Heat Transfer in a Dry CANDU End Shield during a Severe Accident

Abstract

During the in-vessel stage of a postulated CANDU severe accident, heat would be removed from the calandria partly by nucleate boiling of water in the end shield. Even if the end shield water were depleted, the remaining carbon steel shielding balls would constitute a large thermal mass. A transient finite element model is used to investigate heat transfer in a dry end shield during a CANDU 6 severe accident. Estimates of the time to failure of the calandria tubesheet are calculated for different values of the heat flux from the corium to the end shield.