Breeder Breakthrough for Cavendish Nuclear at Dounreay

It’s an engineering and scientific challenge that has stumped the industry for decades. Now, a team led by Cavendish Nuclear is breaking new ground by recovering the last of the nuclear material trapped inside the UK’s experimental fast breeder reactor.

Dounreay Site Restoration Ltd, a wholly-owned subsidiary of the Cavendish Dounreay Partnership, today announced it has started to remove almost a thousand elements from the Dounreay Fast Reactor.

Remotely-operated cutting and retrieval equipment developed by the company and its supply chain underwent years of trials and tests.

It is now being deployed inside the core of the reactor to clear out the last remaining material.

The Dounreay Fast Reactor once led the world in nuclear technology, proving the concept of an electricity-generating reactor that could also breed its own fuel.

The experimental, dome-shaped plant was built in the 1950s at a time when there was a worldwide shortage of uranium for electricity generation. Its core was surrounded by a blanket of natural uranium elements that, when exposed to the effects of the radiation, would “breed” to create a new fuel, plutonium.

The reactor closed down in 1977 and most of the core fuel was removed. But work to remove elements from the surrounding breeder zone came to a halt in the early 1980s when some were found to be swollen and jammed. Almost 1,000 – around two-thirds of the total - were left in place.

Decommissioning stalled for 20 years until the creation of the Nuclear Decommissioning Authority in 2005 gave the task fresh momentum.

Some 57 tonnes of highly reactive liquid metal in the primary cooling system had to be removed and destroyed before remotely-operated cameras could inspect the condition of the breeder material. This programme took more than 10 years.

Now, following the appointment in 2012 of a Cavendish Nuclear-led management team, work has restarted to remove the breeder material.

The NDA, which described the retrieval of the breeder material as a UK priority, said it was “very pleased” to see the work underway, delivering hazard reduction of “national importance”.

Ron Hibbert, senior project manager at DSRL, added: “Reaching this important stage has been a huge achievement by the project team.

“Emptying the reactor vessel of this material is one of the biggest engineering challenges we face in decommissioning the site and it’s a great moment for DSRL and our contractors to see their hard work deliver results.”

During a recent visit to the reactor, Jamie Stone, Member of Parliament for Caithness, Sutherland and Easter Ross, said: “Actually watching on screen the removal of an element from the reactor core was fascinating. Seeing the intricate techniques and skills, and the special locally designed equipment, being used was absolutely inspirational.

“In an age when sometimes you begin to wonder where British technology is going, it is hugely encouraging to see what is being done at Dounreay. I take my hat off to the workforce.”

Once removed from the reactor, the material is transferred to a purpose-built facility where the elements are cut open, the fuel “slugs” removed, cleansed of any traces of liquid metal, and packaged in robust transport containers ready for transfer to Sellafield in Cumbria.