Torness System Based Inspection - SBI 07 - No Break Supplies System
- Site: Torness
- IR number: 17-196
- Date: January 2018
- LC numbers: 10, 23, 24, 27, 28, 34
Purpose of Intervention
This was a planned inspection of EDF Energy Nuclear Generation Ltd.'s (NGL's) Torness power station, undertaken as part of the planned intervention strategy for the Operating Facilities Division (OFD) of the Office for Nuclear Regulation (ONR).
The work was carried out in-line with the planned inspection programme contained in the Torness Integrated Intervention Strategy (IIS).
Interventions Carried Out by ONR
During this intervention, the following key activities were undertaken:
- System Based Inspection (SBI) of the No Break Supplies System
- Variable Frequency Convertor (VFC) thyristor event - Information Gathering
Explanation of Judgement if Safety System Not Judged to be Adequate
From the inspection, I judged that the no break supplies system met the requirements of the safety case and was adequate.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
From the System Based Inspection on the no break supplies system I concluded that:
- LC 10 (Training) - I examined the training records of a number of personnel involved in maintenance and inspection activities associated with the no break supplies system. I judged that the personnel undertaking these maintenance and inspection activities were suitably qualified and experienced. I therefore assigned a rating of Green (no formal action) for LC 10 compliance.
- LC 23 (Operating Rules) - The technical specifications inspected adequately specified the limits and conditions of operation (LCO) reflecting those specified in the safety case. In addition the surveillance records and compliance check sheets inspected demonstrated that the technical specifications were complied with during operations. I therefore assigned a rating of Green (no formal action) for LC 23.
- LC 24 (Operating Instructions) - My sampled inspection of a station operating instruction (SOI) and several maintenance instructions (MIs). I have judged that these documents to meet legal duties and therefore I have assigned a rating of Green (no formal action) for LC 24.
- LC 27 (Safety Mechanisms, Devices and Circuits) - The no break supplies system was considered as a safety related system. I examined several completed maintenance and test records relating to these systems and confirmed that they were adequately maintained and tested on a regular basis. I judged that a rating of Green (no formal action) was appropriate for LC 27.
- LC 28 (Examination, Inspection, Maintenance and Testing) - I examined several MIs and work order cards. I confirmed that the periodicity of maintenance activities was appropriate and the MIs check lists were appropriately completed. I judged that the no break supplies system's plant and equipment meet legal duties. I therefore assigned an IIS rating of Green (no formal action) for LC 28.
- LC 34 (Leakage and Escape of Radioactive Material and Radioactive Waste) - The no break supplies system does not contain radioactive material and therefore LC34 was not considered as part of this inspection.
For the information gathering intervention on the VFC thyristor event, I was content, from an electrical engineering perspective, that the station was continuing to work towards fully identifying and understanding the causes of this event and were developing and implementing appropriate remediation strategies.
The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.
Conclusion of Intervention
From the evidence sampled during this SBI-07 inspection against LCs 10, 23, 24 and 28, I consider that the no break supplies system met the requirements of the safety case.
For the information gathering intervention, I was content with the explanations, discussions and advice given and was content that there was no need for any regulatory action at this point.
There are no findings from this inspection that could significantly undermine nuclear safety. At present, no additional regulatory action is needed over and above the planned interventions at Torness Power Station as set out in the Integrated Intervention Strategy, which will continue as planned.