Studies on chemical decontamination of JRR-3 primary cooling system, No.1 (decontamination by CAN DECON process)

The primary cooling system of JRR-3 is contaminated with activated stellite metal powder from pump runner, uranium oxide from failed fuel and fission products and plutonium from the contaminant uranium. This makes JRR-3 maintenance difficult. The plan of upgrading JRR-3 is now in progress, which involves replacement of the core tank and primary cooling system. To make the reactor disassembly safe, chemical decontamination processes have been investigated. The CAN DECON process developed and approved for the CANDU reactor in CANADA, a heavy water reactor similar to JRR-3 is possibly the most suitable. In this report are described feasibility of the CAN DECON process to the JRR-3 primary cooling system and the decontamination tests made with sludge collected from the primary system. The process is found to be effective and economical for the decontamination of uranium, fissionn products and plutonium, but not for stellite metal. (author)