Office for Nuclear Regulation

This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

Sizewell B Power Station - Licence Condition Compliance Inspection of LC22 and Information Gathering Meetings

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake licence condition (LC) compliance inspections at EDF Energy Nuclear Generation Limited (NGL) Sizewell B power station, in line with the inspection programme contained in the Sizewell B integrated intervention strategy (IIS) for 2016/17.

Interventions Carried Out by ONR

As part of this intervention, I carried out a compliance inspection against licence conditions LC 22: Modification or experiment on existing plant to inspect the implementation of the arrangements supporting the modification upgrade being conducted on the existing Pond Fuel Handling Machine (PFHM) located within the Fuel Storage Building. This inspection was conducted in support of ONR's permissioning of the consent for Dry Fuel Store (DFS) active commissioning. The inspection included a review of the Engineering Change (EC) safety case proposal, the EC due process including verification and approval, a plant walk down of the installation work and a review of the implementation documents and records. The inspection was based on sampling the implementation of the arrangements in place at the station against the licence condition and ONR inspection guidance. I also attended a number of information exchange meetings with Station personnel during this visit.

Explanation of Judgement if Safety System Not Judged to be Adequate

No safety system inspection was undertaken, hence this is not applicable.

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

The PFHM upgrade has been developed following a series of reviews which had identified shortfalls in protection. The upgrade involves a complete control and protection system replacement to reduce risk to As Low As Reasonably Practicable (ALARP). The opportunity to introduce enhancements to operability, functionality and relevant modern standards has also been incorporated in the upgrade.

From my sample of the safety case/ EC I judged this to be sufficiently detailed in setting out the claims, arguments and supporting evidence. The system design is in accordance with NGL company standard CTS214 and is supported with reliability and dependability reports. The Design Substantiation Report is a working document and NGL took an action to substantiate the compliance statements where they are currently only partially met.

The EC is judged to have had an appropriate level of independent verification and assessment including presentation to the Sizewell B Nuclear Safety Operational Review Committee. From my plant walk down I observed the installation work as being well controlled and supervised with appropriate supporting method statements and witnessing/ sign off. To fulfil a commitment to ONR, NGL took an action to address EMC/ RFI testing on installed equipment during the site acceptance testing. The implementation of the modification is progressing to a detailed programme which includes associated documentation updates.

In summary, the upgrade of the PFHM has provided a comprehensive Hazard & Interlock schedule, with a modern standard design that should address the protection shortfalls, improve diagnostics, provide engineered facilities and enhance operation and maintenance. The arrangements in place to comply with LC 22 are in line with ONR guidance and the findings of this intervention support ONR's decision on granting consent for active commissioning of the DFS. I have rated this inspection as Green.

The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.

Conclusion of Intervention

From the information gathered and evidence obtained during this intervention, no matters have been identified that are likely to have significant impact on nuclear safety on the station at this time. Therefore I consider that no additional regulatory action arising from this visit is necessary currently, and the interventions for Sizewell B power station, set out in the integrated intervention strategy, should continue to be implemented as planned.