Halfway point reached in Dounreay reactor fuel removal

11 October 2019

Half of the last remaining radioactive fuel elements inside the Dounreay Fast Reactor (DFR) have now been removed, Dounreay Site Restoration Ltd (DSRL) has announced. The elements had been jammed inside the reactor, and their removal has been a top priority for its decommissioning.

DFR's iconic spherical dome (Image: DSRL)

DFR, at Dounreay in northern Scotland, achieved criticality in November 1959 and in October 1962 became the world's first fast reactor to supply electricity to the grid. Developed at a time of uranium shortage, the reactor's core was surrounded by a blanket of natural uranium elements that, when exposed to radiation, would "breed" to create a new fuel, plutonium. The reactor, which was cooled by a liquid sodium-potassium alloy, achieved a maximum electrical power of 14.5 MWe and was shut down in 1977.

Most of the core fuel was removed from the reactor after its closure, but almost 1000 elements from the breeder zone were found to be swollen and jammed, and were left in place.

Recovery of the jammed elements, using purpose-built remotely-operated tools that reached down into the reactor to cut the breeder elements free and lift them into a flask for removal to the next stage of the process, began in 2017. Locally manufactured tooling has played a big part in the successful removal of half the remaining radioactive fuel inventory inside the reactor vessel, DSRL said. Local companies who manufactured mechanical equipment included JGC Engineering and Technical, Precision Machining Services, and Calder Engineering. Contec Design Services carried out electrical, control and instrumentation works.

Material-being-moved-inside-Dounreay-DFR-screenshot-(Dounreay).jpgDSRL has released a video showing material being removed inside the DFR (Image: DSRL)

Decommissioning the 60-year-old DFR is one of the most technically challenging projects in the UK Nuclear Decommissioning Authority's (NDA's) estate, DSRL said.

DSRL is the site licence company responsible for the clean-up and demolition of the former centre of fast reactor research and development. It is a wholly-owned subsidiary of the Cavendish Dounreay Partnership, a consortium of Cavendish Nuclear, Jacobs and AECOM, and is funded by NDA to deliver the site closure programme.

Researched and written by World Nuclear News