Office for Nuclear Regulation

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Planned Intervention at Heysham 1

Executive summary

Purpose of intervention

The purpose of this intervention was to conduct a system based inspection of EDF Energy Nuclear Generation Ltd’s (the Licensee) Heysham 1 Power Station in relation to control and instrumentation (C&I) systems important to safety. This was undertaken as part of a series of planned interventions that are listed in the Heysham 1 Integrated Intervention Strategy (IIS) 2015/2016. The inspection was undertaken by an ONR Principal Inspector with technical support provided by a C&I Specialist.   

Interventions Carried Out by ONR

In this intervention a SBI was carried out on the C&I systems important to safety that prevent hot steam and gas releases in the bottom cap areas of the reactor building. The arrangements in place to confirm the adequacy of implementation of relevant safety claims for these C&I systems were subject to compliance inspections performed against Licence Conditions (LC): LC 10 (training), LC23 (operating rules), LC24 (operating instructions), LC27 (safety mechanisms, devices and circuits), and 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. 

Explanation of Judgement if Safety System Not Judged to be Adequate

From this inspection I judge that overall the safety provisions applicable to the sample of C&I systems important to safety considered during this intervention for protection from hot steam and gas release meet the requirements of the living safety case and are adequate.

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

From an LC10 perspective, staff training records and profiles were judged to be in accordance with the requirements for the roles performed.  The Licensee demonstrated an effective knowledge and understanding in the areas of the living safety case examined. I judged the LC10 element of this inspection to be adequate, warranting an IIS rating of 3 (adequate).

From an LC23 and LC24 perspective, based on evidence sampled during this inspection, the implementation of the technical specifications, commentaries, and schedules were judged to have adequate alignment with the claims presented within the living safety case. I found that there was a clear link between the living safety case and operational documents. I judged the LC23 and LC24 element of this inspection to warrant IIS ratings of 3 (adequate) and 2 (good), respectively.

Based on evidence sampled during this inspection, I found that the Licensee’s list of essential systems included the hot steam and hot gas protection and is used by duly authorised persons to maintain compliance at the station. I considered the arrangements for LC27 to have been adequately implemented and warrant an IIS rating of 3 (adequate).

From an LC28 perspective, the Licensee demonstrated use of processes, procedures and records for the examination, inspection, maintenance and testing the hot steam and hot gas protection. I found two issues, one relating to a lack of clarity and consistency in relevant documentation regarding the Bottom Cap Hot Gas Release system temperature trip setting, and the other related to what appears to be a gap in the maintenance strategy that results in part of this system not being adequately tested. I judged the LC28 compliance element of this inspection to warrant an associated IIS rating of 4 (below standard).

Conclusion of Intervention

After considering the evidence sampled during the inspections undertaken against LCs 10, 23, 24, 27 and 28, I consider that the C&I systems important to safety that provide protection from hot steam and gas release satisfy the requirements of the living safety case. ONR Issues have been raised to manage the actions raised in relation to the shortfalls identified during the LC28 element of this intervention.

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