Office for Nuclear Regulation

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Sizewell B - SBI 15 Inspection

Executive summary

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:

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;

I judged that in the areas sampled ONR's expectations have been met and therefore have assigned an inspection rating of green to LC10.

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.