Fusion Science and Technology / Volume 56 / Number 2 / August 2009 / Pages 573-580
Fusion Technology Plenary / Eighteenth Topical Meeting on the Technology of Fusion Energy (Part 2)
In order to support the licensing application for the ITER facility at Cadarache, a preliminary safety case has been prepared and submitted to the French nuclear safety authorities. This paper provides an overview of technical aspects of this case, which is based on an evolution of the safety approach developed and applied in earlier phases of the ITER project.
The basis of the safety of ITER derives from the fundamental safety characteristics of fusion. The potential radiological hazards that arise are related to the tritium fuel and material activated by neutrons. The confinement of these materials is therefore the principal safety function, and it is reliably provided by robust barriers inherent in the design together with filtering and detritiation as a secondary level of confinement provision.
A Defense in Depth approach is taken to ensure that off-normal events are minimized in their frequency, and that the consequences of accidents, even though extremely unlikely, are limited. A comprehensive set of analyses of postulated event sequences provides the demonstration that the consequences of enveloping scenarios are well within acceptable limits, and that even for hypothetical events involving two or more independent failures, the public and environmental impacts remain limited. An ALARA approach is taken to minimizing occupational radiation exposure, as well as other potential impacts of normal operation such as routine releases.
Other hazards arising from internal and external risks are also considered, with design provisions, for example the Tokamak building is built on seismic isolation pads to minimise the effect of an earthquake.