Office for Nuclear Regulation

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Readiness inspection of the new nitrogen storage and distribution system as part of the planned permissioning activity for the diverse hold-down project

Executive summary

Purpose of intervention

The primary purpose of the intervention was to conduct a readiness inspection of the new diverse hold-down (DHD) system at EDF Energy Nuclear Generation Limited’s (NGL’s) Hinkley Point B (HPB) power station. The aim of the inspection was to obtain evidence to inform the permissioning process that will consider the forthcoming request from the licensee.  The request will be made to the Office for Nuclear Regulation (ONR) to issue Agreement to put the new DHD system into service under the licensee’s arrangements for Licence Condition 22 (modification or experiment on existing plant). The work was carried out in line with the planned intervention programme included in the ONR diverse shutdown system intervention project record.

Interventions Carried Out by ONR

Licence Condition 22 requires the licensee to make and implement adequate arrangements to control any modification or experiment carried out on any part of an existing plant or processes which may affect safety.

I undertook inspection of the new DHD system at HPB and held meetings with appropriate members of the project team; commissioning team; engineering team; and a nuclear safety group engineer. The inspections were based on sampling and obtaining evidence for the implementation of arrangements in place for the new system, that are associated with Licence Condition 22. I focused on the safety case requirements, commissioning, operating rules, operating instructions, plant component maintenance and examination, and operating staff training.

My intervention was a joint inspection with the licensee’s Internal Nuclear Assurance (INA) function.

Explanation of Judgement if Safety System Not Judged to be Adequate

No system inspection was undertaken during this intervention.

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

My inspection was, by intent, undertaken before the new DHD system was put into service and therefore, changes to operating rules, operating instructions and plant component maintenance and examination have not yet been implemented. My inspection therefore sampled the licensee’s progress to date on its implementation of Licence Condition 22 arrangements. I judge that, based on the evidence of the samples taken, the licensee has adequately implemented its arrangements for compliance with Licence Condition 22. 

I identified three minor points that required further clarification. I have asked INA to include these points in its concurrence inspection that it will undertake as part of its due process to provide an independent judgement on supporting putting the new system into service. INA also identified a point that required further clarification which it will include in its concurrence inspection.

I consider that the licensee has effectively implemented a number of measures to improve compliance with Licence Condition 22. These include integrating operations staff into the training, project, testing and commissioning programmes, and liaison with its sister station, Hunterston B which is also installing a similar system.  I identified three minor points that require further clarification. I have therefore assigned an IIS rating of 3, adequate, to this intervention, based on the ONR IIS rating guide.

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

Conclusion of Intervention

From the evidence obtained during my intervention, I am content that sufficient progress is being made in relation to the implementation of the modification under Licence Condition 22 for putting the new DHD system into service. I did not identify any shortfalls that would prevent ONR issuing an Agreement to put the new system into service.

My findings were shared with, and accepted by, the licensee. No new ONR regulatory issues were raised as a result of this inspection.