Executive summary
Date(s) of inspection:
- November 2023
Aim of inspection
Confirm that arrangements in place for management of plant material condition (in particular corrosion management) are adequate.
Confirm that the associated arrangements in relation to the following Licence Conditions (LCs) are being correctly implemented:
- LC27: Safety Mechanisms, Devices and Circuits (SMDCs).
- LC28: Examination, Inspection, Maintenance and Testing (EIMT).
- LC29: Duty to carry out tests, inspections and examinations
- Pressure Systems Safety Regulations (PSSR).
Subject(s) of inspection
- LC27 – Safety mechanisms, devices and circuits – Rating: Green
- LC28 – Examination, inspection, maintenance and testing – Rating: Green
- LC29 – Duty to carry out tests, inspections and examinations – Rating: Not rated
- PSSR – Rating: Green
Key findings, inspector’s opinions and reasons for judgement made
The aim of the inspection was to confirm adequate arrangements were in place related to material condition following experience from recent failures in the turbine hall. In addition, I selected the essential diesel system as this system previously suffered from material condition issues. The inspection was performed under three licence conditions (LC27, 28 and 29) and Pressure Systems Safety Regulations (PSSR). There is strong link between LC28 and PSSR and given the experience of failures in the turbine hall, these areas and systems often fall under both aspects of legislation. LC27 was sampled in areas where safety mechanisms were considered. There was no requirement to implement any specification of inspections under LC29 therefore this was unrated.
Turbine hall
Steam leaks are being well managed generally from what I witnessed. I saw areas where leak management was not present which can cause water ingress through lagging, giving rise to potential degradation. Station is making good progress on initiating the independent Atkins assessment and I noted the good collaboration with central and other stations through revised arrangements in relation to PSSR, all the KPIs are green and I am confident compliance can be sustained under the current regime.
There are good aspects witnessed and discussed to improve management of steam systems, station need to keep this momentum. In particular, an improved use of the leak management database may assist in this. There are still many lower level defects, this was the nature of those we witnessed during our plant walk down. It would be prudent to clear some of the lower defects before they become more significant, recognising the balance with other potentially more significant defects.
Nitrogen (secondary shutdown) and Essential Diesels
Back in 2016, I visited this area and the condition of the roof equipment was either in a unknown or degraded condition without any structured inspection regime. At the time, there were some clear strategies and remediation on-going to improve this and it is now clear that this has continued, with most of the equipment in a good condition or planned for remediation in the near future (rolling programme).
An aspiration of 10-15 design life seems achievable noting the new coating methods and preventative maintenance routines in place. I did note lagging methods were different to what I have seen elsewhere. I have suggested this is discussed more widely in fleet meeting to ensure consistency. The diesel engine room was well maintained with good work area with all plant looking organised and tidy. The fuel storage tanks were in good condition, with no obvious no change since last inspection (2016). I saw evidence of good knowledge of the systems and proactive management of plant, particularly good demonstration of corrosion management knowledge and in particular, good sharing of OPEX, e.g. water hammer and corrosion knowledge.
Conclusion
Based on the sample conducted, I am satisfied that the station demonstrated compliance against Licence Condition 28 and Pressure Systems Safety Regulations with no significant shortfalls. I identified some areas where I provided advice to station. On this basis, I have rated this inspection green.