Safety evaluation for bolting design of a transportable storage canister of spent nuclear fuels

摘要

This paper is to perform safety evaluation for bolting design of a transportable storage canister of spent nuclear fuels in a nuclear power plant. To develop the related techniques for inter unit transfer of the spent nuclear fuels, a seamless metal canister design with reopening function is adopted. The canister with bolting flange needs to maintain its seamless and structural integrity under normal operation and postulated accident conditions. For bolting design, the requirements on material and structural strength are completely examined by following ASME Boiler and Pressure Vessel Codes. All calculations in this work are performed by using the commercial finite element analysis software, ANSYS. With different sensitivity analysis results of numerical finite element models, the maximum and minimum operation value of bolting preload torque can be thus obtained. Moreover, during the inter unit transfer and operation of spent nuclear fuels, fatigue of the bolt is addressed and no leakage occurs as the canister keeps closure with lids subject to the accident condition is also verified. The structural functions and safety of a transportable storage canister with new bolting design can be shown.