Guidance

Sellafield Ltd priorities and progress

A snapshot of Sellafield Ltd’s key activities and priorities. This page is continually updated with the progress we're making in each of our business areas.

About Sellafield Ltd

We are delivering against national safety, security and energy needs. In operating, developing, and decommissioning the Sellafield site, we are also delivering the largest environmental restoration project in Europe.

In short, we solve complex nuclear, engineering, and infrastructure challenges for the UK every single day.

In the past, we have been responsible for breakthroughs such as the world’s first full-scale commercial nuclear power station, and today we are helping to keep lights on across the UK by safely receiving and storing spent nuclear fuel from the UK’s fleet of power stations.

Sellafield is the only site in the country that can safely manage all forms of nuclear waste, with our teams finding new ways to ensure it is kept safe until a permanent disposal facility is ready.

We are also guardians of the UK’s largest stockpile of nuclear materials.

Our world-class engineers and nuclear professionals tackle these challenges with the same spirit of innovation that has always run through our organisation.

All our activities are driven by a single purpose: to create a clean and safe environment for future generations.

We deliver on that purpose while providing value to:

  • Our people – helping them to grow, develop and flourish

  • Our communities – creating a positive social impact in West Cumbria, Warrington and beyond

  • Our industry – supporting the nation’s nuclear infrastructure, completing our decommissioning mission, and shaping best-practice standards.

Priorities

NDA strategy

We are one of four vital component parts of the Nuclear Decommissioning Authority (NDA) Group, which shares a collective mission to safely decommission the UK’s legacy sites and facilities.

The Sellafield Ltd priorities are embedded within the NDA strategy.

Sellafield Ltd strategy

Our strategy outlines the type of organisation Sellafield wants to be, whilst clearly setting our 2020 - 2025 objectives.

Progress overview

An overview of our past progress across all our activities, within previous financial years can be found in our catalogue of annual review documents.

High-hazard risk reduction priorities and progress

Among the more than 200 nuclear facilities on the site are some of the most hazardous nuclear buildings in the country – our legacy ponds and silos.

These legacy facilities include:

They present complex decommissioning challenges and getting the waste out of them remains one of our top priorities. By doing so we are actively reducing these hazards and protecting the environment.

To support our retrievals work, we have continued to maintain the integrity of the facilities, and deliver the projects required to establish the required waste routes.

Read more about our legacy ponds and silos

Turning the corner to exciting times - Blog

Pile Fuel Storage Pond

Built between 1947 and 1949, the Pile Fuel Storage Pond (PFSP) is the oldest nuclear pond on the Sellafield site. It is also the largest open air nuclear fuel storage pond in the world.

Pile Fuel Storage Pond, Sellafield

It provided storage, cooling and decanning of irradiated fuel and isotopes from the two Windscale Pile reactors in preparation for reprocessing.

Although taken out of operation in 1962 it continued to receive irradiated fuel and miscellaneous intermediate level waste (ILW) from the UK nuclear programme until the early 1970s.

By the mid-1970s, the import of waste ceased and the plant, with its inventory, was placed into a passive care and maintenance regime.

The priority

Retrievals from the PFSP commenced in the 1990s. The facility is now entering its final phase of retrievals.

Our priority today is to continue to retrieve the remaining inventory of waste in the pond – solid ILW, sludge, sludge debris and fuel materials - so it can be placed treated appropriately and placed into safe, modern storage.

Our progress

76% of the radioactivity has now been removed from the PFSP. We are accelerating the removal of ILW with a series of decommissioning dives which started in 2023.

We have established proven waste routes for the waste coming out of the pond (whilst continuing to explore further future opportunities).

Pile Fuel Cladding Silo

Commissioned in 1952, The Pile Fuel Cladding Silo (PFCS), is the oldest store on the Sellafield site. The six-compartment silo was built to store cladding from nuclear fuel used by the Windscale Piles.

Pile Fuel Cladding Silo, Sellafield

As the UK’s civil nuclear power industry grew, the silo also received and stored cladding from used Magnox fuel from power stations around the country.

In 1972, the facility was full and placed into care and maintenance.

Read more about the Pile Fuel Cladding Silo

The Pile Fuel Cladding Silo - Case study

The priority

We started retrievals from the PFCS in 2023.

Our priority today is to continue waste retrievals from the legacy silo so it can be placed a safe and modern store called the Box Encapsulation Plant Product Store (BEPPS).

Our progress

We are currently in the early retrievals phase of this project and are on track to achieve our target of filling 18 of the bespoke-built 3 metre cube stainless boxes with waste in 2024/25.

First Generation Magnox Storage Pond

Constructed in the 1950’s, the First Generation Magnox Storage Pond (FGMSP) was commissioned to receive and store irradiated fuel from Magnox reactors and remove the fuel cladding prior to fuel being reprocessed.

The legacy pond predominantly received fuel from Calder Hall, the UK’s first nuclear power station, on the Sellafield site. However, the pond also received and processed fuel from the UK’s fleet of 26 reactor units, Latina in Italy and Tokai in Japan.

First Generation Magnox Storage Pond, Sellafield

The plant operated safely for over 30 years with the final fuel being received into the facility in 1992. During this period 27,000 tonnes of fuel were processed – nearly 2.5 million fuel rods.

The priority

We started retrievals from the FGMSP in 2015.

Our priority today is to continue with the retrievals of the sludge, intermediate level waste (ILW) and spent fuel within the pond. The various forms of retrieved waste will be treated appropriately and placed in safe, modern stores.

Our progress

We are currently in the bulk waste retrievals phase of this project. We successfully removed the first zeolite skip from the pond in 2024.

The solid waste retrieved from the pond is being transferred and self-shielded boxes and safely-stored in a new purpose-built legacy facility called the Intermediate Storage Facility (ISF).

Magnox Swarf Storage Silo

The Magnox Swarf Storage Silo (MSSS) is the most hazardous building on the Sellafield site.

The silo contains approximately 10,000 cubic metres of historic waste within 22 individual compartments of the silo.

MSSS was built more than 50 years ago for the underwater storage of Magnox fuel cladding (or swarf) that was removed from used nuclear fuel rods. This allowed the rods to be reprocessed.

It received swarf from the First Generation Magnox Storage Pond and the Fuel Handling Plant, along with a range of other items of intermediate level waste.

The final batch of waste was tipped into the legacy silo in June 2000, at which point the facility was put under a regime of care and maintenance.

Read more about the Magnox Swarf Storage Silo

What is the Magnox Swarf Storage Silo? - Case study - GOV.UK

The priority

We started to retrieve the stored waste from Magnox Swarf Storage Silo (MSSS) in 2022.

Our priority today is to continue to retrieve the stored waste and silo liquor so it can be placed in a safe and modern store. Most of the solid waste from MSSS will be placed in the Box Encapsulation Plant Product Store (BEPPS).

There is an ongoing leak of radioactive liquid from the MSSS facility at Sellafield into the ground. The risk to the off-site environment and public is expected to be very low. There is no risk to public water supply boreholes from the leak.

Working closely with the Environment Agency and the Office of Nuclear Regulation (ONR), the priority for our teams is to continue to monitor the leak. We must do this whilst continuing to retrieve waste from the silo and exploring the possible implementation of measures to reduce the consequences of the leak. Read more about the leak.

Our progress

Waste retrievals were temporarily halted but successfully restarted in February 2024. This was following the successful commissioning of the new Nitrogen Generation Plant and the completion of some electrical repairs needed on the Silo Emptying Plant machine.

Magnox Swarf Storage Silo, Sellafield

The second Silo Emptying Plant machine has been installed. Preparation and commissioning work on the machine is being conducted inside the silo. Once completed, retrieval operations will commence.

We are also continuing to closely monitor the ongoing leak of radioactive liquid from the MSSS facility. in 2023/24 we added sixteen more boreholes close to the silo to enhance this monitoring capability.

Updates to this page

Published 28 March 2025

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