According to the Monju decommissioning plan that JAEA had submitted to the Nuclear Regulation Authority (NRA) of Japan in 2017, the entire process runs to FY47 and is divided into four stages. The removal of the fuel assemblies was the main work to be implemented in the first stage (FY18–22).

When the decommissioning began, there were 370 assemblies in the nuclear containment vessel and another 160 at an outside fuel storage facility. All 530 of the assemblies have now been transferred to a water-filled storage facility, or fuel pool.

Commenting on the situation going forward, JAEA said that, with top priority on ensuring safety, it would work steadily to obtain understanding from the public both in the siting area and throughout the nation. In the second stage (FY23 onward, starting next April), it will begin preparations for dismantling sodium-related equipment.