Selection of the teleoperation system for dismantling the PETRUS shielded line (Building 18, CEA Research Center at Fontenay-aux-Roses)

Building 18, a former radiochemistry laboratory dedicated to spent fuel reprocessing studies and the production of transuranic radionuclides, is now reaching the end of its decontamination phase and will be dismantled immediately thereafter. The PETRUS shielded line for plutonium chemistry contains alpha hot cells, process vessels and very high-level storage tanks located behind the hot cells with removable lead biological shielding. The issue in dismantling the PETRUS shielded line is its radiological condition: contact dismantling is impossible. The hot cells contain tanks that could not be decontaminated, and for which the radiological measurements are not representative due to poor accessibility. The contamination and irradiation measurements are subject to uncertainty. This paper describes the use of a teleoperated arm for cutting, handling and waste removal. The results of experience with remote dismantling operations are also discussed. The studies led to the development of the MAESTRO system concept: a heavy-duty, force-feedback master/slave system, easy to decontaminate and maintain, hardened and suitable for decontamination and dismantling projects in nuclear facilities. The main risk is related to the lack of operational experience with this system and could extend the duration of the project. This risk is mitigated by a pilot phase to qualify the system under realistic conditions. Using the same teleoperated system for multiple projects has a strategic advantage by reducing the production cost, standardizing the operating and maintenance procedures while developing extensive experience related to reliability, and to conventional and nuclear safety. (author)