Early construction deals for Finland’s final waste repository indicate costs meet expectations but commodity price rises remain a risk over the long term, Sami Hautakangas, Head of Spent Fuel & Disposal Services at Fortum, co-owner of repository developer Posiva, said.
In December 2016, Posiva began construction on a 6,500-tonne final waste repository, the world's first permanent underground nuclear waste storage facility, on Olkiluoto island, Finland.
Finland's government awarded a construction permit for the project in November 2015 and a year later Finland’s Nuclear Safety Authority authorized works to begin. The facility is expected to be operational by 2024.
The final disposal facility will consist of an above-ground encapsulation plant, where spent fuel will be dried and packed into final disposal canisters made of copper and cast-iron, and a repository consisting of a network of tunnels deep inside the bedrock.
Posiva, which is jointly-owned by nuclear utilities Fortum and TVO, is to execute repository excavation work in a series of eight phases, which will allow investments to be broken down into portions over time and provide new site data to aid subsequent construction decisions.
Many first-of-a-kind nuclear new build and decommissioning projects have seen project schedules slip and cost estimates balloon from initial estimates.
Posiva's construction phase procurement costs indicate the developer’s original cost estimate and schedule is "more or less in the right place," Sami Hautakangas, Head of Spent Fuel & Disposal Services at Fortum, told the Future of Nuclear Decommissioning & Waste Management Europe webinar on April 13.
Going forward, the cost of key materials-- such as copper and bentonite-- will remain a project risk due to the long timelines involved, Hautakangas noted.
"There are risks, but at the moment it seems that when it comes to the construction itself, it seems to be nicely [within] budget and timetable," he said.
In December, Posiva signed a 20 million-euro ($21.3 million) contract with contractor YIT to commence construction of the first excavation tunnels. The contract with YIT covers the excavation of the first central tunnels and vehicle access tunnels and this phase is expected to take around two and a half years to complete.
Posiva has calculated it will require 137 disposal tunnels to accommodate current spent nuclear fuel projections, equating to 42 kilometres of tunnels within an area of 2 to 3 square kilometres. An estimated 2,800 final disposal canisters will be required.
Posiva has already drilled down some 455 metres to the final disposal level. Since 2004, the developer has been collecting scientific data on the bedrock from its Onkalo underground research network facility, consisting of tunnels and shafts leading down to the final disposal level.
Data from the tunnels was used in the construction licence application submitted in 2012 and approved by the government in 2015. The Onkalo network has also allowed the developers to improve excavation techniques and final disposal techniques in real-life conditions.
New types of machinery and equipment have been developed to carry out the excavation and placement of disposal canisters. These include specialised boring rigs, canister hole boring devices, bentonite buffer installation devices, as well as canister installation and tunnel backfilling vehicles.
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