13 December, 2018
Decommissioning FBR Monju: Processing of Fuel Assemblies Is Underway
On December 7, the Japan Atomic Energy Agency (JAEA) reported to the Safety Monitoring Team of the Nuclear Regulation Authority (NRA) on the state of decommissioning the prototype fast breeder reactor (FBR) “Monju.”
The decommissioning plan for the FBR, approved by the NRA at the end of March, comprises four stages. In the first stage, designated a period of removal of fuel (FY18 through 22), major items to be carried out include sampling of secondary system sodium, removal of fuel assemblies, and evaluations of pollution distribution.
The removal of Monju’s fuel assemblies consists of work to transfer the assemblies from the reactor core to a fuel storage tank outside the core (fuel removal), and then from that tank to a fuel pond (fuel processing and storage).
According to JAEA’s explanation at the meeting on December 7, the transfer of fuel assemblies from the tank outside the core to the fuel pond began at the end of August, but as of December 6, only 54 of the 530 assemblies had been transferred, and the target for completing processing of one hundred assemblies, which was initially set for mid-December, has been postponed until January 2019.
As of the end of November, a total of 64 “faults” or “phenomena” had occurred in the course of the work, which were corrected, with improvements reflected in the subsequent work.
Toward FY19 (starting in April 2019), when the processing of fuel assemblies will be in full swing, experience will be accumulated in maintenance related to sodium adherence. A five-team system will then be launched based on skills acquired using a three-team system.