Office for Nuclear Regulation

Heysham 1 – Inspection ID: 52602

Executive summary

Date(s) of inspection:

May 2023

Aim of inspection

This was a planned inspection of EDF Energy Nuclear Generation Ltd.’s (NGL’s) Heysham 1 Power Station, undertaken as part of the planned intervention strategy for the Operating Facilities Division (OFD) of the Office for Nuclear Regulation (ONR). The work was carried out in accordance with the planned inspection programme contained in the Heysham 1 Integrated Intervention Strategy (IIS) for 2023/24.

Subject(s) of inspection

  • LC 10 – Training – Rating: GREEN
  • LC 23 – Operating rules – Rating: GREEN
  • LC 24 – Operating instructions – Rating: GREEN
  • LC 27 – Safety mechanisms, devices and circuits – Rating: GREEN
  • LC 28 – Examination, inspection, maintenance and testing – Rating: GREEN
  • LC 34 – Leakage and escape of radioactive material and radioactive waste – Rating: GREEN
  • Overall Inspection Rating – Rating: GREEN

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

This Systems Based Inspection comprised discussions with EDF staff, review of records, and observations on plant.
This inspection was undertaken by ONR Mechanical Engineering and an ONR Control and Instrumentation Specialists. The current and replacement nominated Site Inspectors were also present for many of the inspection activities.

Plant Walkdown:

Overall, we judged the housekeeping within the locations we visited and the condition of the equipment we inspected to be of appropriate standard. A small number of shortfalls were identified, which the dutyholder acknowledged and committed to address.

LC10, Training:

We examined the training records of personnel associated with the oversight and maintenance of essential cooling water and pressure vessel cooling water equipment sampled throughout the inspection and found that all had completed the necessary training for their roles.

We reviewed the system handover documents for the essential cooling water and pressure vessel cooling water systems which were considered informative, however it appeared these were not being maintained as ‘living’ documents and several key topics and sources of information were not included. We raised these observations with the system engineers who accepted them.

LC23 Operating Rules:

We examined the Living Safety Case Documents relevant to the essential cooling water and pressure vessel cooling water systems. These identified the key safety significant components of the systems, together with identifying those considered to provide the highest safety significance. It was confirmed that the living safety case identified limits and conditions in the interest of safety and identified the relevant Technical Specifications ensuring these were appropriately met.

The means for ensuring compliance with the Technical Specifications is detailed in the ‘schedule of compliance methods for Heysham 1 technical specifications’ (also referred to as schedule 41) and that signing for the central control room supervisors log was the means of confirming that the surveillances had been undertaken. However, upon reviewing both documents we noted that surveillances were not all identified in the central control room supervisors log and not referenced in schedule 41. The reactor desk engineer stated that this was an oversight and amended the central control room supervisors log before we completed the inspection and took an action to amend schedule 41.

LC24 Operating Instructions:

We sampled several Site Operating, Plant Operating and Maintenance Instructions, which we judged to be clear and unambiguous. They clearly described how tasks should be carried out and contained the necessary prerequisites, checks, precautions and actions to be taken in the interest of safety.

LC27 Safety Mechanisms, Devises and Circuits:

We had previously (as part of our LC23 inspections activities) discussed the process for demonstrating how technical specifications surveillances were undertaken, and considered this partly demonstrated that safety mechanisms, devices and circuits important to safety were properly connected and in good working order. Our activities during the LC28 portion of this systems based inspection completed this element of the inspection regarding the demonstration that equipment important to safety is in and remains in good working order.

We discussed how work on the essential cooling water and pressure vessel cooling water systems is controlled, such that maintenance work on, emergency cooling water and pressure vessel cooling water equipment is strictly controlled to maintain plant configuration.

Sustainability of configuration was assured through availability of sufficient spares and sustained through additional availability of spares through Hartlepool (Heysham 1 sister station) if needed.

We stated we considered the proactive obsolescence management system tool to be useful and asked if this was being utilised. The Reactor Systems Group Head acknowledged that the use of the proactive obsolescence management system tool had waned due the end of generation originally scheduled for 2024; but were now looking to reinvigorate its use following the announcement to extend generating life.

LC28 Examination, Inspection, Maintenance and Testing:

We reviewed a sample of maintenance working instructions, associated work order cards and checksheets. We considered that the associated maintenance tasks had been adequately defined and had been carried out as specified.

We also checked the sampled maintenance activities had been undertaken in line with the periodicity specified in the maintenance schedule and found that they had. However, we did note a number of shortfalls:

  • pass / fail’ tolerances were not stated on several of the working instructions and / or checksheets
  • acceptance criteria in the format ‘X ± Y’ or ‘X ± Y%’ can introduce mental calculation errors
  • Use of ambiguous language
  • A missing figure
  • ‘Circle and slash’ place-keeping practice had not been employed

The system engineers took an action to review our findings and address them as appropriate.
Also, in relation to the above, we recommended that maintenance technicians should be encouraged to highlight shortfalls when using working instructions and checksheets and submit them for revision. In response the Maintenance Group Head informed us that they had instigated a series of briefs to do so, which we welcomed.

We reviewed a sample of plant walkdown reports and based on the information presented we were content that the plant was being inspected on a regular basis. However, we noted that these did not include C&I participation. Given the large C&I content of the systems, we considered undertaking plant walkdowns with a C&I specialist would be beneficial and therefore recommended that cross-functional plant walkdowns of each system are undertaken, in response the dutyholder committed to give due consideration to this recommendation.

LC34 Leakage and Escape of Radioactive Material and Radioactive Waste:

The pressure vessel cooling water system is sampled on a monthly basis, it was explained that although no radioactive leaks were likely from the essential cooling water system, sampling was undertaken as a conservative measure. Results of these measures were provided in an annual report.

In addition to this LC34 element of our inspection, due cognisance was taken of a recent ONR LC34 inspection, which had concluded that HY1 was judged compliant against LC34 and met the required standard and a green rating (No formal action) given.


Based on the evidence sampled during this SBI, I judge that the licensee has adequately implemented the basic elements of the essential cooling and pressure vessel cooling water systems safety case, fulfilling its safety functional requirements. Taking due cognisance of ONR’s inspection rating guidance, it is my opinion that an inspection rating of Green (no formal action) is merited.