|Fig. 1: The insufficient, classic nuclear trefoil. Source: Wikimedia Commons|
Even with the current stringent international standards on nuclear safety, radioactive materials are surprisingly prevalent globally. Medical, scientific, energy, and military applications of nuclear radiation mean that radioactive material is a potential threat to many humans. The growing stockpile of indestructible nuclear waste ensures that radioactive material will be a threat for not only the near future, but also millennia from now. While international bodies such as the International Atomic Energy Agency (IAEA) oversee nuclear radiation safety, safety risks are inevitable, and it is impossible to predict how long such an organization will exist to look after spent nuclear fuel and other radioactive dangers. The IAEA and global nuclear community require an effective, unchanging method of conveying radiation hazards to humans not only from all over the world, but also from many different generations if the methods are to be effective in the long term. The IAEA has a standardized warning method already, however, the historical changes to this method do not bode well for a system to protect humans from nuclear waste repositories. The problem is complicated, but interesting because of its implications to the fields of nuclear energy, graphic design, materials science, geology, anthropology, and even art history.
Man made nuclear hazards have been present for less than a century, and already the symbols intended to warn of danger have changed many times. In fairness, it has only been about a century since negative health effects were directly observed due to exposure to radiation, and the radiation hazard signs have improved greatly over this time.
The first warning symbols were inaccurate and generic, and probably should have existed before the 1940's as scientists had already been experimenting with radiation for decades.  The skull and crossbones symbol was used, as well as ambiguous lightning bolts, incorrectly implying electrical hazards. 
|Fig. 2: The supplementary, new radiation warning. Source: Wikimedia Commons|
It was only in 1946, the same year that Hermann Muller received the Nobel Prize for Physiology or Medicine for his work on mutations caused by X-ray radiation, that the now well-known trefoil symbol was born to warn of radiation dangers.  The sign was created at the University of California in Berkeley, and is based on either propeller warning signs, the three types of radiation emanating from an atom, or the Japanese World War II flag. No matter the true origin, the symbol has become engrained in the minds of many, but must be obvious for all humans, as radiation is now present in "open and remote areas as the deserts of Africa and the jungles of South America, as well as the concrete jungles of our inner cities."  The trefoil's weaknesses have been known since at least 1975, when the International Organization for Standardization (ISO) claimed the symbol is "possibly accompanied by additional symbols or words," making it clear that the trefoil is not sufficient alone to convey radioactive hazards. 
In 2007, the IAEA released an additional nuclear hazard symbol, as a study found that the trefoil's understanding rate was only 6% for Brazil, Kenya, and India. The new symbol is more of a pictograph than a symbol, which hopes to make the sign's meaning more universal. The new sign is a combination of many symbols used to denote radiation danger in the past: the trefoil, emanating waves, and a skull and crossbones, any of which convey a similar meaning of danger.  Despite its more intentional design, the new supplementary symbol was not intended to replace the original trefoil, but rather to be added to many existing radiation hazards.  It also has a different purpose than the trefoil, as it is intended to signify an absolute "Do Not Touch" message, so will not be applied to radiation sources that are meant to be opened, such as transport packages. 
The new supplementary sign is the second of two major changes to the warning symbols for radioactive dangers since just the 1940's. For a more effective warning system, the lifetime of symbols needs to be many orders of magnitude longer since some radiation hazards, especially nuclear fission waste, last for an inconceivable length of time.
|Fig. 3: Not an origin of the trefoil, but a powerful image nonetheless. Used with permission from Fake Science|
The almost endless storage time for nuclear wastes is one of the most discouraging aspects of nuclear power. The inevitable waste produced is severely radioactive for 1,000 years, when it will still generate over 1,000 Curies per metric ton of initial heavy metal (CU/MTIHM), which is essentially a measure of how much waste radiation is created by a standard amount of Uranium fuel. Immediately following spent fuel's release from a pressurized-water reactor's reprocessing, high level waste produces a staggering 10,000,000 CU/MTHIM, a rate that decreases exponentially with time as radioactive materials naturally decay. Even after one million years, however, the spent fuel still releases 10 CU/MTHIM. 
Practically, a nuclear waste repository must remain untouched for 10,000 years, which is the goal of the United States' Waste Isolation Pilot Plan (WIPP) in the Chihuahuan Desert in New Mexico.  Some nuclear waste repositories, including Onkalo in Finland, however, are being designed to keep the nuclear waste isolated for an astonishing 100,000 years.  For comparison, the species homo sapiens is on the order of 100,000 years old. 
The radioactive lifetime of nuclear waste makes it an entirely unique problem for humans. Besides the immense materials science and geological task of designing time-proof containment vessels for the nuclear waste, a huge multidisciplinary approach is needed to ensure that humans stay away from nuclear repositories for longer than recorded history.
A few different teams have approached the subject in the United Kingdom, United States, and Finland, and all conclude that underground burial of the nuclear waste is the best option to contain the waste physically, but some creative thinking is required to protect future humans from accidentally or intentionally uncovering the nuclear waste. 
The Egyptians built the Great Pyramid at Giza with the intent that it would never be opened. Nonetheless, archeologists have ignored the wishes of the Egyptians, and have mapped out the interior, walked inside, and sent in robots to learn more about the giant tomb. All of this is even after we decoded the Egyptian hieroglyphics, due to the fortuitous discovery of the Rosetta Stone, and understood the purpose of the pyramids. The Great Pyramid at Giza is an amazing 4,500 years old, and yet already the changes to mankind during that time, or even just in the last millennia, completely compromised its impenetrability.  How do we possibly prevent future generations of humans from breaching underground nuclear waste repositories for over twice the age of the Great Pyramid at Giza?
Consultants worldwide have proposed drastically different solutions. The US decided to focus on creating lasting markers at the site of the nuclear waste, a plan considered to be the "long-term concept." This strategy places very little trust in the flexibility of knowledge, and society's ability to pass down information in a relevant and accurate way to future generations.  Essentially, the group responsible for protecting future humans from the WIPP decided that information is too rapidly changing and hardly eternal, but physical landmarks that convey danger on an instinctual level are more likely to effectively keep humans away from radiation for thousands of years. This might seem risky at first, but considering the fact that even today abandoned mines less than a century old are often drilled into, it is hard to trust future generations to consult archives over the locations of nuclear waste before any kind of excavation or drilling. The proposed physical markers themselves were hugely diverse, ranging from massive granite blocks, to fields of spikes, to signs with a recreation of 'The Scream.'  These long-term markers very intentionally built on basic human instincts; "[t]he designs address this seemingly impossible specification through the brilliant application of archetypal theme and form - parched earth, snakelike earthworks, and claws and thorns - to warn future humans of the radioactive hazards on an affective, instinctive level.' 
|Fig. 4: The Grand Gallery inside the Great Pyramid at Giza. Source: Wikimedia Commons|
Four separate groups were asked to analyze the protection of the WIPP, and one group found it essential that the area be actively guarded or patrolled. While it is unreasonable to assume that society would unquestionably actively guard the area for ten millennia, their group actually considered the first 200 years of storage to be quite dangerous, but also the easiest to actively control.  Active control has the added effect of protecting against people intentionally breaching the repository to use the nuclear waste for dirty bombs, but also highlights the weakness of the "long-term concept" as a solution, since inhuman physical landmarks are probably insufficient.
The Scandinavians brainstorming for the Onkalo nuclear repository site, unlike the Americans, have focused their efforts on keeping good archives and information on nuclear waste repository sites, called a "short-term concept."  The motivation behind a short-term concept is that any physical markers, languages, or symbols based warnings would lose their meanings too soon.
An even more intriguing approach is not marking a nuclear repository site at all; burying nuclear waste hundreds of meters underground in the middle of a barren desert is a better safeguard than any structure or warning signs that could eventually just bring attention to the location. In fact, two of the four teams organized to brainstorm protection ideas for WIPP agreed that no markers was the safest approach, as it defends the nuclear waste from "curiosity seekers."  More importantly, not marking the site, but creating it in secrecy would by default add a layer of protection against anyone seeking to use the radioactive material for harmful purposes. Not marking the site at all completely avoids the problems of language, symbolic, or cultural robustness, but of course adds the moral question of our generation's responsibility to protect future generations, as well as future generations' right to our knowledge.
Others take the conclusions of nuclear waste protection as solid proof that our current generation should not be producing the waste in the first place. A study of how information is changed over millennia reveals that, for the most part, any information designed in the near future will either be completely lost or so mutated that its original meaning is completely lost. Furthermore, since no physical containment schemes can unquestionably protect thousands of future generations from being exposed to the nuclear waste, the only reasonable conclusion is that the creation of nuclear waste repositories will inevitably lead to human contamination at some point in the next 10,000 years. 
Of course, this view is pessimistic, and makes as many guesses about the future as any other conclusion about nuclear waste protection; technological advancement is likely, and at least over great time scales, mankind values the pursuit and collection of knowledge. This could mean either the eventually discover of a short-term solution to radioactive nuclear waste, or a persistent and active guarding of the knowledge of nuclear waste sites, if not the sites themselves. Claiming that nuclear warning signs for nuclear waste repositories pose an impossible problem is defeatist. Scientists discovered how to unlock the energy stored in the nucleus of an atom; the difficult design of warning signs is not going to keep them from harvesting the energy. Even if no better method of disposal is found for nuclear waste in the next 10,000 years, there is plenty of time to continue to research effective and long-term warning methods for nuclear radiation dangers.
© Charles Dunn. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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