Office for Nuclear Regulation

Sizewell B – Inspection ID: 52014

Executive summary

Date(s) of inspection:

  • February 2023

Aim of inspection

The purpose of this intervention was to support my assessment of the Sizewell B Cycle 19 reload safety case (a modification implemented through EDF Energy Nuclear Generation Limited (EDF NGL)’s License Condition (LC) 22 arrangements) by verifying that new fuel and rod cluster control assembly (RCCA) receipt inspections have been undertaken in compliance with the EDF NGL’s arrangements.

EDF uses the reload safety case to justify the safe operation of the reactor for the period of operation approximately 18 months following Refuelling Outage 18. An assumption of the reload safety case is that all fuel assemblies and core components planned to be loaded in the core are operable. For new fuel and RCCAs, receipt inspections are undertaken in addition to vendor quality assurance activities, to confirm the components have no visible defects, are free of foreign material and are therefore considered operable.

My assessment of the Cycle 19 reload safety case (AR-01042) recommended that a successful outcome from this intervention should be a precursor to ONR providing Consent for the restart of the Sizewell B reactor following Refuelling Outage 18 (permissioning decision PR-01033).

Subject(s) of inspection

  • LC 22 – Modification or experiment on existing plant – rating: Green

Key findings, inspector’s opinions and reasons for judgement made

Informed by guidance in NS-INSP-GD-022 (ONR’s technical inspection guide for LC 22 – modification or experiment on existing plant), I set out to verify by sampling that fuel and RCCA receipt inspections for Refuelling Outage (RO) 18 had been undertaken in accordance with approved procedures, by suitably qualified and experienced personnel (SQEP), and that appropriate records were in place. Where any unexpected or abnormal observations were made during the inspections, I looked for evidence of conservative decision-making. I also looked for evidence that appropriate records of fuel vendor quality assurance activities had been received and stored. The inspection included a plant walkdown to view the inspection location and equipment. I focused primarily on the fuel inspections due to the greater potential consequences of minor visible defects on the fuel being unobserved.

I sampled the quality plans used by EDF NGL to control the fuel and RCCA receipt operations and inspections for RO 18. I sampled the station operating instruction (SOI) used by operators during fuel receipt and inspection, as well as the plant operating instruction (POI) checklists used to record completion of detailed activities. I also sampled completed fuel inspection checklists authored by EDF NGL and by Framatome, the fuel vendor. I was satisfied that fuel and RCCA receipt operations and inspections were conducted for RO 18 in accordance with approved procedures and that adequate records of this are in place.

I viewed the slides from two of the associated training briefs that had been given to EDF NGL operators. I sampled classroom and on-the-job training records for a fuel route engineer who had signed off a number of fuel inspections and confirmed in-date accreditation for the fuel route duly authorised person (DAP) who had signed some of the quality plan documentation. I was satisfied that EDF NGL staff had been adequately briefed and there were adequate records to show they were SQEP.

I found a shortfall in evidence that EDF NGL had checked that Framatome staff contributing to the inspections were SQEP. EDF NGL have identified an improvement and set an appropriate internal Action Request to address this shortfall within the fuel receipt arrangements for future cycles. I do not consider the shortfall found for RO 18 to be significant enough to warrant an ‘amber’ rating for this intervention, because the fuel inspections were led by EDF NGL staff for whom suitable records exist. The improvement action identified is straightforward and I judge that raising a new Regulatory Issue to track this would not be proportionate.

EDF NGL made a single significant observation during the inspections for RO 18, when a clump of swarf was found attached to the bottom nozzle of a fuel assembly. EDF NGL explained to me the steps taken to remove the swarf and confirm that the fuel then met inspection criteria, which included consultation between the fuel route engineer present and fuel vendor staff. I sampled guidance provided to EDF NGL operators in the relevant visual inspection standard and judged that the steps taken were compliant with this guidance. I noted that Framatome have conducted an investigation as to how this clump of swarf was present on the fuel, which will be discussed further as part of normal business in nuclear fuel supply and strategy (NFSS) Level 4 meetings.

I observed that records of fuel vendor quality assurance activities are in place for the fuel delivered for RO 18.

I undertook a walkdown of the fuel building to observe the locations and equipment used for both fuel and RCCA inspections. Those for the fuel had changed for RO 18. I was satisfied that they allowed for a close inspection of 100% of the outside surface as required by the inspection checklist, and that measures were in place to ensure that maximum lift heights were not compromised due to the change of inspection location.

Overall, informed by guidance in NS-INSP-GD-022, I judge that EDF NGL adequately implemented its arrangements for new fuel receipt and inspection for Sizewell B RO 18.


My inspection found that EDF NGL has adequately implemented its arrangements for new fuel and RCCA receipt and inspection at Sizewell B Power Station ahead of RO 18. This is necessary to support implementation of the Cycle 19 reload safety case, a modification under LC 22. As a result of my findings, I have rated this inspection Green. (No formal action).

AR-01042 recommended that the ONR Project Inspector (for PR-01033) provide Consent for EDF NGL to proceed with the restart of the Sizewell B reactor following RO 18, subject to two things, one of which was a successful outcome from this inspection. I judge that this need has now been met.