PSA Level-3 Study—Estimation of Area and Persons Affected for Postulated Accidental Release from Indian PHWR After Implementing Urgent Protective Actions

Abstract

A PSA level-3 study has been carried out for postulated accidental release from an Indian PHWR. Postulated release due to triple failures (LBLOCA with simultaneous failure of ECCS and containment isolation failure) in typical 220 MWe Indian PHWR is simulated in this study to know the impact of accident. The principal phenomenon for atmospheric transport of effluent is considered using a Gaussian plume model, MUSEMET which takes hourly variation of meteorological condition into account. Site-specific meteorological and demographic data has been considered for this study. Appropriate meteorological sampling has been done to represent 5-year meteorological data and severity of accident. COSYMA Code is used for calculation of projected doses for seven days to estimate the area and persons affected after implementation of urgent protective actions on the basis of IAEA GSR Part-7. As an element of emergency response planning, affected sector and area are determined under variety of meteorological conditions. The protection offered by iodine prophylaxis and sheltering has been emphasized in this study. Sheltering can be effective by keeping the public out of the plume exposure pathway during the time when the radioactive concentration of plume is high and iodine prophylaxis will avert thyroid dose significantly if taken at appropriate time. The effect of accident in public domain can be minimized effectively using proper countermeasures strategies. Further, risk to public and health effects has been found limited in this study.