The IRSN Airborne Pollutants and Containment Department (SCA) is participating in a study conducted by the CEA and Onet Technologies aimed at demonstrating that laser cutting can be used to extract the corium (magma resulting from the melting of nuclear fuel and structures) of the damaged Fukushima reactors. This technique is currently being used to dismantle the dissolvers of the CEA fuel processing plant in Marcoule. It is one of the techniques envisaged by the Japanese for the future dismantling of the Fukushima-Daiichi reactors by 2021.
The feasibility study currently being conducted with the assistance of the IRSN was selected in 2015 by the Mitsubishi Research Institute (MRI) within the framework of an international tender, and is funded by a grant from the Japanese state (Meti). A first preparation phase involving the definition of the corium simulants, the determination of the cutting parameters by CEA and the design of an aerosol sampling passage by IRSN has just been completed. The cutting and aerosol characterisation test campaigns will now be spread out between November 2016 and March 2017.
In order to demonstrate the feasibility of the cutting technique, tests will first be conducted in a laboratory on non-radioactive materials simulating the corium. They will take place on the
CEA Altea platform in Saclay. During these tests, the IRSN will implement its know-how and specific expertise in measuring the mass concentration, the particle size distribution and the chemical composition of the aerosols emitted during the cutting, when in the air and when submerged in water. These measurements with non-radioactive aerosols will contribute to assess the nature and the amount of the radioactive particles that could be emitted during the fuel debris recovery operations in the Fukushima-Daiichi reactors, in order to enable the Japanese to define the best strategy for containing the radioactive aerosols and for preventing their release into the environment.
The CEA's laser cutting technique received the French Nuclear Energy Society (SFEN) prize for Technological Innovation in June, as well as being nominated for the WNE Awards at the World Nuclear Exhibition (WNE).