Office for Nuclear Regulation

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Planned interventions carried out as part of the regulation of the Atomic Weapons Establishment

Executive summary

Purpose of intervention

This report covers planned interventions carried out as part of the regulation of the Atomic Weapons Establishment. Planned Compliance Inspections form part of the identified intervention programmes of work specified in the Integrated Intervention Strategy and Major Projects Intervention Plan for the ONR Weapons Sub-Programme.

Interventions Carried Out by ONR

I attended AWE’s Burghfield site to undertake Compliance Inspections on the Mensa project in relation to Licence Condition (LC) 19 (Construction or installation of new plant), LC20 (Modification to design of plant under construction) and LC21 (Commissioning). Also reported here are meetings to discuss opportunities for Flexible Permissioning on Mensa and Mensa programmes of work identified during safety case generation.

Explanation of Judgement if Safety System Not Judged to be Adequate


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

Mensa demonstrated that they have good control of their activities under LC19 and LC20. However, there is room for improvement in recording actions and implementing site preservation measures. On balance I judge that an adequate IIS rating is appropriate for both Licence Conditions.

AWE’s processes under LC21 for the Mensa project appear to be well embedded with a competent team responsible for delivery. However, as found during the LC19/20 inspection, control of actions could be improved, especially as the project’s activities under LC21 ramp-up. On balance I believe that an adequate IIS rating is appropriate.

It is my judgement that the nuclear criteria stated within AWE’s Arrangements for asset change control need to be reviewed regarding thresholds stated for each of the four change categories. Specifically the lowest consequence thresholds appear to be at odds with ONR’s Safety Assessment Principles (SAPs).

I consider that AWE needs to focus on procedural compliance and generation of right-first-time safety cases to enable Flexible Permissioning on the Mensa project.

Conclusion of Intervention

Mensa delivery against the requirements of LCs 19, 20 and 21 was demonstrated as being adequate.

In my opinion, AWE needs to review the nuclear criteria specified in the asset change control Arrangements for compliance against the ONR SAPs.