The SCDAP/RELAP5 development and assessment highlights

The SCDAP/RELAP5 code is being developed at the Idaho National Engineering Laboratory (INEL) under the sponsorship of the U.S. Nuclear Regulatory Commission (NRC). The current production version of the code is SCDAP/RELAP5/MOD3.1, which was released to authorized members of the NRC Cooperative Severe Accident Program (CSARP) in 1994. The current developmental version is SCDAP/RELAP5/MOD3.2. The SCDAP/RELAP5 code is designed to describe the overall reactor coolant system thermal-hydraulic response, core damage progression, and fission product release during severe accidents. The code is the result of merging the RELAP5/MOD3, SCDAP, and COUPLE codes. The SCDAP portion of the code includes a combination of representative core component, debris bed, and molten pool models. The initial heating and melting of the core assemblies are described by detailed representative core component models. Debris bed and molten pool models are invoked in the regions of the core where the original geometry has been significantly altered. The accumulation of debris in the lower plenum, heating of the debris and adjacent structures, and the formation and growth of a molten pool within the lower plenum debris are described by the COUPLE portion of the code.