Validation of initial fission product inventory calculations for level 2 calculations for PHWR reactors

Determination of the extent of activity released from fuel into primary heat transport system, its transport in PHT system and release into containment during accident conditions is important factor in evaluation of source term and safety of a reactor. Release from fuel also depends upon initial inventory in the fuel. Initial inventory depends upon various factors like fuel burnup, irradiation environment, fuel rod pressure, release mechanisms etc. A number of test irradiations had been conducted, both on MOX as well as on ThO2 based fuel elements in PWL, CIRUS. Fission gas release data have been generated on these fuel pins. Two high burnup fuel bundles from KAPS - 1 and 2 have also been examined recently and PIE data of FGR and fuel restructuring are available. In this work computer code SCDAP/RELAP5 has been used for analyzing one of the tests. The SCDAP/RELAP5 code has been developed for best-estimate transient simulation of light water reactor coolant systems during a severe accident. It is also used for analyzing CANDU reactor to certain extent. The code models the coupled behavior of the reactor coolant system, core, fission product released during a severe accident transient as well as large and small break loss-of-coolant accidents, operational transients such as anticipated transient without SCRAM, loss of offsite power, loss of feedwater, and loss of flow. The theoretical model used in SCDAP is a simplified version of the FASTGRASS code that has been used for predicting the behavior of fission gas in UO2-based fuels during steady-state and transient conditions. This paper simulates one of these tests conducted for KAPS-l fuel bundle using RELAP5/MOD3.2/SCDAP code for fission product inventory calculations for 6 species and other relevant parameters. (author)