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Licence Conditions 23 and 24 compliance inspection

  • Site: Hunterston B
  • IR number: 21-049
  • Date: June/July 2021
  • LC numbers: 23, 24

Executive summary

Purpose of Intervention

This was a planned Licence Condition (LC) Compliance Inspection on the fuel route at EDF Energy Nuclear Generation Limited’s (NGL) Hunterston B (HNB) Power Station in preparation for end-of-generation (EoG), in line the Operational Facilities Division (OFD) Intervention Strategy for 2020-21.

Interventions Carried Out by Office for Nuclear Regulation (ONR)

The inspection considered compliance with regulatory expectations for LC 23 Operating Rules and LC 24 Operating Instructions.  Specifically, it sought assurance NGL would have a suite of Operating Rules and Operating Instructions broadly meeting regulatory expectations when it expects to commence de-fuelling activities (currently scheduled for January 2022).

This inspection focused on the HNB back-end fuel route; from the removal of irradiated nuclear fuel from the reactor through to preparation for dispatch off-site.  This inspection considered activities involving the charge machine (CM), the irradiated fuel dismantling facility, the pond and the flask handling areas.

The visit was also used to undertake an assessment of the adequacy of NGL’s arrangements for compliance with COVID-19 social distancing and other health protection measures, and the implementation of these measures on site.

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

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable.

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

The inspection found NGL’s extant re-fuelling arrangements form a sound foundation on which de-fuel arrangements can be developed.

The inspection found NGL could clearly articulate: the limits and conditions (LACs) identified in de-fuelling safety cases; how they were derived; why they are important to nuclear safety; and how they are set so as to maintain margins to safety limits.  Sampling demonstrated NGL has implemented suitable and sufficient management arrangements and operating instructions to ensure compliance with extant re-fuelling LACs.  Operating instructions contained some good practices which are captured in HNB’s topic related guidance.

The plant walkdown demonstrated that compliance with proposed de-fuelling LACs is technical achievable and operators understand their role maintaining compliance with extant LACs and the actions to be taken if a breach is detected.  Equipment providing alarms and indications was observed to be in good condition.  A number of new panels were observed which appeared clearly and logically laid out and compliant with good human factors practice.

I found a suite of interrelated operating instructions are used during extant re-fuelling activities and challenged NGL whether they could be simplified to minimise risk of human error.  NGL accepted its instructions appear complex, as multiple documents are used simultaneously, but argued the format is informed by many years operating experience (OPEX) from successful re-fuel campaigns.  I inspected a suite of instructions used during a recent campaign and found expectations for procedure use and adherence (PU&A) were met.

A small number of shortfalls were observed in the documents and equipment inspected, none of which are considered sufficiently significant to challenge the delivery of safety functions.  I received assurance from NGL that such matters will be resolved via HNB’s preparations for de-fuelling.

I welcomed NGL’s commitment to review and, where necessary, update the full suite of the operating instructions which support de-fuelling.  I found that NGL understands which documents require review and demonstrated progress made to deliver on this commitment.  During the on-site inspection, NGL could not provide a formal programme of work with delivery timescales.  I could not therefore assure myself that suitable and sufficient resources were available to update all identified documents, and complete due process, in-line with the current de-fuel schedule.  NGL assert that it will not proceed until necessary work is complete and I note the quality plan identifies hold points for this purpose. I also acknowledge that compliance with the extant shutdown case should manage nuclear risk in the interim.  Given the stated timescales, I was concerned that individuals may feel under pressure (real or perceived) to shortcut due process to achieve the January 2022 date.  I was subsequently provided an implementation programme, with defined dates for delivery of work packages, including operational documentation, required to support de-fuelling.  Whilst this is not a guarantee of delivery, the programme provides a defined baseline against which progress can be monitored and informed decisions made as to when it is appropriate to commence de-fuel.

NGL’s COVID-19 arrangements were judged to compliant with government guidance in relation to working safely during the pandemic in factories, plants and warehouses.  The arrangements were judged as effectively implemented.

Conclusion of Intervention

The inspection provided a valuable insight into NGL’s preparations for the de-fuelling of HNB which will inform my subsequent assessment of these activities.  No shortfalls or issues were found which significantly affect nuclear safety or were judged to be of such regulatory concern as to require immediate action. 

Overall, NGL’s implementation of its arrangements for LC 23 and LC 24, in relation to extant re-fuelling operations, was judged to be broadly in-line with regulatory expectations.  A GREEN (no formal action) rating was assigned against each LC.  The inspection found NGL’s extant re-fuelling arrangements form a sound foundation on which de-fuel procedures can be developed and progress is being made to update them.  Progress to date, and the forward work programme, indicates how NGL intends to achieve commencement of de-fuelling in January 2022.  This programme appears challenging and NGL must maintain oversight of time and resource to ensure dates are met and robust due process, in-line with its arrangements, is applied.  ONR should consider mirroring this oversight to ensure its expectations are met in a timely manner.