25.06.2014 15:54

A world first

Special. New. Educational. Requiring know-how and precision. Surprising. Interesting. There are many ways to describe the big ten-year project. At Posiva, these attributes refer to the construction of ONKALO which commenced in summer 2004, opening a path to a totally new research world.

Posiva's construction controller Kimmo Lehtola and research manager Kimmo Kemppainen have overseen the ONKALO underground research facility project right from the initial blast.

"This has been a special project alright. We have seen the full palette of rock construction techniques being put into use. This has given us the perfect opportunity to learn new methods in rock construction", says Mr Lehtola.

"At the start of construction, I was enough of a novice myself that I did not have the imagination to envision the finished/completed ONKALO. After excavating the first 300 metres, we understood that we needed to take another look at the plans. The first change was implemented quite soon", says Kemppainen.

However, the mission of ONKALO remained unchanged during the construction project. It has provided Posiva with essential information about rock construction and the prevailing conditions in the Olkiluoto bedrock.

1400134044 kimmot2
Have a question about ONKALO? These two Kimmos know the answer. Posiva's Kimmo Lehtola and Kimmo Kemppainen have been involved in the ONKALO construction project from its inception.

Technology catering for construction needs

Over the past ten years, ONKALO has taught many lessons to those involved in the project, and to the Posiva organisation as a whole. If boring-drilling experts are required during an excavation, ONKALO builders are first in line in terms of talent.

"Over the years, I have learned new things about construction development, as well as construction as a whole and contractual matters", says Lehtola.

The ONKALO project has also led to the development of new technologies. When an ONKALO-customised rock reinforcement bolt was needed for construction, we developed it in tandem with a trusted partner.

One should be ready for surprises, as this is the first time a research facility has ever been built to cater for the needs of a final disposal project related to spent nuclear fuel. Even though the plans had been carefully drawn up and were kept updated, the precision nature of the work (requiring simultaneous construction and research processes) and the maximising of industrial safety made for a particularly challenging scheduling process.

"It is easy for outsiders to say that should be able to plan more reliably. We must keep in mind that we are the first operator in the world to do almost all these things and we really want to thoroughly explore all of our findings. For example, almost every rock hole takes a surprising amount of time to survey ", says Kemppainen.

 New efforts with the same levels of enthusiasm

Even though the ONKALO vehicle access tunnel has been excavated at its planned depth (455 m), Lehtola and Kemppainen will have more tasks related to the underground research facility.

Research is still being performed at ONKALO and preparations are being made for large-scale testing.

"The researcher is the last one to switch off the lights", says Kemppainen.

Lehtola's tasks this year include ONKALO shaft reinforcement, amongst other things. New shafts will be built later.

"Were I again given the challenge of building ONKALO to the same scope, I would do it again just as enthusiastically", says Lehtola.

Return to headlines

Share article:
This website stores cookies on your computer. These cookies are used to improve our website and provide more personalised services to you.


To make this site work properly, we sometimes place small data files called cookies on your device. Most big websites do this too.

1. What are cookies?

A cookie is a small text file that a website saves on your computer or mobile device when you visit the site. It enables the website to remember your actions and preferences (such as login, language, font size and other display preferences) over a period of time, so you don’t have to keep re-entering them whenever you come back to the site or browse from one page to another.

2. How do we use cookies?

A number of our pages use cookies to remember your actions and preferences (such as login, language, font size and other display preferences.)

Also, some videos embedded in our pages use a cookie to anonymously gather statistics on how you got there and what videos you visited.

Enabling these cookies is not strictly necessary for the website to work but it will provide you with a better browsing experience. You can delete or block these cookies, but if you do that some features of this site may not work as intended.

The cookie-related information is not used to identify you personally and the pattern data is fully under our control. These cookies are not used for any purpose other than those described here.

3. How to control cookies

You can control and/or delete cookies as you wish – for details, see You can delete all cookies that are already on your computer and you can set most browsers to prevent them from being placed. If you do this, however, you may have to manually adjust some preferences every time you visit a site and some services and functionalities may not work.