COMPARATIVE RADIOLOGICAL ASSESSMENT OF DECOMMISSIONING OPTIONS FOR FUSION ENERGY PLANTS

Four options for fusion plant decommissioning-''Early Stage 3'', ''Saf estore'', ''In-situ Decommissioning'' and ''Safestore with Recycle''-a re compared on the basis of overall radiological impact. This impact i s calculated as a weighted sum of six components representing the coll ective doses to workers and the public, and the risk to individual mem bers of the public. Calculations are performed for two variants of a r eference design, one employing standard structural materials and the o ther partially utilizing low activation materials. For the standard pl ant, Early Stage 3 has the lowest overall impact, while the impact of the Safestore option is also low. Both the Safestore with Recycle and In-situ Decommissioning options have a high relative impact for the st andard plant, while the In-situ Decommissioning option would be preclu ded by the risk to individual members of the public. For the low activ ation variant, the In-situ Decommissioning option is again precluded b ut the other options give low impacts. This scoping study indicates th at the use of low activation materials could be beneficial with respec t to the freedom of choice of decommissioning options.