The Sellafield site is home to a wide range of interdependent nuclear facilities and operations. These range from hazard and risk reduction, decommissioning, reprocessing and nuclear waste management.


Supporting the war effort

The Sellafield site has been operational since the 1940s, when it was used as a Royal Ordinance Factory supporting the war effort and the National Defence Programme. The factory was constructed to inspect and package small arms ammunition.

In September 1947, the site was announced as the new atomic energy site and work began on the construction of the Windscale Piles and its two air cooled reactors. 

By March 1952 the Windscale reactors were in operation producing plutonium for military purposes. These were distinguished by their very tall chimneys. In the same year the first active operation of a plant to separate uranium and plutonium from the used fuel from the Windscale reactors became operational.


Harnessing the power

All of the work on the site up to the mid 1950′s was in support of military programmes; however the peaceful use of nuclear energy was an issue at the forefront of world affairs at that time and coincidentally the first commercial nuclear power reactors in the world were commissioned at Calder Hall, Sellafield.

In 1952 the decision was made to build a commercial sized nuclear power station to harness the heat, which in the Windscale pile reactors was simply released up the ventilation stacks.

The site name was then changed to include the new Calder Hall power station, becoming Windscale and Calder Works.

Construction of the power station commenced in 1953 and only four years later on 17 October 1956, Her Majesty the Queen opened Reactor 1 at Calder Hall.

Three more reactors followed and they successfully operated until 2003, after nearly 46 years of electricity generation.


Completing the fuel cycle

In the mid 1950’s commercial opportunities were recognised, and the United Kingdom Atomic Energy Production Group was charged with identifying markets for the sale of nuclear reactors, fuel enrichment, fuel manufacture and irradiated fuel re-processing.

At about the same time the then Central Electricity Authority (later the Central Electricity Generating Board) ordered a modest programme of nuclear power stations based on the Calder Hall design and the expansion of commercial work, rather than research or military requirements and this became the mainstay of activities at Sellafield.

In 1963 the Windscale Advanced Gas Cooled Reactor (WAGR) prototype began operating.


Safely Managing Nuclear Waste

From the 1990s onwards Sellafield began constructing a comprehensive suite of waste management facilities to treat and dispose of the waste arisings from the commercial and decommissioning operations of reprocessing.

In 1990 the Magnox Encapsulation Plant (MEP) became operational and still deals with the encapsulation of Intermediate Level Waste today, this is along with the Waste Encapsulation Plant (WEP) which became operational in 1996.

In 2002 the new High Level Waste Vitrification plant started active commissioning. This plant was commissioned to convert the high-level waste into a solid form so that it can be stored safely for permanent long term storage.


Accelerating the clean-up

2005 saw the ownership of Sellafield transfer to the Nuclear Decommissioning Authority (NDA) along with all other civil nuclear sites in the UK. The NDA oversee the operations and decommissioning work at Sellafield.

The NDA competed the contract to operate the Sellafield site which was awarded to Nuclear Management Partners in November 2008.

In 2011/12 the Windscale Advanced Gas-cooled Reactor became the first nuclear powered reactor to be decommissioned in the UK; nuclear fuel was retrieved from a legacy storage pond for the fist time in over sixty years and a detailed plan was published detailing work to be undertaken at Sellafield up until 2025/26.


The next chapter

Sellafield Ltd and the Nuclear Decommissioning Authority are working in partnership to make Sellafield and its workforce the obvious choice for potential new missions.