Further contract for Finnish repository construction

29 August 2019

Finnish waste management company Posiva has awarded a contract to YIT, the country's largest construction firm, for the second phase of excavation works at the Onkalo repository near Olkiluoto. The contract - worth about EUR17 million (USD19 million) - covers the excavation of two more central tunnels and five deposition tunnels connected to them.

An artist's impression of the planned Onkalo repository (Image: Posiva)

Work under the contract is scheduled to begin towards the end of this year and is expected to take about two-and-a-half years to complete.

Posiva said the deposition tunnels to be excavated are "unique on a global scale and subject to exceptionally strict quality requirements".

"This one-of-a-kind EKA project we have launched covers not only excavations for the final disposal facility, but also the encapsulation plant as a whole and the systems which are needed to begin final disposal in the rooms that have already been excavated," said Posiva CEO Janne Mokka. "Upon the completion of this contract, we will have excavated in Onkalo the first deposition tunnels approved by the Finnish Radiation and Nuclear Safety Authority STUK for the execution of final disposal."

YIT has already successfully completed two excavation contracts for Posiva. In November 2016, Posiva signed a contract, worth some EUR20 million (USD22 million), with YIT covering a period of about two-and-a-half years and including the excavation of the repository's first central tunnels, as well as the vehicle access tunnels to them. That contract also included preparatory excavations as well as rock sealing works in preparation for the raise boring of a canister shaft where the canister lift will later be installed. Excavation works for the canister receiving station at the depth of about 430 metres were also part of the contract.

"During our previous contracts, our cooperation with Posiva was very smooth and we are very pleased to be able to continue this cooperation through such a challenging new contract," said Aleksi Laine, YIT's senior vice president for rock and special engineering. "YIT has a lot of experience in demanding tunnel construction and for us, this new contract represents an interesting opportunity to leverage the strong competence we have."

The site for Posiva's repository at Eurajoki near Olkiluoto was selected in 2000. The Finnish parliament approved the decision-in-principle on the repository project the following year. Posiva - jointly owned by Finnish nuclear utilities Fortum and Teollisuuden Voima Oyj - submitted its construction licence application to the Ministry of Employment and the Economy in December 2013. Posiva studied the rock at Olkiluoto and prepared its licence application using results from the Onkalo underground laboratory, which is being expanded to form the basis of the repository. The government granted a construction licence for the project in November 2015. Construction work on the repository started a year later. Posiva is still required to obtain a separate operating licence for the facility. Operation of the repository is expected to begin in 2023.

Researched and written by World Nuclear News