Office for Nuclear Regulation

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Fact-finding intervention into a confined space entry event during September 2015 on Sellafield Ltd.’s nuclear licensed site at Sellafield, Cumbria

Executive summary

Purpose of intervention

The Office for Nuclear Regulation (ONR) regulates nuclear and conventional health and safety on the Sellafield site. Sellafield Limited (SL), the site licensee, identified and notified ONR that planned man entries into two chemical process tanks on its uranium finishing/medium active evaporation plant (UF/MAE) in September during the 2015 periodic shutdown had been undertaken without the appropriate confined space control measures in place.  Sellafield Ltd stated that there was no harm or injury to any of the personnel involved in the event and that nuclear safety was not threatened.

ONR Sellafield Programme management considered that the event was significant and warranted further investigation. This intervention record describes the findings from ONR’s intervention into the event and the remedial actions undertaken subsequently by Sellafield Ltd.

Interventions Carried Out by ONR

An ONR human factors specialist inspector and I undertook this intervention in two parts. Firstly, we reviewed Sellafield Ltd.’s investigation report into the event and examined Sellafield Ltd.’s written arrangements for compliance with the Confined Spaces Regulations. Secondly, we undertook an information-gathering site inspection between 15 and 16 March 2016, comprising a number of meetings with Sellafield Ltd staff and a contractor whom we considered were relevant to the event.

Those dutyholders, such as Sellafield Ltd, who work or control work in confined spaces must comply with the Confined Spaces Regulations 1997 and meet the standards of risk management identified in the associated Approved Code of Practice (ACoP) and guidance. The ACoP gives practical advice on how to comply with the law. If a dutyholder follows this advice it will usually be doing enough to comply with the law in respect of those matters on which the Code gives advice.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable. The intervention was not a safety system inspection.

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

From the sample evidence examined associated with the confined space entries carried out during the September 2015 event, I consider that Sellafield Ltd did not comply with the Confined Spaces Regulations 1997 or meet the standard presented in the associated ACoP. It is, however, my opinion that the actions Sellafield Ltd took immediately after the event were suitable and sufficient and give me appropriate confidence that adequate arrangements are now in place to ensure ongoing compliance with these Regulations.  

With regard to Sellafield Ltd.’s root cause investigation into the event, it is our opinion that their issued report did not provide sufficient clarity as to why it had occurred, particularly with regard to the human factors aspects. In response to the concerns we raised during the intervention, Sellafield Ltd provided additional information during our site inspection, particularly around shortfalls in human performance that we had highlighted, the management and supervision of contractors and how it planned to address these.

Conclusion of Intervention

It is my opinion that Sellafield Ltd did not comply with its own arrangements for ensuring compliance with the Confined Spaces Regulations 1997 when carrying the confined spaces entries into two chemical process tanks on its UF/MAE plant. I believe these uncontrolled entries represent a significant breach of the Confined Spaces Regulations 1997. It is, however, my opinion that the actions taken by Sellafield Ltd.’s local management after this event are sufficient to bring the facility back into compliance with Sellafield Ltd.’s arrangements for ensuring compliance with the Confined Spaces Regulations 1997. Furthermore, it is my judgement that the learning from this event has been used effectively by Sellafield Ltd as part of on-going work to make improvements to its conduct of operations.

When considering the finding from my intervention, ONR’s Enforcement Management Model (EMM) will be used to help determine what is the appropriate regulatory response.

Based on my findings at the time of this intervention, when appropriate corrective actions had been put in place by Sellafield Ltd, I believe that an IIS rating of 3 (adequate) against the Confined Spaces Regulations is justified. 

Prior to completion of ONR’s consideration of its regulatory response to this event, I have not raised any Regulatory Issues as a result of this intervention.