The Japan Sodium-cooled Fast Reactor (JSFR) has adopted an in-vessel fuel handling system that consists of a single rotating plug, an upper inner structure (UIS) with a vertically penetrating slit, and a fuel handling machine (FHM) with a pantograph arm enhancing a compact reactor vessel design. Since the reactor vessel design depends on the in-vessel fuel handling system, the feasibility of the JSFR compact reactor vessel design is directly related to the feasibility of the new FHM. In this study, we have fabricated a full-scale mock-up of the JSFR FHM and performed tests in air. From the tests, the FHM mock-up shows sufficient performance in terms of positioning accuracy, motion speed, and stiffness to ensure durability for practical use in commercial plants. Structural analyses have been conducted to validate and improve the seismic analysis model and the positioning control of the FHM. The numerical results are in good agreement with the vibration and positioning tests, showing that there is a sufficient possibility that the model has enough performance to conduct seismic analysis and improve positioning accuracy.

Japan sodium-cooled fast reactor is going to adopt an advanced fuel handling system. As for ex-vessel spent fuel handling, a transfer pot with two fuel subassembly positions has been developed so as to shorten refueling period increasing plant availability. The pot is required to provide sufficient cooling capability in case of transportation malfunction. To evaluate cooling capacity of the transfer pot, a mockup pot has been fabricated and heat transfer experiments have been conducted on the mockup pot.

Japan sodium-cooled fast reactor (JSFR) is going to adopt an advanced fuel-handling system. From the viewpoint of spent fuel cleaning, a new dry-cleaning process instead of the conventional process with water rinse is under development. In this study, drain performance tests on the JSFR subassembly inner duct and dry-cleaning performance tests with a pin bundle model are summarized. Based on the experimental data of the inner duct and pin bundle model tests, residual sodium on the spent fuel subassembly after argon gas cleaning has been evaluated to be 400 g. Water alkalinity and purification performance have been evaluated and the JSFR water pool system has shown the capability to accept 400 g residual sodium on the spent fuel subassembly after argon gas cleaning.

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