In 2025, a UK nuclear waste site began installing railway sleepers made from about 90 kilograms of recycled plastic each - their claimed lifespan was 50 to 100 years

A UK nuclear waste site has installed composite railway sleepers made from approximately 90 kilograms of recycled plastic waste each. According to Nuclear Waste Services (NWS), the sleepers have a lifespan of between 50 and 100 years, are made in the UK and are fully recyclable.

The sleepers were installed at the Low Level Waste Repository as part of planned routine maintenance and replacement work on the site's rail sidings. The Repository Engineering team saw the work as an opportunity to improve sustainability by considering an alternative to traditional hardwood sleepers.

Engineers looked for a more sustainable alternative

Andrew Little, Senior Engineering Technician, identified the potential to use composite sleepers instead of traditional hardwood.


After researching their specifications, he recommended sleepers made from approximately 90 kilograms of recycled plastic waste.

NWS said it is the first site in the Nuclear Decommissioning Authority (NDA) group to have installed the composite sleepers. The organisation plans to transition fully to composites as required.

Ruth Davey, Senior Environmental Advisor, said, "It’s great to see that after 40 years of service, Vault 8 is now full and ready for capping. Filling the ‘tennis court’ required precise operation of heavy equipment in a very limited space – and is testament to the dedication and skill of the operations team," as quoted in a NWS report.

Rail deliveries mark progress on the STIM project

Elsewhere at the Repository, work is underway on the Southern Trench Interim Membrane (STIM) project. The project involves placing a new protective layer over the southern end of the historic trenches.

GRAHAM Construction Ltd was awarded the main STIM contract last summer and mobilised on site late last year. NWS has also completed its first rail delivery campaign for the project.

During February and March, 63 trains transported 49,000 tonnes of material from Breedon's quarry in Cumbria to the Repository.

Mike Pigott, Director of Sites and Operations at NWS, described the work as a first-of-kind activity in the UK and said it showed progress on the project. He highlighted the collaboration between Nuclear Transport Solutions (NTS), GRAHAM and c, as well as the amount of material moved by rail.

Pigott said that, "It is important that NWS caps the existing vaults and trenches to provide long-term protection of the environment for generations to come, adding, "This work is integral to our mission, to make the UK’s nuclear waste permanently safe, sooner," as quoted in the NWS report.

The Repository is working to limit disruption

NWS said it is working to minimise or mitigate potential disruption from the STIM project, including noise, dust, traffic, ecological and visual impacts.

Measures include noise barriers, visual screening bunds and regular noise monitoring. The use of rail to transport most of the aggregate and other materials is also part of the approach.

Alastair Lewis, GRAHAM Contracts Director, said the rail deliveries marked the beginning of an extensive programme and represented a significant milestone for the project team and its stakeholders.

Work on the STIM project currently includes stockpile areas and trial panels of Geosynthetic Clay Liner on the trench cap. Another rail campaign was planned for June, alongside continued community engagement.

Vault 8 reaches a major milestone

The Repository also reached a major milestone in its waste disposal operations in mid-February, when half-height ISO containers were placed in the last remaining space in Vault 8, an area compared with the size of a tennis court.

Vault 8 opened in 1988, replacing the individual clay-lined trenches that had been used at the site since 1959. The current disposal system uses multiple barriers, with waste arriving in steel containers before being grouted and placed inside reinforced concrete vaults.

The milestone enables the final capping of Vault 8 and the adjacent trenches once the STIM is replaced.

Chris Sharples, Site Operations Manager, said It’s great to see that after 40 years of service, Vault 8 is now full and ready for capping. Filling the ‘tennis court’ required precise operation of heavy equipment in a very limited space – and is testament to the dedication and skill of the operations team," as quoted by NWS.

Composite sleepers add another sustainability measure

The railway sleeper replacement began with planned maintenance work on the Repository's rail sidings. The Engineering team used the opportunity to investigate whether composite sleepers could replace traditional hardwood.

The selected sleepers are made using approximately 90 kilograms of recycled plastic waste each and have a stated lifespan of 50 to 100 years. They are made in the UK and are fully recyclable.

NWS plans to transition fully to composite sleepers as required, while work continues on the wider STIM project and the capping of historic waste areas.