Cavendish said the contract builds on its experience of decommissioning fast reactors in the UK. The company will use the skills and experience gained during the decommissioning of the fast reactors at Dounreay, which are at an advanced stage of cleanout and dismantling.
The main elements of the contract with JAEA involve technical support for creating a lifetime plan for the decommissioning of Monju and a feasibility study into the treatment of sodium coolant from the Monju site.
A 30-year decommissioning plan for Monju was approved by the regulator at the end of March 2018.
Monju is a 246-MW sodium-cooled fast reactor designed to use mixed fuel rods of uranium and plutonium and to produce more fissile material than it consumes.
It reached criticality for the first time in 1994, but it has mostly been offline since 1995 when 640 kg of liquid sodium leaked from a cooling system, causing a fire.
Japan’s government decided to permanently shut down the reactor in 2016.
Decommissioning and dismantling costs are estimated at $3.2bn, according to reports in Japanese media.
