SAFETY APPROACH OF DFBR DESIGN STUDY IN JAPAN

The goal of the safety design for the demonstration fast breeder react or is to ensure that the safety level is equivalent to or higher than that of the light water reactors of the same period. The design of the safety features such as reactor shutdown, decay heat removal and conf inement systems is of importance to reach the goal. The reactor core i s equipped with two independent fast shutdown systems, the primary sys tem and the backup system. In addition, it is planned to strengthen th e passive shutdown capability by using self-actuated systems such as a Curie point device for the backup system. The decay heat is removed f rom the core to the atmosphere through the safety lines of the direct reactor auxiliary cooling system which is composed of four independent lines. Furthermore, under the severe conditions that no active functi on of the decay heat removal system is available, the heat can be remo ved by natural convection through the safety lines by taking advantage of the high boiling temperature of sodium. For the confinement functi on, the reactor vessel is surrounded by a containment vessel and a con finement area. The design concept of these safety features is describe d in this paper. (C) 1997 Published by Elsevier Science Ltd.