Execution and key achievements
- 24,195 contractor hours completed safely
- Processing of 40 loads of mixed construction waste
- 5 loads of mixed metals
- 2 loads of roof felt
- 232 lorry movements removed almost 4,000 tonnes of reusable demolition waste
- Reduction of 7,548 m² of site buildings to slab level
The history of Harwell
Building B401.8 at Harwell is a site of historic importance in Britain’s nuclear heritage. Built in 1953, it housed the UK’s first fast fission reactor, Zephyr, before the reactor moved to Winfrith in 1959. The building also supported pioneering vehicle emissions research and prosthetic limb development. Since 2012, it had been under care and maintenance and was no longer financially viable to repair.
Project highlights
Partnering with Nuclear Restoration Services
B401.8 building demolition project, Harwell, Oxfordshire
Total project costing £2.3 million
Executed over 2 years and 5 months
The three-phase demolition approach
The decommissioning of building B401.8 followed a three-phase approach: pre-demolition characterisation, controlled demolition with monitoring, and post-demolition remediation to support site delicensing and permit surrender.
Pre-demolition activities
- Health physics surveyor training (half-day NRS-led)
- Development of risk assessments, method statements (RAMS) and quality plans
- Pre-demolition radiological characterisation, including:
- Collimated large-area gamma surveys of Main Reactor Hall
- Collection of 14 drilling cores from the Zephyr and Tank basements, 2 additional cores from reactor locations and composite reference background samples
- Gamma survey and sediment sampling from designated manholes
Controlled demolition
- Removal of all waste and recyclable materials, including licensed and unlicensed asbestos
- Controlled demolition of Building B401.8 (1,498m² footprint) to floor slab level
- Continuous Health Physics Monitoring (HPM) during demolition
- Waste segregation and disposal through appropriate waste streams
- Collection of targeted samples during demolition activities
Post-demolition activities
- Removal of floor slabs and foundations with HPM support
- Legacy drains removal
- 3-week hold point for comprehensive radiological surveys and sampling
- Large-area gamma surveys before backfilling
- Systematic soil sampling and analysis
- Site backfilling with certified materials meeting radiological acceptability criteria
Challenges faced in the demolition and how we overcame them
- Careful planning around live 132 KVA electrical cables
- Radiological monitoring to manage contamination risks
- Rapid response to unexpected asbestos finds
- Environmental oversight for bat presence in collaboration with local ecologists
Harwell decommissioning and demolition results
- Project completed two weeks early
- Site remediated to delicensing standards
- All waste disposed of correctly
- Area left clean and safe for future use
- Detailed documentation provided
- No environmental or safety incidents
- Successful clearance of a historic nuclear facility supporting wider decommissioning goals
Hear from our client
I have nothing but praise for the excellent safety culture and high standards of safety, environmental and security compliance demonstrated by KDC Veolia, together with their Celadon partners Altrad and NSG, and other supporting subcontractors. This has resulted in no lost-time accidents or injuries and an open, challenging attitude, meaning issues are identified and positive interventions are enacted to prevent events from occurring. This commitment to safety has been evident through thorough safety performance monitoring protocols and oversight. KDC Veolia's dedication to maintaining a safe working environment has been instrumental in achieving our project goals and key targets without compromising on safety standards. KDC Veolia's site team and their subcontractors consistently exhibited high levels of professionalism and exemplary behaviour, fostering strong relationships with the NRS Project Team and key site stakeholders. This visit reflects the strong partnership between NRS and KDC Veolia and highlights the shared commitment to safe, efficient, and sustainable project execution.
NRS Senior Project/Site Delivery Manager
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