Office for Nuclear Regulation

Atomic Weapons Establishment Aldermaston – Inspection ID: 50461

Executive summary

Date(s) of inspection:

  • February 2023

Aim of inspection

The aim of this joint intervention is to ensure the AWE Plc has fit-for-purpose arrangements for decommissioning, including post-operational close out (POCO), and confirm compliance with licence condition (LC) 35 (Decommissioning) and environmental permit QB3535DR within the Legacy Production Facility (A**).

The inspection is focussed on progress with the strategy and plans for POCO in the facility prior to handover for decommissioning, including for the management and disposal of radioactive waste.

Subject(s) of inspection

  • LC 35 – Decommissioning – Rating: Green

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

The Office for Nuclear Regulation (ONR) undertakes all regulatory interactions with the Aldermaston site licensee (AWE plc) against a strategy defined by the ONR Weapons sub-Division. In accordance with that strategy, a planned Licence Condition (LC) 35 (Decommissioning) compliance inspection was carried out in AWE’s Legacy Production Facility. The inspection focussed on plans and preparation for undertaking Post-Operational Clean Out (POCO) in the facility.

The intervention was undertaken jointly with the Environment Agency and comprised discussions with AWE staff and a review of records and documents relevant to compliance with LC 35. AWE staff were well prepared for the inspection and engaged in an open and honest way regarding the challenges faced in preparing the facility for POCO with the added complexity of continuing limited operations whilst maintaining safety standards in this ageing facility.

Overall, I consider that the dutyholder has generally met regulatory expectations with respect to planning and preparations for POCO when considering the challenges faced by a legacy facility undertaking concurrent workstreams and I welcome the early work on low-hazard activities. However, I have identified the following areas where further work is required to meet regulatory expectations, which will give confidence that the POCO end state will be achieved; progress to address these will be tracked through the regulatory issues process:

  • There is no overarching strategy, plan or programme for POCO activities that reflects enabling activities or interdependencies with other facilities
  • The POCO end state document does not clearly identify the full scope of POCO activities
  • There is no characterisation plan to support POCO activities and handover to Decommissioning
  • Knowledge has not been retained from operational staff prior to their departure from the facility.


On the basis of the evidence sampled at the time of the inspection, I judged that the licensee has made progress in implementing its arrangements for POCO in compliance with LC 35 (Decommissioning). I consider that an inspection rating of Green (no further action) is merited in respect of LC 35 for the facility.