Dispelling the Myths of Nuclear Energy (Live Lecture)

hello i'm professor david ruzick illinois energy prof and today i'm going to tell you about dispelling the myths about nuclear power this is a talk that i typically give to high school students and freshmen and non-majors in fact today we actually have a live by zoom studio audience each of the topics i'm going to talk about are presented in greater detail in one of my other illinois energy prof videos but this is an overview and i want to start this first by asking just a couple simple questions all right so think in your mind don't go look it up you know there's no grade being given what percentage of u.s energy use is from solar and wind combined everyone think of a percentage in your mind you see the windmills everywhere you hear about the solar panels okay that number is 3.6 percent uh more than it used to be as you'll see okay now i want to ask another question what percentage of u.s energy is from fossil fuels so again think of a number think of your mind right and this answer is 80 percent now you think about those numbers and you realize that there's a long way to go if we have a significant worry about greenhouse gases and global warming let's look at u.s energy by source and here are the 2019 numbers this is uh pre-pandemic so it gives us stuff and if i looked at those top three that's the fossil fuels that's the 80 percent you know this is in quads quadrillion btus but it's around 100 right and then we can see hydro and we can see solar and wind and we can compare this to 13 years ago and you can see several important things has happened we have built many more natural gas power plants and taking coal plants off of line coal makes more co2 per unit energy than natural gas that's great wind has gone up by a factor of 10 that's impressive ethanol biodiesel up by a factor of four and solar energy by a factor of 15. and you say wow that was great 13 years from now let's do those same percentages we're really cooking yeah let's compare five years ago to today you can see the wind progression has slowed down dramatically and the solar has as well so if we're thinking about energy there's one thing here that's been pretty constant nuclear power and it makes 20 percent of our electricity and it makes no co2 so why don't we just use more of this we don't depend on the wind blowing or it being daytime or you we already use on ethanol something like 40 of our corn so what are the objections to nuclear power okay and i bet you know them i bet you know if you just think in your mind you'd say ah radiation aka simpsons we're all gonna end up with three eyes all right accidents oh my god they could melt down and blow up like atom bombs and and that that would be unmitigated disaster and wastes the wastes are there forever there's no place to safely put them we are hurting future generations like yours these are the myths and in the rest of this talk i'm going to try to explain that there are objections to nuclear power predominantly on the economic side but they're really not these so let's start off and give you a quiz all right compared to background levels how much radiation is given off by a nuclear power plant during normal operation all right got some answers there think of one in your mind answer is a all of the waste all of the radioactive material is contained and extremely well shielded a coal power plant gives off some radiation not much not much to worry about at all all right just because there's some uranium thorium other radioactive materials and small amounts in the coal so let me talk a little bit more about radiation and i brought here a geiger counter all right handheld geiger counter i'm going to turn it on all right and you can hear some clicks i've got this by my microphone you hear that and you can see if you could and zoom in maybe but you could see that the meter is moving i'm not particularly radioactive more than the next person but this is background we always live in the world in a bath of ionizing radiation and so what you really need to do if you're worried about radiation is compare it to background levels 15 000 gamma rays go through you every second has nothing to do with nuclear power or other things i realize you still hear those clicks and maybe it's disconcerting i'll turn it off but we are bathed by radiation and there's a number for it miliram 300 milligram per year naturally and you know if you live in denver colorado i pick out denver not because of something bad about denver happens to be the mile high city right the elevation of denver is 5280 feet all right and because of that there's less atmosphere there compared to us down here in champaign at 740 feet right so we have a lot more shielding it knocks out right it knocks out that radiation this extra atmosphere or if you fly in a plane up here at 30 thousand feet or more you get even more radiation does it kill you no you can measure it though all right power plants have no radioactive emissions and even an accident like three mile island the worst accident in the united states gave people only one and a half milligram extra that's the amount when you get one transcontinental flight so what about accidents all right so that's going to be another topic and of course there have been very well publicized accidents in the world and probably the absolute worst one ever was a chernobyl power plant but it can't happen here and there are two very good reasons and the first one of those is containment all right containment building you see a containment building is around all of the reactors not just in the united states but in japan in actually everywhere except for the former soviet union right and these containment buildings are massive they're expensive they're big and they're in place before anything goes wrong and even before 9 11 the safety criteria was if a jet airplane crashes into them they don't break now they never imagined someone would intentionally crash an airliner into this they thought maybe an engine would fall off and the engine would go hurtling in okay they're made in a dome-like structure right three feet thick of reinforced concrete inside of that a five-eighths inch steel layer these things are not going to break chernobyl did not have a containment building around it and therefore when things went wrong inside they got out things go wrong in reactors in the rest of the world they don't get out now just to prove how this works i'm going to show you a short movie it's got some german subtitles even better for my european audience of a plane crashing in to a containment building okay this is an f4 phantom jet all right and it's on a track because otherwise it would take off and they are actually going to propel this to 500 miles per hour and it will hit a section of a containment building wall i love blowing things up and this would be so fun now that's the block right there and you'll see the tip of the wing goes past that's not slicing the block the block is actually perfectly fine from this the wingtip goes through not through the block just over the edge of the block okay but the rest of the block is fine sure some scorch marks the plane is atomized but you can really build a structure that can stand up to that type of punishment now that was number one we have containment buildings chernobyl did not there's a second reason okay our reactors are moderated and cooled by the same water the water leaks out boils away the nuclear reaction stops the chernobyl reactor was cooled by water after all you turn water into steam make electricity but it was moderated by blocks of carbon now let me explain this in a little more detail right you're going to get a little bit of a nuclear physics lesson here all right we're going to have a neutron that's what this is right here this is a neutron a blue dot and it's going to crash into some type of fissile material say u-235 right so it does this and it gets absorbed so right now this becomes u236 which is unstable all right so it's kind of shaking around and it may fission split we get fission products okay and there are a variety of things they end up being the high level nuclear wastes and you also get three neutrons right not every time you get three right it's uh on average something like i don't know somewhere between two and three right those are more neutrons and these neutrons are going really fast all right the neutrons are really moving if i put this in perspective here is a graph of the chance of fissioning happening and it's a log graph if i look on this vertical axis each of those marks is a factor of 10 and here is the energy of the neutron those neutrons that came out of the fission reaction they were here at a million ev okay they're created at this energy if you look across at the chance of fissioning it's pretty low right it says 1 there 10 to the 0. but if i slow them down to here to thermal energies that chance of fissioning is a thousand times higher so to get a nuclear reactor to work you have to moderate that's why you use a moderator it means you have to slow down the neutrons otherwise you just can't sustain a fission reaction so you've got to slow them down so what do we do it with well fast neutrons are produced but it's slow ones that cause the fissions right and you have a couple choices of what you could use to slow down neutrons all right you can slow down neutrons with blocks of graphite okay neutron could come and hit here or you could slow them down with water all right there has to be a moderator there has to be something that slows down the neutrons now we also need water to cool the reactor right this is the water that turns into steam that turns the turbine that runs the generator that makes electricity all right and you need that so it won't overheat but if you use the same water for both all right then a meltdown is physically impossible right here's the water and if my neutron was coming through say this little bottle caps my neutron right and i'm pouring it and i'm hitting the water that fast neutrons hitting the water right that is stopping it it's slowing it now this neutron could also hit the graphite all right that will slow it down too but this is our coolant and if you think about this let's say someone uh lets all the water leak out maybe there's an earthquake maybe there was a mistake a break in the color line or someone turned it off this neutron has nothing to slow down with anymore it will keep going it will stay a fast neutron and that means the chain reaction will stop at chernobyl you still always had the graphite even though the cooling water was empty and that meant the neutrons could slow down and the chain reaction would continue so can a nuclear power plant explode like a nuclear bomb under the right circumstances think about this talked about the reaction turning off but is there something you could do to make it explode like an atom bomb [Music] 100 billion 100 million 100 000 one in 10 000 or no it's physically impossible and that's the answer we've talked about moderation of why chernobyl can't happen here but this is yet another safety feature people don't recognize which is even true in chernobyl okay you see to make a bomb you need the fissile isotope right the one that can fission to be ninety percent and to make a reactor you only need it to be three percent and indeed at both chernobyl and the reactors in the west that percentage is about three percent you have to enrich it right in the ground uranium starts out point seven percent u235 so you need a big enrichment plant that's why there's always controversies over companies or machines or or countries making enrichment because they could enrich it all the way up the bomb level finding uranium isn't that hard so if we have to have 90 percent but a reactor is only 3 percent uranium-235 i don't care how hot it gets i don't care if the reaction keeps going it will keep going and make heat as chernobyl did but it will not blow up like an atom bomb all right so if we have graphite right and it's going to get very hot and we have water which could decompose into hydrogen while you have something much more like a chemical explosion you know like one of these and since you don't have a containment building what we get is a actual bang like that explosion of chernobyl was an ordinary one like dynamite would cause and indeed if we look at the pictures of it right afterwards you can see that no containment building and you've got a big hole where the reactor was and that means the fission products went up in the air and around europe and those are the high level wastes there's another picture right after the accident by the way this other side there's another nuclear reactor here it kept going this is not a nuclear explosion so it would be like glass that was an atom bomb now what they did in the former soviet union is that they built a containment building afterwards all right much better to have at first we had it first we wouldn't be talking about chernobyl now now you might say okay well there's other reactor accidents fukushima was in the west what about that one well remember the disaster came from a giant tsunami an earthquake a magnitude 9 earthquake with a 40-foot wall of water and those were beyond the design considerations they didn't think they'd have that big they had a sea wall up to protect the generators i don't know 30 some feet not enough for that wave right and actually even though that happened the reactor defense systems worked as planned the problem is that look that's a ship on the ground right this tidal wave and disaster and earthquake killed 18 000 people the nuclear plant killed no one now what about uh the explosions you heard about at fukushima well there are panels on the top of it called blast panels right in case it collected hydrogen up here and it did they're supposed to blast away and they did the containment building is this thick area here this three foot thick concrete around it reinforced they had a containment building the containment building survived the earthquake right there's a picture of a person down there to give you a sense of scale the thing though is that the spent fuel the fuel that they've already taken out of the reactor right to ultimately go and dispose of is in a swimming pool you use swimming pools to protect against the radiation exposure right because you would lift out in a crane and you take that's the crane you take it apart and you put it down here and that's suspend fuel there's a couple problems with this one is it's way above ground level okay and that needs to contain water and it's outside of the containment building so what happens is because the first line of defense was back up generators okay all right back up generators to make electricity to keep the pumps going right and you want the pumps going because they have to keep that spent fuel under water and the waves crashed over right and uh wiped them out but there's a second backup there are batteries right because we need to run electricity to run pumps and those batteries you know six hours wow that should be a long time in six hours we should be able to get a truck over there we should be able to get either backup batteries or we should be able to get a generator online but not if you have an unmitigated disaster of a tidal wave and earthquake wiping out the local population and all the roads so eventually the batteries died away and then the spent fuel gets uncovered it warms up it's not a nuclear explosion it evolves hydrogen right and the spent fuel does have radioactive material in it when it gets too hot and radiation is released and now we come back to this question about magnitudes of release people were evacuated except for the workers at the plant who were all monitored the dose to the public was low by the comparisons of what you get under normal background and yes it messed up miles from the plant which are being cleaned up differences between fukushima and other reactors in the united states or other places in the world first it was pretty old plant about 40 years old at the time of the accident and one of the things that caused those blast panels to go off and the radioactive material to be dispersed were hydrogen explosions ever since three mile island in the united states our plants have hydrogen absorbers to guard against that particular accident scenario but i think the most important thing is that new plants since the year 2000 are called generation 3 and they're passively safe which means i needed both of these things to pump water right i needed these to pump water onto the waste fuel or to pump water into other varieties of cooling cooling the current fuel in the generation 3 reactor i don't need to pump water i have walk away safety natural convection hot air rising cool air falling what you can't stop is enough to be able to keep those reactors cool or their waste fuel cool etc so now let's talk about the third myth wastes nuclear wastes i have another question for you how much high level nuclear waste has been produced in the u.s in the last 60 years maybe i should say 63 years our first commercial power plant was the year i was born 1958 right so 63 years ago enough to fill up a mountain a town a large building a big room or none at all the answer is not none at all we do have high level nuclear waste it's the fission products but amazingly you don't make that much of them if you only took out the fission products the high-level long-lived nuclear waste would be enough to fill up a big room now the waste of the things the uranium fell into it is true that those neutrons go and make the reactor vessel itself radioactive we call those low-level nuclear wastes they typically have very low half-life short half-lives so they would decay quickly but the stuff that uranium was can be much longer half-lives and it can actually have some forms of not just the things you split the uranium into but if you added that neutron and then added another neutron before it fissioned you get things heavier than uranium and those can have very long lifetimes here's the key though you don't make much all right got my little uh my little table here with the cardboard box the amount of waste made in one plant in one year fits under a chair right now that's not a chair you want to sit on okay or being here but that's the magnitude and the other thing is that they're in solid form all right they're not made out of radioactive green goo that's going to go um you know turn turtles into ninja warriors and you could store it in a dry mountain or probably much more cost effectively just in a big dry concrete block next to where they were made and you might say oh how can you be sure to store them how can you make sure nothing gets out well pretty straightforwardly let's take a canister and we fill the canister with grout that's concrete before you add the water so if someday somehow some water leaked in it would solidify anyway you make it with stainless steel you line it with all the right types of materials okay then you dig holes in solid rock right and you make sure all those holes are like a thousand feet below the surface and another thousand feet above the water table and you do this in a stable mountain in a desert no rain no erosion no earthquakes this is a stable mountain it's called yucca mountain that was the plan outside of of nevada near the nuclear test site the place where we used to blow up bombs underground with no containment around them okay and this was the plan now this plan hasn't really happened in part because it's very expensive you can take those wastes they're made at a nuclear power plant they're already there even if the plant's been operating 60 years or 50 years all its waste is still there because not a lot of volume and you could put it in a big giant concrete block okay big block outside the power plant right and inside here you've got your waste and you can put monitors all around this and monitors everywhere else right and and you could check on these monitors and make sure that you aren't seeing any radioactivity levels you can come right up with your handheld geiger counter and be a background and this stuff is called dry cask storage which is probably makes a lot more sense sometimes some of these fission products in here in future generations might be considered valuable you might want to get to them okay but in some manner either someday you need to move them or you want right away to move them to this mountain the question is how do you get them there and it's really safe to get them there and you might say oh i don't believe that that truck's going to crash there's accidents all the time we're going to radiate my town we better pass special rules that say you can't put nuclear materials through my town but um i got a video here that was done and it's kind of fun and i have a feeling it it might convince you and so let's go to the videotape all right now this was done actually on real imovie film and this was from the late 70s as you can probably tell from the haircuts which look an awful lot like my haircut for the same reason and here is a spent fuel cask and we move them around on open flatbed trucks all right and why open trucks well because you have a chase car going behind them and if it somehow falls off you want to know the government already does this right because we have nuclear waste made from when we have nuclear weapons and we manufacture nuclear weapons for a long time so they want to make sure that this type of storage isn't going to break so they did computer models but no one really trusts computer models i know i'm an experimentalist all right so let's make a real one and let's put monitors all over it and then let's put it on truck and strap some rocket engines on the back of the truck and crash the truck into a giant cement block without a driver okay here it is in slow motion that's why you don't want a head-on collision with a truck now it withstand so little damage that they said ah let's do it another truck this time going 80 miles an hour runaway truck oh well uh that's a lot more impact remember mv squared right all right and that looks pretty bad until you realize that's part of the truck a couple dents no loss of integrity but just wait what if the after crashing it landed on a railroad track okay and now we can take a rocket propelled freight train locomotive and have it crash into it okay um then few nicks and scrapes no leaks no loss of pressure sometimes we move these things by rail if you move them by rail well then the rail car could somehow crash and you know what maybe an airplane had recently crashed so there it was in a pool of jet fuel okay so let's take our crash railroad car with the fuel cask in a pool of jet fuel what brought down the twin towers wasn't the impact of the plane it was the burning from the jet fuel so we'll have an hour and a half of jet fuel fire not exactly sure why the fuel wouldn't have just leaked into the ground but could have been over a swimming pool all right and we do this and even after all of this our storage container did not leak did not lose pressure and was still intact right there so in the first part of the conclusion nuclear power is expensive to build but it's not dangerous to the public and the common objections radiation accidents wastes exist predominantly because the population isn't educated on the subject right when we talk about waste we should talk about waste in compared to other types of wastes particular the co2 from fossil fuel you see i've got one more graph here for you energy use by country statistics lag a little behind so i only have 2018. and you notice that the us for the past 14 15 years even longer than that we've used about the same amount of energy every year this is in quads but the two biggest countries in the world india and china even in the last 14 years their energy use has more than doubled right because they have all these people and if you wanted to get up to the same standard of livings as in europe or asia or other parts of the west united states canada right here's the other countries you are going to have a larger energy level and you can see that in the last you know 15 years or so we've had a 33 percent increase in energy this is even more impressive if you look at a graph 600 quads or more in 2019 that's that number way up here and this is time right and those colors you see right you got coal oil natural gas that's that's the 85 worldwide the red band right is uh is nuclear and are beloved and they are i do research on them solar power other things right there they're up there in the in the small levels so if we are going to combat and not use fossil fuels for climate or global warming concerns or other health concerns we're going to need everything we've got here folks all right so my last conclusion is we're going to need nuclear thank you very much and that's what you need to know about dispelling the myths of nuclear power

Channel: Illinois EnergyProf

Views: 258,658

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Id: c1QmB5bW_WQ

Length: 35min 50sec (2150 seconds)

Published: Tue Aug 03 2021