The Contrast of MELCOR and SPEEDI Codes in Evaluating the Radioactive Material Release Amount in a Serious Nuclear Accident at Light Water Reactor

When a nuclear accident occurs in a nuclear power plant(NPP),the most attention for the public and the plant operators is about the release amount of the radioactive materials from the NPP.How to evaluate the release amount more accurately is significant for the plant operators,because the evaluation directs their emergency acts.At present,two kinds of methods are mainly used for the evaluation of the radioactive material release amount in an accident.One method is the evaluation based on plant behavior analysis,such as MELCOR code,and the other one is based on inverse estimation using environmental monitoring data,such as SPEEDI code.The first method needs the specific situation of the NPP,and the second is the method with real - time capability.With contrasting two codes,MELCOR and SPEEDI, which have been used in the Fukushima accident,the efficiency of the two codes in evaluating the release amount of the radioactive materials is elaborated.