Soils radiological characterization under a nuclear facility

Nowadays, nuclear industry is facing a crucial need in establishing radiological characterization for the appraisal and the monitoring of any remediation work. Regarding its experience in this domain, the French Alternative Energies and Atomic Energy Commission (CEA) of Fontenay-aux-Roses, established an important feedback and developed over the last 10 years a sound methodology for radiological characterization. This approach is based on several steps: - historical investigations, - assumption and confirmation of the contamination, - surface characterization, - in-depth characterization, - rehabilitation objectives, - remediation process. The amount of measures, samples and analyses is optimized for data processing through geostatistics. This approach is now used to characterize soils under facilities. The paper presents the radiological characterization of soils under a facility basement. This facility has been built after the first generation of nuclear facilities, replacing a plutonium facility which has been dismantled in 1960. The paper details the different steps of radiological characterization from historical investigations to optimization of excavation depths, impact studies and contaminated volumes