The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at EDF Energy Nuclear Generation Ltd (NGL) Torness power station, in line with the planned inspection programme contained in the Torness Integrated Intervention (IIS) plan for 2017/18.
As part of this intervention, the nominated site inspector supported by two specialist inspectors (Fault Studies) and a further Principal Inspector undertook compliance inspections against the requirements of LC 14 - Safety documentation, LC 22 - Modification or experiment on existing plant and LC 23 - Operating rules, in each case with an emphasis on the activities, hazards and safety cases associated with the station's Fuel Route.
Regarding LC14, we sampled the site arrangements with a particular emphasis on how well it is ensured that the safety case is applied in practice, including:
Regarding LC22 compliance, we sampled the station's specific arrangements for modifications to safety cases and their implementation by examining a series of recent Category 2 modifications provided by the station in advance of the inspection, and through on site discussion of processes including the arrangements for dealing with safety case 'anomalies'.
The intervention on LC23 focused on how operating rules are derived from the safety case and implemented in Technical Specifications. We also specifically tested the claimed post-fault actions captured in existing operating rules, and checked the general understanding of the safety case by Fuel Route Engineers, including knowledge of hazards and risk and relevant operating rules to the claimed post-fault actions.
In addition to the above activities, we undertook a number of engagements with the licensee's representatives. These included:
The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.
Not applicable as no system inspection was undertaken during this intervention.
For LC 14 - the station presented the current structure of its safety case and with particular reference to the fuel route demonstrated that it is accessible and maintained live by means of commentary and re-issue statements that interpret the safety case and its evolution.
We found through conversation with key staff that the safety case was well-understood. The site demonstrated that there were clearly laid out responsibilities for safety cases across the site, and that the station had reacted positively to feedback about this provided by ONR during a previous LC14 inspection in 2012.
In relation to the stations' continued capability to implement LC14 arrangements, we examined the management of capability of the Nuclear Safety Group (NSG) at Torness including numbers, demographics, and competence assurance. We found no evidence of immediate or medium term resource or capability constraints. The evidence we found concerning management of competence, including examination of training records and interviews with staff, aligned with the expectations of the role.
Regarding LC22 compliance, we sampled recent category 2 modifications to safety cases and were satisfied that they were clearly laid out and self-explanatory. We also examined site specific arrangements to resolve safety 'anomalies' and were satisfied that they comply with legal requirements.
For LC23, we examined a sample of the licensee's operating rule documentation including technical specifications and the associated operating instructions and check-sheets with an emphasis on limits and conditions of operation (LCOs) and claimed post-fault actions related to the fuel route. We were satisfied that these operating rules were clearly written and directly supported the safety case. We found staff to be knowledgeable about the technical specifications, hazards and risks relevant to their roles. Based on this sample, we were therefore satisfied that the arrangements and their implementation met legal requirements.
Part of the Torness safety case addresses the challenge to adequate post trip cooling from a loss of off-site electrical power for up to 72 hours as a result of a nationwide 'blackout'. This makes claims on adequate essential stocks of diesel for electricity generation and water for reactor cooling using the boilers. ONR carried out a limited inspection of the reserve feed water tanks and the tanks used to store fuel for the diesel generators. From our limited external inspection, the diesel and water tanks were in a good condition and contained their intended stock levels. During the inspection we requested confirmation concerning practical measures for supplementing or replacing stocks of diesel and water after a nationwide blackout event, which the licensee provided prior to the issue of this report, and which we found acceptable at this stage.
As a result of the evidence sampled and discussions with the station staff, and in line with ONR's Inspection Rating Guide, a rating of 'Green' has been assigned to the compliance inspection for all of LC14, 22, and 23.
After considering the evidence examined during the sample inspection undertaken against Licence Conditions 14, 22, and 23, we concluded that the licensee complied with its legal duties.
There are no findings from this inspection that could significantly undermine nuclear safety at Torness nuclear licensed site.