The Hunterston B nuclear power station has recorded a decommissioning milestone by reducing its holdings of dangerous substances, now placing it outside of the Control of Major Accident Hazards Regulations 2015 (COMAH).
EDF Energy Ltd has notified the Office for Nuclear Regulation (ONR) and the Scottish Environmental Protection Agency (SEPA) that the Ayrshire site has made this significant change, reducing these materials below the lower tier COMAH thresholds (see “What is COMAH?” below). In September, ONR and SEPA inspectors visited Hunterston B after receiving their notification, working closely together as part of the COMAH Competent Authority.
During this inspection, EDF successfully demonstrated that their arrangements for removing and reducing dangerous substances met the required standard.
Insights from Hunterston B, along with learning from Hinkley Point B’s exit from COMAH in June 2024, will be taken forward to inform future risk reduction activities at other operating facilities.
These observations will also inform how the Competent Authority regulates COMAH exit arrangements at other relevant nuclear licensed sites being decommissioned.
Tom Eagleton, ONR’s Head of Regulation for Decommissioning, Fuel and Waste, said: “This is a significant milestone for Hunterston B and wider efforts to decommission the UK’s fleet of advanced gas-cooler reactors.
“It reflects the industry’s ongoing commitment to minimising hazards at their source – in this instance, by removing dangerous substances from site. It also demonstrates the value of regulatory collaboration in the decommissioning process.”
In early 2022, Hunterston B reached the end of its operating life after nearly 46 years of generating electricity and moved into its defuelling phase.
Since then, nuclear fuel has been removed from the reactors and transported by rail to Sellafield in Cumbria for storage. The Ayrshire site was declared fuel-free last April.
The ownership of the site is set to be transferred from EDF to Nuclear Restoration Services to manage the long-term decommissioning programme.
What is COMAH?
Dangerous substances are present on many industrial sites, including nuclear facilities. COMAH aims to prevent major accidents involving these dangerous substances and limit the consequences for human health and the environment of any incidents that might occur.
On nuclear facilities across Great Britain, COMAH is jointly regulated by ONR and the relevant environment regulator (the Environment Agency, the Scottish Environment Protection Agency or Natural Resources Wales), known collectively as the Competent Authority. COMAH applies to sites holding amounts of dangerous substances that exceed certain thresholds – denoted as either lower tier or upper tier.
Regulators expect COMAH establishments to take all measures necessary to minimise the risk of a major accident and control any remaining risks. COMAH establishments must minimise the quantity of dangerous substances held on site and consider nuclear safety and security risks to ensure any action taken to remove substances does not have wider adverse impacts.
COMAH does not apply to nuclear material or irradiated chemicals on nuclear sites, which are covered by other legislation.