NRS clears 97,000 tonnes in largest land remediation at Harwell nuclear site

Nuclear Restoration Services (NRS) has completed its largest ever land remediation project, removing more than 97,000 tonnes of material to restore 4.2 hectares at its Harwell site in Oxfordshire, the company and the Nuclear Decommissioning Authority (NDA) announced on 9 November.

The work covered the former Liquid Effluent Treatment Plant (LETP) and the neighbouring Sewage Farm Area. According to the release, teams located, excavated and removed buried tanks, pipelines, pumping stations, reinforced concrete structures and treatment infrastructure, some of it up to 10 metres below ground.

Gary Reid, Harwell Site Director, said the scheme had been a complex undertaking "requiring years of careful planning, specialist expertise and collaboration across NRS, the NDA and our supply chain".

With physical remediation finished, NRS said the project is now moving through the final regulatory stages to delicence the land and surrender the environmental permit.

The site

The LETP was built in 1948 to treat liquid waste from Harwell's nuclear research programmes, NRS said. Active and trade drainage from across the site flowed to the plant, where waste was treated before discharge through a dedicated pipeline to the River Thames. Operations ended in 2013.

The Sewage Farm Area is older still. NRS said it was originally built in the 1930s to serve RAF Harwell and was later expanded as the site developed.

NRS said the 97,000 tonnes excavated exceeds the fully loaded displacement of the aircraft carrier HMS Prince of Wales.

A new Sustainable Drainage System (SuDS) pond has been created within the former Sewage Farm Area. Material dug out for the pond was reused to reprofile the LETP area, which NRS said avoided importing about 60,000 tonnes of material and prevented an estimated 2,700 vehicle movements.

Public access has also been restored to Icknield Way, a designated public bridleway alongside the former LETP area that was closed while the work was under way.

Clive Nixon, the NDA's Chief Nuclear Strategy Officer, said: "Transforming this historically important land into an asset for future use is a clear example of the lasting benefits we aim to deliver through the NDA mission."

Timeline

Primary sources differ on when the LETP project finished. The NDA's UK Radioactive Waste Inventory page for Harwell records the remediation, carried out under the site's previous operator Magnox, as completed in 2021. In August 2021 Magnox itself described the project as "well advanced", and the 9 November 2026 NRS and NDA release announces completion now.

The wider clearance

The NDA describes Harwell as a 91-hectare site and the birthplace of the UK nuclear industry. It was an RAF station before becoming the Atomic Energy Research Establishment in 1946. The Office for Nuclear Regulation (ONR) says more than 100 facilities have been removed from the site, with others still being decommissioned.

Plans to redevelop Harwell as a Science and Innovation Park were agreed in 1992, when decommissioning started, according to the NDA inventory. The site joined the NDA's decommissioning programme in 2005.

In August 2026 NRS said decommissioning at Harwell had removed more than one million square feet of facility footprint, cleared 1.6 million square feet of land and enabled 23 hectares to be delicensed and released for redevelopment. Delicensed land has become part of the wider Harwell Campus, which NRS said supports thousands of jobs.

The previous milestone came in August 2025, when NRS announced the demolition of a reactor complex that once housed the Zephyr fast fission reactor. That job, delivered with KDC Veolia, part of the Celadon Alliance, removed almost 4,000 tonnes of reusable demolition waste in 232 lorry movements.

NRS, part of the NDA group, is responsible for decommissioning 15 nuclear sites across the UK. The NDA is sponsored and funded by the Department for Energy Security and Net Zero.

Reid said returning the land for potential future use at Harwell Science and Innovation Campus means an area that once enabled nuclear research can continue to support science, innovation and economic benefit. The delicensing and environmental permit surrender process for the 4.2 hectares is now under way.