Development of the passive safety concept for ITER

Since the start of the ITER (International Thermonuclear Experimental Reactor) design effort, safety experts have attempted to guide designers in developing a machine that will demonstrate the potential safety and environmental advantages of fusion. Offsite dose limits (based on regulatory requirements) have been translated into release rates or radiological inventories, which provide useful guidance to designers. The ITER team is attempting to protect the public, to the extent possible, against major accidents with passive means, that is, without relying on active systems. The concept of passive safety is developed by the US safety team for internal events and for external events that are within the envelope of design-basis accidents selected for the ITER. In addition to overall safety guidance, implications of passive safety for ITER systems (as envisioned by the US safety team) are discussed. An approach to implementing passive safety in the ITER with reference to the blanket, plasma-facing components, fuel-cycle systems, plasma shutdown, and magnet design is described. The need for a confinement building is addressed, and the role of such a building in the context of passive safety is also discussed