Maintenance Services at Olkiluoto Nuclear Power Plant

The Olkiluoto Nuclear Power Plant is located on the Olkiluoto Island on the Eura River and it is owned by Teollisuuden Voima Oyj (TVO). The nuclear power plant units Olkiluoto 1 and Olkiluoto 2 (OL1 and OL2) consist of two BWRs (boiling water reactors), each producing 890MW of electricity. OL1 was first connected to Finland’s national grid in September 1978 and OL2 followed in February 1980. Since then, Teollisuuden Voima Oyj (TVO) has systematically modernized the OL1 and OL2 plant units during annual outages and modernization projects to ensure safe and efficient operations, currently planned until 2038. Heatmasters was on-site again during this year’s annual outage, utilizing our heat treatment solutions during the repair of valves in OL1 and OL2.

Annual Outages 2020

This year, the annual outages at the OL1 & OL2 plant units were carried out with some adjustments due to the ongoing COVID-19 pandemic. There were several measures taken to safeguard the health and safety of every individual involved in the annual outages. All larger maintenance works which were not critical in terms of safety or availability were postponed to a later date. However, there were still multiple significant works taking place including reactor refueling. With a total of 730 contractor employees, 4800 work phases were carried out. The total duration of the annual outages was approximately four weeks.

Heatmasters On-Site Heat Treatment

During the project, Heatmasters was working with Recion Oy, a leading industrial service provider carrying out projects throughout Europe and delivering prefabricated products globally with niche expertise in high-pressure piping solutions.

Heatmasters provides custom-tailored heat treatment solutions and industrial services anywhere in the world, with a focus on flexible and cost-efficient solutions that do not compromise on quality. Our operators are specialized in on-site works taking place across a multitude of industries with high-standards and quality requirements. For this project, in addition to their decades of heat treatment experience, our operators required additional background checks and multiple safety certificates related to working at the plant.

Our wizards were already familiar with the work being done as they had prior experience working at the plant units during previous years. The maintenance work went smoothly, even though the current COVID-19 situation added some things to take into consideration. Upon arriving at the site, our heat treatment specialists passed through a disinfection station and were given personal protective equipment such as masks. They also received detailed instructions in advance from TVO’s annual outage coronavirus group at the site.

During the first week, our team transported equipment to the site in OL2 and prepared everything for heat treatment. Transporting equipment to the site is always a complex process within facilities such as nuclear power plants due to strict safety measures and reporting. Our heat treatment operators utilized our HM406T transformer with several resistive heating mats during this project.

The HM406T2 is a semi-automatic preheating unit, suitable for on-site preheating of metal parts. These thyristor-controlled transformer units have been designed with usability in mind, their simple and lightweight structure allows effortless mobility and efficient pre-heating at any location. Along with our experienced operators, it was the perfect solution for this project which required moving around on-site.

Due to the location of the job, there were further restrictions regarding loose equipment & tools. This meant we could not attach heating mats to parts being treated with clips and bands as is usually done. Our heat treatment specialists on-site had a creative solution and used thermocouple wire to attach the heating elements to the valves which were being pre-heated.

“This year, annual outages were completed successfully despite exceptional circumstances.” – TVO

After the first week, pre-heating had gone well, and one valve was repaired in OL2 and our team moved to the other plant unit. At OL1, two valves would be pre-heated & repaired. Moving equipment from one plant unit to the other did not take as long since it was already at the plant area, which was taken into consideration during planning and we had two valves that required pre-heating at OL1.

Olkiluoto Nuclear Power Plant with Visualization of OL3 unit which is currently under construction.

Of course, all heat treatment processes were digitally documented, and the process was done in accordance with our extensive quality management system, ensuring the highest level of customer service and quality. The work phases were completed successfully and the annual outages of 2020 were completed as the Olkiluoto 1 plant unit (OL1) was once again connected to the national grid and electricity production on the 8th of June, 2020.

”Working with the Heatmasters team at Olkiluoto Nuclear Power Plant during the annual outage maintenance works has been great, in a working environment which presents extremely challenging conditions and high-standards.”
-Miika Vähäkangas, Welding Coordination & QC/A, Recion Oy

In addition to on-site pre-heating and post-weld heat treatment (PWHT), Heatmasters provides custom-tailored solutions including:

• Heat treatment of large workpieces in fixed or portable temporary furnaces
• Refractory dry-outs
• Wide range of industrial services (NDT, surface treatment, welding, etc.)
• High-tech heat treatment equipment (furnaces, transformers, temperature control systems, etc.)
• Modernizations for all manufacturer’s heat treatment equipment

Images: Hannu Huovila / TVO.