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Radioactive Cats and Nuclear Priests: How to Warn the Future About Toxic Waste

Nuclear waste can remain toxic for tens of thousands of years. How do you warn the future that they’re standing on nuclear waste when there’s no one around to translate?

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In 1999, the Waste Isolation Pilot Plant outside of Carlsbad, New Mexico accepted its first deposit of mid-level nuclear waste. A massive network of tunnels extending nearly a quarter of a mile into the Earth, WIPP is tasked with safely storing the United States' growing stockpile of nuclear waste for the next million years.


Due to the timescales involved when handling nuclear waste, designing deep geological repositories like WIPP is one of the most challenging engineering problems ever faced by our species. But, as it turns out, the main problem has less to do with engineering, and more to do with linguistics: namely, how to design a warning message about the repository that will be intelligible to future generations of humans who might happen across it hundreds of thousands of years from now.

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The solution isn't as simple as it seems. Humans have only been writing for about 5,500 years, and many ancient languages have forever been lost to history. The idea of using a language to write out a warning message that would last 200 times longer than the most ancient languages seems improbable at best. Even conventional warning symbols like the skull and crossbones are far from universal.

As for building giant, foreboding monuments to scare people away? One need only look to the great pyramids to see how well that worked at keeping people out. Another idea was simply to bury the waste and forget about it, which raises a significant ethical issue: Do we have an obligation to warn future generations about our nuclear waste?

One semiotician proposed breeding "radiation cats" that would change color when they came near radioactive sites

In 1981, the US Department of Energy convened an eclectic panel of experts to design a warning message that would last millennia. Known as the Human Interference Task Force, the group was led by the renowned semiotician Thomas Sebeok.


The group's message was being designed for Yucca Mountain, a controversial high-level waste repository in Nevada that is still not open for business, largely due to the extremely complex nature of designing a million-year nuclear vault.

Following the initial call for ideas, a poll was conducted by the German Journal of Semiotics between 1982 and 1983 that asked for proposals addressing the question of how to communicate the dangers of a nuclear waste repository to people 10,000 years in the future. The most compelling was Sebeok's plan for a nuclear priesthood, which would pass on information to future generations through myths and rituals. It was based on the idea of the Catholic Church, which has managed to transmit its messages for nearly 2,000 years.

Less formal styles of oral tradition, such as Icelandic family sagas, have also been shown to retain a high degree of accuracy after 1,000 years.

Other ideas were slightly more outlandish. Stanislaw Lem, a Polish sci-fi writer, suggested periodically putting satellites into orbit that would transmit information about the sites to Earth for hundreds of years at a time. A similar proposal was put forth by Philipp Sonntag, who advocated for "an artificial moon in the sky" as the safest place to store information about the repository. Another of his ideas was to encode information about the site into the DNA of plants, which would then be planted around the repository opening.


In a similar vein, the Italian semiotician proposed breeding "radiation cats" that would change color when they came near radioactive sites. The thinking was that, based on the long history of human-feline cohabitation, there was a good chance that this would continue into the future and our feline friends could warn us of the danger.

After two years of deliberation, the Human Interference Task Force issued a large technical report for the Department of Energy containing their final recommendations. Perhaps unsurprisingly, neither ray cats nor radioactive flowers made the cut. Instead, the task force proposed creating a large monument over the site, consisting of several stone monoliths inscribed with information in all human languages, as well as a subterranean vault with more detailed information, and a number of earthen walls making access to the site intentionally difficult.

Furthermore, the group recommended dispersing detailed information about the site to libraries around the globe, to prevent some sort of cataclysmic, Library of Alexandria-type of information loss should a disaster strike one of the sites.

A diagram of the center of the monument to be placed at Yucca

The monument and message have yet to be realized IRL, in part because the Yucca repository is still embroiled in controversy. But a decade after the task force issued their report, the US government called together another group to redesign nuclear warning messages for the Waste Isolation Pilot Plant in New Mexico, which became the first operational deep geological repository in the US in 1999.


The group was summoned at the behest of the Sandia National Laboratories, which designs and tests the non-nuclear parts of nuclear weapons. Like the original Yucca group, it consisted of an eclectic mix of engineers, astronomers, linguists, anthropologists, archaeologists, geologists, and artists. Even Carl Sagan was invited to contribute, but he had to decline due to his failing health.

Still, he had some strong opinions on the subject, writing to the group that he was convinced that "what we need is a symbol that will be understandable not just to the most educated and scientifically literate members of the population, but anyone who might come upon this repository. There is one such symbol…used on the lintels of cannibal dwellings, the flags of pirates, the insignia of SS divisions and motorcycle gangs: the key is the skull and crossbones."

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To ensure a wide variety of solutions, the WIPP group was split in two. Group A took a more architectural approach and designed a number of "menacing earthworks" as warning signs. Group B decided to focus on developing ways to simply convey information about what was hidden in the WIPP site to future visitors, rather than trying to scare them away.

The earthworks developed by Group A included a landscape studded with giant spikes sticking out in odd directions, and a giant "black hole" made of dyed concrete or granite to be placed over the site. These structures would be accompanied by basic information and warning messages, as well as symbolic representations, such as the face from Edvard Munch's famous painting, "The Scream."


Subsurface markers would contain far more detailed information about nuclear waste, its effects on the human body, and the purpose of the geological repository.

Overall, the designers hoped the site would communicate the idea that "sending this message was important to us. We considered ourselves to be a powerful culture. This place is not a place of honor. No highly esteemed deed is commemorated here."

Group B, on the other hand, focused more on how to convey messages to a far distant future. Given the relatively short shelf-life of human language, this is a considerable difficulty. The group considered various emblems used to convey danger or biohazards, but also recognized that the probability of a symbol retaining its meaning over time is quite low. Despite Sagan's conviction, it seemed to the others as though the skull and crossbones would be inadequate for the task at hand.

"A cognitive psychologist on our team showed that you can't demonstrate that the universal, Jungian archetypes of fear and danger exist in non-Western cultures," Jon Lomberg, an artist who worked closely with Sagan to design the Voyager records and also served on the WIPP development panel, told me over the phone. (He was in Group B.) "Symbols are by and large culturally determined."

In lieu of symbols, the group considered using pictographs, where the image has a direct relationship to the thing it is depicting, much like cave drawings can still be understood as depicting ancient hunting scenes. Even these, though, run a high risk of misinterpretation.


Ultimately, Group B realized that one of the most potent ways of conveying information was the use of scientific diagrams, such as the periodic table, which would likely be intelligible to any future society, even one with a relatively low degree of scientific knowledge.

The WIPP panel submitted its recommendations to Sandia in 1994. Five years later, the Waste Isolation Pilot Plant received its first shipment of nuclear waste, and will continue receiving shipments until the 2030s, at which point it will be permanently sealed. At this point, none of the markers or warning messages have actually been implemented. It is unlikely that this will change anytime soon—so long as the site is being actively managed and guarded, which is likely to continue for a century or more, the message is not needed.

Defining the equality of symbols, art by Jon Lomberg. Image: Sandia National Laboratories

There's another problem, though: what if an obvious warning message has the opposite of its intended effect, and actually entices citizens of the future to open the vault out of sheer curiosity? In this case, the best option might be simply to let nature reclaim the site and allow the nuclear repository to be forgotten forever.

One of the most important, yet frequently ignored, aspects of "nuclear semiotics" is its universal nature. Although WIPP is one of the only operational deep geological repositories in the world, there are several others planned or currently under construction, in places like Canada, Finland and Germany. So far, the US is the only country to commission panels devoted to designing warning messages for the future of nuclear waste dumps, and other countries don't seem to interested in pursuing this problem.


Lomberg recalled a recent conference he attended at Sweden's Forsmark repository, during which the subject of nuclear warning messages was broached without any consideration for the work outlined in the two technical reports compiled in the US.

"When markings came up in the discussion at Forsmark, it was clear that they really hadn't heard much about what WIPP had done," Lomberg said. "The idea that we should go to these elaborate extremes to put a warning marker for people 10,000 years from now is something so crazy that only Americans would think of doing [it]. And if they did anything at all, they were going to reinvent the wheel."

He considers this a lapse of judgment, insofar as a standardized warning message at each site around the world could help curtail widespread disaster, should our descendants decide to open one of the nuclear vaults. If another deep geological repository is discovered by future generations that looks the exact same as the one they had opened previously with disastrous results, they would know better than to repeat this mistake.

Then again, there's also a chance that no message will ever be designed for US repositories, and that these reports were simply commissioned to assuage public fears about the facilities.

"A lot of us had been around the block a few times and knew this was going to be a report that the government only did because they needed it to show compliance," Lomberg said. "They didn't really care what we said, I think."

In Lomberg's opinion, creating a message for the future is necessary.

"I think it's possible to create a successful warning marker. It's just about the political will to do it," he said. "You can't control the future, all you can do is give them the facts. So if the people of the future decide to ignore it and dig anyway, that's their responsibility. It's their world."

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