Office for Nuclear Regulation

Heysham 2 Power Station - Inspection of SBI17

Executive summary

Purpose of intervention

The purpose of this intervention was to carry out a number of Licence compliance inspections and undertake a system based inspection of the Gas Circulators 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, I, the ONR Nominated Site Inspector, and an ONR Electrical Engineering Specialist Inspector performed a System Based Inspection (SBI) of the Gas Circulators 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). The inspections were based on sampling the implementation of the arrangements in place at the station against each licence condition.

The standard consideration of licence conditions during system based inspections includes LCs 10, 23, 24, 27, 28 and 34, with conditions added or excluded depending on their applicability. In this case, LC 34 that relates to leakage and escape of radioactive material and waste is not applicable to the electrical aspects of the gas circulators and therefore deemed not applicable to the inspection.

Also, as part of this intervention I also undertook compliance inspections against LC22 - modification or experiment on existing plant and LC26 - control and supervision of operations, attended a routine meeting with the station internal regulators and discussed progress with ONR issue 3692 relating to the Essential Diesel Generator roof mounted plant.

Explanation of Judgement if Safety System Not Judged to be Adequate

From the inspection, we judge that overall the Gas Circulators meet the requirements of the safety case and is adequate.

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

The LC22 inspection involved inspection of the arrangements for LC22, which I considered to be robust.  On inspection of the implementation of three modifications sampled, I judged that the implementation of the LC22 arrangements on plant is be good and, therefore, have rated this element of my inspection through the IIS as 2 (good).

The LC26 inspection involved consideration of both generic and local implementation documents as defined within NGL's arrangements for: review of events associated with plant status and configuration control; the management of contractors performing work on power stations acting as field supervisors; and the oversight of managers and supervisors for new system engineers.

On balance of the evidence presented I judge that the implementation of the arrangements for LC26 are adequate and have rated this element of my inspection through the IIS as 3 (adequate).

Based on my inspection of the remediation activities undertaken by Heysham 2 to address ONR issue 3692, relating to maintenance of EDG roof mounted plant, I am content with progress, and will continue to monitor to closure. 

During the course of the system based inspection it was found that Heysham 2 has made arrangements to ensure that the Gas Circulators are maintained and operated in accordance with its safety case and the arrangements are deemed to be implemented in an adequate manner, based on the areas sampled by the inspection.  The inspection identified a number of areas for potential improvement, and although none gave rise to significant concern two issues have been entered on to the ONR Issues Database to monitor station’s actions to address them.  ONR will monitor their progress through routine regulatory business.

In summary, the outcome from the safety inspection of the Gas Circulators is that the arrangements and their implementation are deemed to be adequate and therefore we have given IIS ratings of 3 (adequate) in relation to LCs 10, 23, 24 and 27, and 4 (below standard) for LC 28. The IIS rating of 4 for LC 28 reflects a number of areas where potential improvements are needed to bring the plant and maintenance arrangements in line with good practice.  

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 Gas Circulators met the requirements of the safety case.

There are no findings from this inspection that could significantly undermine nuclear safety.  At present, no additional regulatory action is needed over and above the planned interventions of Heysham 2 power station as set out in the Integrated Intervention Strategy, which will continue as planned.