Office for Nuclear Regulation

AWE Aldermaston - LC27 and LC28 Inspections  

Executive summary

Purpose of Intervention

This intervention, conducted at the Atomic Weapons Establishment (AWE) Aldermaston licensed site, was undertaken as part of the 2018/19 intervention plan and weapons sub-division strategy.

Interventions Carried Out by ONR

We completed an inspection within Decommissioning covering Licence Condition 27 (Safety Mechanisms, Devices & Circuits) and Licence Condition 28 (Examination, Inspection, Maintenance & Testing).  This inspection was supported by an ONR specialist inspector in mechanical engineering.  We met with the licensee’s personnel and reviewed the safety case claims and maintenance arrangements for the High Efficiency Particulate Air (HEPA) filters.

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 was not a systems inspection.

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

LC 27 (Safety Mechanisms Devices and Circuits - SMDC) - Rating = Amber

SMDCs were difficult to identify through specific designation in the safety case and associated instructions, based on the evidence we sampled.  We judged that this did not meet relevant good practice and rated LC27 as Amber with respect to the HEPA filters in Decommissioning.

LC 28 (Examination, Inspection, Maintenance and Testing - EIMT) - Rating = Amber

We considered the maintenance being applied to the HEPA filters in decommissioning fell below Relevant Good Practice.  However, we noted that as there are no decommissioning operations currently being undertaken the level of challenge on the filters from routine operations is low.  As a result of these shortfalls we rated LC 28 as Amber.

Conclusion of Intervention

From the evidence we sampled, including a plant walk-down and our interactions with key licensee personnel, we judged that a rating of Amber was appropriate for both licence conditions 27 and 28.