Design of A Fuel Storage Cask Using Cygas Code for Multi Layered Shielding Analysis

Abstract

A dry storage facility based on the concept of using the concrete canister has been suggested as a storage facility for a fuel assembly. The objective of this research was to perform a preliminary analysis for the design of dry storage of booster fuel. Criticality calculations performed by WIMSD-4 code indicated that booster fuel might become critical when placed in the fuel storage bay under light water. Shielding analysis for calculations of exact thickness of transfer flask and concrete required the gamma spectrum, which was being emitting from the booster rods due the buildup of radioactive fission products in the booster fuel. ORIGEN computer code performed the calculations for the prediction of fission product compositions, multigroup gamma release rate as well as the thermal decay heat in the booster fuel as a function of bum up and cooling time. The proposed dry storage canister would have 90 cm thick concrete walls with 15 cm thick lead lining inside. Storage flasks each containing a fuel assembly will be arranged in square array in the cylindrical concrete canister. Shielding analysis performed by CYGAS computer code showed that a thickness of few centimeters for lead transfer flask and 90 ern of concrete is enough for the design of dry storage. Validation of the CYGAS analysis has been performed by multilayer calculations. Lead transfer flask having wall thickness of 15 cm will be used to transfer the storage flasks to the concrete canister. Keywords: Shielding analysis, fuel assembly, ORIGEN Code, exposure rate, CYGAS code, shielding thickness DOI : 10.7176/JETP/9-6-05 Publication date : August 31 st 2019