Experimental and numerical investigations of an emergency condenser

1. Experimental and numerical investigations of an emergency condenser E. Krepper 4th NC IAEA Research Coordination Meeting Vienna, Sept. 10th-13th 2007

2. Outline • Experiments at NOKO • Experiments at TOPFLOW • CFD simulations

3. 0. Introduction SWR Safety concept

4. 0. Introduction Operation scheme of an BWR - emergency condenser

5. 1. Experiments at NOKO NOKO test facility • Operated in FZ-Jülich 1995-2000 • Main subject: • Investigation of the heat transfer capability of an emergency condenser by condensation in horizontal tubes • A. Schaffrath; E.F. Hicken; H. Jaegers, H.-M. Prasser: Experimental and Analytical Investigation of the Operation Mode of the Emergency Condenser of the SWR1000; Nuclear Technology 126 (1999), May 1999, p. 123-142 • Additional experiments 1998-2000: • Investigation of the heating up processes on the secondary side • E. Krepper, E.-F. Hicken, H. Jaegers: Investigation of Natural Convection in Large Pools; Int. J. of Heat and Fluid Flow Vol. 23 (2002) pp. 359-365 • E. Krepper, A. Schaffrath, A. Aszodi: Numerical Simulation of the Emergency Condenser of the SWR-1000; Nuclear Science and Engineering 135 (2000), 267–279

6. 1. Experiments at NOKO Schematic view of the NOKO-test facility • Parameters: • Primary pressure 1 MPa • transferred power ca. 0.6 MW • Measurements • Thermocouples on the secondary side arranged in 5 planes • Heating up experiments: • Level in the core simulator was adjusted, that only the upper three tubes of the condenser were filled with steam

7. 1. Experiments at NOKO Arrangement of the thermocouples in the measuring plane

8. 1. Experiments at NOKO Measured temperature distributions after a heating up time of about 2000 s • All 5 measuring planes show in principle the same temperature distribution • 2D approach by modelling of only one plane is justified

9. 2. Experiments at TOPFLOW TOPFLOW – Multipurpose Transient TwoPhase Flow Test Facility

10. 2. Experiments at TOPFLOW Condenser tank Steam inlet Condensate outlet Parameters: Maximum Pressure:1 MPa; Maximum temperature: 180 °C; Length: 6,4 m; Outer diameter: 2 m; Wall thickness: 50 mm; Volume: 17,7 m³ Weight: 40 t

11. 2. Experiments at TOPFLOW Arrangement of thermocouples in the tank

12. 2. Experiments at TOPFLOW Condensing tubes

13. 2. Experiments at TOPFLOW Arrangement of thermocouples in the tank

14. 2. Experiments at TOPFLOW Experimental procedure • Injecting steam in the bundle at a certain pressure (1…6.5 MPa) • Secondary side: at normal conditions (0.1 Mpa) • Differences to NOKO tests: • more detailed measurements • tests are performed and recorded until steam production at the secondary side • Heating up the tank by removing of maximum condensate • Determination of the characteristic curve of the bundle by removing determined amounts of condensate

15. 2. Experiments at TOPFLOW Injected steam and removed condensate (Test at 6.5 Mpa)

16. 2. Experiments at TOPFLOW Characteristic curves of the bundle

17. 2. Experiments at TOPFLOW Heating up of the secondary side (6.5 Mpa)

18. 2. Experiments at TOPFLOW Heating up of the secondary side (6.5 Mpa)

19. 2. Experiments at TOPFLOW Time development of the Temperature in the tank (steam pressure 1.0 Mpa)

20. 2. Experiments at TOPFLOW Time development of the Temperature in the tank (steam pressure 5.0 Mpa)

21. 2. Experiments at TOPFLOW Time development of the Temperature in the tank (steam pressure 6.5 Mpa)

22. 3. CFD-Simulations CFX-4 calculations

23. 3. CFD-Simulations CFX-11 simulations (single phase)

24. 3. CFD-Simulations CFX-11 simulations (single phase)

25. 3. CFD-Simulations CFX-11 simulations (single phase)

26. 3. CFD-Simulations Two phase simulation

27. Safety related importance of the temperature stratification • Saturation temperature near the upper surface is earlier reached than with ideal temperature mixing: • temperature stratification : Boiling after ca. 2000 s • with homogeneous mixing: Boiling after ca. 8000 s • Earlier steam release into the containment • Earlier containment pressure increase