Office for Nuclear Regulation

System Based Inspection – SBI 08 – Short Break Electrical Supplies

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake a system based inspection of the short break electrical supplies system at EDF Nuclear Generation Limited’s (NGL’s) Heysham 2 power station in line with the planned inspection programme contained in the Heysham 2 Integrated Intervention Strategy (IIS) for 2015/16.

Interventions Carried Out by ONR

As part of this intervention, the ONR Nominated Site Inspector and I (Electrical Specialist Inspector) performed a System Based Inspection (SBI) of the Short Break Electrical Supplies system to judge the system performance against its safety function.  Through examination of this system and associated sub-systems we performed compliance inspections against Licence Conditions LC10 (Training), LC23 (Operating rules), LC24 (Operating instructions), LC27 (Safety mechanisms, devices and circuits), LC28 (Examination, inspection, maintenance and testing). LC34 (Leakage and escape of radioactive material and radioactive waste) was not considered applicable to this system.  The inspections were based on sampling the implementation of the arrangements in place against each licence condition.

Explanation of Judgement if Safety System Not Judged to be Adequate

From the inspection, we judge that overall the Short Break Electrical Supplies system meets the requirements of the safety case and is adequate.

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

During the course of the system inspection it was found that Heysham 2 has adequate arrangements to ensure that the Short Break Electrical Supplies system is maintained and operated in accordance with the safety case and the station’s arrangements, based on the areas sampled by the inspection.  The inspection identified a specific maintenance concern which has given rise to two issues which have been entered on to the ONR Issues Database.  A number of areas for potential improvement have also been identified and, although none gave rise to significant concern, NGL has agreed to follow them up in accordance with their own arrangements.  ONR will monitor progress through routine regulatory business.

In summary, the outcome from the SBI of the Short Break Electrical Supplies system is that the system adequately fulfils the requirements of the safety case.  Ratings for the Licence Conditions are as follows:

The intervention was performed in line with ONR’s guidance requirements (as described in our technical inspection guides) in the areas inspected.

Conclusion of Intervention

After considering all the evidence examined during the sample inspections undertaken against LCs 10, 23, 24, 27 and 28, we considered that the Short Break Electrical Supplies system met the requirements of the safety case.

ONR Issue Number 3692 was raised to address a specific maintenance concern which has given rise to two recommendations within this Intervention Record.

There are no findings from this inspection that could significantly undermine nuclear safety.