Executive summary
Date(s) of inspection:
April 2025
Aim of inspection
The purpose of the inspection is to gain confidence that the licensee, NNB Generation Company (HPC) Limited (NNB GenCo), has sufficient oversight of its contractor, MTU, for the manufacture and test of the Ultimate Diesel Generator (UDG), through adequate implementation of its Licence Condition (LC) 12, 17 and 19 compliance arrangements. The inspection will include discussions with the licensee NNB GenCo, MTU managers and workers, observation of factory acceptance testing, and a sample review of documentation.
ONR selected the UDG due to its importance to nuclear safety as the UDG are required to supply the Station’s Emergency Power Supply System (EPSS) during a Station black Out (SBO) in the event of a Emergency Diesel Generators (EDG) (class 1) system failure.
LC12 (Duly authorised persons and other suitably qualified and experienced persons) requires a licensee to ensure that anyone carrying out work that may affect nuclear safety on the site is a suitably qualified and experienced person (SQEP). This includes all of the supply chain of the site and, where appropriate, off-site work by contractors and vendors, wherever in the world they happen to be.
LC17 (Management systems) requires a licensee’s quality management arrangements to robustly encompass all work carried out for the site, including by contractors - whether as an on-site contractor or as a vendor of products and services.
LC19 (Construction of New Plant) requires a licensee during the construction of any new plant which may affect safety shall make and implement adequate arrangements to control the construction.
Subject(s) of inspection
- LC12 - Duly authorised and other suitably qualified and experienced persons - Rating: Amber
- LC17 - Management systems - Rating: Amber
- LC19 - Construction or installation of new plant - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
This inspection was undertaken against license condition (LC) 12 (Suitably Qualified and Experienced Persons), LC 17 (Management Systems), and LC 19 (Construction or Installation of New Plant).
The inspection is rated Amber overall. One Level 3 Regulatory Issue (RI-12650) was raised concerning Intelligent Customer capability under LC 17 (and associated LC 12), and one Level 4 Regulatory Issue (RI-12641) was raised concerning the delayed engine start anomaly under LC 19.
Most factory acceptance test (FAT) activities were conducted satisfactorily, apart from concerns around governance and oversight, which represent a significant shortfall in LC 17 expectations. This shortfall reduces regulatory confidence in the licensee’s implementation of its Intelligent Customer role and SQEP assurance, justifying the Amber rating.
Conclusion
Overall Judgement:
- LC 12: Amber
- LC 17: Amber
- LC 19: Green
Overall Inspection Rating: Amber
The Amber outcome reflects a significant governance shortfall in LC 17 and linked concerns in LC 12 and LC 19.