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150,000 Tons of
Radioactive Waste Were Dumped in The Atlantic. Decades Later, It's Visibly
Oozing.
The second half of the 20th century was something
of a golden age for nuclear technology. Following the atomic devastation of WWII, the world
found new, more benign uses for radioactive decay. Power plants, medical
treatments, scientific research, and industry all blossomed under a
benevolent nuclear glow. But with the nuclear revolution came a significant
problem – what to do with all the thousands of tons of radioactive waste
generated in the excitement. For Europe, the solution was relatively simple. There was a perfectly good seafloor at the bottom
of the Atlantic Ocean that, as far as the authorities were concerned, no one
important was using. So, between 1949 and 1982, that's where it went –
more than 200,000 barrels of low-level radioactive waste, totaling more than
150,000 tons, mostly dumped at depths between 3,000 and 5,000 meters (9,840
and 16,400 feet). For decades, no one really knew what had become of
them. Now, scientists have descended to the wreckage in a
crewed submersible to investigate – and found many of the barrels corroded
and degraded, their contents spilling across the seafloor. Surprisingly, this isn't necessarily a subversion
of the original plan. Radioactive waste categorized as low-level, or LLW,
doesn't mean that it's not hazardous. It comes from sources such as medical
and industrial use and typically contains lower levels of long-lived
radionuclides. The International
Atomic Energy Agency recommends that LLW be
disposed of in robust containment in isolation for at least a few hundred
years – but back in the mid-20th century, the recommendations were a little
different. The contemporaneous guidelines recommended that
containers needed to reach the seafloor intact and remain sealed only long
enough for the short-lived radionuclides to decay.
After that, the remaining waste was expected to slowly
escape and disperse through the surrounding ocean. Not everything in the barrels would conveniently decay
away, however. They contained a radioactive hodgepodge, including cesium-137,
plutonium isotopes, and tritium, some of which can persist for thousands of
years. When the dumping stopped in the 1980s, everyone pretty
much just dusted off their hands and walked away. The precise locations and
conditions of the barrels remained poorly known for decades. But then, a few years ago, nuclear engineer Patrick
Chardon and marine geologist Javier EscartÃn of the French National Center for Scientific Research
started to wonder what had become of the dumped waste. That question eventually became NODSSUM – Nuclear Ocean Dump Site Survey Monitoring – an
interdisciplinary project bringing together nuclear physics, geology,
oceanography, biology, and marine chemistry to find the barrels and
investigate what, if anything, they were doing to the surrounding
environment. The first expedition set sail in
June 2025
aboard the research vessel L'Atalante. In this first foray, the
team sent
an autonomous underwater vehicle called UlyX
sweeping across the seafloor to map and photograph the barrels,
while collecting water, sediment, fish, and crustaceans from the surrounding
area. In just a month, they located and mapped 3,355
barrels. That first expedition was
reconnaissance,
giving the researchers something they hadn't had before – targets Then, in May 2026, they went back. This time, aboard
the Pourquoi Pas?, the team
brought Nautile, a three-person
submersible capable of descending 6,000 meters. Over 20 dives, it carried
scientists more than 4,700 meters down to inspect the barrels directly and
collect samples from their immediate surroundings. At first glance, the condition of some of the
barrels was alarming.
They were heavily corroded and degraded, with
material visibly oozing out onto the surrounding sand. But here's where the expedition became puzzling – because
the barrels also appeared to function as tiny oases on the otherwise sparsely
populated sandy seafloor. Anemones had attached themselves to the barrels. Sponges,
sea cucumbers, fish, and crustaceans lived around them, with crabs apparently particularly fond
of the artificial shelters. This presented the researchers with an unexpected
problem. The barrels weren't simply containers slowly releasing radioactive
material into an empty abyss. They had become part of the ecosystem. Which raised a much more complicated question: Was any of
that radioactive material making its way into the animals themselves? There was no question that radioactive material had
escaped containment. Instruments aboard the ship detected significant signals
of cobalt-60 and niobium-94, which the researchers could specifically link to
the dumped waste. Cesium-137 and americium-241 were also present at
levels well above the background expected from atmospheric nuclear testing
and accidents.
Whether that radioactivity is accumulating in the
animals living on and around the barrels is another matter.
At five sites, Nautile collected sediment,
water, organisms and microbial communities from immediately around – and even
in contact with – the barrels. The researchers also sampled nearby rocky
habitats to give them something to compare the barrel communities against. Those samples are now being analyzed to determine what
effect – if any – these strange habitats are having on the creatures that now
call them home.
There is precedent, however, to suggest that even
striking levels of radioactivity around a source don't necessarily spread
very far. A recent study of the
sunken Soviet submarine Komsomolets found
radionuclide levels hundreds of thousands of times above background
immediately around the leaking reactor – but those levels dropped sharply
within just a few meters as the material dispersed through the seawater.
The NODSSUM team similarly found that, despite the
significant radioactive signals around the barrels, activity levels weren't
high enough to pose major radiation-protection problems for the scientists
handling the samples. Nautile and the instruments it carried
showed no signs of contamination.
None of this means the waste is harmless – nor does it
mean we're about to be overrun by radioactive crabs. But for the first time, researchers have a detailed map
of thousands of barrels and samples that can reveal what is happening around
them.
While we pride ourselves on our
process, we are only human. If you spot a mistake, please let us know.
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