Office for Nuclear Regulation

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Heysham 2 - SBI026 - Post Trip Sequencing Equipment

Executive summary

Purpose of intervention

    The purpose of this intervention was to undertake a system based inspection of the post trip sequencing equipment at EDF Energy 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 2016/17.

Interventions Carried Out by ONR

As part of this intervention two C&I Specialist Inspectors performed a System Based Inspection (SBI) of the post trip sequencing equipment to judge the system performance against its safety function. The ONR's Information Technology Director also observed part of the inspection and undertook a site tour. 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 sequencing equipment.

On 06/12/2016 a site incident was declared due to higher than normal levels of hydrogen being detected on site. One of the C&I Specialist Inspectors was invited to take the ONR position in the Emergency Control Centre (ECC) and relayed information, as necessary to ONR. Staff responded in accordance with their emergency response arrangement and all staff were accounted for promptly. No persons were injured and there was no release of radioactivity. The area of the incident was made safe and non-essential staff were allowed to leave the site.  An investigation is currently on going to determine the root cause and the site inspector will follow up any lessons learnt from the internal investigation.

Explanation of Judgement if Safety System Not Judged to be Adequate

From the system based inspection, we judge that overall the post trip sequencing equipment meets the requirements of the safety case.

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

Based on the areas sampled during this system based inspection, it was found that Heysham 2 has adequate arrangements to ensure that the post trip sequencing 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 sequencing equipment was:

During a review of the latest E12 (post trip sequencing equipment) system health indicator programme (SHIP) data we noted that 3 out of the 4 condition records were not related to the E12 system. An action was placed on NGL to ensure that the correct system has been attributed to condition records for the November 2016 E12 SHIP data and CR 1017230 was raised.

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 requirements of the safety case have been adequately implemented at Heysham 2, 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.  As a result of this inspection, no additional regulatory action is needed over and above the planned interventions for Heysham 2 power station.