MK-III Heat transport system modification work in JOYO; Installatlon of radioactive waste material storage facility for old IHXs

not registered; Ashida, Takashi ; not registered; not registered; not registered; Isozaki, Kazunori ; not registered

The MK-III project has been proceeding to improve the irradiation capability of the experimental fast reactor JOYO since 1987. The MK-III project has three major purposes such as increasing high neutron flux, improvement of plant availability factor and upgrading in irradiation techniques. The increase of high neutron flux increased thermal output of core from 100MW to 140MW. The main components in the cooling system such as IHXs (Intermediate Heat Exchanger) and DHXs (Dump Heat Exchanger) were replaced in MK-III modification in order to increase heat removal capability. These components replacement has been safely carried out from october 30, 2000 to September 21, 2001. The radioactive corrosion products such as Co and Mn, and radioactive sodium were resided on the inner surface of old IHX which had been already removed from the system in the MK-III modification work. We may dismantle old IHX and remove the residual sodium only after enough decrease of their radioactivity. We have to store it safely over a fairly long Period. Therefore, we examined the safety storage way of old IHX. Based on the examination, we selected the free space inside the pump cleaning pit in the maintenance building as a radioactive waste storage facility. Before the modification work of pump cleaning pit, we needed the permission of design and the construction as well as the change of establishment for installation of radioactive waste storage facility. Modification work of the pump cleaning pit including removal of the interfering pipes were done for two months from April to May, 2000. Enlargement work of opening in pump cleaning pit and coating work of the wall surface were done from August, 2000 to January, 2001. Installation work of the metallic plate for shielding was done for two months from April to May of 2001 after installation of old IHXs in the pump cleaning pit. This report shows the records of installation of radioactive waste storage facility for ...