Office for Nuclear Regulation

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Planned system based inspection of the nuclear fire safety systems within the First Generation Magnox Storage Pond

Executive summary

Purpose of intervention

In accordance with the Office for Nuclear Regulation's (ONR's) Sellafield Strategy, each year ONR performs a series of planned system based inspections (SBIs) targeted at key safety significant systems on those facilities with the potential to give rise to significant offsite effects to the public. The purpose of this inspection was for ONR to determine the adequacy of implementation of Sellafield Ltd.'s (SL's) safety case claims in respect of the First Generation Magnox Storage Pond (FGMSP) nuclear fire safety system.

Interventions Carried Out by ONR

Between 13-14 September 2016, ONR carried out a planned two-day inspection of the FGMSP nuclear fire safety system utilising an Internal Hazards specialist inspector and the plant's Site Inspector.

In order to determine the adequacy of implementation of the licensee's safety case claims in respect of this system, ONR examined evidence regarding the implementation of SL's arrangements for the six pre-defined licence conditions (LCs) listed at paragraph 5 below. These LCs have been selected in view of their importance to nuclear safety and are defined within ONR's formal process for system based inspection.

The inspection involved reviewing the applicable safety case claims and sampling, through a combination of document reviews, discussions with operators and plant inspections, suitable evidence to determine compliance against these LCs on the plant.

ONR assessed compliance in FGMSP with the following LCs using the applicable ONR inspection guidance:

Explanation of Judgement if Safety System Not Judged to be Adequate

It is my opinion, based on the sampling undertaken, that SL demonstrated that the FGMSP nuclear fire system has been adequately implemented in accordance with the safety case requirements.

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

My inspection of on-plant fire protection measures found them to be in good condition and well maintained and, if called upon to do so, they would deliver the safety case requirements made of them. Furthermore, I found that day-to-day operational control of nuclear fire safety was adequate. .

Whilst some opportunities for minor improvements to SL's compliance against LCs 10, 23, 24 and 28 were identified, it is my view that all six of the licence conditions examined are adequately implemented with regards to the nuclear fire safety system. Consequently, it is my opinion that a rating of GREEN (No formal action) for all the licence conditions inspected and, an overall rating of GREEN for the system as a whole, is appropriate.

Conclusion of Intervention

I judge, based on the sampling undertaken, that the nuclear fire safety systems adequately fulfil the FGMSP safety case requirements. Whilst some opportunities where identified for improvement, I am content that these shortfalls were minor in nature and as such do not represent a significant nuclear safety risk which requires immediate action.