Feedback from the operation of the ISOCS in support to the plutonium facility decommissioning project at the MARCOULE UP1 reprocessing plant (France) and possible gain for new projects with new CANBERRA systems

After the decision was taken in 1998 to shut-down the operations of the UP1 reprocessing plant in MARCOULE (FRANCE), where more than 19,000 metric tons of spent nuclear fuel have been reprocessed, decommissioning projects started in the various buildings, particularly in the Plutonium Facility. In this facility many glove boxes had to be decontaminated before dismantling. To have waste compatible with surface storage, the main objective was to prove that each glove box had on hold up of less than 37 GBq (ie about 10 g with the corresponding Pu isotopic composition). Historically the method used for such characterisation was based on smears and dose rate measurements to extrapolate the mass of Pu in the glove boxes with a very high uncertainty. In 1998 AREVA NC decided to deploy new characterization tools to meet the performance goals of the Plutonium Facility Decommissioning Project. These tools consist on portable Germanium gamma spectrometer coupled with MGA Pu isotopic composition and ISOCS 3D modelling codes.