Office for Nuclear Regulation

Dungeness B – Inspection ID: 51743

Executive summary

Date(s) of inspection:

  • December 2022

Aim of inspection

In accordance with the Office for Nuclear Regulation’s (ONR’s) Dungeness B (DNB) intervention plan, ONR performs a series of planned compliance inspections of identified licence conditions (LCs) and other applicable legislation, to ensure that DNB is meeting its legal requirements.

LC28 requires that “the licensee shall make and implement adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety.”

The aim of this inspection was to ensure that Dungeness B (DNB) is managing its maintenance activities appropriately and ensuring that required maintenance and any defects are being addressed in a timely and appropriately prioritised manner. This intervention focused on maintenance/work management oversight and management aspects as deep slice sampling of maintenance schedule compliance has been undertaken in pre-defueling outage inspections and system-based inspections.

Subject(s) of inspection

  • LC 28 – Examination, inspection, maintenance and testing – Rating: Amber

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

Whilst DNB has in place appropriate arrangements for maintenance schedule suspension ONR found that some suspensions appeared to be have left in place for an extended period without apparent timely resolution of the original reasons for the suspensions.

Overall DNB has implemented appropriate dashboards and management information which facilitate oversight of maintenance.

Whilst some progress has been made in reducing a number specific defect types, improvements are required to the management/oversight of the stations more significant defects (priority 2 defects).

DNB is appropriately reviewing it systems ongoing requirements/maintenance post generation which should free up maintenance resource availability/capability by removing activities which are no longer required.


I judge that an inspection rating of Amber (seek improvement) is appropriate for LC28.This is because whilst I found that DNB was generally adequately implementing the sampled LC28 arrangements specific improvements were judged to be required in relation to oversight/management of maintenance schedule suspensions and management of the station’s priority 2 (1 being the highest and 4 the lowest) defects. This was however a finely balanced judgement as ONR observed some significant progress being made in relation to the station’s maintenance reviews which should enable further focusing of maintenance capacity to those systems which support defueling. These issues have been added to a new level 3 regulatory issue.