Office for Nuclear Regulation

Hinkley Point C – Inspection ID: 51662

Date(s) of inspection

  • October 2023

Executive summary

Aim of inspection

The aim of the inspection was to sample NNB Generation Company (HPC) Ltd’s (NNB GenCo) commissioning arrangements, including for compliance with Licence Condition (LC) 21 – Commissioning.

Ahead of the “Early Commissioning Hold Point”, NNB GenCo has developed a set of processes and arrangements to safely undertake the commissioning activities up to active commissioning. In addition, NNB GenCo will start commissioning some systems/components ahead of the hold point, such as the polar crane, temporary control room and the electrical boards to allow the commissioning of the auxiliary transformer (TA) (constrained activity associated with the hold point). This inspection took place a few weeks before the start of pre-TA commissioning activities, therefore, the LC21 arrangements related to those activities were expected to be sufficiently mature to provide ONR with the opportunity to test the arrangements and deep dive in some areas.

The objective of this inspection was to sample and test the LC 21 arrangements ahead of those pre-commissioning activities, focusing on the site readiness to conduct the activities and witness the arrangements in the Operations Control Centre (OCC).

Subject(s) of inspection

  • LC21 – Commissioning – Rating: Amber

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

The readiness inspection was carried out over three days at NNB GenCo’s offices (in the Site Delivery Centre) and at the Hinkley Point C (HPC) site. Each day was structured around an agenda allowing discussions with key personnel and sampling of the documentation provided ahead of the meeting.

The inspection team found: shortfalls in NNB GenCo’s processes and arrangements, including significant shortfalls in the health and safety aspects sampled; insufficient evidence; and a lack of clarity on when the identified shortfalls need to be resolved by to allow the commissioning activities.

The key shortfalls found were associated with:

  • Configuration control – there was a lack of clarity around the control of the different types of modifications (configuration open points).
  • Shortfalls were identified in the management of open points from handovers, in particular type B and C open points and how those are considered/managed. There was also a lack of clarity on prioritisation of open points.
  • Graded approach
  • Industrial safety – there was a lack of clarity on how industrial safety may inform/change the test grade. The process implied that industrial safety will be considered for certain grades of systems/components (class 1 and 2).
  • Implementation of a graded approach within the licensee’s processes (for example, surveillance of design, manufacture, install and commission (DMIC) contractors, verification, and open points management). It was unclear how the different grades of a system or a test may determine different aspects of the processes that rely on grading.
  • Surveillance of DMIC contractors
  • The process and guidance did not provide clear expectations for “enhanced” and “baseline” surveillance. It was left to suitably qualified and experienced personnel to decide the range of surveillance within each of the definitions.
  • The process and the documentation required to develop a surveillance plan was unclear.
  • There was a lack of consistency on the approach to DMIC surveillance, including a lack of justification for having different surveillance regimes and documentation.
  • The lack of risk assessments and lack of an approved risk assessment process impacts on the licensee’s ability to demonstrate control and adequate planning of the commissioning activities.
  • Health and safety plan
  • How the activities carried out by DMIC contractors will be controlled from a conventional health and safety perspective was not demonstrated.
  • There were significant gaps on the statements regarding temporary works and working at height.
  • There was a lack of evidence of the reviews performed.
  • There was a lack of clarity on management of site interfaces, in particular, under the Construction (Design and Management) (CDM) regulations duties of a Principal Contractor.
  • Due to the lack of maturity of the licensee’s arrangements, hierarchy of control of the conventional health and safety risks was not demonstrated during the inspection.

A number of observations were also raised which will be tested during follow up inspections.


Shortfalls were found in processes and arrangements associated with: configuration control, implementation of the graded approach, surveillance of DMIC contractors and open point management. NNB GenCo was aware of most of these gaps and was working towards resolving them. In addition, more significant shortfalls were found in the health and safety aspects sampled, which included: the commissioning health and safety plan; the lack of clarity over application of the commissioning health and safety plan to DMIC contractors; lack of risk assessments; lack of demonstration of hierarchy of control and lack of clarity on managing the interfaces on site.

From the evidence presented, ONR concluded that the commissioning arrangements, including for compliance with LC21, sampled during the inspection were immature, and in some areas deficient for the current stage of development of the project, and the inspection was rated amber. This rating has taken into consideration the fact that the commissioning activities have not yet started and there should be time to resolve the shortfalls before commissioning activities start.

A level 3 regulatory issue has been raised that captures the shortfalls identified during the inspection. It is also proposed to carry out a readiness inspection, in particular on the site arrangements, prior to start of significant commissioning activities.