Executive summary
Date(s) of inspection:
November 2024
Aim of inspection
This was a planned Systems Based Inspection of EDF Energy Nuclear Generation Ltd’s (NGL’s) Heysham 1 power station, undertaken as part of the planned intervention strategy for the Operating Facilities Division (OFD) of the Office for Nuclear Regulation (ONR).
The purpose of this inspection was to examine the implementation of the safety case in relation to steam turbine overspeed protection systems (including safe and reliable operation of items that could put a demand on protection systems).
Turbine overspeed prevention systems are recognised as protecting against potential turbine disintegration.
Subject(s) of inspection
- LC10 - Training - Rating: GREEN
- LC23 - Operating rules - Rating: GREEN
- LC24 - Operating instructions - Rating: GREEN
- LC27 - Safety mechanisms, devices and circuits - Rating: GREEN
- LC28 - Examination, inspection, maintenance and testing - Rating: GREEN
- Overall Inspection Rating - Rating: GREEN
Key findings, inspector's opinions and reasons for judgement made
The inspection comprised of discussion with EDF NGL staff, sampling and review of site records and a plant walkdown of the turbine hall, reactor control room and stores.
Site Licence Condition 10 – Training
I examined EDF NGL’s arrangements for training those who have responsibility for operations relevant to the steam turbines and turbine protection systems, which included associated training and completion of Systems Handover Documents.
Site Licence Condition 23 - Operating Rules
The main steam turbine system has no Nuclear Safety claims and is not essential to reactor safety, however in the event of a turbine disintegration, possibly initiated by a turbine over-speed, the consequences could result in structural damage to adjacent plant. Subsequently I identified steam turbine speed/over-speed as a surrogate Operating Rule for the remainder of this inspection.
Licence Condition 24 - Operating Instructions
I sampled written instructions for overspeed testing comprising on load testing and turbine post overhaul trip testing in accordance with Company Technical Standards. I also examined a number of Station Operating Instructions to undertake Intermediate pressure turbine governor valve freedom of movement test using flow diagram methodology.
Site Licence Condition 27 - Safety Mechanisms, Devices and Circuits (SMDC)
I reviewed the latest system health indication programme (SHIP) scorecard for the steam turbine and turbine protection systems.
I discussed the management of equipment obsolescence with the System Engineers (SEs) and recent updated through life management plans. I also discussed equipment support contracts in place with original equipment manufacturers.
Site Licence Condition 28 – Examination, Inspection, Maintenance and Testing (EIMT)
I sampled a number of maintenance schedule routines. I reviewed the associated work instructions and completed checksheets,
I discussed current micro-governor maintenance arrangements with the responsible SE and reviewed a sample of associated maintenance Work Instructions. I also reviewed the supplied equipment reliability reviews and examined and reviewed a sample of plant walkdown reports.
Conclusion
Site Licence Condition 10 – Training
From the evidence sampled, I judged that EDF NGL met relevant good practice (RGP) and implemented adequate arrangements for suitable training for those who have responsibility for the steam turbines and turbine protection systems. No significant shortfalls were identified; hence I consider a GREEN rating (No Formal Action) to be appropriate for LC10 compliance.
Site Licence Condition 23 - Operating Rules
Overall, from the evidence sampled, I consider that EDF NGL has met RGP and adequately demonstrated that the steam turbines and turbine safety systems are operated in accordance with the safe operating parameters identified in the safety. No significant shortfalls were identified; therefore, I consider a GREEN rating (No Formal Action) to be appropriate for LC23 compliance.
Licence Condition 24 - Operating Instructions
From the evidence sampled I am content that EDF NGL are adequately operating the plant in accordance with written instructions with no significant shortfalls being identified; therefore, consider a GREEN rating (No Formal Action) to be appropriate for LC24 compliance.
Site Licence Condition 27 - Safety Mechanisms, Devices and Circuits (SMDC)
From the evidence sampled, I consider EDF NGL has met RGP, with no significant shortfalls identified. I am content that EDF NGL have suitable and sufficient safety mechanisms, devices and circuits properly connected and in good working order. I therefore consider a GREEN rating (No Formal Action) to be appropriate for LC27 compliance.
Site Licence Condition 28 – Examination, Inspection, Maintenance and Testing (EIMT)
From the evidence sampled, I consider that EDF NGL has met RGP and that that the maintenance and inspection activities are being adequately completed in accordance with schemes laid down in writing. I therefore consider a GREEN rating (No Formal Action) to be appropriate for LG 28 compliance.
Overall Judgement
From the evidence sampled during this SBI, I judged that there were no matters that have the potential to impact significantly on nuclear safety. Consequently, an overall rating of Green was considered appropriate for the steam turbine and turbine protection systems. ONR considers NGL adequately demonstrated ownership and implementation of the Steam Turbine systems safety case to ensure and maintain nuclear safety.