Solution to level 3 dismantling of gas-cooled reactors: the graphite incineration

Abstract

This paper presents an approach developed to solve the specific decommissioning problems of the G2 and G3 gas-cooled reactors at Marcoule, and the strategy applied with emphasis on incinerating the graphite core components, using a fluidized-bed incinerator developed jointly between the French Atomic Energy Commission (CEA), Electricité de France and FRAMATOME. The incineration option was selected over subsurface storage for technical and economic reasons. Environmental studies have shown that gaseous incineration releases are environmentally acceptable. By using a pilot plant of a fluidized-bed incinerator (30-50 kg h-1), it has been demonstrated that it is possible to incinerate moderator blocks or other graphite components of gas-cooled power reactors, and to reduce significantly the residual amount of waste to be stored after incineration. More than 20 tons of nuclear-grade graphite was incinerated in a fluidized-bed incinerator pilot plant located at the FRAMATOME research centre. The volume of secondary waste after incineration is about 1%-2% of the original mass, and the combustion efficiency is very high at more than 99.8%. © 1995.