The purpose of this intervention was to conduct a system based inspection of EDF Energy Nuclear Generation Ltd's Torness power station in relation to the gas circulator system and carry out routine site inspection activities. This was undertaken as part of a series of planned interventions as set out in the Torness integrated intervention strategy for 2016/2017.
The inspection was undertaken by the ONR nominated site inspector, an ONR mechanical engineering specialist inspector and an ONR electrical engineering specialist inspector.
We performed a safety case informed system based inspection of the gas circulator system. Through examination of this system, compliance inspections were performed against nuclear site licence conditions 10 (training), 23 (operating rules), 24 (operating instructions), 27 (safety mechanisms, devices and circuits), 28 (examination, inspection, maintenance and testing) and 34 (leakage and escape of radioactive material and radioactive waste). The inspections were based on sampling the implementation of the arrangements in place at the station against each licence condition. The objective of the inspection was to determine whether the Licensee's arrangements were in accordance with the system's safety case requirements.
The above interventions were performed in line with ONR's guidance requirements (as described in our technical inspection guides, which can be found at www.onr.org.uk/operational/tech_insp_guides/index.htm) in the areas inspected.
From this inspection, we judged that overall the safety provisions applicable to the gas circulator system met the requirements of the safety case.
Torness power station has arrangements in place to ensure that the gas circulator system is inspected, maintained and operated in accordance with its safety case. The arrangements examined by ONR complied with NGL's legal duties in the areas sampled during the inspection. The inspection identified potential areas for improvement; however, none gave rise to significant concern. These minor observations were acknowledged by NGL who will address these through its own arrangements.
From a plant walk down, we are satisfied that housekeeping is generally of a good standard. We identified one example of a local gauge that was not functioning. However this did not affect nuclear safety and the station staff took appropriate action by switching over to a back-up system. In addition, we placed an action on Torness to provide a safety justification covering the interim period between the detection of the fault and its resolution.
In summary, the system based inspection of the gas circulator system inspected, for licence conditions 10, 23, 24, 27, 28 and 34, is rated as GREEN on the basis that relevant good practice was generally met and identified deficiencies in compliance arrangements were minor.
Independently of the system based inspection, we reviewed the station's progress in investigating a recent event reported to ONR concerning the operation of reactor control rods. We are satisfied that Torness has adequately investigated and followed up this event to learn lessons and prevent a recurrence. An ONR issue has been raised to monitor the station's progress to completion of corrective actions.
After considering the evidence examined during the inspection undertaken against licence conditions 10, 23, 24, 27, 28 and 34 we concluded that the licensee complied with its legal duties regarding the gas circulator system and met the requirements of the safety case.
There are no findings from this intervention that could significantly undermine nuclear safety.