Nuclear Waste: What Do We Do With It?
nuclear power used to be a conversation stopper luckily we now all agree that it's the fastest safest and most reliable way to get off fossil fuels if it wasn't for this little issue with the radioactive waste do you get super powers if you roll around in it if you came here to answer that question you've got the wrong Channel but we'll talk about the next best thing to superpowers numbers how much nuclear waste is there how dangerous is it what can we do with it and what the heck is a ray cat that's what we'll talk about today possible by Squarespace that's a platform on which you can create your own website with just a few clicks whether you want to set up a Blog for your travels or need a landing page for your new Quantum Computing startup you can do it on Squarespace and it's not just that they have a great selection of templates that'll get you started you can also use this platform to set up and manage an email list add buttons to accept donations and keep track of who's visiting your website so go check out squarespace.com for a free trial and when you're ready to launch go to squarespace.com Sabina to save 10 of your first purchase of a website or domain now let's talk about nuclear waste almost all existing nuclear power plants run with uranium the uranium is formed into small pellets which are then sealed into metal tubes called rods a bundle of such rods forms the core for reactor in the reactor the few rods are exposed to nutrient radiation which starts a control Chain Reaction this generates heat which evaporates water which spins turbines which creates electricity as a theoretical physicists I'd say it kind of works like a Watermill just a little more dangerous the fission processes that generate the energy in the nuclear power plant it creates a lot of new Atomic nuclei many of which are radioactive in the course of time the number of atomic nuclei in the few rods that can still be split declines and the power generation becomes less and less efficient eventually the few rods must be replaced How often this must be done depends on the reactor but typically it's every three to eight years think of few rods like world leaders but a bit more reliable this process of energy generation in a nuclear power plant leaves behind radioactive waste that must be safely disc carded it can roughly be distinguished into three categories lightly contaminated waste intermediate level and high level waste though there's no International agreement on the exact classification going by volume most of the waste is slightly contaminated and won't radiate for long this is stuff such as tools equipment building materials shielding clothing and so on this makes up about 90 percent of all nuclear waste seven percent is intermediate and about three percent of it is the high level waste that we're concerned with here that's primarily what's left from the few rods it's really very similar to wealth distribution the highest three percent are the most toxic the main components of the high level waste are strontium-90 and cesium-137 which each have half-lives of about 30 years and then there's plutonium-239 that has a half-life of 24 000 years it's the plutonium with its long Half-Life but is the major problem because it means this high level waste remains harmful for about a hundred thousand years in this figure you see how the radio toxicity of the high level waste that's the green line capacitor of naturally occurring uranium that's the straight horizontal line as you see spent fuel starts out about 10 000 times more radio toxic than uranium in its natural form and takes a few hundred thousand years to Decay back to that level even Keith Richard won't be alive at that point just how deadly is the stuff well it depends on how much of it you're exposed to and in which way the uranium them in the unused fuel rods isn't all that highly radioactive there's a handy website here which lets you calculate just how high the radiation dose would be if you touch it inhale it or eat it if you happen to eat one gram of an unused nuclear fuel Rod that'll give you about 1.3 millisievert this is about the maximum recommended annual dose the fresh nuclear waste from the used rots is as we just saw a 10 000 times more radioactive eating a gram of it would probably kill you in a couple of weeks so please do not eat used nuclear fuel rods it's not healthy and also probably not all that tasty how much of this stuff do we have lying around according to your 2018 report by the international atomic energy agency we have globally about 400 000 metric tons of spent nuclear waste that's the total amount of nuclear waste ever produced since the first nuclear power plant the amount increases each year by about 12 000 tons most nuclear waste producers are currently located in Europe and the Americas 12 000 metric tons a year sounds like a lot but let's put this number into perspective the total amount of hazardous waste created globally each year by industrial production is a few hundred million tons that's about 20 000 times as much as nuclear waste another useful comparison a one gigawatt power plant can supply electricity to about a million people in the developed world if you do this with nuclear power it produces about three cubic meters of high level waste per year if you do it with coal that produces approximately 300 000 tons of Ash and more than 6 million tons of carbon dioxide every year just the ash of one coal plant in one year is more than all the high level nuclear waste ever produced globally and the ash of coal plants by the way is also radioactive yeah that's right coal ash is radioactive not as radioactive as used fuel rods and not as long-lived but you shouldn't eat it either why is there so little waste produced by nuclear power plants it's because the energy density of uranium is dramatically higher than that of fossil fuels this is why nuclear fluorots last years whereas you constantly have to shovel new coal into a coal plant okay so for one thing we see that when you put the numbers into context nuclear power plants produce very little waste also in contrast to other ways that for the most part you don't even know what it is before they tell you it's in your drinking water radioactive waste is easy to detect afraid of radioactivity by a geiger counter afraid of chemical pollution well I guess you could move to the moon but what happens to the nuclear waste when they used few rods are taken out of the Reactor Core they are first stored in a pool of water at the reactor site they sit there for a few years to cool down and let some of the nucleotides with short half-life Decay it's the same physical principle that's also behind Twitter suspensions after a few years the spent fuel is moved to a dry Cask storage container at the power plant site these are temporary storage solutions they are canisters made of concrete and steel filled with inert gas such as helium or nitrogen each might weigh more than 100 tons these encased rods still emit roughly 100th of a millisiever per hour so if you sit next to one of them for 100 hours you've got your annual dose you shouldn't exactly use them as a dining table but dry Cask storage is safe enough if you know what you're looking at the problem is keeping an eye on those things for a hundred thousand years of the near 400 000 tons of existing spent fuel 47 percent are currently in the cooling pools that's called wet storage 20 are in the canisters that's called dry storage and the remaining 33 percent have been reprocessed more on that later this highly radioactive waste has to be transported sometimes for which there are special containers and train carriages in the 1984 test a train was crashed into one of these containers filled with non-radioactive stuff at over 100 miles per hour it was quite a scene after the crash the pressure inside the container was almost unchanged from before the Collision if the test containers had actually held nuclear waste nothing would have happened to it but everyone on the train would have been dead the small nuclear reactors by the way that are currently rather fashionable and that we talked about in this earlier video create more waste per energy according to a recent study from researchers at Stanford University the currently planned small modular reactors will increase the total volume of nuclear waste by a factor of 2 to 30 depending on design most of this is lower intermediate of waste coming from the need of more construction material per fuel they also found that the high level waste that those small reactors create is more radio toxic than that of conventional nuclear power plants because the smaller size leads to somewhat different fission reactions okay so we conceal the stuff up in concrete and move it around but what do we do with it eventually we could shoot it into space but given that every once in a while a rocket blows up in the atmosphere or falls back down it may not be such a great idea it also wouldn't be fair to aliens I mean suppose a spaceship comes by our solar system and everyone is very excited but it turns out to be nuclear waste that would be really disappointing we don't want to disappoint aliens do we so we keep the stuff down here but where at the moment no long-term storage facility exists it's a difficult task because it'll have to survive independent of human maintenance for hundreds of thousands of years the best storage solution for nuclear waste that Engineers have come up with is geological repositories the caves basically located inside stable geological formations that are expected to remain stable for at least a few millions of years in the 1980s the USA tried to create the first such facility at Yucca Mountain in Nevada it was supposed to open in 1998 but it didn't work out as planned to this day nothing's been stored there that's partly due to government Hang-Ups on safe radiation levels but mostly because it turned out people don't like having nuclear waste in their vicinity Finland is currently building the world's first deep geological repository it's scheduled to be opened next year the ancolo spent nuclear fuel repository is located near nuclear power plant on the west coast of Finland it it's basically a lot of tunnels about 400 meters under the ground in them thousands of corrosion resistant copper canisters will be buried and the holes will be plucked with bentonite which is a water absorbing clay each tunnel will then be filled with more Bentonite and sealed with concrete the fins have created a computer model of the whole tunnel Network to forecast how groundwater will move through cracks and fractures and the effects that this may have on people living on the surface there's really a lot of planning and Engineering that went into this it's not like they just dump the stuff in a cave lock the door and go away people often ask me but would you want to live near a nuclear waste site guys I've grown up next to chemical industry I made an internship in the chemical industry today I live near the largest chemical production site in the world every once in a while something blows up there and we're all us to close the windows and pray that the dilutes quickly if I had to pick one of the two eyed Peak nuclear waste storage any time but most people don't like to have plutonium in their backyard and I have some understanding for that so how do we keep the stuff locked up safely for a hundred thousand years that's quite a challenge even written language has only existed for about 5 500 years God knows what language people will read in a hundred thousand years if there are still people and they still read this question was studied in 1981 by the human interference task force that was commissioned by the U.S
department of energy their task was to find a way to warn people of the future of the nuclear waste that was planned to be deposited at Yuka Mountain it was a team of Engineers anthropologists nuclear physicists behavioral scientists philosophers and semioticians that's folks who study science they came up with some general rules including that whatever the warning message it should be read top to bottom and should repeat the message in several different ways so basically like a storybook for children the semiotician Thomas seberg had the idea that if the site can be rendered repulsively malodorous for a lengthy period that'd be at least provisionally a deterrent against casual exploration he proposed creating a mythology where the actual truth would be entrusted exclusively to an atomic priesthood and other people are told scary stories and these weren't even the craziest ideas a book from 1984 collected contributions from scientists who suggested among other things that the exact location of the waste be forgotten and instead only information about the existence of nuclear waste repositories and about methods of measuring radiation be preserved others propose that animals can be bred that will react with discoloration of the skin when exposed they called them Ray cats and proposed that we create proverbs and myths that would tell people if your cat changes color you're near a dangerous place I really love how they assumed that in a hundred thousand years everyone alive would be a complete idiot in 1993 San Diego National Laboratories published a report with ideas to protect another deep repository in New Mexico they came up with the idea of a physical language that they thought would be understood by Future civilizations examples of that would be Thorns spikes and other sharp shapes that may induce uneasiness or fear they also propose to draw human faces expressing horror though the future people might think it's an early Munch in the end they mostly concluded that the best thing might be to just make sure that the storage is only accessible with Advanced technical equipment the idea is that the civilization who has the technology necessary to drill into the nuclear waste should also know what radioactivity is so we've talked about just hiding our waste on the ground but how about recycling it almost all spent nuclear fuel actually can be reused this recycling requires extracting the plutonium and uranium from the used fuel rods and mixing it with fresh uranium this is currently done for example in lahag in France and a few other places like the UK and in India in the hawk they've been recycling few rods since 1976 with a capacity of about 1 700 tons per year they extract plutonium which is then used to create a mixed oxide fuel mocks for short this type of view can be used on the most common type of reactors the light water reactors like the uranium fuel rods the French use some part of this moxfield themselves and sell some of it to other countries what this reuse does is basically to allow you to get more energy out of the original uranium it doesn't avoid waste but it reduces the amount of waste per energy produced however it currently doesn't make economic sense to reuse this fuel a second time why isn't this done in more places because it's expensive in 1996 the U.S national research Council estimated that reprocessing all the existing used nuclear fuel in the US would cost more than a hundred billion dollars in 2007 the council declared that research and development of such technology should be halted because the money could be better spent on Next Generation reactors since there isn't much of this waste to begin with and what there is can be stored underground this decision makes economic sense however the question of whether it makes economic sense depends on how much energy you can still get out of the used few rods and there has been quite some research on that in the past decades for example Russia is currently testing a different way of reprocessing spent fuel it's called remix and they say it can be used up to five times it's still in the testing phase though another way to reduce nuclear waste is to use a pressurized heavy Water Reactor but the water is heavy it doesn't mean it likes its muffins too much it means that the hydrogen in the water is replaced with deuterium so that's hydrogen with an additional Neutron in the nucleus pressurized heavy water reactors are currently the second most common reactors in use and they already have the potential of reusing their own nuclear waste they can run on natural unenriched Uranium on a mix of uranium and plutonium oxides this includes plutonium from dismantled nuclear weapons and also on thorium and plutonium this fuel can be recycled and reused in a number of ways then there are the so-called fast reactors fast because they use fast neutrons if they produce more plutonium than they consume they are called Fast breeder reactors the good thing about fast reactors is that they destroy the nuclear waste with the longest Half-Life most of the remaining waste decays to harmless in a few centuries rather than hundreds of Millennia you can feed used fuel from the other reactors into those fast reactors this isn't new technology but it hasn't been used as much as it could have been Canada is currently building two of those fast reactors there are many ways to reuse reprocess and cycle around radioactive stuff from one power plant to another the whole topic gets very confusing very quickly and I know you didn't come here for a two hour lecture let me therefore just show you a summary figure from a report to which I'll leave you a link in the info below this is the amount of conditioned high level waste in cubic meters per terawatt hour of created energy but it's conditioned means it's been prepared for disposal the most common type of running nuclear efficient plants is presently scenario 1A scenario 1B is one with one round of recycling the scenario 1D is if you take the spent fuel from the most common light water reactors and stuff it into a heavy Water Reactor the ones on the right are various Advanced nuclear fuel cycles that are possible with current technology but are not presently used the bottom line is that we could significantly reduce the amount of nuclear waste if we use some of the modern technology and final deposit sites are under development personally I think that the whole topic of nuclear waste is totally overblown burying the stuff underground seems a perfectly fine solution to me there are good reasons to object to nuclear power and I went through those in my earlier video but nuclear waste isn't one of them if you like science without the gobbledygook we have a newsletter that you can subscribe to on my website zabinohosenfelda.com newsletter you can support us on patreon or right here on YouTube by clicking on the join button below special thanks to our patreon supporters 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2022-11-29 23:58
