Fission product release analysis program 'FIPRAP' for estimation of transient release of volatile fission products from PHWR fuel

During fuel irradiation a broad spectrum of Fission Products (FPs) ranging from mass number 60 to 160 gets produced within fuel matrix and can be grouped in to three volatility classes: volatiles, semi-volatiles and non-volatiles. Due to their radioactive nature these FPs poses a radiological hazard if released to environment. Due to large yield and mobility within fuel matrix, release behaviour studies of volatile FPs have special importance both during reactor normal operation and during accident. Keeping this in view, study of volatile FPs release within Indian Pressurised Heavy Water Reactor fuel has been initiated and a semi-mechanistic FPS release model 'FIPRAP' is developed. The developed semi-mechanistic code is capable of estimating potential FPs release during normal and accident scenarios. As a benchmark, an inter-model comparison exercise has been carried out against the Accident Source Term Estimation Code (ASTEC) and the NUREG based CORSOR-M code. Release predictions made by FIPRAP are found to be in good agreement with these two models. (author)