Office for Nuclear Regulation

Hinkley Point B - Conventional Plant Asset Care

Executive summary

Purpose of Intervention

This inspection forms one of three planned site-based inspections that aim to enable ONR to have confidence that:

And as a result,

Interventions Carried Out by ONR

A team of four inspectors (two site inspectors, an Internal Hazards specialist inspector and a Conventional Health & Safety specialist inspector) examined Hinkley Point B (HPB) Power Station’s arrangements for asset care and operation of high-hazard conventional plant.  The inspection comprised a number of office-based sessions, reviewing the evidence provided and discussing relevant topics with NGL personnel.  A substantial plant tour was also organised, allowing time to examine a number of high-hazard, conventional/process risk areas; oxygen, methane & hydrogen compounds and diesel, carbon dioxide & bulk chemicals storage.

Explanation of Judgement if Safety System Not Judged to be Adequate

No system based inspection was undertaken hence, this is not applicable for this intervention.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

One significant shortfall with respect to relevant good practice (DSEAR zone management) was identified during the plant walk down.  Recently revised DSEAR calculations have resulted in DSEAR zones increasing in size, which means that some DSEAR zones now cover personnel walkways and encompass electrical equipment.  Work is ongoing to address these issues, but the industrial safety risks are significant and need to be addressed with a suitable level of urgency. A regulatory issue has been raised to ensure these improvements are delivered to a suitable timescale.

Also during the walk down a surface defect was identified on the ammonia tank.  Due to the location of the defect it was not possible to determine the level of corrosion. An issue has been raised for the site to confirm the level of corrosion and take any action necessary.

It was also identified during the inspection that the corporate risk assessment and return to service improvements developed following the steam system failure event at Heysham 1 Power Station had only been fully implemented during February 2020, despite the revised requirements having been issued during November 2019.

In line with findings at other stations there are a number of defects that are on AMS which do not appear to be actively managed. There are defects dating back to 2003 and a number of defects remain open, when the safety work has been completed, making it difficult to determine the overall impact and scale of existing defects. We also note that the ‘lifetime’ coding is not used yet at HPB. This would allow defects that are going to be accepted for the lifetime of the facility to be identified, which together with improved close out of defects that have been addressed, would allow a clearer picture of the overall risks from any open defects on systems.
With respect to the COMAH element of the inspection, we were satisfied that Hinkley Point B had met its legal duties.

Two level 4 regulatory issues will be raised to track progress made against the potential shortfalls identified during the inspection:

Conclusion of Intervention

Based on the sample inspected, I rate the inspection as GREEN – no formal action. We considered an amber rating due to the DSEAR issue, however we took account of the short timescale since the issue had been proactively identified by the site and the current work that was in progress to address it.  

The output of this inspection, together with those on the same theme at other stations, will be collated and assessed later in 2020 to give a fleet-wide appraisal.

I believe that no additional regulatory interventions are needed over and above those already planned at Hinkley Point B Power Station; though the scopes of existing inspections may be expanded to revisit some of the topic areas in the future.