Caithness.org News Bulletins

The UK Atomic Energy Authority today signed an agreement with six companies to carry out one of the most complex decommissioning projects in the Dounreay Site Restoration Plan.

 Partners Sign Contract

Bob Mathews, Head of Decommissioning outlined the development and progress up out he signing of today's contract with the Alliance formed to carry out the pioneering work of decommissioning the Fast Reactor site. 

The alliance will use robots inside the concrete vault of the site's experimental fast reactor, DFR, to cut up and remove more than nine kilometres of pipework that is contaminated by the liquid metal used to cool the reactor.

Pipework to Be Removed

Decontamination of the reactor vessel and its associated pipework is due to begin once most of the coolant has been drained and after work has started to remove the remaining breeder fuel. It will take until 2013 at least to complete and cost up to £30 million.

       Pipework Inside

Energy Minister Brian Wilson said: "The decommissioning of the Dounreay Fast Reactor provides an excellent opportunity for UK companies to undertake the necessary clear up work. I have made a particular commitment to maintain as much of the work as feasible within the local area and I am delighted that today's announcement will benefit both UK companies and the Caithness economy."

In Front Of DFR       

UKAEA site director Peter Welsh said: "This is a milestone in the site restoration plan. When this alliance finishes its task, we will have successfully completed the first and most crucial stage of decommissioning a reactor that represents one of the major engineering and environmental challenges on this site."

Mr Welsh added that there were more opportunities for local training providers and Thurso College as part of the University of the Highlands to run courses.

The Dounreay Fast Reactor (DFR), which operated from 1959 until 1977, used an alloy of sodium-potassium (NaK) as its coolant. Seventy-three tonnes of the liquid metal was removed from its secondary circuit shortly after its closure but 57 tonnes remain in the primary circuit. A significant number of the 977 elements still in its breeder blanket are jammed. All fuel has been removed from the core except a single experimental fuel assembly.
Site Before Decommissioning

"Before we can dismantle the primary circuit, we must drain the remaining NaK and begin cutting out the breeder fuel, " explained Bob Mathews, UKAEA's head of decommissioning at Dounreay. "We plan to remove and destroy the bulk of the NaK during 2004-05 and expect to announce shortly a separate alliance to remove the breeder fuel, so today's announcement is a major plank in our overall strategy."

The six companies in the DFR Primary Circuit Decontamination Alliance with UKAEA are Halcrow (design), Interserve (mechanical and electrical), Edmund Nuttall (building and civil works) Mitsui Babcock (plant operations), NNC (safety and environment) and Framatome (robotics).

Site After DEcommissioning

Approximately £10 million of the contract value is expected to go to locally-based companies, with an initial 50 jobs created or retained locally. A key feature of the alliance will be the transfer of specialist skills, such as robotics, from major contractors to local firms. This will improve their ability to compete for future decommissioning work at Dounreay and elsewhere in the world.

The cutting and removal of the labyrinth of pipes that carried the radioactive NaK coolant within the heavily shielded concrete vault must be carried out remotely because of the levels of radiation present. Remotely operated vehicles, working in a temperature of minus 18 degrees Celsius to eliminate the risk of ignition in the NaK-wetted circuits, will lay their own working platforms before cutting sections of pipework into pieces that will be removed for cleaning and disposal.

Notes
DFR was an experimental reactor to test fast breeder technology. The reactor is housed in a concrete vault 90ft in diameter, which is housed in the lower half of a spherical steel containment vessel 135ft in diameter. The reactor and sphere weigh 10,000 tonnes and sit on reinforced concrete foundations 10ft deep and 60ft in diameter.

UKAEA estimates it will take until 2013-2022 to complete the removal and destruction of the NaK, decommissioning of the DFR fuel pond, removal of the breeder fuel, and the removal and cleaning of the NaK-wetted primary circuits, at a cost in the region of £173 million. The total estimated cost of decommissioning DFR by 2026-2042 is in the region of £250 million.

Some 1500 activities required to decommission Dounreay over a 50-60 year period at a cost in the region of £4 billion are contained in the Dounreay Site Restoration Plan, which can be viewed at www.ukaea.org.uk