Office for Nuclear Regulation

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Heysham 1 - SBI026 - Two Day Inspection - Post Trip Logic Equipment

Executive summary

Purpose of intervention

The purpose of this intervention was to undertake a system based inspection (SBI) of the post trip logic (PTL) equipment at EDF Energy Nuclear Generation Limited’s (NGL’s) Heysham 1 power station in line with the planned inspection programme contained in the Heysham 1 Integrated Intervention Strategy (IIS) for 2016/17.

Interventions Carried Out by ONR

As part of this intervention a control and instrumentation (C&I) specialist inspector performed an SBI of the post trip logic equipment to judge the system performance against its safety function. During the inspection, for training purposes, a second C&I Specialist Inspector and a defence nuclear safety regulator (DNSR) assisted in the inspection. 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) and LC28 (Examination, inspection, maintenance and testing). LC34, which relates to leakage and escape of radioactive material and radioactive waste, was not considered applicable to the post trip logic equipment.  

Explanation of Judgement if Safety System Not Judged to be Adequate

From the system based inspection, we judge that the implementation of the arrangements for the post trip logic equipment meet the requirements of the safety case.

Key findings, inspectors’ opinions and reasons for judgements made

Based on the areas sampled during this system based inspection, it was found that Heysham 1 has adequate arrangements to ensure that the post trip logic equipment is maintained and operated in accordance with the safety case and the station’s arrangements.

In summary, the outcome of the SBI of the post trip logic equipment was:

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 inspection undertaken against LCs 10, 23, 24, 27 and 28, we considered that the post trip logic system meets the requirements of the safety case and has been adequately implemented at Heysham 1, with a rating of green assigned against licence conditions 10, 23, 24, 27 and 28.

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 1 power station as set out in the Integrated Intervention Strategy, which will continue as planned. ONR will monitor progress for the resolution of the issues raised through normal regulatory business.