Office for Nuclear Regulation

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System Inspection (SBI-09 Main Electrical System)

Executive summary

Purpose of intervention

This report covers the nuclear safety related inspection of Heysham 2 Power Station, undertaken as part of a series of planned interventions which are listed in the Integrated Intervention Strategy (IIS) plan for the station.

Interventions Carried Out by ONR

As part of this intervention, we carried out a safety case based system inspection of the Main Electrical System. Through examination of this system we performed compliance inspections against Licence Conditions LC 10: Training; LC23: Operating rules; LC24: Operating instructions; LC27: Safety mechanisms, devices and circuits; LC28: Examination, inspection, maintenance and testing. 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 main electrical supplies safety system provisions meet the requirements of the safety case and are adequate. Further details are provided below.

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

A safety case based system inspection of the main electrical supplies system was carried out as part of the programme of safety system inspections included on the Heysham 2 site intervention plan for 2014/15, to identify the adequacy of the station arrangements made to ensure the system will perform its safety function. In deciding if suitable and sufficient measures have been put in place for the safety system, these inspections consider compliance with a number of licence conditions to test the adequacy of the arrangements implemented. The standard consideration of licence conditions during safety system inspections includes LCs 10, 23, 24, 27, 28 & 34, with conditions added or excluded depending on their applicability. In this case, LC34 that relates to leakage and escape of radioactive material and waste is not applicable to the main electrical supplies system and therefore has been deemed not applicable to the inspection.

During the course of the system inspection it was found that station has made arrangements to ensure that the main electrical supplies system is maintained and operated in accordance with its safety case and the arrangements are deemed to be implemented in an adequate manner, on the basis of the areas sampled by the inspection. The inspection identified a number of areas for potential improvement, and although none gave rise to significant concern, the station has agreed to take action to address them.

In summary, the outcome from the safety inspection of the main electrical supplies system is that the arrangements and their implementation are deemed to be adequate, and therefore we have given an inspection rating 3 (adequate) in respect of LCs 10, 23, 24, 27 & 28.

The licence conditions were inspected against ONR's published guidance requirements (as described in our technical inspection guides).

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 main electrical systems met the requirements of the safety case.

No actions or issues were identified during the inspection.

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