Office for Nuclear Regulation

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Site inspection - Wylfa

Executive summary

Purpose of intervention

The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Wylfa (WYA) site licensee, Magnox Limited, against a strategy defined by ONR's Sellafield, Decommissioning, Fuels and Waste Programme.

In accordance with that strategy, a system based inspection (SBI) of the WYA System 4.3 Heating and Ventilation (H&V) was planned and undertaken in July 2016. The purpose of this inspection is for ONR to examine whether the licensee's safety case claims in respect of this system important to safety have been adequately implemented.

This report also includes interventions in pursuit of the ONR integrated intervention strategy for Wylfa, in particular to address regulatory issues identified as part of the Inspection plan and carry out other planned Compliance inspections.

Interventions Carried Out by ONR

This report covers interventions undertaken at WYA. The SBI is undertaken against the following Licence Conditions (LCs): including a SBI for System 4.3 H&V, as follows:-

In addition to the inspections a number of liaison meetings were attended. These included the following topics:

Explanation of Judgement if Safety System Not Judged to be Adequate

The SBI for System 4.3 H&V mechanical engineering identified that the system should be judged to be implemented adequately and in accordance with the requirements of the safety cases.

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

From the SBI on the H&V system we concluded that:

Overall, we concluded that the arrangements and their implementation on the H&V system from a mechanical engineering perspective met the requirements of the safety case and were deemed to be adequate taking in to account minor improvements identified through the course of the inspection.

Event WYL-001455, 'Pile Cap Lead Coffin' relates to the inadequate management of radioactive waste from the maintenance of fuelling machine 2 at Wylfa. The issue was identified during a previous planned inspection by the Site Inspector.

Only the Compliance inspections and follow-up inspections are included in the executive summary as all other interventions are for information only. In conjunction with the ONR Site Inspector, an ONR Radiation Protection Inspector undertook a reactive inspection into this event. The Senior RPA at Wylfa provided significant additional detail, documentation and information into this event including a written response to the follow up questions provided in advance of the inspection. Given the overall positive discussions, inspection and additional information provided by the Senior RPA, the judgement of the ONR Inspectors is that no further enforcement action should be undertaken for this event so long as an adequate Root Cause Investigation is produced, by Magnox Ltd, with smart objectives to address the identified learning and issues.

This inspection against Licence Condition 11 focussed on aspects of the Magnox Ltd arrangements for capturing learning from the emergency exercise and training programmes undertaken across Magnox Ltd and the wider nuclear industry. Magnox Ltd demonstrated compliance with legal duties, no significant shortfalls have been identified and no formal action is required in response to this inspection. Consequently, an inspection rating of Green is assigned.

Conclusion of Intervention

There were no findings from this inspection that could significantly undermine nuclear safety. At present, no additional regulatory action is needed over and above the planned interventions at WYA. I award an inspection rating of GREEN (adequate) for the SBI for System 4.3 H&V from a mechanical engineering perspective based on the inspection findings.