Safety design for ITER and fusion power reactors

The present paper outlines key design features of relevance for the safety of international thermonuclear experimental reactor (ITER) and fusion devices of reactor scale. These features support the intrinsic safety characteristics of fusion. The most important safety function is the confinement of radioactivity. The first barrier is based on the vacuum vessel (VV) and its extensions. A pressure suppression system limits the maximum pressure of the VV in the event of loss of coolant. The second barrier is the Cryostat and its extensions. Outward leakage from the second confinement can be captured in surrounding rooms where necessary. Open penetrations of the VV will be protected by at least two separate barriers such as windows or valves. Nuclear decay heat will be removed passively by the VV cooling system. Other safety systems have been identified which play an important role for both ITER and a fusion power reactor.