VALIDATION OF COSTA ON PREDICTING CORE DAMAGE ACCIDENT PROGRESSION WITH THE TMI-2 ACCIDENT DATA

COSTA (A Computerized Support System for the Emergency Technical Advis ory Body in Japan) has been developed by the Japan Atomic Energy Resea rch Institute to provide national response capability during radiologi cal accident emergencies. COSTA can be used to identify plant status a nd predict accident progression based on emergency data reported by th e utility of an affected plant. To assess the capability of COSTA, it was applied to the TMI-2 accident progression in the reactor cooling s ystem during the period that neither the emergency core cooling system nor the auxiliary feed water system was available. Although there are some differences in the steam generator between the TMI-2 plant and J apanese PWR plants, these differences would not significantly affect t he accident progression of interest. A case study was also made by alt ering the amount and content of emergency data, as well as the timing of reporting. This study was performed to investigate the dependency o f the COSTA predicted results upon the emergency data. This study show ed that COSTA predicted results were reasonable when accurate emergenc y data were reported a few times an hour.