Office for Nuclear Regulation

Compliance inspection of Licence Condition 21 (Commissioning)

Executive summary

Purpose of Intervention

The Office for Nuclear Regulation (ONR) undertakes all regulatory interventions with Rolls Royce Submarines Limited (RRSL) against a strategy defined by the ONR Propulsion Sub-Division. In accordance with that strategy, a Licence Conditions (LC) compliance inspection was undertaken on the Dreadnought Production Facility (DPF) Wet Side, as planned, on 23rd and 24th March 2021. 

RRSL are currently preparing to enter inactive commissioning on the DPF Wet Side. The inactive commissioning will involve the use of acids and dummy fuel (with no fissile material content). As such this stage will introduce conventional hazards, but not radiological hazards.

The purpose of the intervention was to consider the adequacy of RRSL’s arrangements for compliance with LC21 (Commissioning) and to inspect the implementation of those arrangements at the DPF. The findings of the intervention will also inform ONR’s future permissioning decision on RRSL’s readiness to safely implement active commissioning of the DPF Wet Side, currently anticipated to be late 2021.

Interventions Carried Out by ONR

The intervention focussed on the people, plant, and process that RRSL has in place to comply with its LC21 arrangements and was undertaken via targeted discussions with licensee staff, sampled review of relevant documents and facility inspection.

The original intention was for this inspection to be conducted with one ONR Inspector on site and the others connecting remotely via RRSL’s teleconference systems. This would have provided the benefit of face to face discussions and facility inspection whilst also balancing the risk associated with travel to site during the ongoing COVID-19 pandemic. Due to illness on the day however, no ONR presence on site was possible. The facility walkdown was therefore undertaken by the Internal Regulator, with findings briefed to the ONR inspection team.

The intervention was undertaken and rated against published guidance on ONR’s expectations, as described in the Technical Inspection Guides (TIGs), which can be found at Specifically, this included NS-INSP-GD-021 Rev 7 and ONR-INSP-GD-064 Rev 5.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable. This was not a system-based inspection and so no judgement was made in this regard.  

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

Based on the evidence sampled at the time of the intervention, I consider RRSL adequately demonstrated that:

I found that the local controls in place for the DPF Wet Side project are broadly in line with my expectations informed by NS-INSP-GD-021. The controls implemented on the project go above and beyond RRSL’s extant arrangements for LC21 compliance, against which shortfalls when compared to Relevant Good Practice were observed. The inspection found no shortfalls which, in my opinion, have the potential to challenge nuclear safety at this stage of the DPF Wet Side project. However, the following observations, which I expect to be remedied prior to the commencement of active commissioning, were noted:

RRSL acknowledges that it is having to supplement its overarching LC21 arrangements with local arrangements to maintain control of commissioning activities and deliver commissioning goals. RRSL further recognises that an overview of how the various elements link together to achieve compliance with regulatory expectations is missing. RRSL therefore intends to update the Core Design and Manufacture (CDM) Commissioning Strategy and supporting documents with learning from DPF and ensure that identified improvements are captured for future commissioning activities across the site. No formal scope or plan for implementing identified improvements has been developed to date however, and so it is not currently clear how this will be managed by RRSL. I am therefore raising a regulatory issue to ensure that necessary improvements are secured in a timely manner.

My judgement that local control of commissioning activities appeared to be adequate for the current commissioning activities is supported by the Internal Regulator’s observations, resulting from the facility walkdown.

Conclusion of Intervention

Based on the findings of the intervention, I consider that RRSL has adequately implemented local arrangements for the control of the current stage of commissioning in the DPF Wet Side. However, I have observed shortfalls against my expectations, informed by NS-INSP-GD-021 with regards to the overarching arrangements for compliance with Licence Conditions 21. Nevertheless, given that:

I do not consider these shortfalls to be significant in the delivery of nuclear safety at this stage of the project. Work is required by the licensee however, prior to demonstrating readiness for active commissioning of the facility. Further ONR interventions are therefore planned during the inactive commissioning phase, to inform the permissioning of active commissioning.

I therefore judge, noting the ONR guidance on inspection ratings in ONR-INSP-GD-064, that an inspection rating of Green (no formal action required) is merited for this Licence Condition. I will however be raising a Level 4 Regulatory Issue to ensure that the overarching arrangements are updated to reflect the good practice demonstrated in the local controls sampled, and capture learning on the Wet Side project for the wider site.