Office for Nuclear Regulation

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Dounreay Planned compliance inspection (LC4 and LC34) and Safety System Inspection S1.3 (Criticality)

Executive summary

Purpose of Intervention

This was one of a series of planned inspections to seek evidence of compliance with several  Licence Conditions (LC) and to undertake a safety system based inspection (SSI) in accordance with the 2017/18 Integrated Intervention Strategy (IIS) for Dounreay to confirm that the licensee is controlling its hazards and complying with its statutory obligations.

Interventions Carried Out by ONR

The SSI focused on the systems in place to manage the criticality hazard within the D1208 Liquor Store and the requirements of the following Licence Conditions:

The SSI within D1208 comprised discussions with DSRL staff, plant walk-downs and reviews of plant records and other documentation

We also took the opportunity to conduct an inspection of the D1215 Laboratories in support of the LC27 [Safety mechanisms, devices and circuits] and LC28 [Examination, inspection, maintenance and testing] requirements for D1208.

In addition an inspection of the Site’s arrangements made under LC4 (Restrictions on nuclear matter on site) and LC34 (Leakage and escape of radioactive material and radioactive waste) was made and these were based on examining a sample of the licensee’s arrangements and their implementation as follows:

Explanation of Judgement if Safety System Not Judged to be Adequate

The criticality safety systems were judged to be adequate.

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

From the evidence examined during the SSI, we consider that DSRL has adequately implemented the requirements of the facility safety case that we examined relating to criticality safety systems.  The Authority to Operate (ATO) holder and their staff demonstrated a good knowledge and understanding of the limits and conditions related to criticality safety derived from the criticality safety case and implemented on plant.

We reviewed evidence of training against a sample of procedural claims and engineering system functions, including the effective operation and maintenance of criticality safety systems.

In addition, we examined documentation related to maintenance activities for the criticality safety systems and consider that they provided adequate evidence of asset maintenance and inspection.  Part of this includes an inspection regime examining the integrity of containment for the various tanks and vessels that hold radioactive liquids, including their bunds.

We undertook a review of progress to date against the Level 3 Regulatory Issue raised during the LC25 [Operational records] compliance inspection conducted in November 17  and considered that adequate progress is being achieved in addressing this issue and agreed that the next formal review will be conducted during a future planned inspection.

We consider that the licensee has a robust process for receiving nuclear matter on site, tracking it while it is there, and ensuring that it is stored in an adequate manner.

We further consider that the licensee has adeqaute arrangements for the monitoring of the wet silo. The output from the monitoring regimes gives no reason to question the integrity of the wet silo at this time.

Conclusion of Intervention

Overall, we consider that the arrangements and their associated implementation for LC4 and LC34 for the areas inspected met with the required standards.  We also consider that the criticality safety system within D1208 met the requirements of the safety case. We did not identify any matter impacting on nuclear safety that required immediate regulatory action.