Office for Nuclear Regulation

This website uses non-intrusive cookies to improve your user experience. You can visit our cookie privacy page for more information.

Torness Planned Intervention, System Based Inspection SBI-013, Decay Store

Executive summary

Purpose of intervention

This intervention included a system based inspection of the Decay Store led by the Fuel Performance Inspector. The inspection is in line with the planned programme contained in the Torness Integrated Intervention Strategy (IIS) for 2016/2017. The aim of the inspection was to confirm that the Decay Store, with its associated operating instructions and maintenance schedule, is able to meet the safety case functional requirements.

Interventions carried out by ONR

The system based inspection of the Decay Store was conducted against compliance with the following licence conditions:

The inspections were based on sampling the implementation of the arrangements in place against each licence condition. Pre- and post- inspection meetings with the site personnel were held and the main findings were communicated.

Although aspects of the containment integrity of the system were considered the role of the system with respect to the management of leakage and escape of radioactive material and radioactive waste was judged to be such that LC34 was not applicable on this occasion.  

Explanation of judgement if safety system not judged to be adequate

Based on the sample made during this inspection we judged that the Decay Store adequately meets the requirements of the safety case.

Key findings, inspectors’ opinions and reasons for judgements made

The training records and role profiles of a number of fuel route staff, who work with the decay store, were sampled.  We found the quality of the training manuals to be of a good standard with clear statements of the steps in training and sign off of completion. The register of training was up to date.  However, the role profile for the decay store system engineer role was found to only contain generic system engineer training requirements.  This is the case for all system engineer roles and has been previously identified as a weakness by ONR both at Torness and corporately.  Therefore, although the decay store system engineer had demonstrated that he had a good understanding of the plant through his interactions with us, there was no documented evidence of his competency. A regulatory issue at Level 4 has been raised to capture and track this issue.  Notwithstanding this, we consider that it is appropriate to rate LC10 as ‘Green’.  We judge that a lower rating would be disproportionate to the risk gap identified.

The inspection of LC23 and LC24 was conducted in parallel and therefore they have been reported together within this report. In advance of the inspection visit the licensee’s safety case documentation was examined in conjunction with relevant technical specifications, operating procedures and check-sheets. The procedures and critical steps were also discussed with the EDF-NGL staff.  Post-fault actions and procedures were discussed and the procedures examined.  We found the station procedures to be clear and the explanation of the operation of the system given by the EDF-NGL staff demonstrated a high level of understanding of the key safety functions of the plant.

However, the link between the safety case documents (Station Safety Report) to limiting conditions of operation (LCOs) and the plant procedures was not as clear as on some other stations of the EDF AGR fleet, which is brought about by the format of the safety case. The fleet good practice is to use a “Living Safety Case” which more clearly identifies the safety functions and safety case claims.  We advised EDF that it would be good practice to update the documentation in-line with fleet approach.  Since the safety case is up-to-date, the documentation is in order and the staff demonstrated a good understanding, we consider this to be a presentational matter for this system at this time.  We therefore judge that this was a minor shortfall and did not constitute a non-compliance with LC23 requirements.  Accordingly we consider that a rating of ‘Green’ is appropriate for LC23 and LC24.

In order to assess compliance with LC27 we requested that EDF-NGL identify how it manages safety mechanisms.  LC27 compliance is through the EDF arrangements for LC23, 24 and 28, and this position has been agreed with ONR at a corporate level. The relevant documents were provided. We therefore consider a rating of ‘Green’ to be appropriate against LC27.

The station’s maintenance inspection and testing (MIT) records were sampled via the asset management system (AMS) for a subset of those systems identified in the safety case.  There is satisfactory evidence from this sample that maintenance on the decay store is being carried out in accordance with the requirements of the plant maintenance schedule.  A minor example of below standard work order card completion was identified and raised with the station’s technical and safety support manager to investigate.  However, the evidence of compliance with LC28 is adequate and requires no formal follow up actions.  We therefore consider a rating of ‘Green’ to be appropriate.

Conclusion of Intervention

From the evidence gathered during this intervention, we do not consider there to be any matters that have the potential to impact significantly on nuclear safety in relation to the decay store. Several low level items were identified for follow up by the nominated site inspector as part of normal regulatory business.  However, at present, no additional formal regulatory action is needed over and above the planned inspections of Torness power station as set out in the Integrated Intervention Strategy.