LA--10639-MS DE90 00 9219 An Investigation of Steam-Explosion Loadings with SIMMER-II W. R. Bohl '-...;'•- ;-Ofi :,F T Los Alamos National Laboratory L( Los Alamos,New Mexico 87545 CONTENTS LIST OF TABLES i x LIST OF FIGURES x FOREWORD , xi x ACKNOWLEDGMENTS xx i i ABSTRACT xxv I. SUMMARY OF THE REPORT 1 A. Introduction 1 B. Modification of SIMMER-II 2 C. Calibration to SNL Steam-Explosion Experiments 4 D. Calibration to Los Alamos Shallow-Pool Experiments 7 E. SIMMER-II Reactor Case Calculative Results 11 F. Containment Failure Probabilities 16 G. Conclusions and Recommendations 19 II. SIMMER-II MODIFICATIONS FOR THE MOLTEN-CORE/COOLANT INTERACTION PROGRAM 23 A. Introduction , 23 B. Summary of Modified Equations 25 1. AEOS Modifications 26 2. Heat-Transfer Modifications 29 3. Vaporization/Condensation Modifications 30 C. Discussion of the AEC" Modifications 33 1. Review of Difficulties in the Version 10 SIMMER-II Formulation 33 2. Examination of Proposed Solutions to AEOS Problems 35 3. The Vapor Heat-Capacity Modification 36 4. Modification of the Gas "Constant" at High Pressures 42 5. Definition of the Vapor Temperature for Single-Phase Cells and Other Modifications 43 6. Discussion of Results 46 7. Suggestions for Further Improvement 59 8. Conclusions 64 D. Modification of SIMMER-II Liquid-Liquid Heat Transfer for Water 64 E. Vaporization/Condensation Model Changes 71 F. Miscellaneous Corrections for the Molten-Core/Coolant-Interact ion Program 85 III. LOWER HEAD MODEL FOR SIMMER-II 87 A. Introduction 87 B. Input 87 C. Head Failure 90 D. Lower Head Motion 90 E. Boundary Conditions and Edits 93 F. Correction Set 98 G. Sample Problem 98 IV. CORRELATION TO SNL STEAM-EXPLOSION EXPERIMENTS 107 V. ANALYSIS OF LOS ALAMOS EXPERIMENTAL DATA FOR SHALLOW POOLS 119 A. Introduction 119 B. Experimental Correlation 119 C. Hypothetical Cases with NonunifoTtn Interfaces 130 D. Experimental Comparison with a Pressure Ratio of 50:1 150 E. Experimental Comparison with a Nonuniform Initial Interface .. 156 F. Conclusions 153 VI. ANALYSIS OF STEAM EXPLOSIONS WITH SIMMER-II 169 A. Case 1 - 20% Premixed 169 1. Investigation of Water Surface Area 173 2. Comparison with the ZIP Study Using the New Models 173 3. Case 1 Update 181 B. Case 2 - Conservative Premixing, Explosion, and Expansion .... 195 1. Explosion After 1 s of Mixing (Scoping Calculation) 197 2. Explosion after 0.7 s of Mixing (Second Scoping Calculation) 209 3. Case 2 - Final , 210 C. Case 3 - 75% Premixed 227 D. Case 4 - Simulation of an Incoherent Explosion 235 E. Case 5 - Upper Bound 238 F. Summary of SIMMER-II Steam-Explosion Cases 246 VII. PROBABILITY OF CONTAINMENT FAILURE 249 VIII. RESEARCH PRIORITIES ON STEAM EXPLOSIONS 265 APPENDIX A THE SIMMER-II MANUAL AEOS TREATMENT 273 I. MATERIAL TEMPERATURES 273 11. TWO-PHASE FLOW PRESSURES 280 III. SINGLE-PHASE FLOW STATES 284 IV. LIQUID MICROSCOPIC DENSITIES 287 V. AEOS INPUT 288 VI. DETERMINATION OF COMPONENT TEMPERATURES 297 VII. DETAILS IN THE EVALUATION OF SINGLE-PHASE LIQUID STATES 301 A. Sing]e-Component Systems 301 B. Multicomponent System 305 APPENDIX B CFS NODE /VAPOR/WRBAEOS (EOS CORRECTION SET) 311 APPENDIX C REVISED SIMMER-II INPUT DESCRIPTION FOR THE AEOS 321 APPENDIX D AEOS SIMULATION PROGRAM 327 APPENDIX E SUGGESTED VALUES FOR THE WATER AEOS INPUT 337 APPENDIX F STANDARD SIMMER-II LIQUID-LIQUID HEAT-TRANSFER MODEL 339 APPENDIX G CORRECTION SET FOR MODIFIED LIQUID-LIQUID HEAT TRANSFER 349 APPENDIX H VAPORIZATION/CONDENSATION CORRECTION SET , 353 APPENDIX I SIMMER-II MANUAL TREATMENT OF THE VAPORIZATION/CONDENSATION MODEL 359 APPENDIX J MISCELLANEOUS CORRECTIONS 373 APPENDIX K SUMMARY DESCRIPTION OF THE HEAD-FAILURE MODEL SUBROUTINE 377 APPENDIX L DEFINITIONS OF VARIABLES IN THE PLUGW CORRECTION SET 379 APPENDIX M LOWER HEAD DYNAMIC ANALYSIS 381 I. INTRODUCTION AND SUMMARY OF RESULTS OF ADINA STUDY 381 II. THE FAILURE MODEL AND CRITERIA 383 III. BASIS FOR SIMPLE MODEL TO ESTIMATE REQUIRED FAILURE IMPULSE (COLUMN 1 OF TABLE M-II) 384 IV. A SDOF MODEL THAT APPROXIMATES FAILURE TIMES 385 V. CONCLUSION 391 APPENDIX N CONSIDERATIONS REGARDING THE RESULTS FROM THE SDOF LOWER HEAD FAILURE MODEL 393 APPENDIX 0 A LIMITED REVIEW OF SNL STEAM-EXPLOSION EXPERIMENTS 395 APPENDIX P SIMMER-II INPUT FOR THE ANALYSIS OF THE MD-19 EXPERIMENT USING A UNIFORM MIXING ZONE 403 APPENDIX Q COMPARISON OF THREE-FIELD AND SIMMER-II CALCULATIONS OF COARSE PREMIXING 407 VI 1 APPENDIX R SIMMER-11 INPUT FOR THE ANALYSIS OF THE MD-19 EXPERIMENT USING A NONUNIFORM MIXING ZONE 433 APPENDIX S EFFECTS OF CHANGING THE RADIAL AND AXIAL CONSTRAINTS IN THE SIMULATION OF MD-19 441 APPENDIX T EXPLOSION CALCULATION STARTING WITH A STANDARD SIMMER-11 PREMIXED CONFIGURATION 445 APPENDIX U SIMMER-II PREMIXING WITH HIGH STEAM PRODUCTION RATES 447 APPENDIX V DETAILS ON THE UPPER BOUND SIMMER-11 STE.AM-EXPLOSION CALCULATION 453 REFERENCES 463 LIST OK TABLES 3 I. HIGHEST F ZERO WITH P(- = 171.4 kg/ir. AND ec; = 3.197 MJ/kg 52 11. AEOS/STEAM-TABLE COMPARISON FOR THE 22~MPa ISOBAR 53 III. AEOS/STEAM-TABLE COMPARISON FOR THE 50-MPa ISOBAR 54 IV. AEOS/STEAM-TABLE COMPARISON FOR THE l(H)-MPa ISOBAR 54 V. AEOS/STEAM-TABLE COMPARISON FOR THE 22-MPa ISOBAR IF a(J M IS SET TO 75 K 55 VI. SESAME RESULTS FOR FIG. 24 61 VII. LOWER HEAD MODELING INPUT 89 VIII. PLUG DATA FOR BOTTOM/TOP HEAD CALCULATION 95 IX. SAMPLE OUTPUT EDIT BEFORE LOWER HEAD FAILURE 96 X. SAMPLE OUTPUT EDIT AFTER LOWER HEAD FAILURE 97 XI. DEFINITION OF THE PXPLOT ARRAY 98 XII. CORRECTION SET FOR THE SIMMER-11 LOWER HEAD MODEL 99 XIII. INITIAL CALCULATIONS FOR FITTING TEST MD-19 112 XIV. SIMMER-II INPUT FOR THE REFERENCE CALCULATION 131 XV. FLUID KINETIC ENERGY PARTITION 192 XVI. SUMMARY OF STEAM-EXPLOSION CASES 247 XVII. DEFINITION OF PROBABILITY SPLIT LEVELS 249 XVIII. FEATURES THAT COULD BE USED IN SIMMER-II PARAMETERS OF STEAM EXPLOSION/EXPANSIONS 268 XIX. PRESENTLY INVESTIGATED IMPROVEMENTS COMPARING THE INITIALLY PROGR.AMMED THREE-FIELD FLUID-DYNAMICS ALGORITHM AND SIMMER-11 271 E-1. WATER AEOS INPUT 337 M-I. PRESSURE TRANSIENTS USED IN LOWER HEAD DYNAMIC ANALYSIS 381 M-II. SUMMARY OF LOWER HEAD FAILURE STUDY FOR A GENERIC PWR VESSEL 383 M-111. COMPARISON OF SDOF MODEL AND ADINA RESULTS 390 0-1. INTERMEDIATE-SCALE FITS TESTS 397 Q-I. SIMMER-II INPUT FOR THE MD-19 PREMIXING CALCULATION 414 LIST OF FIGURES la. SNL reported water chamber base pressures in experiment MD-19 6 lb. Calculated water chamber base pressures in experiment MD-19 6 2. Shallow-pool experimental apparatus 7 3a. P4 transducer pressures reported for the shallow-pool experiments .... 9 3b. Calculated P4 pressures in the shailow-pool experiments 9 4. PWR structural representation for SIMMER-II steam-explosion calculations 12 5. Integrated upper head loading for case 1 13 6. Integrated upper head loading for case 2 14 7. Integrated upper head loading for case 3 15 8. Integrated upper head loading for case 4 16 9. Integrated upper head loading for case 5 < 17 10. Sample problem results 26 11. Triple-valued "F" function for water vapor 34 12. Temperature-averaged vapor heat capacities for water 37 13. SESAME/SIMMER-11 comparison plot for fitting <t>w 44 14. "F" function for the revised AEOS 47 15. Steam-table comparison with saturated density and temperature inputs , 48 16. Saturation pressures with internal energy and density input into SIMMER- II 49 17. Internal energies of vapor with density and temperature input along the 22-MPa isobar 50 18. Derivative of (Eq. 25) as a function of &Q ^, with TQ just above 1"crt for water 51 19. Remaining triple-valued nature of the "F" function near the critical point 52 20. A typical EOS comparison at low steam densities 56 21. Additional comparison of EOS data at low density 57 22. EOS comparison at high temperature 58 3 23. A SESAME/SIMMER-II comparison at PQ = 316 kg/m 59 24. Pressure as a function of liquid internal energy taken from the density and temperature describing a ficticious saturation curve above T^ . .. 60 25. An example showing that p > p* is not permitted 63 26. Pressure in the sample problem with new heat transfer 69 27. Pressure in the sample problem with original heat transfer 69 28. Water temperature in the sample problem with new heat transfer 70 29. Water temperature in the sample problem with original heat transfer .. 71 30. Pressure in the sample problem with new revised heat transfer 72 31. Water temperature in the sample problem with new revised heat transfer 72 32. Mesh and structure geometry for the quasi-mechanistic reactor steam-explosion problem 88 33. Geometric indices for a radial node in the SIMMER-II moving lower head model . , , 92 34. SIMMER-II treatment of the fluid dynamics at the lower head interface 93 35. EXO-FITS apparatus 108 36. Typical instrumented water chamber 109 37. Initial configuration for the SIMMER-II representation of test MD-19 110 38. Base pressure 6,f the water chamber in experiment MD-19 Ill 39. Best fit for a uniform interaction zone (water-droplet size 75 ^m; heat-transfer multiplier 1.7) 113 40. Initial thermite distribution for the three-field calculation compared with the reported experimental results 114 41. Sensitivity of the peak pressure to the heat-transfer multiplier for a 0. 3-mm fuel droplet and a O.O75-mm water droplet 115 42. Best fit starting from a nonuniform interaction zone with a 0.3-mm fuel droplet and a 0.075-mm water droplet 115 43.