Small Nuclear Reactors - Natrium

foreign Illinois energy problem today I want to talk to you about small nuclear reactors the natrium variety it's a liquid metal cooled Halo fuel reactor so a little background a couple months ago I talked about another type of reactor you can see my uh video on small modular nuclear reactors gas cool and it was one of the winners of a large competition for advanced reactor demonstration programs by the department of energy the other winner is from the company tarapala and it is a liquid metal cool fast Reactor with high assay low enrichment uranium fuel with molten salt energy storage a lot to unpack but we're going to do it and they call it natrium why do they call it an Atrium well n a is the a symbol for sodium and this liquid metal inside here is sodium all right first what is a fast reactor when a neutron hits uranium-235 and if it splits if it's Visions right that's the first time panel now we've got two pieces right and we make more neutrons and these neutrons start really fast at the mega electron volt area and on this graph over here you can see that this is where they're big at mevs and this blue line is the chance for this first reaction to happen the chance of it fissioning you can see that many reactors the ones we all use today actually try to slow down the neutrons because they're going to take advantage of the fact that the reactivity the ability to make more efficients is a thousand times higher but you don't have to do it that way you can just have more uranium-235 and then you can run the reactor in this fast regime you might say well do you want to do that because you can burn up the wastes you see these two parts that it breaks into are called fission products they're always a little different they're almost always radioactive you can't do much about that that's where you're getting your energy from but their radioactivity is not that bad and if you look at the lower curve here you get back to the normal uranium ore you took out of the ground in about 300 years but this stuff the transuramics it's when this reaction doesn't do that but rather okay we didn't get a fission but rather a neutron hit something and most of the uranium is uranium-238 this just adds to it it just gets a little bigger it gets to u-239 and that keeps going and you make things heavier than uranium so we call them trans uranics things heavier than uranium and those have a very long Half-Life those are very long-lived wastes you don't get back to this natural uranium number by Decay for 300 000 years so the advantage of having a fast reactor is it will burn up these transuranics right as it makes them because it will also fission them the reactor still has to be cooled and we use Liquid Metal because if we use water it turns out that water is H2O HR protons and the best way to stop a neutron is to have it run into something that's the same weight like a neutron hits a proton both of them get half the energy you slow it down the protons are in hydrogen like H2O so we can't lose water but the whole point is going to be to get heat out have to cool the reactor so we're going to do something that's heavier and still a liquid and the best use and idea for that is liquid sodium sodium melts at something around 100 C it doesn't boil to something around 900 C so it has a really good temperature range where it's still a liquid you don't have to put it under pressure and it's so heavy that when a neutron gets sodium all right the neutron just bounces off and stays fast in a tiny little velocity for the sodium meaning it gets a little bit warmer now this is not the first time sodium's been used in reactors in fact it has a very long history of having sodium cooled reactors in the 1960s there was a device called the experimental reader reactor number two it was in Idaho and it works so well they even tried a really important experiment where they stopped cooling it and they see what happens normally oh my gosh that's a disaster it's going to lead to a meltdown you need this safety system and this safety system and this that as I'll explain a little later the nice thing about these types of reactors is they just stop working if they get too hot now sodium fast reactors were also used commercially in France they built both the Phoenix and the super Phoenix power plants sodium cooled fast reactors and they're connected to the power grid so you know things are new about this technology but this concept is something that has worked and has a lot of Engineering in it the thing is that those two examples EBR and Phoenix and super Phoenix were reader reactors their idea is that a neutron a fast Neutron hits the u-238 and through a couple steps ends up making plutonium to 39 and the reactor is actually fueled with a lot of plutonium now this is great from a resource utilization standpoint uranium-238 is the common isotope and so you can make fuel virtually forever with a breeder reaction unfortunately you can also make bombs out of plutonium-239 and so there was a lot of worry about nuclear proliferation about what happens to the fuel both in producing it or afterwards so why don't we keep the same great advantages of the sodium cooled reactor the fast reactor but use a different fuel Halo fuel High assay low enrichment uranium so you start with uranium you'll see it up here it's only less than one percent point seven percent is u235 u-235 is the good stuff that's the stuff that can fission now if I go all the way down to the bottom graph this is high enriched uranium 85 90 percent you can make a nuclear bomb out of that right it's visionable you have to get up to that concentration to make the bomb but that's called high enrichment and what about something in between if you're in the five to fifteen percent they call it high assay low enrichment uranium and this fuel can be really useful because it's made in a metal form and you still put it in fuel pellets and in fuel pins and in fuel rods and you are going to have to take the fuel in and take the fuel out now and then but once you take it out really pretty well used up okay you don't need to reprocess it you don't have to take the plutonium-239 out because the way the reactor is designed these transuranics have been fissioned and we use up most of that u-235 that was in it this also gets used up by the time you take the rod out so what about safety foreign this type of fuel is pretty great because if it gets too hot it stops working you say huh how can that happen well there's this thing called the Doppler effect and when something moves faster these resonances and I'll get to that expand all right you can see that in the graph here so that is this first graph you see the green line and that's the one you saw before that's the chance of fissioning but these other lines of the chance of capturing the neutron if you capture all the neutrons none of this fission reaction goes on so those hash mark lines you see the blue ones the red ones the resonances if they all get broader it means any Neutron that gets into that region of energy boom it gets gobbled up if you gobble up these neutrons if you get rid of them then there are no more visions no more Visions means the plant is shut down another thing about a metal Fuel and I think all of you know this is that it heat up a metal it expands a little and that means that the density also goes down that something else that tells you that if the temperature goes up that reactions now what about this molten salt energy storage this is one of the most exciting things about these reactors you have to cool off the liquid sodium don't turn it right to water water and sodium don't mix well you may be worried about that but remember the sodium is not under pressure it's not going to spurt into something and you keep water away from it good instead we're going to cool off the sodium with another solid that's melted a molten salt and then you store that salt in a big tank right here now this gives us a heat source and whenever we want to make electricity from it we can pump it here and then interchange it with water make Steam and make electricity the standard way we've been doing it all right and what are the big advantages of storing this heat well a nuclear power plant has to run at a constant level right and if you don't do this okay this is the nuclear fissions then you build up Xenon and if you see my video on Xenon can be a problem you'll see why well see not gonna be a problem the nuclear power plant can't go up and down in power the thing is our electric demand during the day well we're all asleep we're all asleep oh we all woke up we turned on coffee makers we turned on everything else a little bit during the day turn on everything at night it gets dark we go to bed and that's the electric use over the day sure it's not zero in the middle of the night you still have stuff on maybe some people are charging their cars here okay great that's not this and that's a problem wind and solar are renewable energies well what a solar energy look like uh solar energy well it's dark at night right so it really is zero and uh it's gonna Peak up in the middle of the day and it's going to go back when I can't predict the wins but it's not always going to be constant so here's the deal even though our fission power plant stays here our decision to make the energy out of the molten salt can give us the curve we want right this is what we use this we can now pull stuff off in the night tailor it down in the middle of the day ramp it back up oh it's real windy right here tailor it down and this curve can do what we call load following so the salt storage also can be piped a bit away and this means we can build these nuclear power plants next to existing steam production plants you said well where do we have those how about all those coal power plants we've shut down because we've built new Natural Gas for plants turbines and everything else still work and that brings us to the natrium reactor by Terra power in conjunction with GE Hitachi you can make 345 megawatts Electric standard nuclear power plants that exist today are around a thousand so this is still what we call small a much more usable number now here's the grade level and the reactor is underground yes it still has a containment building around it that's also underground it makes a lot of sense a lot of containment the fuel storage spent fuel storage also underground over here and you notice it takes the sodium away go away to somewhere else right until those salt storage tanks then connected to a power plant because of the variability even though my reactor runs constant this can produce between 100 and 500 megawatts electricity now you do have to refuel it and that's what the rest of the buildings are for they pull out fuel rods they put them back over here to the temporary storage it's about every 18 months here's the cool thing you only take out about one seventh of the rods whereas in a typical reactor you take out a third and this allows those trans uranics to get burned up and the fuel to be used very efficiently the first plant is going to be built in Wyoming and it's going to be built next to a retired Coal Power Plant haven't picked out which one yet but stay tuned construction for this will finish in the late 2020s there's some additional safety features of course these are fall under just like Generation 3 reactors passively safe fuel gets too hot reaction stops and you don't have to worry about the cooling Loops keeping going because just the convection of the sodium itself is enough to keep the core contained and safe and shut down and take away the waste heat and that was proven in 1968 when they intentionally did that accident Walk Away safety the system is not under pressure the lithium the sodium is is in a tank so you know you rupture the pipe it doesn't go spreading out everywhere it burns up most of its own high-level nuclear waste as we talked about and it has a small containment building big enough so we have that extra level of safety that it uses something like 80 percent less nuclear grade concrete but like in all videos we have to come to the bottom line how much does this cost well the first reactor is always going to cost more and that's why the government has stepped in with some of some additional funding not all of it to help provide a startup what the people at Terra power say is that the nth unit they haven't specified in but they hope in the steady state that you could build one of these for a billion dollars no billions a lot but your standard nuclear power plant today in the best of cases cost 5 billion often more this brings you down to two thousand eight hundred dollars per kilowatt of installed capacity you can look at my other economics lectures and see how this compares there's a way to figure out levelized cost of electricity yes these reactors do use more fuel right more of the u-235 you have to pay for that enrichment but they believe the cost will be around five cents per kilowatt hour now you can do gas for two and you can do a coal for three even cleaning it up a bit but remember these numbers got no credits for the CO2 the global warming cost and of course nuclear reactors make no CO2 so if you had some realistic charge for this this is comparable and you might say what about wind and solar well there are a lot of variable costs in those too but we can't have an entire grid on wind and solar because it gets dark at night and sometimes the wind doesn't blow and maybe you could store it in batteries but the batteries in your cars right this type of storage the thermal storage is extremely more efficient and much more contained you don't need enormous amounts of land so in conclusion the future of nuclear power Our Generation for reactors we'll be doing some more videos so you can see a lot more about them and one of the Beauties is you can put one of these next to an existing an already retired Coal Power Plant for instance which has its whole steam generator system up there and intact in fact natrium is going to demonstrate how well that works in Wyoming in this decade and that's what you need to know about small nuclear reactors that are liquid metal cooled Halo fuel thank you

Channel: Illinois EnergyProf

Views: 114,816

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Id: 47jP4YlqPZ4

Length: 19min 48sec (1188 seconds)

Published: Tue Jun 29 2021