Office for Nuclear Regulation

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Sellafield Ltd: HALES - Plant visit and meetings to determine compliance with Improvement Notice 307424291 and establish progress in delivery of site wide legionella improvements

Executive summary

Purpose of Intervention

Plant visit and meetings to determine whether Sellafield Ltd. had complied with Improvement Notice 307424291 issued in September 2016 and establish progress in delivery of site wide legionella improvements.

One of the purposes conferred on ONR by the Energy Act 2013 is nuclear site health and safety. The ONR CHS team contributes to this purpose by providing coherent specialist conventional health and safety support and advice to ONR regulatory divisions. This intervention results from a programme of work underway by the ONR Conventional Health & Safety (CHS) team to secure improvements in conventional health and safety management within the nuclear industry. In addition, this work contributes to the ONR Sellafield, Decommissioning, Fuel and Waste (SDFW) Division strategy milestone SC8 ‘Completion of planned corporate inspection schedule’.

Interventions Carried Out by ONR

The intervention was structured around the three main requirements of the Improvement Notice. The Notice required Sellafield Ltd. to clean and repair the Highly Active Liquor Evaporation & Storage plant (HALES) standby cooling tower. The Notice also required Sellafield to review (and if necessary revise) the documented control measures for the HALES cooling system. The purpose of the review was to identify any further action required to ensure that the HALES cooling towers can be maintained in an efficient state, in efficient working order, in good repair and in a clean condition.

The key regulatory activities undertaken during the two day visit were based around:

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

The findings, inspector opinion developed and judgements made during the visit to the HALES facility were made using the relevant legislation, Approved Code of Practices and well-established legionella technical guidance as benchmark standards.

From the review of the documentation (including photographs) provided by Sellafield Ltd., the plant walkdown and discussions with relevant personnel ONR identified:

The refurbishment work completed to the HALES standby cooling tower has included extensive cleaning, replacement and repair of a number of key parts of the cooling tower. The standby cooling tower is now in an improved state of cleanliness and repair.

Increased awareness and managerial oversight of the HALES cooling system, which has led to increased challenge of existing conditions within the HALES cooling system and remaining cooling tower. As a result, Sellafield plans to move immediately into a five month period of refurbishing the current duty cooling tower - due to be taken offline at the end of May 2017.

Some minor repair works remain incomplete, but are planned for completion prior to the tower returning to service.

Work to identify ‘deadlegs’ and map the varying temperatures within the HALES cooling system is ongoing. Deadlegs increase the legionella risk associated with a cooling system and under normal circumstances would require a comprehensive deadleg removal or management regime to be developed. However, Sellafield anticipate that instigating a full deadleg management/flushing regime may not be reasonably practicable - due to the nuclear safety risks posed if human error resulted in sections of the cooling system being isolated as a result of erroneous opening or closing of valves.

A comprehensive review and where necessary revision of the relevant documented arrangements has been undertaken by Sellafield Ltd. A large number of actions have also been identified by Sellafield Ltd. as a result of the review. Notwithstanding this, additional actions were identified by ONR as being required to satisfy the Notice requirements. Sellafield Ltd. subsequently wrote to ONR to provide a written commitment to address the additional actions identified during the intervention.

A short meeting was held to discuss the site wide Legionella Improvement Programme that the Legionella Programme Improvement Manager is in the process of initiating and implementing. A topic of note included the quality of the source water Sellafield uses on the site, its impact on the cooling systems on site and whether pre-treatment was required.

Conclusion of Intervention

At the end of the intervention ONR confirmed that it was satisfied that Sellafield Ltd. had taken appropriate steps to clean and repair the HALES standby cooling tower. It was confirmed that ONR had seen sufficient evidence to confirm that two parts of the Improvement Notice requirements had been met and were therefore complied with.

It was also acknowledged that Sellafield Ltd. had undertaken a significant amount of work to review and revise the assessment of risk and the associated written scheme of control measures for the HALES cooling system to identify any further action required. However, ONR explained that further written commitment to complete additional actions was required before the third part of the Notice requirements could be considered complied with. These actions were agreed with Sellafield Ltd. prior to leaving site.

ONR explained that notwithstanding the work that had been completed by Sellafield Ltd., concerns remain regarding the HALES cooling system as a legionella risk system. It was emphasised that the nuclear safety requirements placed on the HALES cooling system result in compromises to the legionella risk management such that the HALES cooling system is a ‘high risk’ system from a legionella perspective. ONR stated that the compromises introduced into the cooling system due to nuclear safety requirements needed to be offset by enhancing other aspects of the legionella management arrangements.

The Head of SFM acknowledged ONR’s concerns and committed to ensure Sellafield maintains focus on legionella risk reduction at the HALES facility. Sellafield Ltd. subsequently wrote to ONR to provide a written commitment to address the additional actions identified during the intervention. On receipt and review of this letter ONR wrote to Sellafield confirming all parts of the Notice had been met, although it was identified a substantial amount of work remained to be completed.

An ONR Level 2 regulatory issue open (no. 4006) that is related to this intervention will be updated to reflect the intervention findings. The need for further regulatory action will be considered once Sellafield has identified the full nature and extent of risk reduction work required and ONR will monitor Sellafield’s progress in timely completion of the actions identified.