Abstract
Severe accident researches at nuclear power plants (NPPs) have been intensively concerned since the Fukushima event. In this study, a Maanshan Nuclear Power Plant MELCOR2.1/SNAP model was established. A hypothetical Station Blackout (SBO) transient and a hypothetical Loss of Coolant Accident (LOCA) transient of the Maanshan NPP were executed by the model. The aim of this research is to analyze the severe accident process from transients to RPV failure, hydrogen burn and the release of radionuclides. The study is divided into three sections. In the first part, process of building the model is introduced. In this part, steady state calculation results were compared with plant data to ensure the initial and boundary conditions of the model are well done. Second, postulated SBO case and LOCA case of Maanshan NPP were executed by the new MELCOR2.1/SNAP model. Finally, the MELCOR results after core damage were discussed to evaluate the plant safety. Parameters were discussed in detail, such as hydrogen explosion, containment overpressure, debris relocation, radionuclides movement, etc. In conclusion, this study showed the important phenomena during both SBO and LOCA of Maanshan NPP. The results could help NPP safety analysis and emergency procedure improvement in a beyond design basis accident.