and Fluent analysis capabilities are developed and validated for the NPP applications Most of the work has been done by young experts 2 diploma works under way