Office for Nuclear Regulation

Hinkley Point C - Earthing System Installation

Executive summary

Purpose of Intervention

In accordance with the Office for Nuclear Regulation’s (ONR’s) Hinkley Point C Construction inspection plan, ONR performs a series of planned compliance inspections of identified licence conditions, to ensure that NNB Generation Company (HPC) Ltd (NNB GenCo), is proportionately and adequately developing and implementing its licence compliance arrangements commensurate to the current stage of the project.

This intervention included routine licence condition inspection at Hinkley Point C carried out to assess NNB GenCo’s compliance with licence condition 19; Construction or installation of new plant.

Interventions Carried Out by ONR

LC19 requires that “Where the licensee proposes to construct or install any new plant which may affect safety the licensee shall make and implement adequate arrangements to control the construction or installation.”  The focus of this LC19 intervention was the adequacy of NNB GenCo’s processes for managing the installation of the earthing system utilising the following guidance:

Explanation of Judgement if Safety System Not Judged to be Adequate

N/A as this was not a safety systems inspection.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

NNB GenCo and its key tier one contractor provided a clear demonstration of how they manage the earthing system from design through installation, inspection and test whilst ensuring the design and safety case requirements are complied with.

NNB GenCo provided the evidence to show it has appropriate controls in place to manage design changes and that these design changes are appropriately considered and approved prior to implementation.

ONR observed that NNB GenCo and its contractors have implemented a robust system for testing, recording of test results, inspection and surveillance activities for the earthing system installation. 

NNB GenCo staff and its tier one and tier two contractors demonstrated that they had good knowledge and understanding of the processes and procedures used in the installation, testing and surveillance activities employed for implementation of the earthing system. They also demonstrated their understanding and management of non-conformances.

The contents of the surveillance guidelines did not adequately align with the surveillance requirements applied to the deep-earthing system installation methods.  NNB GenCo agreed to implement appropriate improvement strategies to manage this issue.

Conclusion of Intervention

I judge that overall an inspection rating of GREEN (No formal action) is appropriate for licence condition 19; Construction or installation of new plant. This is because I found NNB GenCo to be compliant with its legal duties with only minor areas for further improvement which I have raised as a level 4 regulatory issue to ensure appropriate regulatory oversight of NNB GenCo’s improvements in this area.