Sellafield Ltd priorities and progress
An overview of our priorities at Sellafield and the progress we're making to achieve them. This includes high hazard risk reduction, nuclear waste management and our major projects
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 1 of 4 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
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 2 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 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 intermediate-level waste, 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’re accelerating the removal of intermediate-level waste 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 Storage Pond progress updates
Sellafield clean-up team dives into history - March 2023
It’s been a massive effort in challenging times - March 2021
A simple solution speeds up Sellafield decommissioning - December 2020
Important work in tackling future risks restarts at Sellafield - May 2020
Pond cleaner ready to make a splash - August 2019
Triple tonne triumph - December 2018
Radioactive sludge makes momentous move to modern storage - February 2017
Radioactive sludge removed from Sellafield pond for first time - December 2016
Nuclear clean-up milestone makes Sellafield safer - March 2016
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 priority
We started retrievals from the PFCS in August 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 end goal is to empty the facility.
Our progress
We met our retrievals target for 2024/25 by retrieving enough waste to fill 18 3-metre cubed storage boxes.
As we move out of the early retrievals phase of this project, our focus now is to safely accelerate the pace of routine retrievals from PFCS.
Pile Fuel Cladding Silo progress updates
Sellafield’s ’locked vault’ gives up its nuclear secrets - May 2025
Sellafield makes history with first retrievals from oldest store - August 2023
Sellafield Ltd confirms contract for waste storage boxes - June 2021
High-tech route for silo waste - February 2021
Important work in tackling future risks restarts at Sellafield - May 2020
Sellafield’s ‘locked vault’ ready to be emptied - March 2019
First Sellafield waste boxes cross the finish line - February 2018
Sellafield’s ‘locked vault’ is ready to be emptied - Dec 2017
First hole is cut in world’s oldest nuclear store - Sep 2017
Sellafield’s magnificent six now in place - Dec 2016
Engineering feat opens door to Sellafield clean-up progress - May 2016
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.
Read more about the First Generation Magnox Storage Pond
What is the First Generation Magnox Storage Pond - Case study
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 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 and also introduced Self-Shielded Boxes (SSBs) to transport the zeolite skips to the Interim Storage Facility.
In 2025, we extended the SSB method to include fuel and fuel material skips, improving safety and efficiency.
First Generation Magnox Storage Pond progress updates
The First Generation Magnox Storage Pond - Zeolite skip export
Sellafield clean-up skips ahead after triple first in legacy pond - March 2024
Important work in tackling future risks restarts at Sellafield - May 2020
Robots tackle Sellafield’s notorious radioactive ‘hot spot’ - January 2019
Game changing progress in Sellafield pond - July 2018
Innovative scaffolding helps Sellafield reach new heights - July 2016
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.
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, 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
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.
We have successfully removed 70 tonnes of radioactive waste from the Magnox Swarf Storage Silo (MSSS).
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 16 more boreholes close to the silo to enhance this monitoring capability.
Magnox Swarf Storage Silo progress updates
Sellafield’s most complex clean-up job reaches major milestone - October 2025
Discovering the secrets in the ground underneath Western Europe’s most hazardous building - November 2024
Sellafield silo installs second waste retrieval machine - March 2023
First waste removed from old nuclear Sellafield store - June 2022
SEP2 moves into position for retrievals - May 2021
Sellafield Ltd confirms contract for waste storage boxes - June 2021
Important work in tackling future risks restarts at Sellafield - May 2020
Work begins on second emptying machine at Sellafield waste silo - January 2020
A step forward for Sellafield’s most hazardous building - August 2018
First Sellafield waste boxes cross the finish line - February 2018
Sellafield tackles its biggest risk yet - June 2018
The new robot helping clean up Sellafield - October 2017
Installed: the machine set to clean up Sellafield’s most hazardous building - February 2017
Nuclear waste management priorities and progress
Sellafield is the only nuclear site in the UK that can process, treat and store all classifications of nuclear waste.
Nuclear waste is classified and managed according to its level of radioactivity and the heat that this activity produces. The primary categories are:
We also look after other specialist materials that could also be classified as waste. These include plutonium and spent fuel.
The government’s long-term solution for the country’s most hazardous radioactive waste is to dispose of it, deep underground, in a geological disposal facility (GDF).
We have the skills, experience and facilities (existing and planned) to keep the waste safe and secure until a GDF is available.
Low-level waste
Low-level waste is the waste we produce with the lowest level of radioactivity.
It includes things like gloves, protective clothing, paper towels, metal and concrete.
The priority
Our priority is to minimise the amount of low-level waste we produce. Where we can’t do this, we ensure that it is managed in the most appropriate way.
We minimise the amount of low-level waste we produce by applying the waste management hierarchy.
This approach allows us to safely reclassify some of the low-level waste we produce.
Reclassified waste can be disposed with regular waste at permitted landfill facilities or recycled.
Where low-level waste can’t be reclassified, we look at whether it can be treated, recycled or disposed of in other cost effective ways through off-site supply chain partners.
If this is not possible, we compact the solid low-level waste at our Waste Monitoring and Compaction facility on the Sellafield site to reduce its volume.
Waste Monitoring and Compaction facility, Sellafield
Compacted low-level waste is taken to the country’s low-level waste repository. Nuclear Transport Solutions move the waste, and it’s managed at the repository by Nuclear Waste Services (NWS).
Our progress
We continue to work closely with NWS to ensure the most efficient management of low-level waste.
In recent years, we’ve been able to reduce the volume of waste that is classified as low-level waste and divert other waste for more cost-effective treatment. Around 98% of the solid low-level waste we produce it diverted away from the low-level waste repository.
Low-level waste progress updates
LLWR and Sellafield contracts help Cyclife thrive – May 2019
Intermediate-level waste
Intermediate-level waste is generated across the Sellafield site in many different forms, from both historical and current operations.
Examples of this waste include fuel cladding, contaminated equipment, radioactive sludge, plutonium contaminated material and graphite from fuel elements.
The waste we are retrieving from our legacy ponds and silos is intermediate-level waste.
The priority
Our priority is to make sure we maintain our capability to look after intermediate-level waste until a geological disposal facility is available. This includes retrieving, treating and safely storing this waste.
The way we do this depends on both its origins and characteristics.
For example, the cladding that was stripped from the outside of used fuel rods to be reprocessed, were mixed with cement inside stainless steel containers and placed in stores. This process is called encapsulation.
Waste that is being retrieved from our legacy ponds and silos is being placed inside self-shielded or 3-metre cubed boxes which are placed in store.
To maintain this capability we need to:
- invest in technology to help us retrieve it
- repurpose existing facilities to treat the waste appropriately
- build new facilities, where we can’t repurpose, to treat or store the waste
- Invest in new storage boxes to store some types of waste
Our progress
We continue to retrieve, treat and store intermediate waste using a range of methods.
We have also worked with supply chain partners to design and build specialist storage boxes, which can be used to house waste before final disposal. The design of these boxes means that the storage facilities require less radiological protection.
We are also continue to build new intermediate-level waste treatment and storage facilities to complement those we already have.
Interim Storage Facility, Sellafield
Read more about some of our intermediate-level waste treatment and storage facilities
What is the Interim Storage Facility? - Case study
What is the Box Encapsulation Plant Product Store and Direct Import Facility? - Case study
Intermediate-level waste progress updates
Sellafield Ltd awards high hazard risk reduction framework contract – October 2025
Sellafield boxes to be made in Cumbria – October 2025
NDA launches pioneering robotics partnership to manage nuclear waste – June 2025
Sellafield waste team has 50,000 reasons to celebrate – September 2024
‘Box-in’ day: new Sellafield store receives first waste package – December 2023
New store is ready to take on boxes – February 2022
Sellafield Ltd confirms contract for waste storage boxes – June 2021
High-tech route for silo waste – February 2021
A simple solution speeds up Sellafield decommissioning – December 2020
BEPPS-DIF takes delivery – August 2020
£30m Sellafield Ltd contract will create jobs and boost local economy – August 2020
Forward planning to ensure cement supplies – March 2019
New storage facility is ready for waste – March 2018
First Sellafield waste boxes cross the finish line – February 2018
Sellafield thinks outside the box – November 2017
Radioactive sludge makes momentous move to modern storage – February 2017
Sellafield Ltd and NNL pledge to deliver value for UK taxpayer – January 2017
High-level waste
High-level waste is waste with the highest levels of radiation. By volume, it makes up the lowest quantity of our waste products.
This waste is highly active liquor produced through historical spent fuel reprocessing for UK and international customers.
We have completed reprocessing, so we are no longer creating new high-level waste.
The priority
Our priority for high-level waste on the Sellafield site is to:
- keep it safe and secure – we reduce its volume and store highly active liquor in our Highly Active Liquor Evaporation and Storage facility.
- turn it into a solid and stable form – we do this through a process called vitrification. This turns the waste into glass. We store vitrified waste in a specially engineered stores.
- fulfil our commitment to returning overseas waste back to its country of origin through the Vitrified Residue Returns (VRR) programme.
High-level Waste Plant, Sellafield
Our progress
We continue to vitrify highly active liquor and safely store it until it can be permanently disposed of in a geological disposal facility.
We are currently about three quarters through our VRR returns of vitrified waste. We have completed returns to a number of countries, including Germany, Australia, Switzerland, and the Netherlands.
High-level waste progress updates
Completion of UK’s high-level waste return programme to Germany – June 2026
Third shipment of vitrified waste from the UK to Germany successfully completed – June 2026
Third and final shipment of vitrified waste from the UK to Germany – March 2026
Second shipment of vitrified waste from UK to Germany completed – April 2025
Second shipment of high level waste departs UK for Germany – March 2025
Second shipment of high level waste from the UK to Germany – February 2025
Successful repatriation of intermediate-level waste to Australia – March 2022
Shipment of intermediate-level waste to Australia departs UK – January 2022
Shipment of Intermediate Level Waste from the UK to Australia – December 2021
All foreign-owned waste at Sellafield packaged and set for return – December 2021
Return of intermediate level waste from the UK to Australia – July 2021
Safe repatriation of High Level Waste from the UK to Germany – November 2020
Shipment of high level waste from the UK to Germany – October 2020
Shipment of high level waste from the UK to Germany – September 2020
Shipment of Highly Active Waste from the UK to Germany – February 2020
Thermal solution can reduce waste volumes – March 2019
D-day as evaporator starts its mission – December 2017
Sixth highly active waste shipment to Japan is complete – October 2026
Safe delivery of highly active waste from the UK to Switzerland – October 2016
Other materials
Government policy decisions mean that some other materials may be considered as waste, and could be disposed of in a geological disposal facility (GDF).
This includes spent nuclear fuel and plutonium.
Following the completion of reprocessing, we now store spent fuel produced by the UK’s existing EDF power stations.
We also store the UK’s stockpile of civil plutonium. We’ve done this for many years on behalf of the country.
The priority
Our priority is to use the skills, experience and facilities we have to execute Government policy and deliver value to the UK.
We continue to ensure the spent fuel we receive is managed safely and securely until a long-term disposal route becomes available.
The government announced in 2025 that the UK’s civil plutonium inventory will be immobilised and disposed of in a GDF. Much of this plutonium is stored on the Sellafield site, so we must continue to ensure it remains safely managed while preparations are made for its future disposal.
Our progress
We continue to safely store spent fuel and plutonium.
Spent nuclear fuel is currently stored at the Sellafield site. Its long term storage will be in the Thorp Receipt and Storage Pond. This pond has been reconfigured to make the most efficient use of available storage capacity.
We are building the Sellafield Product and Residue Store Retreatment Plant (SRP) to support the continued safe management of the UK’s civil plutonium inventory. We need this facility to repackage plutonium for long-term storage.
Planning work for a facility to immobilise civil plutonium is now taking place. We need a facility to prepare the plutonium for permanent disposal in a geological disposal facility. This plutonium immobilisation project is being led by the NDA. The facility will be built at Sellafield.
SRP provides an important bridge until that facility becomes operational.
In 2025, we successfully delivered UK Government policy milestone by safely processing a can of plutonium residue into a stable waste form for the very first time. This was delivered within 12 months and marks a significant step toward permanently disposing of the nation’s plutonium legacy.
Other waste progress updates
Sellafield awards contract to support plutonium repackaging – February 2026
UK achieves first plutonium milestone - December 2025
Multi million-pound government investment for pioneering plutonium disposal technology – August 2025
NDA group welcomes Government decision on plutonium disposition – January 2025
Installed: the Sellafield space saver set to save billions – September 2024
Cumbrian firms rack up successes at Sellafield – February 2023
Made in Cumbria: the nuclear storage solution set to ‘rack-up’ the savings – November 2020
Pressure treatment for plutonium – March 2019
Major projects priorities and progress
In order to deliver our mission, we are building on an epic scale. In fact, we have one of the largest portfolios of complex major projects in the country.
Once established, our new fleet of nuclear facilities will support operations to ensure we can continue to keep nuclear waste and materials safe and secure.
In 2019 we formed a new model for project delivery at Sellafield, the Programme and Project Partners (PPP). We brought together KBR, Amentum, Morgan Sindall Infrastructure, Altrad Babcock, and a wider supply chain to deliver a 20-year pipeline of major infrastructure projects.
This new approach was designed to ensure faster and more effective project delivery, with greater workforce flexibility, and local economic benefit.
Some of the current major projects delivered by PPP:
Read more about The Programme and Project Partners
Sellafield Ltd awards 20-year project partnership – May 2019
Many other projects that are ongoing across the Sellafield site are not delivered by PPP. While they are supported by our supply chain, they are managed within Sellafield Ltd.
SIXEP Continuity Plant
Our SIXEP Continuity Plant (SCP) will ensure the site’s existing Site Ion Exchange Effluent Plant (SIXEP) facility can continue its vital work for decades to come.
Operational from 1985, SIXEP receives and filters contaminated water from a range of nuclear buildings and processes, so it can be safely discharged to sea. The plant is often described as the ‘kidneys’ of the Sellafield site.
Our need for SIXEP will go on beyond the original design life of the plant. Which is why we’re currently building an extension.
The new-build SCP facility is being build next door to the current SIXEP building and will ensure that we can continue to treat the water used in our processes for decades to come.
SIXEP Continuity Plant, Sellafield
Read more about SIXEP Continuity Plant
Read more about The Sellafield Site Ion Exchange Effluent Plant
The Sellafield Site Ion Exchange Effluent Plant (SIXEP) - Case study
The priority
Today’s priority is to continue to meet key construction milestones to ensure we can make SCP operations by 2029.
This includes manufacturing and installing pipework, tanks, vessels, pumps and valves and eventually fitting a pipe bridge which will connect SCP with the existing SIXEP plant.
Our progress
The SCP project team recently celebrated a significant delivery milestone as they completed the manufacture of 14 bespoke pump and valve modules that will form the inner workings of the plant.
It is on course to be operational by 2029.
SIXEP Continuity Plant progress updates
Green rating shows confidence in Sellafield infrastructure delivery – February 2023
Major projects progress leads to milestone for SIXEP Continuity Plant – August 2022
The SIXEP Continuity Plant success shows future for our project delivery – February 2022
Major projects progress is transforming Sellafield’s skyline – July 2021
Projects hit the ground running post-lockdown – July 2020
Construction restart continues - June 2020
Sellafield Product and Residue Store Retreatment Plant
Our Sellafield Product and Residue Store Retreatment Plant (SRP) will play an essential role in managing the UK’s plutonium stockpile in support of the government’s plutonium disposition strategy.
Stored safely and securely at Sellafield since the 1940’s, the UK’s inventory of civil plutonium arose from the reprocessing of spent fuel.
In doing so we have developed world leading expertise and are recognised as the UK’s centre of excellence for plutonium management.
Once SRP becomes operational, it will receive and repackage existing special nuclear material packages from across the Sellafield site. This will ensure it can be safely stored for the next 100-years.
Sellafield Product and Residue Store Retreatment Plant, Sellafield
The priority
The priority is to progress the internal and mechanical fit-out of the facility before entering the inactive commissioning phase.
The installation of these systems is a key step in ensuring that SRP will become operational by 2028.
Our progress
In May 2025, the new-build plant hit a major milestone when its process building became weathertight.
The plant is now in a new delivery phase to progress its internal and mechanical fit-out.
The integrated glovebox systems which will be installed across the facility are currently being manufactured and tested off-site to ensure that they are ready for inactive commissioning.
The plant is on track to be commissioned in late 2028.
Sellafield Product and Residue Store Retreatment Plant progress updates
Flagship Sellafield project seals major milestone – May 2025
Sellafield construction project brings in new digital experience – March 2022
We reign when we pour – February 2021
First concrete pour a solid sign work is back on-site – July 2020
Second construction site set to return to work - May 2020
Project lays foundations for success – February 2020
Updates to this page
-
Addition of a new section that covers nuclear waste management priorities and progress at Sellafield Ltd
-
The First Generation Magnox Storage Pond case study has been added to this area.
-
Retrievals in the Magnox Swarf Storage Silo updated.
-
Major projects priorities and progress section added. This includes information about the SIXEP Continuity Plant and the Sellafield Product and Residue Store Retreatment Plant.
-
Addition of the latest progress update to the Pile Fuel Cladding Silo section.
-
First published.