Dounreay at forefront of nuclear decommissioning – 70 years after it all began

Britain emerged from World War II intent on harnessing nuclear energy to power its recovery. But uranium was scarce and its use prioritised for weapons production, so the country launched one of its most visionary scientific experiments: to research and develop a new type of power station that would create more fuel than it consumed.

Dounreay was chosen as the test site for this new technology of fast breeder nuclear reactors after several other locations across Caithness and Sutherland, from Littleferry to Reiss, had been looked at and ruled out. Over the next 40 years, scientists and engineers proved that plutonium could be harvested from a reactor and recovered in adjacent chemical works to create new fuel to generate electricity.

As uranium prices continued to fall, the economics of electricity from plutonium became uncompetitive. In 1988 the UK government announced its withdrawal from fast-reactor technology and within six years Dounreay’s Prototype Fast Reactor (PFR) had been shut down.

Now, after leading the world for four decades in research and development of nuclear technology, Dounreay is again at the forefront of science and engineering – this time in the skills and innovation needed to dismantle one of the most complex and hazardous legacies of the 20th century.

Dounreay today is a site of major construction, demolition and waste management. The experimental facilities are being cleaned out and knocked down, and the environment is being made safe for future generations.

Around 180 separate facilities were built on 135 acres of land at Dounreay. About 50 of these had a history of working with nuclear materials.

The facilities covered every aspect of the nuclear fuel cycle – from fuel fabrication and reactors through to plants for the chemical separation of spent fuel, recovery of plutonium and uranium, and disposal and storage of waste.

Each is now in the process of being cleaned out and dismantled.

Their operation also left an environmental legacy: soil polluted with radioactive and chemical waste and radioactive particles on the seabed that occasionally wash up on nearby beaches.

The first site-wide decommissioning plan published in 2000 envisaged a 60-year programme of work.

The point at which decommissioning is complete is known as the interim end state. This is when all the major hazards have been reduced or eliminated, the historic facilities have been decommissioned, and the site and the environment is in a safe state for future generations.

This will be followed by a period of care and maintenance that will endure for a further 300 years.

In May 2012 a specific end date of September 14, 2023, was put forward. Later it was revised to 2032/33. Now it is more than 40 years beyond that.

Decommissioning a site as complex as Dounreay requires an integrated plan setting out the work needed to dismantle each facility, the routes for managing the different types of waste this creates and the regulatory requirements – all of it matched to a wide range of skills.

All fuel and coolant from the Dounreay Materials Test Reactor was removed after its closure. Decommissioning is now in the final stage of strip-out and demolition.

At the Dounreay Fast Reactor (DFR), all fuel was removed after closure. Removal of the last of the breeder material resumed after a hiatus and it is now being transferred to Sellafield. Sodium-potassium liquid metal coolant was destroyed, leaving residues to be tackled. Once the major radiological and chemical hazards have been removed, the reactor can be dismantled.

All fuel and breeder material from PFR was removed after closure. The bulk of its liquid metal sodium coolant has been destroyed. Once the residual coolant has been removed and destroyed, the reactor can be dismantled.

As for the Fuel Cycle Area, facilities used in the separation of spent fuel and recovery of its uranium and plutonium are at different stages of clean-out and decommissioning.

Underground storage facilities for high-active liquor from spent fuel reprocessing are being emptied to allow the tanks to be decommissioned.

The site’s inventory of unirradiated plutonium and highly enriched uranium was removed between 2015 and 2019. Breeder material continues to be removed from the DFR and transferred to Sellafield. Irradiated spent fuel is also scheduled to leave the site.

Radioactive swarf from the historic dismantling of spent fuel is known to have entered the site’s effluent system prior to 1984 and was discharged to sea. The seabed around the disused outlet was cleaned up between 2008 and 2012.

Monitoring of local beaches continues to detect radioactive particles that are a legacy of these discharges.

In 2023 Dounreay underwent a change of name with new branding incorporating Nuclear Restoration Services (NRS).

Dounreay employs approximately 1400 people directly. Its annual spend of some £225 million a year generates about 10 per cent of the gross domestic product of the north Highlands.

Staffing levels and spending will decline as more of the hazards are reduced and removed. Some workers will see out their careers at Dounreay and others will transition to new roles and other sectors.

An important part of the decommissioning programme is supporting staff to plan their futures beyond decommissioning and supporting the community to diversify its economic base. The site does this in two ways: by helping staff adapt to the changing profile of the work through re-skilling and transition to new employment opportunities, and by investing in major infrastructure projects identified by a local regeneration partnership as being essential to the diversification of the area’s economy.

It was reported in March 2024 that the clean-up would continue until the 2070s – some 40 years later than the previous date of 2033.

The following month it was reported that spending on Dounreay would amount to almost £8 billion between then and the site’s revised end date around 2078.

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