- Site: Sellafield
- IR number: 22-047
- Date: August 2022
- LC numbers: N/A
Purpose of Intervention
The Office for Nuclear Regulation (ONR) undertakes all regulatory interactions with the Sellafield site licensee (Sellafield Ltd) against a strategy defined by the ONR Sellafield, Decommissioning, Fuel and Waste (SDFW) Division.
The purpose of this inspection was for ONR to determine the adequacy of implementation of Sellafield Ltd’s arrangements for the control of legionella in evaporative cooling systems at the Spent Fuel Services (SFS) operating unit, focussing on the Advanced Gas Reactor Storage Pond (AGRSP) and the Thermal Oxide Reprocessing Plant (THORP) cooling systems within the Fuel Storage area.
The relevant legal standards include:
- The Health and Safety at Work etc Act 1974, Sections 2 and 3;
- The Control of Substances Hazardous to Health Regulations 2002, (COSHH) Regulation 6 (Assessment of the risk to health created by work involving substances hazardous to health), Regulation 7 (Prevention or control of exposure to substances hazardous to health), Regulation 12 (Information, instruction and training for persons who may be exposed to substances hazardous to health).
In carrying out this inspection, the following Approved Code of Practice (ACoP) and guidance were used:
- Legionnaires’ disease – The control of legionella in water systems – Approved code of practice and guidance (L8);
- Legionnaires’ disease: Technical guidance – Part 1: The control of legionella bacteria in evaporative cooling systems (HSG274 Part 1)
Interventions Carried Out by ONR
The inspection focused on the following areas:
- Risk assessment and written scheme of control;
- Controlling risk from exposure to legionella bacteria;
- Review of control measures: monitoring and routine inspection; and
Explanation of Judgement if Safety System Not Judged to be Adequate
This was not a system-based inspection, and therefore no judgement has been made of the adequacy of implementation of any part of the safety case.
Key Findings, Inspector’s Opinions and Reasons for Judgements Made
The findings, inspector opinion and judgements made during the intervention were benchmarked against the relevant legislation, ACoP and established technical guidance.
We found that although the Thermal Oxide Reprocessing Plant (THORP) cooling system has a risk assessment and written scheme in place, there are several high priority actions that have lapsed, results are indicating concerning levels of bacteria, there are deadlegs in the system recognised as high or very high risk that require managing, and in our opinion, there is a significant risk associated with this system. The guidance within the ACoP requires that remedial actions are carried out promptly when needed, and we did not have the evidence that this is the case.
The Advanced Gas Reactor Storage Pond (AGRSP) cooling system does not present a similar risk level in that the water treatment programme appears to be effective, there are plans to improve the cleanliness of the system through removal and replacement of the pack in December 2022, and there a fewer deadlegs in the system. The deadlegs that exist have been identified and are managed according to risk. Therefore, at the time of the intervention, the risk from legionella bacteria is being adequately controlled.
Sellafield Ltd was advised to ensure that it takes appropriate remedial action in the event of elevated microbial counts or positive legionella results, as set out in the written scheme of control for the THORP cooling system, while outstanding actions from the risk assessment are implemented, which in themselves may require an update to the written scheme.
Conclusion of Intervention
As a result of our findings, we are satisfied that Fuel Storage is compliant with the regulations and guidance for the AGRSP cooling system in terms of the control of legionella. However, we are of the opinion that regulatory attention is required to oversee improvements at the THORP cooling system, and we have therefore rated this inspection, Amber.