Study on Temperature Estimation Method of PWR Spent Fuel Cladding in Dry Storage

In the Recyclable Fuel Storage Center, which is the first away from reactor (AFR) spent fuel storage facility in Japan, spent nuclear fuel (SNF) from BWRs and PWRs is scheduled to be stored in Dual Purpose Casks (DPCs). In the case of DPC storage in this center, if no abnormality in the external appearance or the inter-lid pressure of DPC is found during the storage period, the DPC and the stored fuel will be considered to be intact throughout the storage period, and the DPC will be shipped without opening its lids for pre-shipment inspection. Therefore, integrity of stored fuel during storage should be confirmed without opening DPC lids. Creep deformation and hydride reorientation are considered as major deterioration mechanisms of fuel cladding during dry storage, and they depend on the cladding temperature history. In this paper we focus on the fuel cladding temperature change during a long-term storage test using a test container which can store two PWR SNF bundles, conducted by the electric utilities in advance of the commissioning of actual storage at the Recyclable Fuel Storage Center, and present a result of the review for the temperature prediction performance of the analysis model which we developed as an approach for fuel cladding temperature estimation by measuring the surface temperature of test container. The performance of the model was reviewed by comparing the analysis results with the measured temperature distributions of the test container in the preliminary heat transfer test.