Office for Nuclear Regulation

Pile Fuel Storage Pond (PFSP) Drum Filling Plant (DFP) Inactive Safety Commissioning Readiness Inspection at the Nuvia Works Test Facility

Executive summary

Purpose of intervention

Decommissioning of the PFSP requires removal of the entire radioactive inventory, including the sludge that has accumulated within the pond and bays.  The sludge will be pumped as slurry from the PFSP via a pipe bridge to the Local Sludge Treatment Plant (LSTP), where it will settle before the supernate is decanted back to the pond.  The sludge will then be pumped from the LSTP via a pipe bridge to the adjacent Drum Filling Plant (DFP).  The DFP will provide the facility for transferring sludge into drums for onward transfer to the Waste Encapsulation Plant.

Inactive safety commissioning of the DFP is subject to a regulatory hold point in the form of an engagement window.  The purpose of this intervention was to undertake a readiness inspection in support of our permissioning decision.  Applicable ONR guidance, including the Safety Assessment Principles, was used as relevant good practice to inform our judgement.

Interventions Carried Out by ONR

The inspection took place on 25 March 2015 at the Nuvia works test facility at NIS in Chorley.  The ONR Project Inspector was supported by control and instrumentation, radiation protection, fault studies, human factors and process engineering Specialist Inspectors.

Explanation of Judgement if Safety System Not Judged to be Adequate

This was not a system based inspection.

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

At the time of the inspection, the project was in its first week of off-site training.  When this is completed the DFP will be transported to, and constructed on the Sellafield site.  This will be followed by on-site inactive safety commissioning.  The evidence presented during the inspection supports our judgement that the licensee has a suitable and sufficient plan in place to prove the design of the DFP before first active use.

We identified that the DFP has been set up as realistically as possible within the off-site test facility, with appropriate temporary structures and fittings simulating those that can only be installed on-site.  We judged that this provides a real benefit in the validation of plant configuration to support operational tasks. 

Based on conversations with operators and observation of a training exercise, we judged that adequate progress was being made and we were satisfied with the standard of the training material and the processes adopted for competence assurance.  However, noting that training was only partially complete at the time of the inspection, ONR may further review these elements in support of our future permissioning decision for active safety commissioning.  

We judged that adequate consideration was being given to operability of the workspaces and user interfaces to support reliable task performance.  In addition, we are content that the facility is fit for purpose from a radiological perspective.

Based on the evidence sampled, we are satisfied with the robustness of the process being employed to manage amendments to the operating and maintenance instructions based on the works testing.  We draw confidence from the multidiscipline approach being taken and the repeated trialling and training of documentation. 

All safety-related documentation is subject to approval by the Commissioning Safety Committee.  Based on the evidence sampled, we judged that the licensee has an adequate system in place for the validation and verification of safety-related documentation for the commissioning of the DFP.

Conclusion of Intervention

We expressed our support for the pragmatic and fit for purpose approach that has been adopted for the DFP project, as this is enabling accelerated hazard and risk reduction compared with the original facility design proposals.

I judge that the evidence sampled during this inspection demonstrates that the work undertaken in support of inactive safety commissioning of the DFP is adequate, and I have sufficient confidence that work will continue in this way. 

Given this, and the information presented in this record, I am satisfied that there are no outstanding issues or concerns to prevent inactive safety commissioning of the PFSP DFP.