Office for Nuclear Regulation

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AWE Aldermaston - SBI Inspection

Executive summary

Purpose of Intervention

This intervention, conducted at the Atomic Weapons Establishment (AWE) Aldermaston licensed site, was undertaken as part of the 2017/18 intervention plan and weapons sub-division strategy.

Interventions Carried Out by ONR

During the Office for Nuclear Regulation's (ONR) December 2017 site inspection week I attended routine briefing meetings with key licensee personnel, to discuss the licensee's progress with important safety related projects within the two AWE inspection portfolios for which I am the ONR site inspector.

Additionally, supported by an ONR criticality safety assessment specialist, I conducted a planned criticality System Based Inspection (SBI) in the A** Legacy Facility on the Aldermaston Site. Through examination of the licensee's criticality safety arrangements (i.e. the system under consideration) we performed compliance inspections against a number of Licence Conditions (LC).

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

From the totality of the evidence we sampled during our inspection, a plant visit and from our discussions with key licensee personnel, we are satisfied that the overall marking for the criticality systems based inspection (SBI) is GREEN.

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

In the case of all the routine meetings I conducted with key licensee personnel, only one matter was identified as requiring regulatory attention i.e. ongoing lack of visibility of the licensee's project and timescales to deliver improvements across the active ventilation system in the Main Production Facility. Accordingly, I intend to raise a Regulatory Issue and will re-engage with the licensee on completion of its Periodic Review of Safety (PRS2) optioneering work on the ventilation system circa March 2018.

Conduct of the criticality SBI was via examination of licensee documentation and records, discussions with key plant personnel and by inspection of the relevant plant area(s). The key findings against each LC are recorded below:

LC 10 - (Training) - GREEN

We sampled the licensee's criticality safety training arrangements for workers in the A** Legacy Facility and found that an adequate training structure was in place, with clear evidence that a training matrix was being maintained to ensure staff were trained as required and were subjected to appropriate and timely refresher training.

LC 23 - (Operating Rules) - GREEN

From sampling of the licensee's safety case documentation we were able to see clear linkage between the safety case analysis work and the Operating Rules (OR). We were also able to follow the implementation of these ORs on the plant, within the Operating Instructions and/or Criticality Clearance Certificates.

LC 24 - (Operating Instructions) - GREEN

We sampled a number of Operating Instructions relating to fissile moves in the A** facility and found these to be of an acceptable quality, with the fissile material mass limits defined by the Operating Rules clearly visible.

LC 27 - (Safety Mechanisms, Devices and Circuits - SMDC) - N/A

No SMDCs related to criticality safety have been specified by the licensee and hence we were not able to sample against this Licence Condition in this inspection.

LC 28 - (Examination, Inspection, Maintenance and Testing - EIMT) - GREEN

We sampled the maintenance instructions and records for two pieces of equipment relevant to the maintenance of criticality safety and these were found to be in order.

LC 34 - (Leakage and Escape of Radioactive Material and Radioactive Waste) - GREEN

Leakage of fissile material from its normal process locations has a potential to lead to accumulation of material, which in a worst-case scenario could achieve geometry conducive to the occurrence of criticality. Accordingly, we sampled the potential for accumulations of fissile material due to material leakage from historic operations in the A** facility and judged that the licensee has appropriate risk registers in place, has characterised any fissile material holdings and is routinely ensuring that no new locations are present where fissile material could have accumulated.

Conclusion of Intervention

In the case of all the routine meetings I held during December 2017 Inspection Week, in the two inspection portfolios for which I am the ONR Site Inspector, only one matter was identified as requiring regulatory attention i.e. the ongoing lack of visibility of the licensee's project and timescales to deliver improvements across the active ventilation system in the Main Production Facility. I will raise a Regulatory Issue to capture and manage my concerns in this area and will continue to engage with the licensee on this project.

For the criticality Systems Based Inspection, conducted in the licensee's A** Legacy Facility, from the totality of the evidence we sampled we rated this inspection as Green.