Office for Nuclear Regulation

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Sizewell B - Dry Fuel Store Project - Readiness to Move into Active Commissioning

Executive summary

Purpose of Intervention

This intervention was undertaken to gather evidence to establish whether the EDF Energy Nuclear Generation (NGL) Sizewell B Dry Fuel Store project was ready to move into active commissioning. The evidence informs the Office for Nuclear Regulation’s (ONR) view on the release of an ONR hold-point established through Licence Instrument (LI) 531, issued under Nuclear Site Licence Condition (LC) 21(4): Commissioning, specifying that NGL require ONR’s consent before commencing active commissioning.

Interventions Carried Out by ONR

This intervention built on a series of ONR inspections carried out to monitor the Sizewell B Dry Fuel Store project’s testing and commissioning arrangements for inactive commissioning and for commencing active commissioning. This intervention focussed on Plant, Process and People in confirming:

Explanation of Judgement if Safety System Not Judged to be Adequate

This was not a Safety System Based Inspection.

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

From inspection findings I formed the opinion that the Dry Fuel Store project has complied with its testing and commissioning arrangements. This is based on sampling of equipment and system test reports; Technical Query (TQ) resolution; and implementation of Engineering Change (EC) plant modifications. However, there were still a number of inactive commissioning tasks outstanding and a need to close out ECs before active commissioning could commence.

I consider the Dry Fuel Store safety case has been satisfactorily implemented based on review of station and plant operating instructions, surveillance procedures and close out of OC.

I consider suitable training has been developed and implemented by NGL and its partner organisations based on evidence gathered from inspection of training material and interviewing dry fuel store operational personnel. Based upon responses I consider that a good understanding of the safety case and process requirements has been gained. Deficiencies were however identified in respect of on the job training for abnormal operation which will need to be addressed.. I consider the dry fuel store organisational structure for carrying out dry fuel processing is adequate with the Fuel Route Duly Appointed Person (DAP) responsible for controlling and supervising work. The structure being based upon that used during refuelling outages.

Conclusion of Intervention

The Sizewell B Dry Fuel Store project has made good progress to date in work confirming equipment’s design and safety functional requirements have been met in line with safety case requirements. However, I am unable to recommend commencement of active commissioning until identified work relating to completion of inactive commissioning tests, close out of EC’s and training for abnormal operation is addressed.

A follow-up inspection is not considered necessary as ONR and NGL site-based independent assurance personnel will monitor close out of outstanding work.


I recommend that ONR does not release its hold-point until identified outstanding inactive commissioning requirements have been met.