Japan's Nuclear Regulation Authority (NRA) has today approved the decommissioning plan for the country's oldest reprocessing plant. The Japan Atomic Energy Agency (JAEA) announced in September 2014 that it would permanently shut down the reprocessing plant in Tokai, Ibaraki prefecture.

The Tokai reprocessing plant (Image: JAEA)

Modifications to the plant required under post-Fukushima safety regulations were too costly, JAEA decided. New safety rules for Japanese fuel cycle facilities came into force in late 2013. Under those regulations, reprocessing plants need to demonstrate these as well as countermeasures specifically for terrorist attacks, hydrogen explosions, fires resulting from solvent leaks and vaporisation of liquid waste.

JAEA submitted its application to the NRA for approval of its decommissioning plan on 30 June 2017 and made amendments to the plan on 2 February and 5 June 2018.

The NRA today gave its approval to JAEA's decommissioning plan for the Tokai reprocessing plant.

According to the plan, some 310 canisters of highly-radioactive, vitrified waste and about 360 cubic metres of radioactive water are currently stored at the plant site, the Kyodo news agency reported. The plan, it reported, calls for highly-radioactive waste to be buried more than 300 metres underground, intermediate-level waste to be buried "several dozen metres" underground, and low-level waste to be buried close to the surface.

It is reportedly expected to take about 60 years to decommission the plant, at a projected cost of almost JPY1 trillion (USD9 billion). Of this, JPY770 billion will be needed for decommissioning the plant and waste disposal, while JPY217 billion will be required for ten-year preparatory work, Kyodo said.

Construction of the Tokai reprocessing plant began in 1971, with trial operation starting in 1977. The plant entered full operation in 1981 but has stood idle since 2006 when a contract for reprocessing used fuel from commercial power reactors came to an end. The plant was mainly used for processing mixed-oxide fuel from the Fugen experimental Advanced Thermal Reactor (ATR), which ceased operating in 2003.

The plant has reprocessed a total of some 1052 tonnes of used fuel comprising 88 tonnes of fuel from the Fugen ATR, 644 tonnes of boiling water reactor fuel, 376 tonnes of pressurised water reactor fuel and 9 tonnes of fuel from the Japan Power Demonstration Reactor.

In a statement, JAEA said: "In the future, we will strive to ensure safety with the highest priority, based on the approved decommissioning plan."