World's first waste repository build contracts confirm cost, schedule targets

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.

(Image credit: STUK's 2014 report on the safety of spent fuel management.)

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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.

Tunnel vision

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.

                           Finland's spent fuel storage, inventory

                                                   (Click to enlarge)

Source: STUK (Finland's Radiation and Nuclear Safety Authority).

Moving ahead

France and Sweden have also made progress towards building their first final waste repositories but Finland remains ahead after decades of planning.

ANDRA, France’s National Radioactive Waste Agency, is developing a high and intermediate level waste repository in northeast France and aims to start operating the facility in 2025.

Sweden's radioactive waste management company SKB plans to start construction of a final repository and encapsulation facility in the 2020s and construction is expected to take around 10 years.

Posiva's project at Olkiluoto benefits from a relatively simple waste inventory as the only high-level waste to be stored will be spent fuel from nuclear power plants, Hautakangas told the webinar.

In addition, the Finnish government handed the development responsibility to operators early in the process and this has facilitated relatively fast and pragmatic decision-making at all levels, he said.

Finland's more recent nuclear power build projects have also allowed it to benefit from experiences in other countries, Hautakangas added.

"It has given us the advantage to learn from the environments of requirements and legislations in other countries...We have been in a position to pick out the good parts," he said.

Like most countries, Finland has had to respond to local groups opposing the siting of new nuclear waste facilities.

Around 100 potential repository sites were identified when the site selection process began in 1980s, but this was reduced to just two existing nuclear power plant sites-- Loviisa and Olkiluoto-- for the final site decision, Hautakangas said.

"It seems to be that the only place where you can really have repositories are those places where you already have nuclear installations," he said.

Nuclear Energy Insider