Radiological Characterization of a Vitrification Facility for Decommissioning

Cleanup operations in the Marcoule Vitrification Facility (AVM) will start in 2007 [ref 1]. This plant includes 20 highly irradiating storage tanks for high-level liquid waste before vitrification. The objective of the cleanup phase is to significantly decrease the amount of highly radioactive waste resulting from dismantling. A comprehensive radiological survey of the plant was initiated in 2000. Most of the tanks were characterized using advanced technologies: gamma imaging, CdZnTe gamma spectroscopy, dose rate measurements and 3D calculations codes. At the same time, inspections were conducted to develop 3D geometrical models of the tanks. The techniques used and the main results obtained are described as well as lessons learned from these operations. The rinsing program was defined in 2006. Decontamination operations are expected to begin in 2007, and radiological surveys will be followed up to monitor the efficiency of the decontamination process. Specific rinsing of all tanks and equipment will be carried out from 2007 to 2009. Concentrated liquid solutions will be vitrified between 2008 and 2010; the decommissioning of AVM will be delayed until the end of 2010. This strategy aims at producing less than 5% “B” type (long-lived intermediate-level) waste from the decommissioning operations, as well as reducing the dose rate and risks by simplified remote dismantling. The paper reviews the main options selected for decontamination, as well as the radiological characterization strategy. Some cost-related aspects will also be analyzed.