ONR reports safe 2025/26 operation for Great Britain's nuclear industry
Waste is now being retrieved from all Sellafield legacy ponds and silos, though progress there has been slower than planned.
Key facts
- Cyber security maturity remains below the level ONR expects across the sector
- Nuclear site conventional health and safety incident rates above the long-term average
- Hunterston B licence transferred to Nuclear Restoration Services to enter decommissioning
- Devonport Royal Dockyard returned to routine regulatory attention for safety
- Themed inspection of construction activity; findings due late next year, per ONR
Great Britain's nuclear industry operated safely and securely through the 2025/26 reporting period, the Office for Nuclear Regulation said on October 8, publishing the Chief Nuclear Inspector's annual report.
The report records variability in performance between dutyholders and names cyber security and nuclear site conventional health and safety as areas where sustained regulatory focus is still required.
Waste retrieved from all legacy ponds and silos
At Sellafield, ONR sought improvements in the management of high hazard facilities and risk reduction. Progress on the legacy ponds and silos programme remained slower than planned because of technical challenges, asset reliability issues and ageing infrastructure. Waste is now being retrieved from all the legacy ponds and silos. A risk-informed approach is being developed and piloted in the remediation area.
ONR oversaw continued safe operation of the UK's operating reactor fleet following EDF's lifetime extension decisions. Devonport Royal Dockyard Ltd returned to routine regulatory attention for safety. Sellafield's cyber security performance improved enough to change its regulatory attention level, and EDF's cyber security arrangements also progressed. Hunterston B's licence transferred to Nuclear Restoration Services to enter decommissioning.
Incident rates above long-term average
Conventional health and safety incident rates remain above the long-term average, indicating that sustained improvement has been limited. ONR chose the topic for this year's Chief Nuclear Inspector's Themed Inspection, focused on construction activity across the sector. Findings will be reported towards the end of next year.
Cyber security inspection showed an improving baseline capability, but overall maturity remains below the level expected, ONR said.
The report cites the Nuclear Regulatory Review 2025, which ONR welcomed, and ONR Together, its rolling strategy published in July 2026, which commits to proportionate, enabling regulation supporting innovation and growth while maintaining public confidence in safety and security.
"The culture, right across the nuclear sector must change to meet the pace and scale of the government's ambition," Chief Nuclear Inspector and Chief Executive Mike Finnerty said.
