Office for Nuclear Regulation

Management of Legionella Risks and familiarisation visit

Executive summary

Purpose of Intervention

The purpose of this intervention was to provide regulatory confidence in the management of conventional health and safety (CHS) hazards present at Atomic Weapon Establishment’s (AWE) Aldermaston site (A site). This is in line with the inspection programme contained in ONR’s Operational Facilities Division (OFD) intervention strategy 2018-19.

The ONR CHS strategy has identified a number of priority conventional health and safety topics/activities to be covered during inspection activities. Legionella Risks (Enforced under the Control of Substance Hazardous to Health Regulations 2002) are a possible ‘matter of major potential concern’ because failure to control these risks has the potential to cause multiple cases of acute or chronic ill-health resulting from a serious outbreak of legionnaire’s disease.

Interventions Carried Out by ONR

The agenda for the site visit was agreed with AWE in advance of the visit. Also, prior to the site based intervention, AWE provided ONR with a range of documentation associated with the Company’s legionella management arrangements.

The key regulatory activities undertaken during the three day inspection were based around:

Regulatory judgement was based on determining compliance with sections 2 & 3 of the Health & Safety at Work etc Act 1974 and relevant statutory provisions made under the Act. A number of key relevant statutory provisions were referred to during the visit, including: the Management of Health and Safety at Work Regulations 1999, the Control of Substance Hazardous to Health Regulations 2002 and the Approved Code of Practice (L8) “Legionnaires Disease: The Control of Legionella Bacteria in water Systems” (4th edition published 2013).

Explanation of Judgement if Safety System Not Judged to be Adequate


Key Findings, Inspector's Opinions and Reasons for Judgements Made

AWE gave ONR Inspectors a summary of how they managed CHS on site and there was a familiarisation tour of the Aldermaston site. ONR then examined the overall system that AWE employed to manage legionella risks and physically inspected 3 cooling towers. ONR visited site locations where there had been positive legionella samples in domestic water systems and spoke to the Facilities Managers on the how they managed and monitored their systems and kept records. ONR Inspectors also scrutinised actions taken after positive samples were discovered and where risk assessments had specified actions.

ONR Inspectors judged that AWE are managing legionella risks very well. The Facilities Managers and Legionella Responsible People (LRPs) demonstrated they know their responsibilities and they are ably overseen by the Legionella Technical Authority (TAL) Team and the Environmental, Safety and Health (ESH) Team. The programme to replace wet cooling towers with adiabatic systems that do not produce aerosol (and are therefore lower risk) is commendable and ranks at the top of the hierarchy of control – eliminating the risk of legionella rather than having to manage it. The actions taken when AWE found low level legionella samples within domestic water systems were effective and usually involved engineering solutions rather than dosing with more chemicals. ONR provided AWE with some advice on improving monitoring of the electronic systems and being more proactive on higher risk domestic water systems, but overall ONR was satisfied with the risk control measures.

ONR Inspectors had a meeting with the site Trade Union safety reps to discuss the management of CHS on site. Concerns were expressed that some CHS Abnormal Events were not being investigated fully and that perhaps the results, and therefore learning, from these investigations were not being shared as fully as they could be. ONR Inspectors noted this concern and told the safety reps that they would look into this issue during the next CHS inspection of AWE.

Conclusion of Intervention

Feedback was provided at a closeout meeting with the Senior Site Operations Director and the Head of Safety and Security present, as well those AWE staff involved in the intervention. ONR Inspectors shared the opinion that they judged that AWE are managing legionella risks very well, but also gave a summary of the advice provided by ONR during the inspection that could improve the risk management system further. Feedback was also provided on the concerns shared by the TU safety reps on the way in which investigations of CHS Abnormal Events were being carried out and ONR told AWE that they would examine these concerns further during the next CHS Inspection.

These concerns aside, health and safety management standards on the subjects examined were good in general. Therefore, an inspection rating of ‘Green – acceptable’ should be applied to all parts of the intervention. ONR’s comments were accepted by the site management team and no objections were raised.