This intervention at the Atomic Weapons Establishment (AWE) Aldermaston licensed site was undertaken as part of the 2017/2018 intervention plan and weapons sub-division strategy.
Accompanied by an Office for Nuclear Regulation (ONR) specialist mechanical engineering inspector and a member of the licensee's own Internal Regulation (IR) team - referred to as 'we' in this report - a planned System Based Inspection (SBI) on the oxidation process was conducted in Bay 1 of AWE Aldermaston's Main Production Facility. Through examination of this system we performed compliance inspections against a number of Licence Conditions (LC). The intervention was conducted via meetings with key plant personnel, a visit to the oxidation work stations in Bay 1 and by sampling of relevant plant documentation and records.
From the totality of the evidence we sampled during our inspection and from our discussions with key licensee personnel, we are satisfied that the overall marking for the oxidation SBI is green (see below).
The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.
We communicated our unease that the required DAP interventions on the process are discretionary and had some concerns with respect to resilience planning (which we noted the licensee is starting to address). However, overall we were content that the licensee has adequate training arrangements in place.
The licensee has adequate Operating Rules in place for the oxidation process and has Operating Instructions in place to ensure compliance with these ORs.
From our sampling we were content that the licensee has adequate operating instructions in place for the oxidation process and is compliant with these operating instructions.
We were content that the required Safety Mechanisms Devices and Circuits (SMDC) had been adequately identified by the licensee's safety case and are shown quite clearly on the Safety Case on a Page document displayed on the plant next to the process. We studied maintenance of two of the key SMDCs under LC 28 and found adequate evidence that these are being suitably maintained.
We were satisfied from the records we sampled and the personnel we engaged with that the licensee has adequate maintenance arrangements in place for the oxidation process and is conducting its maintenance to these arrangements. However, we did draw to the licensee's attention that the maintenance records need to provide more information e.g. as to why certain checks have been omitted, marked as N/A etc. We noted that the licensee already has some sampling in place to try to address this observation.
This LC was adequately inspected under a previous SBI on pyrochemistry, which was rated 'Green' and the systems to detect leak and escape are common across the facility boxline. However, we noted that the licensee team responsible for deriving glovebox hold-up resulting from the conduct of the process may merit a separate ONR inspection to study compliance with its own internal procedures.
From the totality of the evidence we sampled, our visit to the oxidation stations on the plant and from our discussions with key licensee personnel, we are satisfied that the oxidation SBI merits an overall marking of Green. A number of pieces of advice for improvement were provided to the licensee but none of these were significant enough to require additional regulatory action or a regulatory Issue.