The MELCOR code, developed by Sandia National Laboratories (SNL), is capable of simulating the severe accident phenomena of light water reactor nuclear power plants (NPPs).

A specific station blackout accident (TMLB' sequence) for Maanshan NPP is simulated using the MELCOR 1.8.3 code. The MELCOR input deck for Maanshan NPP is established based on Maanshan NPP design data and the MELCOR users' guides. The initial steady-state conditions are generated with a developed self-initialization algorithm. The main severe accident phenomena and the corresponding fission product release fractions associated with the TMLB' sequence were simulated. The sequence of events up to the vessel breach is similar to that in the SNL report simulated with MELCOR 1.8.2. The predicted results provide useful information for the probabilistic risk assessment (PRA) of Maanshan NPP. This tool will be applied to the PRA, the severe accident analysis, and the severe accident management study of Maanshan NPP in the near future.