Office for Nuclear Regulation

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Sizewell B - SBI07 and 08 - Cooling Systems

Executive summary

Purpose of Intervention

The purpose of this intervention was to undertake Licence Condition (LC) compliance inspections at Sizewell B power station in line with the planned inspection programme contained in the Sizewell B Integrated Intervention Strategy (IIS).  The Intervention involved sampling into the Cooling Systems at Sizewell B. The Licence Conditions applied for this system based inspection were:

LC34: Leakage and Escape of Radioactive Material and Radioactive Waste was exempt from this inspection as the system doesn’t contain radioactive material under normal circumstances.

Interventions Carried Out by ONR

I selected the following systems as my sample for inspection as they provide the primary heat removal function:

Excluded from the scope of my inspection were the following systems: Circulating Water System, Auxiliary Circulation Water System, and General Service Water System as there are no safety claims on these systems.

My inspection was described in an Agenda which was shared with the Licensee prior to my inspection [CM9 2020/77245]

Key Findings, Inspector's Opinions and Reasons for Judgements Made

I performed a desktop review of the Licensee’s arrangements and associated documentation for the six License Conditions. I also performed a plant walk-down and had discussions with various System Engineers, Nuclear Safety Group personnel, and operators.

Sizewell B nuclear power station demonstrated that it has arrangements in place to ensure that the Cooling System is inspected, maintained and operated in accordance with its safety case.  The arrangements sampled and examined by ONR complied with Nuclear Generation Limited’s (NGLs) legal duties in the areas sampled during the inspection, and I was satisfied that the System adequately fulfils the requirements of the safety case.

Site Licence Condition 10 – Training – Inspection Rating Green (No Formal Action)

I consider that the Licensee has adequate arrangements in place for training individuals, and I consider the technical specification training to be an area of good practice.

Site Licence Condition 23 – Operating Rules– Inspection Rating Green (No Formal Action)

I consider that the Licensee has an adequate process in place for identifying the operating rules to demonstrate the safety of an operation, ensuring configuration control and ensuring compliance with operating rules.

Site Licence Condition 24 - Operating instructions/Site Licence Condition 27 – Safety Mechanisms, Devices and Circuits– Inspection Rating Green (No Formal Action)

I consider that the Licensee has an adequate process in place for the production and implementation of Operating Instructions, and the management of Safety Mechanisms, Devices and Circuits. 

Site Licence Condition 28 – Examination, Inspection, Maintenance and Testing – Inspection Rating Green (No Formal Action)

I consider that the Licensee has adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety.

Site Licence Condition 34 – Leakage and Escape of Radioactive Material and Radioactive Waste – No rating

LC 34 was exempt from the scope of this inspection due to the systems not containing radioactive material under normal circumstances. However, I briefly discussed leak detection with the system engineers and operators. I was content from my discussions that it appeared that there was appropriate monitoring in place to detect leaks.

Conclusion of Intervention

After examining the evidence sampled against LCs 10, 23, 24, 27, and 28 during my inspection, performing a walk-down, and having discussions with various System Engineers, Training Group personnel and Nuclear Safety Group personnel, I consider that the Cooling System (System 7/8) met the requirements of the safety case and therefore an overall rating of Green (No Formal Action) is appropriate for this Inspection.