A recent version of MELCOR for fusion safety applications

During the engineering design activity (EDA) of ITER, the MELCOR 1.8.2 code was selected as one of several codes to be used to perform ITER safety analyses. MELCOR was chosen because it has the capabilities of predicting thermal–hydraulic transients and self-consistently accounting for aerosol transport in nuclear facilities and reactor cooling systems. The Idaho National Laboratory (INL) Fusion Safety Program (FSP) organization made fusion specific modifications to the MELCOR 1.8.2 code that allows MELCOR to assess the thermal–hydraulic response of fusion reactor cooling systems and the transport of radionuclides as aerosols during accident conditions. The ITER International Organization (IO) used this version of MELCOR to perform accident analyses for ITERʹs “Rapport Préliminaire de Sûreté” (Report Preliminary on Safety – RPrS). Because MELCOR has undergone many improvements since version 1.8.2 was released, the INL FSP introduced these same fusion modifications into MELCOR 1.8.6, and thereby produced a version of MELCOR 1.8.6 with similar capabilities to the version of MELCOR used by the ITER IO for the ITER RPrS. We have applied this recent version of MELCOR to the analysis of a large in-vessel water leak event examined in the ITER Generic Site Safety Report (GSSR). This paper presents the results of this analysis and compares these results to those obtained from the MELCOR 1.8.2 code.