Office for Nuclear Regulation

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Hartlepool - System Based Inspection - SBI 09 - Main Electrical System

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake compliance inspection activities at EDF Energy Nuclear Generation Limited's (NGL's) Hartlepool power station in line with the ONR's planned inspection programme contained in the Hartlepool Integrated Intervention Strategy (IIS) for 2016/17.

Interventions Carried Out by ONR

We performed a system based inspection (SBI) to confirm the implementation of safety claims made on the station's main electrical systems. This inspection was undertaken by the ONR site inspector and a specialist electrical engineering inspector. During this intervention we examined the Licence's compliance with the following nuclear site licence conditions (LCs):

The site inspector also made further enquires following two incidents which occurred at Hartlepool in August and were reported to ONR by NGL via the reporting system. We undertook a LC27 compliance inspection to evaluate arrangements to control the return to service of safety systems following maintenance.

The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides, which can be found at in the areas inspected.

Explanation of Judgement if Safety System Not Judged to be Adequate

Following a system based inspection of the main electrical system, we judge that this system adequately fulfils the requirements of the safety case.

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

SBI: Main Electrical System

From the areas targeted and the evidence examined during this inspection, we consider that NGL has implemented adequately those safety case claims that relate to the Hartlepool main electrical system. The inspection identified several areas of good practice including the use of a dedicated station control room simulator to aid the fidelity of training, and the effective use of data analysis tools by the engineering team to prioritise investments in the main electrical system to address ageing and obsolesce.

The inspection also identified some areas of improvements that could be made to the process used to prioritise maintenance effectiveness reviews conducted on safety systems, including review of the Station's 11kV electrical system. The inspection also identified potential improvements to the provision of vehicle protection around a high voltage cable trench. NGL has acknowledged these areas for improvement and raised actions to address them. An ONR regulatory issue has been raised to monitor completion of this work.

During the inspection, damage was noted to a high voltage enclosure. NGL took immediate action to respond to this observation and has subsequently completed repairs to address the issue.

Overall we judged that the arrangements for safe operation of the main electrical system and their implementation generally met relevant good practice and therefore we have given an intervention rating of Green in relation to compliance with LCs 10, 23, 24, 27 and 28.

Incidents on Site

We undertook follow-up enquires to gather information into the circumstances surrounding two incidents whereby NGL identified it had failed to meet plant availability requirements set-out in the Station's technical specifications. I am satisfied that NGL responded appropriately and promptly to these incidents and is applying its continuous improvement processes to identify corrective actions. I judge that the safety significance of the incidents is low and no additional regulatory action is considered necessary over and above the planned interventions set out in the IIS for Hartlepool Power Station.

LC27 - Return to service of safety systems

This intervention involved the review of documentation and a series of interviews with operations staff with responsibility for activities designed to verify the functionality and alignment of safety systems following completion of maintenance. We found that the station has developed detailed and systematic procedures for prestart-up alignment checks under the overall control of duly authorised persons. These processes are routinely subject to audit with the goal of driving continuous improvement. We judged that some improvements could enhance the clarity of the return to service arrangements with the station's management system. This finding was accepted by the license and an ONR regulatory issue has been raised to monitor the licensee's response.

Conclusion of Intervention

From the evidence gathered during these inspections, it was judged that there were no matters that have the potential to impact significantly on nuclear safety.

At present, no additional regulatory action is needed over and above the planned interventions of Hartlepool power station as set out in the IIS, which will continue as planned.