Office for Nuclear Regulation

Pile Fuel Cladding Silo (PFCS) - System Based Inspection of PFCS containment

Executive summary

Purpose of Intervention

The Office for Nuclear Regulation (ONR) undertakes all regulatory interaction with the Sellafield site licensee, Sellafield Limited (SL), against a strategy defined by the ONR Sellafield, Decommissioning, Fuel and Waste Division. In accordance with that strategy, a System Based Inspection (SBI) was carried out on the Pile Fuel Cladding Silo (PFCS).

The purpose of this inspection was for ONR to examine whether the licensee’s safety case claims in respect of PFCS containment have been adequately implemented. The inspection comprised discussions with SL staff, a targeted plant walkdown and a review of plant records and other documentation.

Interventions Carried Out by ONR

ONR’s SBI process examines evidence to determine compliance against six licence conditions (LC). These LC’s, listed below, have been selected in view of their relevance to ensuring nuclear safety and provide a structured approach to determining whether the safety case has been implemented adequately through the system being inspected.

LC 10 requires SL to make and implement adequate arrangements for suitable training for all those on site who have responsibility for any operations which may affect safety.

LC23 requires SL to produce an adequate safety case to demonstrate the safety of its operations, and to identify the conditions and limits necessary in the interests of safety.

LC24 requires SL to ensure that all operations which may affect safety are carried out in accordance with written instructions.

LC27 requires SL to ensure that a plant is not operated, inspected, maintained or tested unless suitable safety mechanisms, devices and circuits are properly connected and in good working order.

LC28 requires SL to make and implement adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety.

LC34 requires SL to ensure, so far as is reasonably practicable, that radioactive material and radioactive waste on the site is at all times adequately controlled or contained so that it cannot leak or otherwise escape from such control or containment.

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

Explanation of Judgement if Safety System Not Judged to be Adequate

This safety system is judged to be adequate.

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

From the evidence sampled, I judged that Sellafield Ltd has adequately implemented the requirements of the safety case for PFCS containment systems, and I was satisfied that the facility understood the importance of these systems in the safety case.   

During the plant walkdown of the newly constructed retrievals area it was observed that there were some minor shortfalls in the labelling of Safety Mechanism, Devices and Circuits (SMDCs). I intend to manage this minor shortfall by raising a Level 4 regulatory issue.

Notwithstanding the minor shortfall identified above, I found LCs 10, 23, 24, 27, 28 and 34 to be adequately implemented in relation to the systems inspected. Consequently, it is my opinion that for this system based inspection a rating of GREEN - No formal action is appropriate for LCs 10, 23, 24, 27, 28 and 34. 

Conclusion of Intervention

From the evidence gathered during this intervention, I do not consider there to be any matters that have the potential to impact significantly on nuclear safety. 

I awarded Green (no formal action) inspection ratings to LC’s 10, 23, 24, 27, 28 and 34 and have raised one Level 4 Regulatory Issue.