Application of OECD THAI HM Test Results to Simulation of Hydrogen Stratification in VVER-1000 Containment with MELCOR Code
The main thermal hydraulics issue in the containment of light water reactors under severe accident conditions is a hydrogen distribution. Validation of the MELCOR code concerning this topic was done against the OECD THAI HM-2 test during last two years. Successful simulation of the test followed with an application of gained experience to a plant simulation. Very detailed input model for the VVER-1000/320 type of containment was prepared with very similar approach to subdivision of the reactor dome into several nodes like in the input model for the THAI HM-2 test. Analysis of the containment response for realistic sources from the small break LOCA (Deq=30 mm) with loss of all high pressure injection and all feed water systems was performed. Operation of low pressure systems is forbidden by high pressure in primary circuit. Containment response analysis did not predict hydrogen stratification in reactor dome for that source from small break LOCA. For the confirmation of correctness of the input model for the VVER-1000/320 containment the second analysis was performed, but sources from the LOCA break were replaced with hydrogen sources from the THAI HM-2 experiment multiplied by scale factor of the VVER-1000/320 containment to THAI vessel volume ratio. Such analysis predicted stratification of atmosphere with a formation of hydrogen cloud in the top of containment. One additional simulation was performed with an application of sources from small break LOCA, scaled down in ratio of THAI vessel to containment volume, to the simulation of the THAI vessel response. This simulation did not predicted stratification of atmosphere with formation of the hydrogen cloud in the top of vessel. The main difference of both sources, from THAI HM-2 experiment and small break LOCA, was in ratio of hydrogen to steam content. Significantly higher mass rate of steam in the realistic source from small break LOCA is the main reason for prevention of stratified atmosphere formation, because steam condensation on walls is a main accelerator of atmosphere mixing.
Hydrogen distribution atmosphere stratification containment VVER-1000 MELCOR
Ji（r）í Duspiva
Nuclear Research Institute (R)e(z) plc.Husinec-(R)e(z)(c).p. 130, 250 68 (R)e(z), Czech Republic
国际会议
上海
英文
366-377
2010-10-10（万方平台首次上网日期，不代表论文的发表时间）