Office for Nuclear Regulation

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Compliance inspections at Sizewell B power station

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at EDF Energy Nuclear Generation Ltd's (NGL's) Sizewell B power station, in line with the planned inspection programme of the Operating Facilities Operating Reactors sub-programme intervention plan for 2017/18.

Interventions Carried Out by ONR

During this intervention, I the nominated site inspector was supported by two ONR specialist inspectors and an ONR civil nuclear security inspector. We undertook planned compliance inspections against the following license conditions:

Also during this intervention we:

Explanation of Judgement if Safety System Not Judged to be Adequate

No system inspection was undertaken during this intervention.

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

In relation to LC 14, we made the following observations:

In relation to LC 23, we made the following observations:

I, the nominated site inspector undertook follow up enquiries the station's response to a number of lifting events that occurred during Reactor Outage 14 (May 2016), the two most significant of which:

During my follow up enquiries I identified several findings in the areas of procedural use and adherence control and supervision.

Lifting incidents that occurred during RO14 shared common themes in relation to shortfalls in procedural quality (inadequate definition of risk); setting to work of contract staff through the command chain and supervision. Known standards and expectations were not met by those involved and in certain instances left unnoticed or unchallenged by line or field supervision.

Investigations into individual lifting incidents did not effectively address or probe key human performance aspects of that gave rise to the shortfalls in standards and expectations of individual contractor staff and their immediate supervisors. Subsequent work undertaken by the station human performance lead, prompted by INA, resulted in a more critical and holistic evaluation; this has resulted in corrective actions and enhancements that are more likely to address the common shortfalls.

There has been a substantial effort from and considerable resources expended by the station, Areva and Doosan Babcock to ensure lessons are learned in readiness for the 2017 RO15 refuelling outage. Progress towards closure of corrective actions has been slower than anticipated but I am satisfied that the oversight from INA has exerted (and continues to) appropriate pressure and conscience on the station ahead of the shutdown on 3rd November.

There appears to have been weaknesses in the command chain exemplified by EDF investment delivery instructing the Tier 2 contractor to return to work (without setting to work through the Tier 1 contractor). This appears to have manifested as unintended but avoidable exertion of time pressure on the Tier 2 contractor

The investigations allude to questionable judgements from individual contractor staff (and direct supervisors) and a poor reporting culture that fell considerably short of normally high standards of nuclear professionalism prevalent on the station. The investigations do not explore to any real depth the underlying reasons behind this nor indeed the possible extent of condition.

There was insufficient consideration within the investigations of EDF's own shortfalls in control and supervision of work being undertaken through the contractor supply chain. There is much emphasis on the field supervisor framework for ensuring effective supervision; this is understandable given that field supervisors are subject to rigorous authorization which ONR has previously recognised during specialist interventions on other stations and corporately. In my opinion there are inconsistencies in the extent to which the station, as the site licence holder oversaw the quality and consistency with which field supervisors discharge their responsibilities, particularly in more complex contractor interfaces.

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

We consider that, based on the evidence acquired during this intervention, that an inspection rating of Green is appropriate for both LC 14 and LC 23.

We consider that, based on the evidence acquired during this intervention, that an inspection rating of Green is appropriate for LC 11.

I have reviewed the RO14 incidents against ONR's criteria for formal investigation and consider that on this occasion this is not required. In reaching this decision, due consideration has been given to the outcome of the Enforcement Management Model (EMM). I am further satisfied that the station's own Independent Nuclear Assurance team is continuing to exert significant internal regulatory oversight into the planning of the RO15 periodic shutdown planned for 3rd November 2017.

Through ONR's application of the EMM, a letter is to be issued to Doosan Babcock and to the licensee EDF Energy NGL identifying ONR's findings and the expectations each duty holder in order to secure compliance and prevent recurrence.