New MHI safety analysis code package for DBA. (5) LOCA analysis code, MCOBRA/RELAP5-GOTHIC

With intent to adopt the COBRA-TF, RELAP5 and GOTHIC codes as a set of evaluation codes for licensing analysis of PWR Loss-of-Coolant Accident in compliance with US Regulatory Guide 1.203, 'Transient and Accident Analysis Methods.', MHI investigated the applicability of their models to the regulation, found necessary actions to suit them to the regulation with sufficient conservativeness, and finally developed a code named MCOBRA/RELAP5-GOTHIC by combining the three. Through the code development activities MCR5-G has been confirmed to be applicable to licensing safety analyses for Emergency Core Cooling System performance under any LOCA conditions and also to evaluations of Mass and Energy release and Containment Vessel response. In applying MCR5-G to licensing safety analyses, its best-estimate capability is utilized with a statistical safety analysis methodology for Large Break Loss-of-Coolant Accident, while several optional evaluation models are incorporated in the code such that the code allows conservative deterministic safety analysis for small-break LOCAs, mass and energy release and containment vessel response analyses. This paper describes the applicability of the MCR5-G code and statistical and deterministic methodologies to licensing safety analysis of PWR ECCS performance. (author)