Final Cleanup of Buildings Within in Legacy French Research Facilities: Strategy, Tools and Lessons Learned

This paper describes the methodology followed by the French Atomic Energy Commission (CEA) to decommission the buildings of former research facilities for demolition or possible reuse. It is a well known fact that the French nuclear safety authority has decided not to define any general release level for the decommissioning of nuclear facilities, thus effectively prohibiting radiological measurement-driven decommissioning. The decommissioning procedure therefore requires an intensive in-depth examination of each nuclear plant. This requires a good knowledge of the past history of the plant, and should be initiated as early as possible. The paper first describes the regulatory framework recently unveiled by the French Safety Authority, then, reviews its application to ongoing decommissioning projects. The cornerstone of the strategy is the definition of waste zoning in the buildings to segregate areas producing conventional waste from those generating nuclear waste. After dismantling, suitable measurements are carried out to confirm the conventional state of the remaining walls. This requires low-level measurement methods providing a suitable detection limit within an acceptable measuring time. Although this generally involves particle counting and in-situ low level gamma spectrometry, the paper focuses on γ spectrometry. Finally, the lessons learned from ongoing projects are discussed.