The years of planning work are put to the test during the annual maintenance
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I've hired a couple of supervisors for myself so I can manage the annual maintenance with so many subcontractors," says maintenance engineer Onni Isokorpi. Despite being a busy man, he has additional responsibilities during the first annual maintenance of Olkiluoto 3, including several other systems in addition to the turbine. And all the work and inspections must progress to ensure the plant is soon ready for production. There are nearly 200 subcontractors working on the tasks.
The planning for the annual maintenance started well in advance. Concerning the turbine and its systems, it goes back several years to 2019. At that time, Isokorpi was involved in contract negotiations with Siemens where the initial outlines of the annual maintenance were agreed upon.
From there, the identification of spare parts for the upcoming first maintenance began. Later, necessary framework agreements were made with other subcontracting companies.
- Now all this planning is being put to the test, Isokorpi smiles.
- The annual maintenance has gone well in terms of work and personnel resources, Isokorpi continues. When the annual maintenance began on March 2nd, there was still a large number of necessary spare parts on their way. However, everything was delivered to Olkiluoto, and now it looks good.
The planning for the 2025 annual maintenance has already begun. We have a lot of lessons to take from this year's annual maintenance.
Inspections and component replacements
During the R324 annual maintenance of the turbine, all turbine bearings are inspected. For this, each outer casing of the 68-meter-long turbine shaft has been moved aside. Additionally, the last stage rotor blades of the low-pressure turbine no. 3 have been inspected. The inspection work didn’t require lifting the massive outer casing of the turbine; instead, it can be done by climbing up to the turbine via the steam pipe leading from the turbine to the condenser.
Inspections have been carried out on both the steam and seawater sides of the condenser, and based on these, coating damage on the seawater side has been repaired. A full service has been performed on the condenser vacuum pump, resulting in the ability to run the pump at lower power during operation.
Basic maintenance has been carried out on the main steam valves, and a larger maintenance operation has been performed on one of the bypass steam valves, including inspection and replacement of actuators. The hydraulic systems of the turbine valves have also been inspected and serviced. Behind all this inspection and maintenance is, of course, ensuring production runs as smoothly as possible.
Balancing tinkering and yard work
Isokorpi worked for PVO-Lämpövoima Oy until 2016. He holds a degree as a technician. After moving to TVO for the OL3 project, he worked as a device supervisor for pressure equipment for a year before being offered the opportunity to switch to turbine-side device supervision in 2017.
- I haven't regretted a single day. The versatility of the work and nice colleagues are the best parts of my job.
During annual maintenance periods, days can sometimes stretch as tasks need to be coordinated and problems solved. Isokorpi mentions that he likes to unwind from work by tinkering and doing yard work.
During the annual maintenance of OL1 and OL2 units, another supervisor manages the turbine, so perhaps after the OL3 annual maintenance, Isokorpi will have time for a small trip.
- Although there are moments of rush and tight schedules, no one has to go it alone. You can't handle these tasks alone. Helping hands have been available and offered, Isokorpi concludes before picking up the phone and once again focusing entirely on maintenance.
Text and photos: Tapani Karjanlahti
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