Office for Nuclear Regulation

Heysham 2 – Inspection ID: 52339

Executive summary

Date(s) of inspection:

  • April 2023

Aim of inspection

This inspection is aimed at modifications made to plant and operations on the power station and how those modifications are controlled, authorised and implemented. This inspection will cover the arrangements and implementation for plant modifications and operational decision making.

Subject(s) of inspection

  • LC22 – Modification or experiment on existing plant – Rating: Green
  • LC26 – Control and supervision of operations – Rating: Green

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

This inspection looked at a range of NGL arrangements for controlling changes that fall under the scope of LC22 – Modification or experiment on existing plant. LC1 defines modifications as any alteration to buildings, plants, operations, processes or safety cases and includes any replacement, refurbishment or repairs to existing buildings, plants or processes and alterations to the design of plants during the period of construction. The inspection was based around NS-INSP-GD-022 (available on the ONR website) but also included arrangements of how operations deal with minor operational changes and receive technical advice.


NGL’s primary means of controlling modifications is through its EC process. The EC process is governed by fleet arrangements that are implemented locally through a Management Control Procedure. In general, these arrangements are robust and the health of this process is overseen by the Operational Safety Review Committee (OSRC). An issue was identified in relation to the lack of ECs to assess recent changes to the plant release information management system tool (PRISM) this will be tracked by ONR’s regulatory issue system.

Defeats of Interlocks (DOIs) are controlled on the fuel route via a control arrangement outside the EC process, there have been recent improvements to the oversight of the DOIs in the ponds area and I am satisfied that there is an ongoing programme to reduce the number of DOIs in this area.

Small changes to plant operations are implemented via changes to Station Operating Instructions (SOIs), Technical Advice Notes (TANs) or Temporary Operating Instructions (TOIs). These changes are subject to appropriate review and QA depending upon there significant using a graded approach. Plant issues are considered via availability assessments (Interim IAA or Full FAA) and Operational Decision Making (ODM) procedures. These procedures appear to be effective.

Overall, no significant issues were identified, so a rating of Green (meaning no significant issues) has been given against LC22 – Modifications & experiments on existing plant and LC26 – Control and supervision.