Office for Nuclear Regulation

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Heysham 2 - Flood Themed Inspection

Executive summary

Purpose of Intervention

The purpose of this intervention was to conduct a Licence Condition (LC) compliance inspection of EDF Energy Nuclear Generation Limited’s (NGL’s) Heysham 2 power station with an external flooding theme. This was undertaken as part of a series of planned interventions that are listed in the Heysham 2 Integrated Intervention Strategy for 2018/19.

The inspection was undertaken by the ONR nominated site inspector for Heysham 2, an ONR Civil Engineering specialist inspector, an ONR External Hazards specialist inspector and an ONR External Hazards nuclear associate.

Interventions Carried Out by ONR

We performed an external flooding safety case informed inspection to judge the licensee’s compliance against specified Licence Conditions. External flooding hazards to the site may arise from a number of sources, i.e. coastal, pluvial, fluvial and snow melt. Through examination of these hazards and the structures, systems and components (SSCs) which protect against them, compliance inspections were performed against the following Licence Conditions (LC) which are provisions of the Energy Act 2013:

The inspections were based on sampling the implementation of the licensee’s arrangements at Heysham 2 against the LCs. The objective of the inspection was to determine whether the licensee’s arrangements were adequately implemented and in accordance with the external flooding safety case requirements. The day after this intervention a similar external flooding inspection was conducted at the adjacent Heysham 1 power station and SSCs applicable to both sites, such as the sea wall, were included in the scope of the two interventions.

The intervention was performed in line with ONR's guidance requirements (as described in our technical inspection guides) in the areas inspected.

Explanation of Judgement if Safety System Not Judged to be Adequate

No safety system inspection was undertaken, hence this is not applicable.

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

During the course of this intervention, it was found that Heysham 2 has arrangements to ensure that personnel, procedures and SSCs claimed within the external flooding safety case are, and will remain, adequate. We observed a number of modifications to plant implemented in recent years which substantially improve its resilience against external flooding. The arrangements examined complied with the licensee’s legal duties based on the areas sampled during the inspection.

The LC10 (Training) inspection focussed on the implementation of arrangements for suitable training resulting from the installation of Japanese Earthquake Response (JER) equipment and post Fukushima flood/weather resilience enhancements. We judged that compliance with LC10 met ONR’s expectations and hence assigned an inspection rating of Green.

The LC11 (Emergency Arrangements) inspection focussed on the implementation of emergency arrangements for adverse weather, in particular external flooding events. We judged that compliance with LC11 met ONR’s expectations and hence assigned an inspection rating of Green.

Our inspection of LC23 (Operating Rules) aspects highlighted that the licensee’s response to external flooding hazards involves guidance and options in Station Operating Instructions (SOIs) which allows operators to make judgements on the best course of action in the light of their training, the prevailing conditions, data from the Met. Office and other relevant factors. Hence there are Operating Instructions relating to external flooding hazards but no Operating Rules. We judged that compliance with LC23 met ONR’s expectations, taking account of compliance with LC11 (see above) and LC24 (see below), and hence assigned an inspection rating of Green.

The LC24 (Operating Instructions) inspection focussed on the check for adverse weather forecast, etc in the SOI regarding  “Normal Operations of Unit at Power” and supporting SOIs to which it refers. We discussed the application of these SOIs, the briefing of duty Emergency Controllers by the Central Control Room (CCR), the operator response to specific plant failures arising from flooding and extreme weather and decisions to deploy dam boards or shutdown a reactor. We judged that compliance with LC24 met ONR’s expectations and hence assigned an inspection rating of Green.

The LC25 (Operational Records) inspection focussed on the recording of and learning from extreme weather events. We discussed the site’s weather monitoring systems, sampled relevant SOIs and discussed post-job debriefs for Operational Alerts to examine the use of Operational Experience Feedback (OPEX) to drive improvements and develop appropriate action levels in the event of flooding. We judged that compliance with LC25 met ONR’s expectations and hence assigned an inspection rating of Green.

Conclusion of Intervention

After considering the evidence examined during the sample inspection undertaken against Licence Conditions 10, 11, 23, 24 and 25, we concluded that the licensee complied with its legal duties regarding external flooding hazards and met the requirements of the safety case.

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