The world’s nuclear power plants have produced an estimated 448,000 tonnes (494,000 U.S. tons) of spent nuclear fuel, highlighting both the scale of global nuclear energy production and one of the industry’s most persistent long-term challenges: what to do with the waste once reactors have finished using it.

The figure comes from a newly released interactive mapping tool developed by the International Atomic Energy Agency (IAEA), offering what the agency describes as the most comprehensive publicly available picture yet of where the world’s spent nuclear fuel is located and how it is being managed.

The tool arrives as many countries are expanding or reconsidering nuclear power as a low-carbon energy source, placing renewed attention on how radioactive waste is stored, recycled, and ultimately disposed of.

A global snapshot of nuclear waste

According to the IAEA, the newly launched Global Spent Nuclear Fuel Inventory Tool draws on data submitted by countries under the Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste Management.

The interactive platform allows users to explore spent-fuel inventories by country, region, and storage method, replacing decades of fragmented estimates with a single, standardized dataset.

The IAEA estimates that roughly 448,000 tonnes (494,000 U.S. tons) of heavy metal, the standard unit used to measure uranium and other heavy elements in reactor fuel, have been discharged from nuclear power reactors worldwide.

Of that total, approximately 322,000 tonnes (355,000 U.S. tons) remain in storage, while around 126,000 tonnes (139,000 U.S. tons) have been reprocessed. Reprocessing allows some usable materials to be recovered and manufactured into new nuclear fuel, reducing both the demand for freshly mined uranium and the volume of high-level waste requiring disposal.

Where the fuel is stored

The data also provides insight into how countries manage spent nuclear fuel after it leaves a reactor. According to the IAEA, about 41% of the world’s spent fuel inventory is currently held in wet storage systems. These are typically water-filled pools at reactor sites where fuel assemblies are cooled and shielded after being removed from the reactor core.

Another 31% is stored in dry storage systems, including concrete casks, metal containers, storage buildings, and modular facilities designed to safely contain radioactive material without relying on water for cooling.

The agency notes that many countries have gradually shifted older fuel from wet pools into dry storage over the past several decades, reflecting evolving waste-management strategies and the need to free up reactor storage capacity.

Among dry-storage technologies, ventilated vertical storage units account for the largest share, holding more than 50,000 tonnes (55,000 U.S. tons) of spent fuel worldwide.

Why does spent fuel remain a major challenge

While nuclear power produces very low operational carbon emissions, spent fuel management remains one of the industry’s most debated issues. Used nuclear fuel remains highly radioactive and continues to generate heat long after it is removed from a reactor. As a result, it must be carefully managed for decades and, in some cases, thousands of years.

Most countries currently rely on interim storage systems while developing long-term disposal solutions. Finland is preparing to commission the world’s first deep geological repository for spent nuclear fuel, a facility designed to isolate radioactive material deep underground for extremely long periods. Several other nations are pursuing similar strategies.

The IAEA says the new inventory tool is intended to support technical analysis and help policymakers, researchers, and the public better understand how different countries are approaching this challenge.

Bringing transparency to a growing industry

As global interest in nuclear energy grows, so too does the importance of understanding what happens after fuel leaves a reactor. “The newly developed IAEA spent fuel data tool provides a transparent and accessible platform for exploring spent fuel management strategies across Member States,” said Amparo Gonzalez Espartero, Technical Lead in the IAEA Division of Nuclear Fuel Cycle and Waste Technology.

By bringing together information from countries around the world into a single interactive platform, the agency hopes to improve transparency and support informed discussions about one of nuclear energy’s most important long-term responsibilities.

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