Office for Nuclear Regulation

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Dungeness B - IJCO SOI Implementation Inspection

Executive summary

Purpose of Intervention

This intervention was at EDF Energy Nuclear Generation Limited’s (NGL’s) Dungeness B power station (DNB).  It was undertaken by a Human Factors Specialist Inspector and a Structural Integrity Specialist Inspector, both within the Operating Facilities Division (OFD) of the Office for Nuclear Regulation (ONR).  It is required to inform the assessment of the Interim Justification for Continued Operations (IJCO) associated with Boiler Tube Leak Safety Case - Water Ingress to Gas Circulator Duct.

Interventions Carried Out by ONR

The IJCO requires operators to respond to a boiler tube leak in a different manner from that previous outlined in Station Operating Instructions (SOIs).  This inspection examined how NGL undertook the development and subsequent implementation of revised SOIs and considers whether they are adequate to support the Human Based Safety Claims (HBSCs) made in the IJCO.

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

Not applicable.

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

From the evidence presented during this inspection, I am of the opinion that, for the operations required to support the IJCO, NGL has demonstrated the following.

It has implemented adequate arrangements to ensure that those on site who have responsibility for operations, that may affect safety, are suitably trained.

The implemented arrangements provide confidence that operations are controlled and carried out in compliance with conditions and limits necessary in the interest of safety.

The implemented arrangements provide confidence that operations will be carried out in accordance with written instructions and that these documents provide operators with any instructions necessary in the interest of safety.

A number of good practices were observed during this inspection.

No matters were identified as requiring immediate regulatory attention during the conduct of the compliance inspection.

A number of non-compliances with relevant good practices were identified during this inspection, the most notably of which was the absence of a temporary modification of SOIs to prompt personnel to follow the “directive” guidance of Technical Advice Note (TAN) 963.  In addition, I observed a number of differences in the format and content of SOIs at DNB compared to those I have seen at other NGL sites during recent inspections.  It is my intention to integrate these findings / observations into a forthcoming ONR Procedure Use and Adherence (PU&A) intervention.

Conclusion of Intervention

No matters were identified as requiring immediate regulatory attention during the conduct of this inspection.

I am broadly satisfied that the evidence obtained during this inspection indicates that NGL’s implemented arrangements adequately support the HBSCs made in the IJCO.

This conclusion and the Green inspection ratings against LCs 10, 23 and 24 are made on the assumption that the required directed reading, on which NGL’s Human Factors substantiation is contingent, has been completed.  Should NGL not provide evidence that this reading has been completed in a timely manner; regulatory follow-up action will be required.