1. ERMSAR 2012, Cologne March 21 – 23, 2012 EXPERIMENTAL STUDY OF HYDROGEN COMBUSTION DURING DCH EVENTS IN TWO DIFFERENT SCALES Giancarlo Albrecht Leonhard Meyer Alex Miassoedov Karlsruhe Institute of Technology, Germany Institute for Nuclear and Energy Technologies

2. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions The issue: combustion at DCH conditions The containment atmosphere may contain hydrogen, but it’s concentration is generally below the ignition limit Pure hydrogen or a mixture of hydrogen and steam is blown into the containment or reactor rooms and different hydrogen concentrations exist at different locations Many ignition sources are moving through the mixed atmosphere. Concurrent injection and burnout of hydrogen changes the hydrogen concentrations in location and time Several different hydrogen combustion modes can occur in sequence or simultaneously at different locations The pressure increase depends on Hydrogen ejection rate (breach size and geometry of cavity) Hydrogen combustion rates (at different locations) Heat losses due to convection and radiation; both depending on geometry 2

3. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Motivation and objectives Blow down of hydrogen or hydrogen/steam into an air/steam/hydrogen atmosphere Preexisting hydrogen concentration in containment atmosphere between 0 and 8% (below or at ignition limit) Ignition of H2 by melt particles (simulated in tests w/o melt by multiple igniters (thermite sparklers)) Data base of 12 tests with hydrogen blow-down into prototypic atmosphere had been established for small scale (1:18) in the DISCO facility  Solve the problem of scaling by doing experiments in different scale and provide data for code modeling and validation 3

4. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Existing Data Test matrix in small scale experiments (14 m³) 4 G01G02G03G04G05G06 RPV: Hole size mm6025*25 RPV: PressureMPa222222 RPV: Temperature °C 100 230 180 RPV: N 2 or steamN2N2 N2N2 N2N2 H2OH2OH2OH2O- RPV: Hydrogen massg100 50 100 CON: Hydrogen massg--50 100 CON: Hydrogen concentration%003366 CON: PressureMPa0.2 CON: Temperature °C 20 100 CON: Steamno yes * Scaled: 0.45 m diameter

5. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Existing Data 5

6. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Up-scaling of DISCO Facility 6 RPV: V = 1.37 m³ Containment: H = 9.0 m Ø = 6 m V = 227 m³ RPV: V = 0.080 m³ Containment: H = 4.5 m Ø = 2.2 m V = 14 m³ Assumed containment volume: ca. 80.000 m³ All volumes are freeboard volumes DISCO A2 1 m 2 m 3 m 4 m 5 m 6 m 8 m 7 m 9 m 10 m Go from linear scale 1:18 to 1:7 (volume scale: 1: 5800 to 1:350)

7. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions The Test Vessel A2 Pressure vessel A2 w/o insulation and heating equipment 7 RPV/RCS-vessel and cavity

8. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions The Test Facility in A2 8 Positions of 6 gas sample linesPositions of igniters

9. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions The Test Facility in A2 9 Positions of thermocouplesPositions of pressure sensors

10. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions The Test Matrix Test matrix in large scale experiments (227 m³) 10 GL1GL2GL3GL8GL4GL5GL6GL9GL7 RPV: PressureMPa1.81.791.81.751.77 1.69- RPV: Temperature °C 311189412699117113125- RPV: Hydrogen massg1476137580380881682713781276- CON: Hydrogen massg081470016077111610149714352421 CON: Hydrogen conc.%02.822.245.433.056.79 * 5.875.947.82 * CON: PressureMPa0.2000.2050.2030.2120.1600.1650.1770.1700.220 CON: Temperature °C 321189112393111 115122 CON: Steamno yes no * above flammability limit

11. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Test Results 11 Pressures in the RPV-vessel during blow-down N 2 /H 2 ≈ 1 N 2 /H 2 = ¼ N 2 /H 2 < ⅛

12. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Test Results 12 Temperatures at four levels in the containment for test GL7 (no blowdown of H2)

13. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Test Results 13 Temperatures at four levels in the containment for test GL6 (blowdown of H2)

14. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Test Results 14 Containment temperatures at measurement level 1 for large scale test series

15. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Test Results 15 Containment pressure rise, data shifted to 0.2 MPa initial containment pressure No blow-down H 2 -con. = 7.8% GL3 w/o steam GL4 with steam RPV: low, cont: low Cont: high, RPV: low Cont: low, RPV: high

16. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Test Results 16 Comparison of containment pressure rise in 1:18 and 1:7 scale experiments Time axis scaled to prototypic size

17. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Test Results 17

18. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Test Results 18 G01G02G03G04G05G06 RPV: Hydrogen massg100 50 100 CON: Hydrogen massg--50 100 CON: Hydrogen concentration%003366 CON: Steamno yes Fraction burned1.00.730.550.580.860.78 GL1GL2GL3GL8GL4GL5GL6GL9GL7 RPV: Hydrogen massg1476137580380881682713781276- CON: Hydrogen massg081470016077111610149714352421 CON: Hydrogen conc.%02.822.245.433.056.79 * 5.875.947.82 * CON: Steamno yes no Fraction burned0.970.910.570.600.76 0.870.760.78

19. ERMSAR 2012, Cologne March 21 – 23, 2012 Hydrogen combustion tests at DCH conditions Conclusions No scaling effect was found in the simple geometry. Replacement of nitrogen by steam does not reveal any noticeable differences. Only a fraction of available H2 burned, if hydrogen in containment pre-exists (46% – 91%) Only a part of combustion energy is converted into pressure (42% -71%). Data base should suffice to validate code models. 19

20. ERMSAR 2012, Cologne March 21 – 23, 2012 20