- Site: Heysham 2
- Inspection ID: 51921
- Date: August 2022
- LC numbers: 23, 24
Purpose of Intervention
The aim of this inspection was to gain confidence in the use of ESOP (Essential Systems Outage Program) Risk Monitor for Risk Informed Decision Making at HYB. This was a planned intervention and part of the 2022/2023 ONR integrated intervention strategy for operating reactors.
Subject(s) of inspection
The following actives were the subject of this inspection:
- LC23 – Operating rules (rating Green)
- LC24 – Operating instructions (rating Green)
A risk monitor uses the station Probabilistic Safety Analysis (PSA) risk models to provide real-time risk information on current and planned plant states. This information allows for risk informed operational and work planning decisions to be made. NGL currently use risk monitors at HYB, TOR and SZB.
HYB and TOR currently use the Essential Systems Outage Program (ESOP) risk monitor for the following primary purposes:
- Technical Specification and Limits and Conditions of Operation (LCO) compliance
- Operator aid to identify applicable plant conditions and LCOs
- Provide risk information to operators and work planners to inform decision making
NGL have launched the “ESOP Stabilisation project” which aims to upgrade the ESOP Risk Monitor Software at HYB and TOR. In parallel with this project, ONR is undertaking Risk Monitor inspections at HYB and TOR and a series of Level 4 engagements to gain confidence in the use of ESOP for risk informed decision making and to ensure that the ESOP Stabilisation project will achieve an updated Risk Monitor that is fit for purpose through to End of Generation (EoG) at HYB and TOR.
NGL demonstrated how ESOP is used for managing emerging plant unavailability and how it is used for work planning. I sampled a number of ESOP Records for previous plant unavailability scenarios and NSG assessments where ESOP results were used to extend Urgent Maintenance into Normal Maintenance. From the discussions with users and sampling records:
- I found that the users at station (CCR operators, WEC Engineers and NSG) are experienced and confident in using ESOP to comply with operating rules and operating instructions.
- In my opinion, adequate arrangements were available to integrate the use of ESOP into station operations.
- The ESOP software is judged adequate for current purposes, but it has a number of known issues and shortfalls. I am satisfied that HYB ESOP users are aware of these issues and have implemented suitable mitigations but the issues should be addressed in a timely manner via the ESOP Stabilisation Project to ensure that ESOP is fit for purpose through to the end of generation at HYB.
The inspection demonstrated that ESOP is integral to the day-to-day operation at HYB; and how it is used to comply with station Operating Rules and Operating Instructions required to manage emerging plant unavailability, extension of urgent maintenance into normal maintenance, work planning and release of plant for maintenance within the defined operating limits.In my opinion,adequate arrangements were available to integrate the use of ESOP into station operation.I judge that the users of ESOP at station are Suitably Qualified and Experienced in using ESOP to comply with the arrangements. Therefore, in my opinion, an inspection rating of GREEN is merited against LC23 (Operating Rules) and LC24 (Operating Instructions).
Whilst the ESOP software is judged adequate for current purposes, it has a number of known issues and shortfalls. Given the importance of ESOP to the day-to-day plant management and the fact that an ageing plant will increase the use of ESOP (necessitated by increased equipment failures and increased maintenance activities)I consider it essential that these issues are addressed in a timely manner via the ESOP Stabilisation project.
I identified a number of points of good practice but also made a number of observations, which were conveyed to the licensee in the post-inspection de-briefing meeting. A Level 4 Regulatory Issue has been raised to address a key observation made during the exercise with regards to discrepancies between the states where HYB arrangements rely upon ESOP and the scope of the underlying PSA model.