Date(s) of inspection:
February 2025
Executive summary
Aim of inspection
The aim of this inspection was to confirm that Dungeness B is implementing adequate arrangements to
control any modification or experiment carried out on any part of the existing plant or processes which may affect safety. This included examining the adequacy of categorisation of justifications and confirming that modifications had been divided into stages where appropriate and that the progression from one stage to the next is appropriately controlled.
Subject(s) of inspection
- C 22 - Modification or experiment on existing plant - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
LC22 requires that the licensee shall “make and implement adequate arrangements to control any modification or experiment carried out on any part of the existing plant or processes which may affect safety”.
Findings
From the evidence sampled we noted that:
- DNB has an appropriate process to manage its modifications supported by a suitable software tool.
- DNB is appropriately classifying its modifications with adequate nuclear justifications recorded, with only relatively minor areas for further improvement identified.
- DNB’s governance and oversight of its modification process could be improved as we noted a number of instances where modifications had not been progressed fully to the next next stage although it was recognised that this did not appear to have significantly impacted nuclear safety.
- ONR identified an isolated example where the implementation of a lower safety significance engineering change to a waste sorting cabinet could be improved. Whilst the physical modification had been completed appropriately the associated operation and maintenance documentation had not been updated/implemented effectively.
Conclusion
We identified a number of areas for improvement however overall I am satisfied that a Green rating is appropriate. We were satisfied that Dungeness B is implementing appropriate arrangements for the management of modifications. We have however raised two level 4 regulatory issues to provide appropriate regulatory oversight of the improvement areas identified. One regulatory issue is focussed on further strengthening governance and oversight of engineering changes and one is to capture improvements in relation to the implementation of the waste sorting cabinet engineering change.