Office for Nuclear Regulation

Planned System Based Inspection

Executive summary

Purpose of intervention

I carried out planned system based inspection looking at essential nitrogen supplies to the Dounreay Fast Reactor (DFR) and Prototype Fast Reactor (PFR) in accordance with the 2015/16 integrated inspection strategy (IIS) for Dounreay, to provide evidence that the licensee is controlling its hazards properly and complying with its statutory obligations. 

Interventions Carried Out by ONR

I carried out an inspection of the nitrogen supply systems for DFR and PRF against the requirements of Licence Condition (LC) 23 (operating rules), LC 24 (operating instructions), LC 10 (training), LC 27 (safety mechanisms, devices and circuits) and LC 28 (examination, maintenance, inspection and testing).  LC 34 (leakage and escape of radioactive material and radioactive waste) is also normally considered as part of a systems based inspection, but as the nitrogen supply system is not radioactive I did not consider it to be applicable in this case.  The purpose of the inspection was to ascertain whether or not the nitrogen supply systems are being operated in accordance with their safety case.

I also had a series of routine meetings to monitor progress with actions and projects of interest to ONR.

Explanation of Judgement if Safety System Not Judged to be Adequate


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

The licensee has safety cases for both DFR and PFR which clearly identify limits, conditions and safety mechanisms associated with the nitrogen supply system.  The limits and conditions are carried forward into written instructions for both operation and maintenance, inspection and testing. 

I am satisfied that those operations are carried out by suitably trained individuals, and that the specified maintenance is being undertaken as required.  As a result, I consider that the systems in both reactors are being operated and maintained in a manner consistent with their safety importance.

I therefore consider compliance with LC 23, LC 24, LC 10, LC 27 and LC 28 to be adequate, and consequently that the nitrogen supply systems for DFR and PFR are being operated in accordance with their safety cases.

Conclusion of Intervention

I did not identify any matter impacting on nuclear safety that required immediate regulatory action.