Office for Nuclear Regulation

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Planned System Based Inspection at Magnox Ltd.’s Wylfa licensed site, undertaken as part of a series of planned interventions outlined in the ONR Integrated Intervention Strategy Plan Wylfa Power Station 2014/2015

Executive summary

Purpose of intervention

Planned intervention at Magnox Ltd’s Wylfa licensed site. This report covers the nuclear safety related inspection of Wylfa power station undertaken as part of a series of system based inspections deemed necessary to cover safety related systems as outlined in the Wylfa safety case.

Interventions Carried Out by ONR

This inspection bounded planned compliance inspections against the following Licence Conditions (LCs):

Licence Conditions 10, 23, 24, 27, 28 & 34 were covered as the safety system inspection of the Wylfa power station arrangements for the handling of fuel elements during Inter-Reactor Transfer (IRX) operations.

In addition to the inspections identified above a number of liaison meetings were attended to monitor progress with current activities and maintain awareness of any matters of regulatory interest. These included the following topics:

Explanation of Judgement if Safety System Not Judged to be Adequate

On the basis of the inspection, I judge that overall, the IRX fuel route safety provisions, meet the requirements of the safety case and are, on the basis of this inspection, considered adequate.

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

A safety system inspection of the IRX Fuel Route was undertaken as part of the programme of system based inspections included on the Wylfa site intervention plan for 2014/15. The purpose of the inspection was to assess the adequacy of the station arrangements currently in place to ensure that the system safety function is delivered. In deciding if suitable and sufficient measures have indeed been adopted for the safety system, the inspection considered compliance with a number licence conditions. The standard consideration of licence conditions are bounded by LCs 10, 23, 24, 27, 28 & 34.

The system inspection found that the licensee has made arrangements to ensure that the IRX Fuel Route is maintained and operated in accordance with its safety case, and that on the basis of the inspection sample the arrangements are deemed to be implemented in an adequate manner and in some instances to a good standard. Therefore, an inspection rating of 3 (adequate) is assigned in respect of the LCs 27, 28, 34 and an inspection rating of 2 (good standard) in respect of LC 10. For LCs 23 and 24 it is concluded that the fundamental requirements of the safety case are met, however some specific procedural weaknesses were identified and consequently an inspection rating of 4 (below standard) is assigned. It is judged that overall the system meets the requirements of its safety case and is adequate. Alongside of the specific procedural weaknesses, some minor opportunities for improvement were identified in other areas that Magnox Ltd has agreed to address, and ONR will monitor the action it takes during routine inspections at the site.

The inspection found that the Wylfa station has implemented and adhered to appropriate arrangements to ensure that the IRX Fuel Route System is maintained, tested and operated in accordance with its safety case and, on the basis of the inspection sample explored, the arrangements are favourably viewed in terms of adequacy of implementation. As such, I have subsequently assigned an inspection rating as adequate in respect to those LCs inspected.

The various liaison meetings undertaken provided useful updates on matters of regulatory interest and confirmed adequate progress being made by Magnox Ltd in delivering against the topics discussed.

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 information obtained and evidence gathered during this intervention, I do not believe there are any matters identified that have a significant negative effect on the system integrity and there were no issues identified that were considered to adversely affect nuclear safety. It is therefore considered that no further regulatory action arising from this inspection visit is necessary.