A site in Finland is set to use a labyrinth of underground tunnels for the storage of nuclear waste, in what could become a template for others to follow.
According to the World Nuclear Association, Finland is home to four nuclear reactors which provide almost 30 percent of its electricity.
The Olkiluoto 3 project is set to be Finland's fifth. Energy company Teollisuuden Voima Oyj (TVO) says that regular production at the unit is set to begin at the end of 2018. The unit's net electrical output will be around 1,600 megawatts (MW).
"One important change with Olkiluoto 3 is that it is big," TVO's Juha Poikola told CNBC's "Sustainable Energy". "Currently, the biggest power plant in the world is about 1,500 megawatts and this is 1,600, so the size is big … the dimensions are big," Poikola added.
Once OL3 is complete, TVO says that Finland will have taken a "long leap towards self-sufficiency in electricity production."
The plans for the storage of spent fuel in Finland look far ahead into the future and deep into the ground.
"For operational waste, like low and intermediate waste, we have a repository, an underground repository (at a)… depth of 60 meters in the bedrock," TVO's Anne Niemi said.
"And for spent fuel we have interim storage, waterproof storaging and a new underground repository for spent fuel is built in Olkiluoto (at)… the depth of 400 to 450 meters," Niemi added.
The design of the storage facility has taken into account the potential impact of earthquakes and even future ice ages. In addition, huge disposal canisters with copper exteriors have been designed to store spent fuel in bedrock for at least 100,000 years.
William D. Magwood IV is director general of the OECD's Nuclear Energy Agency. He told "Sustainable Energy" that what was happening in Finland was "really a mark for others to follow. They've made a lot of progress, and Finland will very likely have the world's first operating nuclear waste repository."
Back above ground, OL3 is now close to being operational. "Olkiluoto 3 is now in (the) commission phase," Poikola said. "Commissioning a nuclear power plant includes several stages and … We just passed one stage, which was a pressure test," he added.
"We tested that the primary circuit – a very important part of the power plant – is tight. There (were)… no leakages in the pressure test, so it's just one step towards commissioning." There were still many things to be done before electricity production started, he added.