Office for Nuclear Regulation

Hunterston B – Inspection ID: 52538

Executive summary

Date(s) of inspection:

  • August 2023

Aim of inspection

The purpose of this inspection is to test the adequacy of EDF Nuclear Generation Ltd (NGL’s) application of its Licence Condition (LC) 36 management of organisational change (MOC) arrangements to the changes planned in the Operations department at Hunterston B (HNB) in Q4/2023.  As part of the organisational changes taking place during defueling at the station, NGL plans to make reductions in the Operations department once the first reactor (R3) is fuel free.  These are enabled by reductions in workload at this point (e.g. retirement of operational routines once R3 is defueled) and planned changes to the emergency scheme (mainly removal of one of the two Reactor Desk Engineer roles).  Specifically the changes planned to take place at the station comprise a reduction of:

  • 11 Shift operations engineers
  • 5 Generation team operations technicians
  • 5 Fuel team operations technicians
  • 1 Day Operations Services Engineer
  • 1 Chemistry Engineer
  • 1 Chemistry Technician

The actual headcount reduction will be less than this as some staff are being redeployed at the station or being retained for resilience purposes.  ONR has placed a regulatory hold point on these changes which it will release via a flexible permissioning approach, specifically enhanced implementation monitoring and control followed by issue of a letter of no objection.  This inspection supports release of this regulatory hold point.  The changes to the emergency scheme are subject to ONR reapproval of the HNB on-site emergency plan under Licence Condition 11.  The release of the regulatory hold point will not take place until ONR is content with the changes from both a workload reduction and emergency arrangements perspective.

Subject(s) of inspection

  • LC36 – Organisational capability – Rating: Green

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

We were satisfied that, from a workload reduction perspective, NGL has made adequate justification for the planned reductions in staff after the first reactor at HNB has been defueled.  The reduction in the numbers of Shift Operations Engineers and Generation Team Operations Technicians, as well as the changes in the Day Operations Services and Chemistry teams, are linked to retirement of plant and associated operational routines.  The station provided the analysis of redundant tasks, and associated hours, which supports these reductions.  Furthermore it will undertake a period of shadow working for the Shift Operations Engineers and Generation Team Operations Technicians, to confirm the reductions, and has suitable contingencies in place.

From an emergency scheme perspective we were not satisfied that NGL has fully justified the removal of one of the two Reactor Desk Engineer positions.  While the station was able to demonstrate a reduction in the risks of a nuclear emergency, and increased timescales to respond, it had not linked this to a reduction in the tasks of the Reactor Desk Engineer.  The documentation for the change also did not clearly link the proposed changes to the pre-requisite engineering changes.  We have raised a regulatory issue at Level 4 for the station to provide this additional justification.

Finally we advised the station to ensure that it has sufficient contingency, should the re-approval by ONR of its emergency plan be delayed, to ensure that that it maintains sufficient staff to resource its current emergency arrangements.


I was satisfied overall that the station has adequately implemented its Licence Condition 36 arrangements for the organisational changes planned to take place in the Operations department once the first reactor (R3) at the station is defueled.  I identified a shortfall in the justification for the emergency scheme changes which I will follow-up via a Level 4 regulatory issue.  I have rated the station’s compliance with Licence Condition 36 as ‘Green’ (no formal action).