DEVELOPMENT OF TK-26, NEW GENERATION TRANSPORT AND STORAGE CASK FOR PWR SPENT FUELS

The design of TK type transport and storage cask for BWR spent fuels such as TK-69, TK-52 are completed and the safety analysis has been performed. Now, TK type for PWR spent fuels, named TK-26 transport and storage cask is under development using the experience on TN24 series. The demand of higher safety of spent fuel dry storage from customers is being expected. Then, TK-26 has new structure with higher safety, maintaining large fuel capacity and higher economical advantage. One of the features of TK-26 structure is the introduction of the newly developed borated aluminum structure focused on PWR fuels. This structure enables us to design new basket having higher sub-criticality ability and higher structural strength with keeping enough heat transfer ability using very compact structure. Another is the countermeasure for the slap-down test and the impact of the delayed drop of contents at 9m vertical drop test. The effect of this countermeasure is confirmed by the drop test using a 1/3 scale model, and validity of structural safety analysis method is also confirmed. As expand of the demand for storage casks is expected, study for standardization of the design of casks is being conducted to ensure flexibility of supply of several type of casks and stable supply. This paper explains the main feature and the effectiveness of TK-26 structure.