Office for Nuclear Regulation

Hartlepool – Inspection ID: 52717

Executive summary

Date(s) of inspection:

  • June 2023

Aim of inspection

Inspections are an essential element of ONR’s interventions on nuclear licensed sites.

The overarching aim of this inspection was to gather evidence to support closure of RI-11069.

Subject(s) of inspection

  • LC22 – Modification or experiment on existing plant – Rating: Amber
  • Overall Inspection Rating – Rating: Amber

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

The UK experienced high extreme ambient temperatures (EAT) in July 2022. EDF NGL operating stations EAT design bases were challenged, including Hartlepool (HRA). ONR raised level 3 Regulatory Issue (RI)-11069 to ensure an adequate EDF NGL response to EAT shortfalls. This inspection was undertaken at HRA to gather evidence of EDF NGL’s arrangements for EAT and to support closure of RI-11069.

The HRA EAT justification for continued operation (JCO) was not approved at the time of this inspection. ONR inspected EDF NGL’s temporary EAT arrangements, draft arrangements that will be implemented following JCO approval and seasonal readiness work. This covered aspects of various relevant licence conditions including LC24, Operating Instructions and LC28, Examination, inspection, maintenance and testing. The JCO was expected to be implemented imminently. Therefore compliance the LCs was not rated, but advice and guidance was provided by ONR inspectors in relation to these aspects during the inspection, and will be formally communicated by letter. EDF NGL is expected to use this feedback to enhance its EAT arrangements. In addition compliance with the following licence conditions was assessed:
LC22, Modification or experiment on existing plant – to ensure EDF NGL has adequate arrangements for modifying the plant and safety case in relation to EAT.

The following observations were made:

  • Inadequately conceived and executed deployment of portable air conditioning units (PACUs). This included non-adherence with the original equipment manufacturer’s instructions and inadequate risk assessment.
  • Gaps in EAT arrangements including:
  • External ambient temperature monitoring is not aligned with RGP. ONR advised EDF NGL to review its arrangements. Corporate guidance should be provided to ensure a consistent fleet approach.
  • Clarity and scope can be further enhanced. For example, thermal shock of C&I systems is not considered.
  • The link between seasonal readiness and EAT nuclear safety impacts is not established. This was manifest by missed opportunities to repair HVAC defects during summer readiness campaign. Seasonal readiness prepares the plant to withstand potential EAT events. ONR expects EDF NGL’s arrangements to establish links between seasonal readiness and nuclear safety.
  • The timescales for implementation of reasonably practicable measures to improve resilience of plant against EAT effects are inappropriate. ONR expects EDF NGL to accelerate the timescales for implementation of measures that will improve plant resilience.
  • ONR considers the shortfalls with deployment of PACUs to not be compliant with LC22 requirements. This has been awarded an AMBER rating. The L3 RI-11603 has been raised for HRA to review the adequacy of its arrangements for deployment of PACUs, and temporary modifications.
  • ONR has provided regulatory advice to EDF NGL with respect to the other observations relevant to EAT. This is recorded in this IR, and will be formally communicated to EDF NGL via letter. A follow-up inspection will be undertaken at HRA later this year. The purpose of this activity will be to assess compliance of EDF NGL’s arrangements once the JCO is implemented, and to ensure ONR’s advice has been progressed to enhance EDF NGL’s EAT arrangements


This inspection is awarded an overall Amber rating. This is based on the Amber rating awarded to LC22, for inadequately conceived and executed modification of plant with respect to PACU deployment. The shortfalls in PACU deployment are judged significant including non-compliance with OEM instructions. The L3 RI-11603 has been raised for EDF NGL to review the adequacy of its arrangements.

The JCO was not approved at the time of this inspection, although it was expected to be approved imminently. For this reason, compliance with other applicable LCs was not rated. However, ONR has provided advice to EDF NGL in relation to observations made during this inspection. These observations are relevant to other LCs. The advice is recorded in this IR, and will be formally communicated to EDF NGL via letter. ONR expects EDF NGL to use this advice to enhance its EAT arrangements. A follow-up inspection will take place following approval of the EAT JCO and implementation of updated arrangements. This inspection will take place in 2023 and provide opportunity for ONR to ensure HRA has acted on the provided regulatory advice.