Site inspection - Wylfa
- Site: Wylfa
- IR number: 16-058
- Date: July 2016
- LC numbers: 10, 23, 24, 27, 28, 34
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:-
- LC 10 Training - requires WYA to make and implement adequate arrangements for suitable training of those who have responsibility for any operations that may affect safety.
- LC 23 Operating Rules - requires WYA to produce adequate safety cases to demonstrate the safety of its operations, and to identify and implement operating conditions and limits necessary in the interests of safety.
- LC 24 Operating Instructions - requires WYA to make and implement adequate arrangements for the provision of suitable written instructions for undertaking any operation that may affect safety.
- LC 27 Safety Mechanisms, Devices and Circuits - requires WYA to ensure that, before a system is operated, inspected, maintained or tested, all safety mechanisms, devices and circuits are properly connected and in good working order.
- LC 28 Examination, Inspection, Maintenance and Testing - requires WYA to make and implement adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety.
- LC 34 Leakage and Escape of Radioactive Material and Radioactive Waste - requires WYA to ensure that its radioactive material and radioactive waste is at all times adequately controlled and contained, and that no leak or escape of that material or waste can take place without being detected.
- LC's 10, 23, 24, 27, 28 and 34 were covered as the SBI of the WYA power station arrangements for System 4.3 H&V mechanical engineering focused on the shielded facility ventilation system and R1/R2 Annulus heating and ventilation systems.
- A compliance inspection against Licence Condition 11 - Emergency Arrangements was also undertaken.
In addition to the inspections a number of liaison meetings were attended. These included the following topics:
- Chapelcross System 4.4 Lifting and Handling SBI Briefing
- Review of ONR's outstanding Regulatory Issues regarding WYA
- Further enquiries into the WYA pile cap 'lead coffin' incident
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:
- LC 10 (Training) - Examination of training and SQEP records for a sample of the personnel involved in the maintenance of the H&V Systems confirmed for records identified the essential training requirements for each role profile with all essential training in date. We therefore assigned an IIS rating of Green (adequate) for this inspection.
- LC 23 (Operating Rules) - We found no licensee approved Operating Rules that were applicable to the H&V Systems. However, high reliability of these systems is important to provide pressure differentials in maintaining control and containment of radioactive materials and radioactive contamination. As such we targeted the limits and conditions of operations associated with the H&V systems and confirmed monitoring and adherence with them. We therefore assigned an IIS rating of Green (adequate) to this inspection.
- LC 24 (Operating Instructions) - We targeted routine checks undertaken by plant operators of the two H&V systems being sampled and confirmed the instructions were in place and being followed. We assigned an IIS rating of Green (adequate) to this inspection.
- LC 27 (Safety Mechanisms, Devices and Circuits) - We targeted design records, system performance and calibration of measurement equipment. Whilst confirming broadly compliant arrangements were in place, minor improvements were necessary which WYA confirmed through the course of the inspection. We therefore assigned an IIS rating of Green (adequate) to this inspection.
- LC 28 (Examination, Inspection, Maintenance and Testing) - We targeted a site inspection of H&V systems, examination of records in support of HEPA filter management arrangements and system health reporting. Whilst confirming broadly compliant arrangements were in place, minor improvements were necessary which WYA confirmed through the course of the inspection were to be put in place. We assigned an IIS rating of Green (adequate) to this inspection.
- LC 34 (Leakage and Escape of Radioactive Material and Radioactive Waste) - We targeted control of contaminated materials, change room housekeeping, entry and egress from radiation controlled areas, recent events and general observations of SSCs providing radiation containment confirming broadly compliant arrangements were in place with only minor improvements necessary which WYA committed to undertake. We assigned an IIS rating of Green (adequate) to this inspection.
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.