Under the radar: Safeguarding nuclear waste for millennia
How to secure radioactive waste repositories? When radioactive barrels were prohibited from being dumped into the seas, inactive mines and underground shafts became the preferred solution. Mutated plants and radioactive cats have been proposed as guardians for these contaminated landfills.
What happens to a nuclear-powered ship when it becomes outdated and is taken out of service, usually after several decades? The United States has developed a special procedure, the Ship-Submarine Recycling Program (SRP), for the safe dismantling of nuclear-powered vessels.
Over 100 American nuclear submarines have undergone the dismantling process, along with nuclear cruisers and the aircraft carrier ex-Enterprise. Decommissioned ships retain their names during dismantling, prefixed with "ex-". Likely in 2026, the first Nimitz-class aircraft carrier, USS Nimitz, will also be scrapped, possibly on its final voyage with the US Navy.
The hull of a vessel is scrapped like any other, but nuclear-powered ships must first be stripped of their nuclear fuel and then the reactor modules.
The fuel is transported to the Naval Reactors Facility in Idaho, and the propulsion elements are carried by train to the Hanford site in Washington state, where they end up in a nuclear dumpsite called Trench 94.
To ensure the safe transport of potentially dangerous ship parts, a special train (or rather a transport system) called Atlas was built. The 16-axle platform, approved for travel on ordinary railroad tracks, can transport loads exceeding 200 tonnes, monitoring radiation levels along the entire route.
Atlas faces a significant challenge, as the U.S. Department of Energy estimates that by 2060, it will need to transport up to 140,000 tonnes of spent nuclear fuel and radioactive materials. Where should such massive quantities of hazardous waste be stored?
For nearly 70 years, various countries facing this challenge have been trying to find optimal solutions.
Radioactive waste in the sea
For years, the largest producers of radioactive waste disposed of their problem simply by dumping it into the sea. Hundreds of thousands of tonnes of waste from the United States, the UK, Switzerland, France, and the UK were sunk in various basins, and this practice was banned only in 1993.
The Soviet Union also dumped significant amounts of waste. The Russians dealt with the problem by sinking not just containers but also entire ships filled with waste and reactors containing fuel or, as in the case of the K-27 submarine, an entire vessel with a complete nuclear power plant.
The scale of this operation was so dangerous that Western countries like Germany and Norway funded the construction of a storage facility for Russia in the Saida Bay (Sajda Guba) near Murmansk. The storage facility, opened in 2008, was presented by Russian propaganda as a success for the Putin administration.
The agreement allowing the funding countries to oversee the proper securing of waste was terminated by Russia in November 2024.
Underground waste repositories
Ultimately, all these actions are merely stopgaps. Safe and long-term storage of waste that may remain hazardous for thousands of years is expected to be achieved through deep geological repositories. These underground storage facilities are located in geologically stable structures, with no risk of underground water circulation. Radioactive waste is sent there for long-term–from a contemporary human perspective, eternal–storage.
Currently, several such facilities are either operational or under construction worldwide, with plans to store radioactive waste several hundred metres underground.
Examples of such repositories include the Swedish Äspö Hard Rock Laboratory, the Belgian HADES Underground Research Facility, and the Finnish Onkalo (which means "hidden place" in Finnish). The deepest repository, the Mizunami Underground Research Lab, is currently being built by Japan and aims to store waste in granite shafts at a depth of about 1,000 metres.
Nuclear monastic order and radioactive cats
The construction and planning of such facilities come with a significant challenge: not only ensuring their immediate security but also marking them in a way that the dangers within are understandable to both contemporary humans and our distant descendants, who may encounter them in 1,000 or 10,000 years.
This challenge is even greater given that we do not know what language future explorers will speak, which cultural codes they will be familiar with, or what level of technological development they will have reached. If they are not adequately warned, they will undoubtedly breach these sites—much like past explorers who entered ancient ruins without knowing their contents or purpose, nor understanding the builders' language or symbols.
This is why the United States, planning the security of the Waste Isolation Pilot Plant (WIPP), established a group called the Human Interference Task Force, comprising engineers, anthropologists, nuclear physicists, and behavioural scientists. Their task was to develop a method for preserving knowledge about hazardous waste for thousands of years.
Among the ideas was creating a "nuclear monastic order" which, in the manner of religious beliefs, would perpetuate the fear of the repository over the ages. Stanisław Lem, involved in the effort, proposed cultivating plants that, due to genetic modifications, would grow only in contaminated areas.
French philosophers displayed remarkable creativity, suggesting cats be used as carriers of warnings. They assumed that these animals would continue to accompany humans in the future, as they have for thousands of years. The cats would be genetically modified to change colour in response to radiation, and fear of the locations where cats change colour would be instilled into culture through stories or songs.
A warning that will last thousands of years
Ultimately, the task of developing warnings to protect future explorers from accidentally entering the WIPP was entrusted to the Department of Energy, which is working on a marking system called Passive Institutional Controls.
Aside from graphical information, the markings will include above- and underground installations with information, various markers, granite pillars outlining the repository above ground, and metal elements pointing to the location of underground stores.
Additional information in many languages is to be stored in archives scattered around the world—all to avoid the risk that knowledge of the hazardous waste might be forgotten in the future. This comprehensive marking system is expected to be ready by 2033.
