20.02.2014 15:44

ONKALO ventilation is one step closer to being ready – inlet air shaft raise-bored

The inlet air shaft of the underground ONKALO research facility is now complete. The last stretch of the shaft from 455 m to 290 m was raise-bored in early February. The work, which lasted for about 1.5 months, was performed by the Swedish-based Bergteamet AB.

The shaft was raise-bored in four segments and will provide ONKALO with fresh air in the future. " The shaft was built through the technical facilities located at the depth of 437 metres. The raise-boring accuracy was as planned," says Kimmo Lehtola, construction superviser at Posiva.

In addition to the inlet air shaft, ONKALO includes two other shafts. The exhaust air shaft was completed at its final length (depth of 437 m) in early 2012. The personnel shaft has been raise-bored from the depth of 290 m to the ground. The boring of the last segment from 455 m to 290 m will commence in ONKALO in February. "The sealing of all shafts with cement and silica mass has been a great success. After the last segment of the personnel shaft has been raise-bored, we can arrange ONKALO's ventilation to its final form," says Lehtola.

"We will go through the shafts in the spring to find out whether reinforcement is needed. In the spring, additional reinforcement will be performed in ONKALO in any case. In addition, a steel concrete plug will be cast there later. Eventually, final disposal tunnels will be sealed with such plugs."

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.