Office for Nuclear Regulation

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Mechanical engineering pre-outage inspection of LC28 examination, inspection, maintenance and testing

Executive summary

Purpose of intervention

This report records the findings of my intervention visit to Hinkley Point B (HPB) Nuclear Power Station ahead of Reactor 4 (R4), Outage Number 029, (029) 2015 periodic shutdown. The intervention was undertaken to confirm the adequacy of mechanical engineering related activities conducted by the Licensee to comply with the requirements of Licence Condition 28, examination, inspection, maintenance and testing (EIMT) against a sample of nuclear safety significant reactor components in preparations for the periodic shutdown.

Interventions Carried Out by ONR

The intervention consisted of on-site meetings and a plant inspection with relevant staff from EDF Energy, Nuclear Generation (NGL) to determine the adequacy of the work being undertaken on R4 in complying with the requirements of Licence Condition 28. The activities examined were selected due to their nuclear safety significance and included:

The inspection was supported by visits to the following areas:

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

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

From my attendance at operational and outage briefs I am satisfied NGL provide a routine and systematic level of scrutiny to EIMT across the station.  I confirmed day to day operational matters, as well as outage specific matters, are being progressed with the appropriate level of oversight, scrutiny and diligence.

From the review of EIMT of CRA, NGL were able to provide an adequate demonstration from their data that there was no EIMT backlog which may impact their periodic shutdown performance and drop time performance was adequate in achieving their safety case performance assumptions. I was satisfied the EIMT arrangements for CRAs is adequate and in place to support the R4 029 2015 periodic shutdown.

From the review of SACR inspection arrangements, NGL provided an adequate demonstration that SACR drop performance was consistent with the control rod assembly population.  The programme to insert the outstanding SACRs remains in line with commitments given to ONR and the inspection arrangements for the SACR appeared adequate and in place for the R4 029 2015 periodic shutdown.

From the review of GC’s EIMT, 3 GC’s are being prepared for the R4 029 2015 periodic shutdown, 1 GC has all EIMT completed, 2 GC’s remain in overhaul and are therefore incomplete. The GC lubrication oil pump and motor replacement components are not currently available and as such may hinder periodic shutdown plans. The re-barring of rotors appears to be progressing to plan.  The learning from an investigation into a lubrication oil event at Hunterston B has not yet been formally considered by HPB to ensure learning from the event is adopted. I intend undertaking a further intervention to follow up the outstanding EIMT matters for GCs for HPB.

From the inspection of valves EIMT I was satisfied that the steam safety valve was subject to adequate EIMT arrangements generally, but I was unable to confirm the in situ EIMT arrangements for the valve body taking account of known risks [flow assisted corrosion]  within the time available. Similarly I was unable to confirm oversight or verification arrangements for nuclear safety significant valves subject to Trevitest™ and I was unable to confirm the establishment of systematic EIMT arrangements for safety valves, with inconsistency of approach between systems with similar safety classification.  I intend undertaking a further intervention to follow up the findings on EIMT of valves for HPB.

From the plant inspection of EIMT facilities that the control rod assembly maintenance facility was well presented, to a very high level of cleanliness, displayed good standards of housekeeping and foreign material exclusion arrangements. The gas circulator maintenance facility was similarly well controlled with very minor observational improvements noted by the NGL representative, but overall I was satisfied the EIMT facilities inspected are adequate.

Conclusion of Intervention

This report presents the findings of the Mechanical engineering intervention of the LC28 EIMT arrangements in place to support the Hinkley Point B R4 029 2015 periodic shutdown.

After consideration of the findings from the intervention I judge that the LC28 arrangements in place are broadly adequate and I am satisfied they are generally adequately implemented.

As a consequence of my findings, I intend following up with NGL through further intervention matters I was unable to conclude during my visit or which require further investigation.

I have concluded the IIS Rating for LC28 EIMT for this intervention – 3 Adequate. I am satisfied NGL demonstrated broadly an adequate level of LC28 compliance and the improvements and follow up may not be significant.