Office for Nuclear Regulation

Atomic Weapons Establishment Aldermaston – Inspection ID: 52734

Date(s) of inspection

  • November 2023

Executive summary

Aim of inspection

To assess:

  1.  the effectiveness of AWE’s strategy for the management of maintenance of safety significant Structures, Systems and Components (SSCs) in response to the reduced capacity and capability of SQEP maintenance resource, and
  2.  the implementation of that strategy across the key operational areas across both sites to demonstrate compliance against the requirements of LC28 and the regulatory expectations defined within ONR’s NS-INSP-GD-028 (Version 8.1).

Subject(s) of inspection

  • LC28 – Examination, inspection, maintenance and testing – Rating: Green

Key findings, inspector’s opinions and reasons for judgement made

This inspection at Atomic Weapon’s Establishment (AWE) Explosive Technology Centre (XTC) was undertaken as part of a programme of planned inspections across a number of AWE facilities for 2023/24. The scope of the intervention was aligned to the ONR/ AWE Strategy and was to judge the adequacy of AWE’s implementation of its arrangements made under Licence Condition (LC) 28 with a focus on the management of maintenance backlogs.

I, a Mechanical Engineering Specialist Inspector for the ONR Weapon’s programme, undertook a Licence Condition 28 (Examination, Inspection, Maintenance and Testing (EIMT)) inspection at the XTC facility on the AWE Aldermaston site, I was supported by the ONR XTC Site Inspector; an ONR Mechanical Engineering Specialist Inspector; and an Inspector from the Nuclear Internal Hazards and Site Safety specialism.  The inspection focussed on seeking assurance that AWE is:

  • managing any maintenance backlog;
  • assigning adequate SQEP resource to EIMT activities;
  • able to justify the deferral of any maintenance; and
  • managing stores effectively and ensuring that SSC labelling is fit for purpose.

I reviewed the management arrangements for LC28 and was able to establish the “golden thread” in the management system for this Licence Condition.

I sampled the evidence for maintenance backlogs; staff capacity and capability for undertaking EIMT; the deferral process for not undertaking maintenance; and SSC labelling.  It is my opinion that the procedures and controls evidenced by AWE demonstrated that Relevant Good Practice had been observed and that whilst there were minor shortfalls in EIMT capacity and capability, AWE was following its own procedures and that the requirements of LC28 had been satisfied.  AWE presented a clear auditable trail for all of the areas sampled and demonstrated good control of documents, records and certifications.

In my opinion, the Licensee’s arrangements for compliance with LC28 are adequate.  I, therefore, conclude that this inspection identified no matters that may impact significantly on nuclear safety and, noting the ONR guidance on inspection ratings, that an inspection rating of GREEN (no formal action required) is merited for this licence condition inspected


The inspection sought to sample certain areas associated with LC28.  These were: EIMT backlogs; staff capacity and capability; the process of deferring EIMT; storage facilities and SSC labelling.  These will be considered individually based on the evidence presented:

EIMT backlogs.  Evidence was presented that showed up-to-date backlog information.  Whilst there was a backlog, which comprised mostly of breakdowns, it was not a significant percentage of the total AWE backlog.  Neither was it a significant percentage of the assets requiring EIMT within the facility.  There was, however, an increasing trend of backlog jobs predicted (see later re capacity); whilst this was increasing, it was still a relatively low number.  AWE was able to show that the backlog was well understood and being managed appropriately.  On balance I was satisfied that the EIMT backlog in XTC was not a concern.

Staff capacity and capability.  I noted that potential improvements in EIMT capability (as a result of ‘Project Glasgow’), specifically, the introduction of a Principal Maintenance & Reliability Engineer had not yet been fully realised – the PM&RE had recently resigned.  In addition, the cadre of existing maintenance engineers was lower than planned and significant overtime was necessary in order to keep on top of EIMT.  IR-52730 had identified that EIMT capacity was a known corporate issue and Regulatory Issue 11175 exists to cover wider ‘capacity and capability’ across the whole site.  Whilst the sampling of capability did not highlight any issues, the AWE software did not have sufficient detail to provide firm evidence of training details – advice was given in this area.  On balance, I was not satisfied with XTC EIMT capacity and capability,  XTC  had some work to do to both embed the M&RE role and recruit standard maintenance engineers, I have raised a L4 regulatory issue to cover both the shortfall in the maintenance baseline and the loss of PM&RE capability.

EIMT deferral.  XTC followed corporate arrangements to defer maintenance by use of the ACR process.  The process was sampled for 1 item and found to be adequate.  I also sampled the management loading of ACRs and was content that managers were not over-loaded.  I was therefore satisfied that the EIMT deferral process was adequate within XTC.

Storage facilities.  XTC was developing 3 different storage facilities, which would cover PPE, breakdown equipment and critical spares and would be an example of good practice once completed.  I was therefore satisfied with XTC stores.

SSC labelling.  Labelling under the use of the AMS was checked during the walkdown and, with minor exceptions, was found to be adequate.  I was therefore satisfied with XTC labelling.
I judge that overall there were no significant concerns with EIMT backlog; the use of the EIMT deferral process; and the labelling of SSCs.  I also judge that whilst there was a minor shortfall in EIMT capacity and capability, this was not currently causing significant delays in EIMT.  I therefore rate this inspection as Green.