Office for Nuclear Regulation

Hunterston B – Inspection ID: 51005

Executive summary

  • Inspection date(s): September 2022

Aim of inspection

Inspection activities to focus on station’s compliance with the arrangements established in accordance with Licence Condition (LC) 22. The inspection activities will consider aspects of the arrangements established for the implementation of engineering change (EC) 36921. This EC justifies the delivery the work and benefits identified for the physical changes and isolations including management of redundant cabling as the station moves into defueling. At HNB both reactors have reached the end of their generating life and will be shut down. Following the completion of pre-defueling outages, defueling activities will commence to remove all nuclear fuel from both reactors. As this defueling phase progresses a number of systems will either cease to be required and removed from service (retired) or will be retained and partially reconfigured and optimised to support defueling activities. This inspection will focus on providing ONR with regulatory confidence in the implementation the arrangements established for the HNB defueling lifecycle phase through EC 36921.

Subject(s) of inspection

  • LC22 – Modification or experiment on existing plant – Rating – Green

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

The inspection activities undertaken at Hunterston B (HNB) focused on the station’s compliance with the arrangements established in accordance with Licence Condition (LC) 22. The inspection activities considered aspects of the arrangements established for the implementation of engineering change (EC) 369231. The aim of the inspection was to provide ONR with regulatory confidence in the implementation of the arrangements established for the HNB defueling lifecycle phase when a number of systems across the station will either cease to be required and removed from service or will be retained and partially reconfigured and optimised, through the EC. The inspection focused on the changes being implemented on electrical engineering structures, systems and components (SSCs) through the EC.
In addition, the inspection focused on a specific outcome from recent ONR interventions at Hinkley Point B (HPB) and Dungeness B (DNB) and the implementation of Institution of Engineering and Technology (IET) publication BS7671 Requirements for electrical installations and technical guidance note (TGN) 064, safety of fixed low voltage equipment.

From the sample inspected:
  1. EDF Energy NGL adequately demonstrated the implementation of the arrangements established for EC 369231, including the inspection and observation of electrical engineering SSCs across the station that are no longer required and have been removed from service and that are being retained, partially reconfigured and optimised. In addition, EDF Energy NGL adequately demonstrated an auditable trail of documentary evidence, a ‘golden thread’, of two plant configuration changes from the safety case through all relevant documentation to its physical change, in accordance with licence condition 22.
  2. During the inspection EDF Energy NGL advised that they were unable to adequately demonstrate that electrical testing the of lighting and small power (L&SP) installations had been undertaken within the HNB main reactor building in accordance with Institution of Engineering and Technology (IET) publication BS7671 Requirements for electrical installations and the guidance within the EDF Energy NGL technical guidance note (TGN) 064, and therefore demonstrate compliance with the Electricity at Work Regulations 1989. A regulatory issue (RI-11016) to address any shortfalls in compliance with the Electricity at Work Regulations 1989 and the Health and Safety at Work Act has already been raised due to similar findings at HPB and DNB (IR-51964 and IIS 51741 refer). Regulatory issue (RI-11016) has been amended to reflect the emergent findings at HNB and the rest of the fleet of reactor stations.

Conclusion

On the basis of the evidence sampled at the time of the inspection, I judge that EDF Energy NGL has adequately implemented its arrangements for licence condition 22 at HNB. Noting ONR guidance on inspection ratings, it is my opinion that an inspection rating of GREEN, no formal action required is merited here.
Notwithstanding this, during the inspection EDF Energy NGL advised that they were unable to adequately demonstrate that electrical testing of L&SP installations had been undertaken within the HNB main reactor building in accordance with IET publication BS7671 Requirements for electrical installations and the guidance within the EDF Energy NGL TGN 064, and therefore demonstrate compliance with the Electricity at Work Regulations 1989. 
As a result of the compliance shortfalls confirmed, I amended regulatory issue (RI-11016) in order to address any shortfalls in compliance with the Electricity at Work Regulations 1989 and the Health and Safety at Work Act at HNB, HPB (IR-51964 refers), DNB (IIS-51741 refers) and the fleet of reactor stations due to similar findings.