Safety study of primary coolants in fusion power reactor first wall design

Abstract

This paper examines potential safety problems associated with the various primary coolant candidates currently considered for the EPR fusion blanket designs. The basic concern is the possibility of overheating and melting of the first wall and the blanket, induced by a malfunction in the primary coolant system. These accidents include the loss-of-coolant flow, the loss-of-heat removal, overpower transients, and the loss of coolant. Following a mechanistic safety for these four types of accident sequences and comparing helium and liquid metal cooling, it was found that helium has a more adverse effect on the first-wall heat up in the event of a loss-of-heat removal or a loss-of-coolant because its lack of thermal inertia.