Solving Nuclear Energy’s Biggest Problem
New methods like recycling in fast neutron reactors and geological disposal in facilities like Finland’s Onkalo are being explored.
Reprocessing spent fuel in closed fuel cycles can significantly reduce waste volumes.
Geological repositories like Onkalo offer hope for safe, long-term nuclear waste disposal.
As we go into a new nuclear energy era, there are renewed concerns about what to do with the waste generated from nuclear plants. Nuclear waste is toxic and can remain radioactive for around 10,000 years, meaning that it needs to be disposed of appropriately to ensure people and the environment are kept safe. Despite the challenges involved, several countries around the globe are pursuing new nuclear power agendas in support of a green transition and coming up with innovative ways to dispose of the radioactive waste produced at nuclear facilities.
The generation of nuclear energy results in the production of waste products. There are three types of nuclear waste: low-, intermediate-, and high-level radioactive waste. Most of the waste produced at nuclear plants consists of lightly contaminated items, such as tools and work clothing, with a level of around 1 percent radioactivity. High-level waste is made up of spent fuel, which accounts for around 3 percent of the total volume of waste from nuclear energy production, although it contains 95 percent of the radioactivity.
The nuclear industry is responsible for safely disposing of waste materials through the construction of disposal facilities. One of the positive things about nuclear power production is that it generates very little waste compared to other energy sources. Nuclear fuel is very energy-dense, meaning little is required to generate large quantities of electricity. Therefore, it produces little waste, around 5 grams of high-level waste for the provision of a person’s annual energy needs. A conventional 1,000 MW nuclear plant, which can supply over one million people with electricity, produces around three cubic meters of vitrified high-level waste per year, which is far lower than that produced in coal plants.
Nuclear energy companies must store spent fuel in either wet or dry facilities to be either recycled or disposed of. Spent fuel that comes out of the reactor is hot and radioactive, and storing it in water allows it to cool and the radioactivity levels to diminish. Several countries, including the U.S., treat this used fuel as waste. However, many countries recycle their spent fuel, including France, Japan, Germany, Belgium and Russia. Around 97 percent of spent fuel can be reused in certain types of nuclear reactors.
High-level nuclear waste can be used in fast neutron reactors operating in a closed fuel cycle. These reactors can extract between 60 to 70 times more energy than natural uranium than thermal reactors, which helps to boost efficiency and reduce radioactive waste. Mikhail Chudakov, the Deputy Director General and Head of the Department of Nuclear Energy at the International Atomic Energy Agency (IAEA) explains, “When using fast reactors in a closed fuel cycle, one kilogram of nuclear waste can be recycled multiple times until all the uranium is used and the actinides — which remain radioactive for thousands of years — are burned up. What then remains is about 30 grams of waste that will be radioactive for 200 to 300 years.”
While some countries are recycling their nuclear waste, using special reactors, others are looking for safe ways to dispose of it. Finland has plans to bury its spent nuclear fuel in the world’s first geological tomb, where it can be stored for 100,000 years. The project is viewed as groundbreaking for the nuclear energy industry, which has long been searching for a safe method of long-term waste disposal. If successful, it could be replicated in several areas of the world. In 2025 or 2026, the finish company Posiva hopes to begin packing spent nuclear waste into watertight copper canisters to deposit it in bedrock at a depth of 400 metres below the forests of southwest Finland. The long-term disposal facility, known as Onkalo, is located next to three nuclear reactors on the island of Olkiluoto.
Pasi Tuohimaa, the head of communications at Posiva, said that several nuclear energy companies had contacted Posiva to learn more about the project. Tuohimaa stated, “Having a solution for the final disposal of spent fuel was like the missing part of the sustainable lifecycle for nuclear energy.”
Gareth Law, professor of radiochemistry at the University of Helsinki, explained “There are many countries in the world that are still very much in the planning stages and even just trying to find somewhere to put the waste. So, the fact that Finland [has] built a repository now and in the next year or two we’re going to be operating it and start the disposal process … I don’t want to call it a miracle, but it wouldn’t be a bad way of framing it in the global context.”
Several countries around the globe, including the U.K. and the U.S. have long been searching for options for the safe, long-term disposal of nuclear waste, with limited success. The Onkalo project offers hope to the industry, with other countries expected to develop similar disposal methods in the future. In addition, in support of a global green transition, more countries are likely to invest in recycling schemes to reuse and reduce nuclear waste before seeking out disposal methods for the remaining waste.