Photo by Mick Truyts on Unsplash
The power generated by a nuclear plant lasts for decades, illuminating millions. But the waste left behind can be dangerously lively for hundreds of thousands of years—a period that dwarfs all of human history as known. This presents a special challenge, possibly the deepest ever undertaken by our kind: how do we create a warning system and a container form that will persuasively convey danger to civilizations and cultures beyond our imagination, over a time frame of millennia? The solution is not one solution, but a system of multi-layered engineering and communications called "deep geological repository" design, a task that has to be planned on a scale hitherto left to gods and glaciers.
Geology itself is the first and best defense. Geologists and engineers scour the globe for the most stable and impermeable rock structure. The best place is one that has been tectonically quiet for millions of years, with no ground flow of water, and shielded from future glaciations or other catastrophic climate change. Onkalo in Finland, excavated deep beneath old bedrock, is typical of the strategy. The waste, contained in glass or ceramic and stored in durable metal cans, is placed in long tunnels many hundred meters underground. Surrounding rock—most often clay, granite, or salt—is the natural coffin. Salt, for example, is soft; it oozes in slowly and creeps into any cracks that form, trapping the waste in a permanent burial. The goal is to take advantage of the Earth's own gentle geology as the main coffin, a strategy based on the slow, reliable rhythms of the Earth instead of human materials' fleeting strength.
The engineering barriers are then encapsulated around this geologic option. The waste itself is initially blended with molten glass and transferred into stainless steel canisters, a process termed vitrification that traps the radioactive atoms in a stable solid form, similar to a fossil in amber. These canisters are subsequently buried in thicker, corrosion-proof overpacks constructed of copper or some other long-lasting metal. It is then encapsulated in a tunnel of backfilled bentonite clay, a substance which becomes plastic when exposed to water and will seal off impermeably but also one capable of taking up any wayward radiation. This "Russian doll" strategy—glass within metal within clay within rock—is one which provides levels of nested protection precisely because it does so in this order. For threat to manifest on the surface, all of these separate layers would need to fold at the same time, something viewed as approaching the impossible timescale afforded by the present.
But the engineers also know that even the finest metal will corrode and the most immobile rock will move 100,000 years. It is here that the issue ceases to be physical and becomes very human: the communication issue. How do we alert future generations to a threat they have no reference point for? The waste will survive all the languages, all the countries, and all the cultures that currently exist. Written communication is pointless; it will be meaningless. It has given rise to a new academic discipline: "nuclear semiotics," the study of long-term communication.
Suggested solutions are a mix of the realistic and the mythological. One of the ideas is to build a "Landscape of Thorns"—a large, unattractive expanse of enormous, sharp, black rock spires, the pattern of which would be random. The construction would be intentionally ugly and intimidating and serve no visible practical purpose. The message is not "Danger" in a language, but a bodily, non-language sense of danger and discomfort, discouraging excavation or habitation. A second idea is to carve permanent markers into bedrock itself, with pictograms for simple ideas. One symbol string suggested depicts a human face of horror and nausea pointing downwards. The plan would be to leave a global, emotional warning that is independent of grammar or language.
These primitive warnings would be supplemented by an "Archive," which would be hidden in various global locations. This archive would not be based on ephemeral digital versions, but hard material such as ceramic or stone tablets. It would include site maps, hazard diagrams of the waste, and scientific data on radioactivity made accessible in simple pictorial reasoning and the atomic diagram language universal to all. Most importantly, it would simply say "go away" but state why in the hopes a future enlightened society could grasp the ideals of science and take care of the site on its own.
But the most effective system could be societal: developing a lasting "priesthood" or institutional oral tradition. This would involve the creation of a special society, perhaps consecrated by the world's great faiths and science organizations, with the mission of passing on the secret of the site's location and peril from one generation to the next. This "atomic priesthood" would embed the warning in myth and ritual so it becomes a sacred, inviolable element of their culture. Even though this looks ephemeral, several of the world's oldest ongoing cultures have maintained knowledge in oral tradition for millennia, and this is demonstration enough that a tale can, in certain circumstances, be more hard-wearing than stone.
Even planning on this scale is an act of revolutionary responsibility. It makes us face our place in time. We are the brief, temporary guardians of a power whose effect will be felt into an unseen future. To create these spaces is an act of humility, accepting that our own civilization may not survive, and an intimate act of obligation to generations of people who will never have heard of us. It is an undertaking that brings together the hardest of the sciences—geology, physics, materials science—with the most flexible of the humanities—semiotics, anthropology, ethics.
Lastly, a nuclear waste dump is more than a grave; it is a message in a bottle tossed onto the river of time. It is an account of our capacity as much as of our vulnerability. It is an enduring legacy of an era that harnessed the energy of the sun but could not abandon its shadow. Its success will not be measured in centuries or years, but by whether or not it can rest silent and untroubled, its terrible secret hidden behind a wall of stone, a series of obstacles erected by engineering, and a warning inscribed not just into rock, but into the very essence of future human curiosity.
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