Study on concrete cask for practical use. Heat removal test under accident condition

Heat removal tests using two types of full-scale concrete casks were conducted. This paper describes the results under accident condition of spent fuel storage. In the tests, data on heat removal performance on the condition of two inlet blockage (50 % blockage) and four inlet blockage (100 % blockage) out of four inlets were obtained. When two inlets were closed, air flow which goes into the concrete cask decreased. But the decrease rate was small with slight increment in temperature. When the four inlets were closed, different flow patterns were observed for each concrete cask. For one concrete cask, it is observed that cooling air does not go out from the outlet. For the other cask, it is observed that outflow and inflow are obviously observed at the outlet. In both conditions, the overall temperature of the concrete casks increased but it was confirmed that the heat removal function was fully maintained. (author)