Heatup event analyses of the Water Cooled Solid Breeder Test Blanket Module

Abstract

This paper describes the safety evaluation on the heatup events of the Water Cooled Solid Breeder (WCSB) Test Blanket Module (TBM) and proposes the basic method to ensure safety, incorporating the chemical reaction between beryllium and water. One-dimensional analyses are carried out for the three representative event sequences, which were derived by the Failure Modes and Effect Analysis. With respect to the event sequence of loss of cooling of the TBM during plasma operation, once temperature of the TBM totally increases, then a plasma disruption takes place when the temperature of the first wall armor becomes too high. In this event, the requirement to the TBM design becomes apparent that no cooling pipe rupture can be guaranteed under the predicted highest temperature condition to prevent the activation of the chemical reaction under the high temperature condition. With respect to the event sequence of ingress of coolant into the TBM during plasma operation, heat load due to beryllium–water chemical reaction is added to the normal heat load of the TBM. The requirement for the cooling system of the TBM becomes apparent that the cooling system of the TBM should be designed to continue its operation against partial loss of coolant due to the ingress of coolant. With respect to the loss of off-site power after the ingress of coolant, it is confirmed that the event converges.