Modifications to the MELCOR-TMAP code to simultaneously treat multiple fusion coolants

This paper describes recent progress at Idaho National Laboratory (INL) in developing the MELCOR-TMAP computer code for fusion. The MELCOR-TMAP for fusion computer code is being developed by INL's Fusion Safety Program (FSP) by modifying the US Nuclear Regulatory Commission's (NRC's) MELCOR computer code for fission reactor severe accident analyses. Recently the INL FSP completed the process of merging INL's Tritium Migration Analysis Program (TMAP) with MELCOR to provide the US fusion community with a more comprehensive tool for analyzing accidents in future fusion reactors. However, prior to the present modifications, a MELCOR-TMAP user could only substitute one of a number of available fusion coolants for MELCOR's default coolant of water. This new capability corrects this modeling gap needed for safety assessments of fusion reactors that contain more than a single coolant. In this article, we discuss the present code modifications, benchmark MELCOR-TMAP against predictions from previous versions of the MELCOR code, illustrate the application of the code to analysis of an accident in a multiple fluids reactor concept, and describe future plans for the MELCOR-TMAP code.