Sizewell B - SBI 15 Inspection
- Site: Sizewell B
- IR number: 17-202
- Date: January 2018
- LC numbers: 10, 23, 24, 27, 28
Purpose of Intervention
System based inspections (SBIs) are an essential element of ONR's overall interventions on nuclear licensed sites. They are intended to establish that the basic elements of a site / facility safety case as implemented in safety systems and structures are fit for purpose and that they will fulfil their safety functional requirements.
The purpose of this intervention was to carry out a system based inspection of compliance with Licence Conditions (LC) in line with the ONR planned inspections programme contained in the Sizewell B Integrated Intervention Strategy for 2017/2018.
Interventions Carried Out by ONR
This intervention consisted of a System Based Inspection (SBI) of the station's reactor building cooling and combustible gas control systems. Compliance inspections were carried out against the following Licence Conditions (LCs), which are applicable provisions of the Energy Act 2013:
- LC10 - Training.
- LC23 - Operating Rules.
- LC24 - Operating Instructions.
- LC27 - Safety Mechanisms, Devices and Circuits.
- LC28 - Examination, Inspection, Maintenance and Testing.
The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.
Explanation of Judgement if Safety System Not Judged to be Adequate
From the areas sampled during this inspection, I judged that the overall combustible gas control and reactor building cooling systems met the requirements of the safety case.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
With respect to the SBI against ONR's approach I was able to make the following judgements;
- LC10 (Training) - The records were adequately in date. A few records were marginally past the planned renewal date, but this was as a result of the outage overrun at the time of the inspection. I was assured that deferring the training by a short timescale was within the company's arrangements. The station demonstrated that it has planned training courses to remedy these items at an early opportunity.
I judged that in the areas sampled ONR's expectations have been met and therefore have assigned an inspection rating of green to LC10.
- LC23 (Operating Rules) - We examined the link between the safety case and the link to the Technical Specifications. I judged that there were no significant shortfalls when compared with appropriate benchmarks for LC23 compliances and therefore assigned an inspection rating of green.
- LC24 (Operating Instructions) - The inspection looked at a number of supporting procedures associated with the combustible gas control and reactor building cooling systems. This included procedures for plant maintenance and for surveillance. The evidence sampled showed that the operating instructions provided to station staff were appropriate to ensure that operations that could affect safety were adequately controlled and that relevant operating rules were implemented. I judged that in the areas sampled ONR's expectations have been met and therefore assigned an inspection rating of green to LC24.
- L27 (Safety Mechanisms, Devices and Circuits) / LC28 (Examination, Inspection, Maintenance and Testing). The plant was in outage mode and was in the process of refuelling. During the plant walkdown, it was noted the plant was generally in a visibly good condition and that outage operations were well controlled. However we identified some minor damage and corrosion. The corrosion that we inspected was not significant. The extent of the damage was judged to not affect the functionality of the systems. We were satisfied that these observations were also captured as part of the station's plant walkdown process with work plans in place at the next available opportunity. Longer term, the station has committed to replace / overhaul key items of equipment in line with a scheduled maintenance plan. Therefore I judged an inspection rating of green was appropriate for both LC27 and LC28.
- L34 (Leak and Escape of Radioactive Material and Radioactive Waste) - The inspection did not cover any area where the systems sampled could lead to a leak and escape of radioactive materials or waste and therefore it was considered inappropriate to assign an inspection rating to L34 compliance.
Conclusion of Intervention
From the evidence gathered during these inspections, it was judged that there were no matters that have the potential to impact significantly on nuclear safety. The inspection ratings given in relation to LCs 10, 23, 24, 27 and 28 were all "green". Evidence was not gathered pertaining to leakage and escape of radioactive material; and therefore it was judged that a rating for LC34 was not relevant.