The purpose of this intervention was to undertake a system based inspection of the decay store at EDF Nuclear Generation Limited's (NGL's) Heysham 2 Power Station in line with the planned inspection programme contained in the Heysham 2 Integrated Intervention Strategy (IIS) for 2016/17.
A system based inspection (SBI) of the decay store was undertaken by the nominated site inspector, supported by two ONR specialist inspectors. The aim of this intervention was to evaluate implementation of safety claims made on the decay store. During this intervention we examined compliance with the following licence conditions:
The inspections were based on sampling the implementation of the arrangements in place against each licence condition. Although aspects of the containment integrity of the decay store were considered, we judged that an inspection rating against LC34 (Leakage and escape of radioactive material and radioactive waste) was not appropriate.
The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.
From the inspection we judged that the arrangements supporting the decay store and their implementation to be adequate and to have met the requirements of the safety case.
In summary, the outcome from the SBI of the decay store are that the arrangements and the implementation for LC 10, 23, 24 and 27 were judged adequate and we have given an inspection rating of GREEN (no formal action required) for each of these LCs.
Against LC10, we examined the training records and role profiles of a sample of fuel route staff undertaking work at the decay store. We found NGL's training manuals to be of a good standard. The register of training was up to date for those personnel we sampled. We consider that the arrangements and implementation of LC10 to be adequate and have rated compliance against LC10 as Green.
In respect to LC23 and LC24, we examined a selection of the site's safety case documentation technical specifications, operating instructions, and check sheets in advance of the inspection. We consider that there was a clear line of sight of the limits and conditions for the conduct of safe decay store operations within all levels of the site's documentation. This assessment was confirmed through detailed discussions with personnel on site charged with the operation and supervision of decay store operations. We therefore consider the arrangements and implementation of LC23 and LC24 to be adequate and have rated compliance against LC23 and LC24 as Green.
Compliance against LC27 is achieved through the site's arrangements for LC23, LC24 and LC28. This position has been agreed with ONR at a corporate level. The necessary documentation demonstrating implementation of this position was examined by the inspection team; we have therefore rated compliance against LC27 as Green.
For LC28 we examined a sample of the station's maintenance inspection and testing (MIT) records for a subset of those systems identified in the safety case. From our sampled inspection, there is evidence that maintenance of the decay store is being carried out in accordance with the licensee's plant maintenance schedule. We conducted an inspection of the plant associated with the Decay Store and overall, judged the plant was in a good state of health, with evidence of good housekeeping throughout.
An examination of work order cards identified a minor administrative non-compliance concerning the sign-off of the documentation on completion of the maintenance activity. EDF agreed to commission a quality assurance audit to understand the extent of this issue and implement appropriate remedial action. A regulatory issue has been raised on the ONR issues database to monitor progress against this commitment.
We examined the maintenance schedule safety system review for the fuel handling system and the associated engineering change (EC). We considered that the EC justification was not clear in several areas. An ONR regulatory issue has been raised on the ONR issues database to monitor process against a commitment to clarify the station's position.
Overall, we considered that the licensee's implementation LC28 arrangements was adequate. Three regulatory issues have been raised following identification of minor shortfalls. We judge that the following ONR inspection rating is appropriate: Green.
During this intervention, the nominated site inspector discussed a recent contamination event of an individual that took place at Heysham 2. He was informed that a significant adverse condition investigation was being undertaken to understand the circumstances of the event. The site inspector informed the TSSM that he was content with the station's immediate response to the incident and will await the publication of the investigation report and will follow this up through his normal regulatory engagements with the station.
After considering all the evidence examined during the sample inspections undertaken against LCs 10, 23, 24, 27 and 28 (LC 34 was not applicable), we concluded that the Decay Store and its associated supporting sub-systems met the requirements of the safety case.
A number of issues were raised to capture and track minor non-compliances identified during the inspection however, we consider that there are no findings from this inspection that could significantly undermine nuclear safety. No additional regulatory action is needed over and above the planned interventions of Heysham 2 power station as set out in the Integrated Intervention Strategy, which will continue as planned.