Office for Nuclear Regulation

Hunterston B – Inspection ID: 52537

Executive summary

Date(s) of inspection:

  • May 2023

Aim of inspection

The inspection examined the plans for management of the asset during the defuelling phase of operations and beyond.  In particular the approach taken for the retirement of systems no longer required to provide a safety function.

Subject(s) of inspection

  • LC22 – Modification or experiment on existing plant – Rating: Green

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

This intervention was undertaken at the Hunterston B (HNB) power station and consisted of discussions with staff and a review of documentation.

A review of the management of the asset (MoTA) strategy and implementation of identified changes following the move to defuelling operations was undertaken against the EDF Energy corporate arrangements for compliance with Licence Condition (LC) 22 (modifications or experiment on existing plant) .

HNB has undertaken a number of assessments to define the maintenance and management strategy of plant systems throughout the phases of the last years of generation, defuelling and post-defuelling.  A sample of the assessments and associated changes was reviewed and, although the approach taken to implement the identified changes differs slightly from Hinkley Point B, it is still in accordance with the corporate processes required under LC22 (modifications or experiment on existing plant).

As HNB is lead AGR station to undergo defuelling, improvements are often found and implemented and therefore several pieces of advice were given to the station during this intervention to ensure that the rationale for these improvements is appropriately recorded to assist future stations as they move into defuelling.


I was satisfied from the areas sampled that the lifecycle asset management plans and associated engineering changes had been produced, reviewed and approved in accordance with the corporate procedures for compliance with LC22. I therefore judge that the Hunterston B Power Station has adequately implemented the corporate arrangements for LC22 (modifications or experiment on existing plant).  I therefore consider that an inspection rating of Green (no formal action) is merited.