Torness - SBI28 Inspection
- Site: Torness
- IR number: 17-079
- Date: July 2016
- LC numbers: 10, 23, 24, 27, 28
Purpose of Intervention
The purpose of this intervention was to conduct a systems based inspection of EDF Energy Nuclear Generation Ltd’s Torness nuclear power station. The system in question was the Control Rod Shutdown System. The inspection was done as part of ONRs series of planned interventions as set out in the Torness integrated intervention strategy for 2017/18.
The inspection was undertaken by the ONR nominated site inspector and two specialist mechanical engineering inspectors with the assistance of EDF Independent Nuclear Assurance (INA).
Interventions Carried Out by ONR
I carried out a safety case informed ‘systems based inspection’ (SBI) of the control rod shutdown system. ONR’s system based inspection process examines evidence to determine compliance against six key licence conditions (LCs). These licence conditions have been selected to provide a structured approach to determining whether the safety case requirements of the system being inspected (in this case control rods) are adequately implemented. The license conditions are: LC10 (training), LC23 (operating rules), LC24 (operating instructions), LC27 (safety mechanisms, devices and circuits), LC28 (examination, maintenance, inspection and testing) and LC34 (leakage and escape of radioactive material and radioactive waste).
Explanation of Judgement if Safety System Not Judged to be Adequate
From the sampled evidence examined during this inspection, I judged that overall the safety provisions applicable to the control rod – shutdown system met the requirements of the safety case.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
Torness nuclear power station demonstrated that it has arrangements in place to ensure that the control rod shutdown system is inspected, maintained and operated in accordance with its safety case. The arrangements examined by ONR complied with NGLs legal duties in the areas sampled during the inspection. The inspection identified potential areas for improvement; however none gave rise to significant concern.
- LC10 Training – a number of training records were sampled from individuals identified as involved in maintenance of control rods or the associated control rod assemblies. These were examined to ascertain whether those undertaking maintenance together with those supervising were suitably trained to perform the tasks. I determined that a number of the training records sampled contained inconsistencies regarding training records and exception certificates. These were not readily available, possibly leading to individuals being assigned to maintenance tasks without the appropriate training. In view of this I propose to raise an ONR Regulatory Issue. I judged that an inspection rating of ‘amber below standard’ was appropriate for LC10 (training).
- LC23 - Operating Rules – three operating rules were identified and examined. These limits and conditions were specified through station Technical Specifications. They are intended to ensure that under the specified conditions of operation, sufficient shutdown and holddown margin is achieved as required by the safety case. I examined these and their implementation and was content with the evidence that they fulfil these requirements. I therefore judged that an inspection rating of ‘green – adequate’ to be appropriate for LC23 (operating rules).
- LC24 - Operating Instructions – I sampled two written operating instructions and evidence that suggested operations were controlled in accordance with them. I consider an inspection rating of ‘green – adequate’ to be appropriate for LC23 (operating instructions).
- LC27 - Safety Mechanisms, Devices and Circuits – the licensee demonstrated that appropriate checks were undertaken ensuring that operations were not undertaken unless an appropriate number of control rods were available in accordance with the technical specifications. This is managed through a number of per shift checks being undertaken. I judged that this warranted an inspection rating of ‘green – adequate’.
- LC28 - Examination, Inspection, Maintenance and Testing – the licensee demonstrated that there are adequate processes, procedures and records in place for the examination, inspection, maintenance and testing of plant important to safety. The documentation sampled showed that suitable records had been produced for maintenance activities. I therefore judged that an inspection rating of ‘green – adequate’ to be appropriate for LC27 (examination, inspection, maintenance and testing).
- LC34 - Leakage and Escape and Radioactive Material and Radioactive Waste – this licence condition was not considered sufficiently relevant to the system being examined to be rated.
Conclusion of Intervention
From the sampled evidence examined during this SBI 28 inspection against the nuclear site licence conditions 10, 23, 24, 27, 28, I consider that the control rod shutdown system met the requirements of the safety case.
There were no findings identified from this inspection that could significantly undermine nuclear safety.