What is nuclear waste, and what do we do with it?

Nuclear fuel is very energy dense, so relatively small amounts are needed to produce immense amounts of electricity, compared to other energy sources. As a result, a correspondingly small amount of waste is produced.

A 1 GWe nuclear power station can supply electricity to millions of homes, yet it produces only about three cubic metres of solid high‑level waste each year when the fuel is recycled. By contrast, a coal‑fired power station of the same size produces around 300,000 tonnes of ash and more than six million tonnes of carbon dioxide every year.

Fission Fact: About 400,000 tonnes of used nuclear fuel has been produced since the first nuclear power reactor commenced operation in the 1950s. By contrast, over 60 million tonnes of electronic waste is produced worldwide annually.

Since the start of the civil nuclear power industry, nuclear waste has never caused harm to people. The popular misconception is that because certain parts of nuclear waste remain radioactive for billions of years, then the threat must be sustained for that period. However, this is not the case. Whilst remaining weakly radioactive for a few hundred thousand years, the radioactivity from the main component of the waste which could cause health problems will have decayed to safe levels within a few hundred years. 

We are surrounded by naturally occurring radiation, from the cosmic rays, rocks and building materials where we live, the food we eat, as well as the human body. Radiation is an unavoidable part of life on our planet, and life evolved and is thriving in this radioactive environment.  

If you want to read more about radiation and its health impacts, you can read more about it on ours  Radiation and Health pages.

Fission Fact: The dose rate from a nuclear waste repository would be almost 50 times smaller than the average background radiation. 

Used nuclear fuel is kept in either wet or dry storage facilities, before being recycled or disposed of. When used fuel is taken out of a reactor, it is both hot and radioactive and requires storage in water to allow the fuel to cool. The fuel can be kept in wet storage, or transferred into a dry facility after a period of initial cooling. Keeping the used fuel in temporary storage to allow both the heat and radioactivity to diminish makes the recycling and disposal easier. 

These are, however, not permanent storage solutions. Two main waste management strategies exist across the world: some countries have been recycling used nuclear fuel for decades; others have opted for direct disposal. This is fundamentally a strategic decision, taken at a national level and mainly driven by political and economic, as well as technological, considerations. 

Fission Fact: On average, the waste from a reactor supplying a person’s electricity needs for a year would be about the size of a brick. Only 5 grams of this is high-level waste – about the same weight as a sheet of paper. 

Most of the material in used fuel can actually be recycled. Around 97% of it can be reused, mainly uranium, which can be made into new fuel for certain types of nuclear reactors.

Recycling typically involves separating out uranium and plutonium, which can then be mixed with fresh uranium and turned into new fuel. Countries such as France, Japan, Germany, Belgium and Russia already use this approach to produce electricity, while also reducing the amount of long‑lasting radioactive waste. Only a small fraction of the material—about 4%—cannot be recycled. This remaining waste is safely managed by mixing it with glass, a process known as vitrification, before it is placed in a disposal facility.

Fission Fact: Orano Group have found that thanks to recycling, the volume of the most radioactive waste is reduced by 5 and its radiotoxicity by 10. In France, nearly 1 in 10 light bulbs run on recycled nuclear materials.

Direct disposal is, as the name suggests, a management strategy where used nuclear fuel is designated as waste and disposed of in an underground repository, without any recycling. The used fuel is placed in canisters which, in turn, are placed in tunnels and subsequently sealed with rocks and clay. The waste from recycling – the so-called fission products – will also be placed in the repository. 

Fission Fact: Repositories are nearing completion in for instance Finland, where the world's first Geological Disposal Facility (GDF) for spent nuclear fuel is expected to reach completion in 2026.