WEBVTT - How Nuclear Reactors Work 0:00:00.280 --> 0:00:02.960 Brought to you by the reinvented two thousand twelve Camray. 0:00:03.160 --> 0:00:08.920 It's ready. Are you get in touch with technology? With 0:00:09.039 --> 0:00:17.800 tech Stuff from how stuff works dot com. Hello again, everyone, 0:00:17.840 --> 0:00:20.320 Welcome to tech Stuff. My name is Chris Poulette and 0:00:20.360 --> 0:00:22.720 I am an editor at how stuff works dot com. 0:00:22.760 --> 0:00:25.759 Sitting across from me as always a senior writer, Jonathan Strickland. 0:00:25.840 --> 0:00:30.840 Hey there, Okay, I think we'll probably be a little 0:00:30.840 --> 0:00:33.839 subdued for those those of you who are long term fans. 0:00:34.360 --> 0:00:38.600 A few weeks ago we recorded an episode of tech 0:00:38.680 --> 0:00:43.600 Stuff because of a seismic event in christ Church, New Zealand. 0:00:43.760 --> 0:00:49.239 Yet uh did a lot of damage, but hadn't resulted 0:00:49.280 --> 0:00:55.600 in a lot of human costs. Since then, of course, um, 0:00:55.640 --> 0:00:58.520 you know, we've had the earthquake in Japan nine point 0:00:58.520 --> 0:01:03.560 oh earthquake um, which, if you remember in the Seismology podcast, 0:01:04.120 --> 0:01:07.840 each each number in the Richter scale is ten times 0:01:07.880 --> 0:01:11.120 greater in intensity than the previous number, So a two 0:01:11.240 --> 0:01:13.759 is ten times more intense than a one. So nine 0:01:13.920 --> 0:01:20.080 is an incredibly intense earthquake. What's what's interesting about that too? 0:01:20.120 --> 0:01:23.440 Just as a note, um, I understand that that was 0:01:23.480 --> 0:01:27.120 actually an aftershock of a six point two I believe 0:01:27.319 --> 0:01:30.560 magnitude earthquake. It was in the sixes. Yeah, it can 0:01:30.600 --> 0:01:33.679 sound kind of unusual to some of us that an 0:01:33.680 --> 0:01:36.800 aftershock would actually be more powerful than the initial earthquake. 0:01:36.880 --> 0:01:39.480 But you just have to remember those those plates that 0:01:39.520 --> 0:01:43.759 we talked about in the Seismology podcast are the pressure 0:01:44.319 --> 0:01:47.760 is incredible. There's nothing else like it on Earth really 0:01:48.240 --> 0:01:52.640 where uh and if if those plates slip against each other, 0:01:53.120 --> 0:01:56.160 then your you can get a pretty massive earthquake or 0:01:56.160 --> 0:02:00.120 an aftershock. So um, of course, we we touched on 0:02:00.200 --> 0:02:04.760 how earthquakes are measured, the different devices have been used 0:02:04.760 --> 0:02:08.079 to measure them in the past. Um. And uh, you know, 0:02:08.120 --> 0:02:11.519 of course in Japan there were the earthquakes and aftershocks 0:02:11.520 --> 0:02:14.760 in the tsunami that followed, resulting in a lot of 0:02:14.760 --> 0:02:17.000 property damage and loss of life. We're still not sure 0:02:17.160 --> 0:02:21.840 at this point how many people are gone. No, it's 0:02:21.880 --> 0:02:25.840 a tragedy that is definitely on a on a huge scale. 0:02:25.919 --> 0:02:30.239 We just don't know the extent of that yet. And um, 0:02:30.280 --> 0:02:34.200 although no one has really asked about this yet, we're 0:02:34.280 --> 0:02:36.320 kind of thinking that maybe people would want to know 0:02:36.360 --> 0:02:39.880 about the other major news event that has gone along 0:02:39.919 --> 0:02:44.919 with that, which was the the nuclear power plant that 0:02:45.040 --> 0:02:50.519 has suffered catastrophic failures as the result of the earthquake. UM, 0:02:50.639 --> 0:02:52.800 and we thought it might be interesting to talk about 0:02:52.800 --> 0:02:56.040 how nuclear power plants work, and then we'll we'll go 0:02:56.080 --> 0:03:00.720 into exactly what the problem is in Japan. Yeah, with this, frankly, 0:03:00.720 --> 0:03:03.040 this could be a marathon episode. We could talk about 0:03:03.560 --> 0:03:06.639 nuclear power plants for hours because they are very involved. 0:03:06.639 --> 0:03:10.520 So we decided to stick primarily to the general type 0:03:10.639 --> 0:03:15.040 of nuclear power plant being used in question, but also 0:03:15.160 --> 0:03:18.960 some of the others that have had major problems in 0:03:18.960 --> 0:03:23.440 the past, notably the Chernobyl reactor and the one in 0:03:23.480 --> 0:03:26.760 Three Mile Island in in the United States. So let's 0:03:26.760 --> 0:03:30.040 talk first about what a nuclear reactor is and how 0:03:30.120 --> 0:03:35.880 it generates power. Uh, of course, it's using a nuclear process, right, 0:03:35.880 --> 0:03:40.280 It's using decay. Really, it's we're talking about controlling the 0:03:40.360 --> 0:03:47.000 decay of of uranium. Really, it's when you compare it 0:03:47.040 --> 0:03:51.960 to a coal power plant, um, and you and you 0:03:52.000 --> 0:03:55.320 take the very very basics together, this type of nuclear 0:03:55.360 --> 0:03:59.120 power plant is almost exactly the same type. You're using 0:03:59.680 --> 0:04:02.000 a new clear reaction to generate heat as you would 0:04:02.240 --> 0:04:04.680 for a coal fired power plant, right, exactly, you would 0:04:04.680 --> 0:04:07.800 you would burn coal to generate heat in a coal plant? So, yeah, 0:04:07.960 --> 0:04:10.880 same thing, you're trying to use heat to generate electricity. 0:04:11.160 --> 0:04:14.320 You use that to to generate steam. The steam turns 0:04:14.320 --> 0:04:18.080 a turbine and a generator, which generates electricity. It's it's 0:04:18.120 --> 0:04:22.120 the nuclear reaction that makes it so very different from 0:04:22.160 --> 0:04:24.440 the coal plants that. Yeah, And you might ask, well, 0:04:24.480 --> 0:04:26.719 why would you want to use nuclear power in the 0:04:26.720 --> 0:04:30.320 first place. Well, there's several reasons. One is that, unlike coal, 0:04:30.480 --> 0:04:34.440 it doesn't produce uh, greenhouse gases. That's right, right, So 0:04:34.480 --> 0:04:37.200 when you burn coal, you're going to generate greenhouse gases 0:04:37.240 --> 0:04:40.920 and essentially carbon dioxide being chief among them, and uh 0:04:40.960 --> 0:04:44.600 and that can contribute to lots of environmental problems. So 0:04:45.160 --> 0:04:48.960 in some ways, nuclear power, at least from a greenhouse 0:04:48.960 --> 0:04:53.760 gas perspective, is greener than coal technology. Also, you don't 0:04:53.760 --> 0:04:56.680 need as much fuel to generate power as you would 0:04:56.720 --> 0:05:00.400 with coal. It's it's actually an incredible skin you could 0:05:00.440 --> 0:05:03.480 be talking about, you know, a few pounds of uranium 0:05:03.600 --> 0:05:07.839 versus tons and tons and tons of coal. Yes, it 0:05:07.960 --> 0:05:10.560 wasn't that long ago that the uh, those of us 0:05:10.600 --> 0:05:13.400 in the United States were talking about the coal mine 0:05:14.080 --> 0:05:17.400 the coal miners who are trapped in West Virginia. UM. 0:05:17.400 --> 0:05:19.440 And of course people start talking about the pros and 0:05:19.480 --> 0:05:21.480 cons of coal. Now of course we're talking about the 0:05:21.480 --> 0:05:24.960 pros and cons of of nuclear energy. UM. But yes, 0:05:25.400 --> 0:05:30.720 it requires far less uh um raw material to generate 0:05:30.720 --> 0:05:33.960 the nuclear reaction as it would for the coal fired 0:05:34.000 --> 0:05:38.120 power plants. Now, so you're you're talking about material where 0:05:38.120 --> 0:05:42.080 you don't need as much. You aren't genering greenhouse gases UM, 0:05:42.160 --> 0:05:46.480 and you can create an intense amount of heat very 0:05:46.520 --> 0:05:51.200 pretty simply in the grand scheme of things. But there 0:05:51.200 --> 0:05:54.599 are a lot of concerns around nuclear power as well. 0:05:54.680 --> 0:05:57.440 For one, I mean, we're talking about radioactive material, and 0:05:57.880 --> 0:06:01.240 radioactive material that is harmful to human Yes, it's not 0:06:01.400 --> 0:06:05.560 just you know, lots of things radiate energy, and not 0:06:05.600 --> 0:06:08.200 all of that energy is harmful. Yes. Just the other 0:06:08.320 --> 0:06:12.280 night I was watching, uh the CBS news report on 0:06:12.560 --> 0:06:14.239 radio activity, and a lot of people in the United 0:06:14.240 --> 0:06:19.080 States have been concerned that, first of all, the governments 0:06:19.120 --> 0:06:21.560 of Japan and the United States aren't being truthful with 0:06:21.600 --> 0:06:26.159 the amount of radiation being leaked in the atmosphere as 0:06:26.200 --> 0:06:29.760 a result of the explosions that took place at the 0:06:29.800 --> 0:06:34.359 plant in Japan. UM. But they were One of the 0:06:34.400 --> 0:06:36.480 things that I think was interesting was they took a 0:06:36.520 --> 0:06:41.159 Geiger counter around to several different They were basically walking 0:06:41.200 --> 0:06:44.040 around New York City with a Geiger counter, and they 0:06:44.040 --> 0:06:45.800 went to the middle of the park and turned it 0:06:45.839 --> 0:06:49.799 on and it was picking up readings of radio activity. 0:06:50.120 --> 0:06:53.080 And they walked over to granite, a granite monument as 0:06:53.080 --> 0:06:55.599 a matter of fact, and UH and and took the 0:06:55.600 --> 0:06:57.560 Geiger counter. A geiger counter, by the way, as a 0:06:57.560 --> 0:07:02.719 device that measures radioactivity. You hear clicking sounds and it 0:07:02.760 --> 0:07:06.000 has a needle. One of the UH. I think of 0:07:06.040 --> 0:07:07.720 it as an old style, but really I guess it's not. 0:07:08.520 --> 0:07:10.720 With the needle and it shows you roughly how much 0:07:11.120 --> 0:07:14.360 radioactivity is being gendered. And granted is naturally radioactive, and 0:07:14.360 --> 0:07:17.280 I didn't know that now. Of course, you can't take 0:07:17.400 --> 0:07:21.120 just anything UM and throw it in a nuclear reactor 0:07:21.160 --> 0:07:23.720 and have it react. You have to use a very 0:07:23.760 --> 0:07:28.560 special UM type of material. Because to generate a nuclear 0:07:28.560 --> 0:07:33.800 reaction UM, you're splitting an atom, use a stray neutron 0:07:34.560 --> 0:07:39.360 to UH break apart the nucleus of another atom. And 0:07:39.360 --> 0:07:43.680 and some some elements are more likely to be are 0:07:44.000 --> 0:07:45.880 are are easier to do that with than others. You 0:07:45.880 --> 0:07:48.760 need something that's called fistle if you're using a effission 0:07:48.800 --> 0:07:52.480 reaction as the one as these reactors do. Fusion power 0:07:52.640 --> 0:07:55.360 right now is kind of beyond us as far as 0:07:55.760 --> 0:07:58.720 it takes more energy to create a fusion reaction than 0:07:58.960 --> 0:08:01.200 we get back, I'll of it. But there is a 0:08:01.240 --> 0:08:04.520 lot of hope that in the future fusion will become 0:08:04.680 --> 0:08:10.000 the the power source for nuclear facilities. The Sun generates 0:08:10.240 --> 0:08:14.880 energy through fusion, not fission, so uh yeah, we haven't 0:08:15.000 --> 0:08:16.520 we haven't gotten there yet, but there are a lot 0:08:16.520 --> 0:08:19.480 of very very smart people working on ways to create 0:08:19.520 --> 0:08:23.360 fusion power plants, and it's quite a bit of research 0:08:23.800 --> 0:08:27.160 on on these things from Britannica. I like to to 0:08:27.280 --> 0:08:30.000 use that, of course as one of my sources. Um 0:08:30.080 --> 0:08:33.160 and uranium two thirty five, according to Britannica, is the 0:08:33.160 --> 0:08:37.280 only naturally occurring fistle material that's in a ready state 0:08:37.480 --> 0:08:40.760 to be to be split apart this way. Um, there 0:08:40.760 --> 0:08:45.760 are other, uh different kinds of materials. We're we're talking 0:08:45.800 --> 0:08:50.480 about the nucleides um. Somebody probably correct my pronunciation. I 0:08:50.559 --> 0:08:53.720 think that's right, but those some of them basically as 0:08:53.760 --> 0:08:56.839 long as the atoms are in an excited state. Uh, 0:08:56.880 --> 0:08:59.960 they can be um. When they're hit with a slow 0:09:00.120 --> 0:09:03.079 moving neutron, you can you can break them apart. Uranium 0:09:03.080 --> 0:09:06.640 two thirty five to thirty three, plutonium two thirty nine 0:09:06.640 --> 0:09:10.240 and two forty one um Plutonium two thirty nine. You 0:09:10.280 --> 0:09:13.280 actually create with your uranium two thirty eight and then 0:09:13.320 --> 0:09:18.559 you bombard it with neutrons. Yeah, materials that are fertile, 0:09:19.320 --> 0:09:22.600 uh can be that if you are different kinds of 0:09:22.679 --> 0:09:25.040 materials that if you add an extra neutron, you can 0:09:25.240 --> 0:09:28.760 they can become fiztle. Uh. Those are thorium two thirty two, 0:09:28.840 --> 0:09:33.040 uranium two thirty eight, and plutonium two forty um. So 0:09:33.120 --> 0:09:36.719 these are very complex atoms and heavy atoms and very 0:09:36.760 --> 0:09:39.920 heavy atoms and um. There are are the kinds of 0:09:39.960 --> 0:09:43.360 materials required to be used in a in a core 0:09:43.600 --> 0:09:46.600 of a nuclear reactor, and uranium two thirty five will 0:09:46.640 --> 0:09:51.000 break apart naturally decays over time. But but that's not 0:09:51.080 --> 0:09:53.720 the You know, you want to have a controlled and 0:09:54.360 --> 0:09:56.840 a controlled reaction in order to be able to generate power, 0:09:56.840 --> 0:09:58.320 and you want to be able to do it at 0:09:58.600 --> 0:10:00.880 a good time scale. Because we're uh, we don't have 0:10:00.960 --> 0:10:04.319 thousands of years to generate electricity. So with the uranium 0:10:04.360 --> 0:10:07.480 two thirty five, you actually would bombard it with neutrons 0:10:07.480 --> 0:10:10.800 in order to uh to speed up that reaction. Now, 0:10:10.840 --> 0:10:13.960 what that will do is that the the atom splits apart, 0:10:14.040 --> 0:10:16.400 it generates a lot of energy in the form of 0:10:16.520 --> 0:10:20.760 heat and radiation. The radiation comes in the forms of 0:10:20.840 --> 0:10:26.000 gamma radiation, beta radiation, and alpha radiation. Uh So, gamma 0:10:26.080 --> 0:10:30.360 radiation is a form of electromagnetic radiation UM. In fact, 0:10:30.400 --> 0:10:35.000 there are two major kinds of radiation. Electromagnetic radiation, which 0:10:35.040 --> 0:10:39.520 is some form of light. Uh it's it's photon radiation UM. 0:10:39.559 --> 0:10:43.360 That may not be visible light, but it is. It 0:10:43.440 --> 0:10:47.079 falls under the photon radiation. Then you have particulate radiation, 0:10:47.720 --> 0:10:51.720 which is when you're talking about an unstable uh atom 0:10:51.760 --> 0:10:56.880 particle shoots off essentially from the the atom. And uh 0:10:57.240 --> 0:11:01.920 So with alpha radiation uh uh or well, I'll start 0:11:01.920 --> 0:11:07.959 with beta radiation. With beta radiation, you've got electrons being released. Right, 0:11:08.480 --> 0:11:12.800 alpha radiation, it's protons and neutrons being released. Now, protons 0:11:12.800 --> 0:11:16.880 and neutrons are much much much larger in comparison to electrons, 0:11:17.720 --> 0:11:21.720 and they move slower than electrons do. So alpha radiation, 0:11:21.840 --> 0:11:24.720 you get the protons and neutron splitting off. That's a 0:11:24.720 --> 0:11:30.040 particulate radiation that moves slowly. It can actually depending upon you, 0:11:30.080 --> 0:11:32.679 know how how you're being exposed to it. Your skin 0:11:32.880 --> 0:11:37.360 can sometimes block alpha radiation just because your skin is 0:11:37.360 --> 0:11:40.360 thick enough where it's the particles are not moving at 0:11:40.400 --> 0:11:45.440 a speed sufficient to be able to penetrate the skin. Um. 0:11:45.520 --> 0:11:48.400 The beta radiation is different because those electrons are very 0:11:48.400 --> 0:11:51.480 tiny and they're moving really really fast and uh, and 0:11:51.600 --> 0:11:54.840 this is the sort of radiation that the sort of 0:11:54.840 --> 0:11:58.600 particular radiation that can actually cause pretty nasty deep tissue 0:11:58.760 --> 0:12:00.720 damage if it hit to you. And then of course 0:12:00.760 --> 0:12:05.680 gamma radiation is really really high energy electro magnetic radiation, 0:12:05.720 --> 0:12:09.360 and that stuff is serious business. Uh. You know, gamma 0:12:09.440 --> 0:12:14.440 radiation can cause lots of problems in both immediate acute 0:12:14.480 --> 0:12:18.280 problems and chronic problems over time. So why would you 0:12:18.280 --> 0:12:20.600 want to use this, Well, it's because it gives off 0:12:20.640 --> 0:12:24.280 this this amount of energy, this this kind of intense energy. 0:12:24.640 --> 0:12:28.920 It's really good at converting water into steam. So if 0:12:28.960 --> 0:12:32.360 you can control this reaction, uh and generate the right 0:12:32.400 --> 0:12:34.160 amount of heat, you're going to generate a lot of 0:12:34.200 --> 0:12:37.160 steam that's going to move through the system and eventually 0:12:37.200 --> 0:12:41.199 turn the turbine which is going to uh provide the 0:12:41.960 --> 0:12:45.400 power to the generator, and then you you create power 0:12:45.400 --> 0:12:49.079 for the power grid. And some countries rely very heavily 0:12:49.240 --> 0:12:53.440 on nuclear power to create to to supplement their power grid. 0:12:53.920 --> 0:12:56.839 Countries like like France, it's nearly seventy of their power 0:12:57.000 --> 0:13:00.280 that comes from nuclear power. In the United States, it's 0:13:00.320 --> 0:13:05.199 more like it's funny because there are two, um, two 0:13:05.240 --> 0:13:07.520 different things to consider that you might not consider with 0:13:07.559 --> 0:13:11.560 some of the other forms of electricity generation. Here UM 0:13:11.679 --> 0:13:16.680 atomic reactions are deal with probability UM and they deal 0:13:16.720 --> 0:13:21.760 with chain reactions. UM. I remember watching in one of 0:13:21.760 --> 0:13:24.440 my science classes a long long time ago an experiment 0:13:24.480 --> 0:13:26.560 that they did where they had set up we're not 0:13:26.640 --> 0:13:31.160 an experiment, but an an illustration. They had a plexiglass 0:13:31.280 --> 0:13:37.240 or clear plastic box and across the floor of it, 0:13:37.320 --> 0:13:40.600 the entire floor was covered with mouse traps set mouse traps. 0:13:41.160 --> 0:13:44.680 Each mouse trap had two ping pong balls on top 0:13:44.720 --> 0:13:49.080 of it and everything was still. So this is the 0:13:49.120 --> 0:13:51.920 normal state of the atoms that's supposed to represent the 0:13:51.960 --> 0:13:55.280 normal state of the atoms inside the fuel. UM. And 0:13:55.320 --> 0:13:57.120 then there was a small hole at the top of 0:13:57.120 --> 0:14:00.079 the box, and the person said, Okay, this is what 0:14:00.160 --> 0:14:03.360 happens when you add the neutron. The stray neutron is 0:14:03.640 --> 0:14:07.720 another ping pong ball in this illustration, and the person 0:14:07.840 --> 0:14:11.440 dropped the ping pong ball into into the box, and 0:14:11.480 --> 0:14:14.040 of course it hit one of the mouse traps, setting 0:14:14.040 --> 0:14:19.040 it off. The other two ping pong balls representing neutrons again, uh, 0:14:19.320 --> 0:14:22.040 jumped up from the mouse trap in different directions, and 0:14:22.120 --> 0:14:24.720 each of those set off more mouse traps, and each 0:14:24.760 --> 0:14:28.440 of those set off more mouse traps. Exponential growth. Yes. Now, 0:14:28.480 --> 0:14:32.920 of course in the nuclear fuel uh, you know, in 0:14:33.000 --> 0:14:36.120 that particular illustration ended and very quickly within a matter 0:14:36.160 --> 0:14:39.480 of you know, probably two or three seconds, because they 0:14:39.480 --> 0:14:42.040 were you know, forty mouse traps or something like that. 0:14:42.880 --> 0:14:46.480 In nuclear fuel, this continues on UM, but they have 0:14:46.560 --> 0:14:48.880 to control that. They have to look at the probability 0:14:48.920 --> 0:14:51.520 that a neutron will continue, that there will still be 0:14:51.640 --> 0:14:57.560 stray neutrons able to generate more heat energy release UM. 0:14:57.800 --> 0:15:02.280 So when they want to what they call a slightly 0:15:02.320 --> 0:15:07.000 super critical uh level of reaction, because there's that means 0:15:07.040 --> 0:15:09.840 that there is more more than one fission per neutron 0:15:10.280 --> 0:15:11.960 so you're you're you don't want it to be a 0:15:11.960 --> 0:15:14.600 little bit. You don't want to be underneath that. When 0:15:14.600 --> 0:15:17.840 it gets subcritical, that's when there are a few there 0:15:17.720 --> 0:15:22.400 are fewer neutrons available to make the nuclear reactions, which 0:15:22.440 --> 0:15:24.600 means that you would actually have to pour more power 0:15:24.720 --> 0:15:27.720 into the system to to shoot more neutrons into it 0:15:27.760 --> 0:15:29.680 in order to generate power. And of course, you know, 0:15:29.720 --> 0:15:32.000 the whole goal here is to make it as efficient 0:15:32.040 --> 0:15:36.440 as possible when you're generating electricity. Otherwise you're actually consuming 0:15:36.760 --> 0:15:40.800 far more power than you are able to convert into electricity. Yes, 0:15:41.000 --> 0:15:44.320 when it's one spare neutron to a reaction, that's or 0:15:44.640 --> 0:15:48.880 to a nucleus of another atom, that's critical. That literally, 0:15:48.880 --> 0:15:51.680 that is what they call critical, and that's the reactive 0:15:51.720 --> 0:15:56.200 state of the the reactor core um. From what I understand, 0:15:56.200 --> 0:15:59.160 they do want it to be slightly super critical, but 0:15:59.320 --> 0:16:03.560 only lightly, and so controlling the reaction is very important, 0:16:03.640 --> 0:16:06.600 and it's done in a number of different ways. Sure, 0:16:07.080 --> 0:16:09.080 let's talk a little bit about the way the fuel 0:16:09.200 --> 0:16:11.120 is put together and then we can talk about how 0:16:11.160 --> 0:16:13.400 that control happens. Yeah, I think that that would be 0:16:13.440 --> 0:16:16.560 excellent because that is a big part of how they 0:16:16.560 --> 0:16:20.840 control the reaction. Yeah, so, so the uranium is enriched 0:16:20.920 --> 0:16:25.320 with uranium two thirty five right now for a nuclear facility, 0:16:25.880 --> 0:16:29.320 I was gonna say, we should might maybe explain what 0:16:29.400 --> 0:16:33.800 that means, because uranium two thirty five is naturally reactive, 0:16:34.040 --> 0:16:36.920 but there's only so much of you two thirty five 0:16:37.000 --> 0:16:40.560 found in a chunk of uranium. So enriched uranium is 0:16:40.640 --> 0:16:43.640 basically they've added more uranium two thirty five to the 0:16:43.760 --> 0:16:48.160 uranium overall to make it, to make it more reactive 0:16:48.200 --> 0:16:50.680 so they can use it as nuclear fuel. And so 0:16:50.840 --> 0:16:55.480 for UH, you have to for for fuel for a 0:16:55.560 --> 0:16:58.960 nuclear power plant, you need to have added enough you 0:16:59.040 --> 0:17:02.000 two thirty five, So it's got two to you two 0:17:02.080 --> 0:17:05.959 thirty five and the overall fuel now you two thirty 0:17:05.960 --> 0:17:08.159 five is the same element that you're going to find 0:17:08.840 --> 0:17:14.080 in UH in nuclear weapons. But nuclear weapons require a 0:17:14.200 --> 0:17:19.200 much higher percentage of you two thirty five to thirty 0:17:19.280 --> 0:17:21.600 five within the uranium in order for it to be 0:17:21.720 --> 0:17:24.960 weapons grade. So that's a pretty easy way to tell 0:17:24.960 --> 0:17:28.040 if someone's making weapons grade uranium is you measure how 0:17:28.200 --> 0:17:31.280 how the percentage of you to to thirty five in 0:17:31.320 --> 0:17:34.040 the fuel itself. If you've been following the news and 0:17:34.320 --> 0:17:39.800 you've seen pieces on where some countries are concerned about 0:17:39.840 --> 0:17:44.200 Iran enriching uranium. This is why you can enrich uranium 0:17:44.240 --> 0:17:47.800 for a nuclear power program, or it can also be 0:17:47.880 --> 0:17:50.800 used in weapons. Right, So if you're enriching beyond that 0:17:50.840 --> 0:17:53.280 two to three percent, then that's a good indicator that 0:17:53.320 --> 0:17:57.760 you're looking at something more uh dangerous than the nuclear 0:17:57.800 --> 0:18:02.800 power plant. So the what the bits of uranium are 0:18:02.840 --> 0:18:06.840 actually formed into what what is called pellets, and they're 0:18:06.840 --> 0:18:10.639 about an inch long. They're about the diameter of a dime. 0:18:10.720 --> 0:18:12.360 So you can think it's kind of like a cylinder 0:18:12.640 --> 0:18:16.360 right now. These pellets are stacked together to form rods. 0:18:17.000 --> 0:18:21.760 Yes they are. They are contained within a metal rod, yes, yes, 0:18:21.880 --> 0:18:23.359 so yeah, you can think of like a there's like 0:18:23.560 --> 0:18:26.880 a sheath, a metal sheath, and these uranium pellets are 0:18:26.920 --> 0:18:30.399 stacked within that sheath. Now, these rods are then grouped 0:18:30.440 --> 0:18:35.080 together into a collection called a bundle. And if if 0:18:35.119 --> 0:18:37.080 that's all it was, if that's all you had and 0:18:37.080 --> 0:18:39.639 then you started introducing neutrons into it, you would have 0:18:39.720 --> 0:18:43.720 no way to to modify to moderate that at all. 0:18:43.800 --> 0:18:46.280 It would just the reaction would would increase and increase 0:18:46.359 --> 0:18:48.960 until either you would spent all the fuel or you 0:18:49.000 --> 0:18:51.359 had had a melt down. And meltdown essentially is when 0:18:51.400 --> 0:18:55.560 the fuel itself gets so hot that it melts um. 0:18:55.600 --> 0:18:59.720 So in order to control this, they have control rods. 0:19:00.560 --> 0:19:03.480 And control rods are made of material that are that 0:19:03.600 --> 0:19:06.560 absorbs neutrons, because as we were talking about, you know 0:19:06.600 --> 0:19:10.960 these neutrons that that fly off and hit uranium two five, 0:19:11.040 --> 0:19:15.200 that's what initializes this reaction. So if you have material 0:19:15.280 --> 0:19:17.960 that absorbs neutrons, it's like taking you know, you're you're 0:19:18.200 --> 0:19:21.879 you're putting the brakes on things, and the control rods 0:19:21.880 --> 0:19:24.320 tend to be you can you can insert them either 0:19:24.440 --> 0:19:28.480 all the way down where they are going to control 0:19:28.600 --> 0:19:32.000 the reaction as much as possible, keeping in mind that 0:19:32.200 --> 0:19:35.080 there's still some decay heat that's going on here. It's 0:19:35.119 --> 0:19:37.520 not like it's not like you immediately switch it off. 0:19:37.640 --> 0:19:41.119 It's just slowing it down to the point where you 0:19:41.200 --> 0:19:43.840 call it a nuclear shut down, but there's still heat. 0:19:44.880 --> 0:19:46.600 Or you can raise them all the way up and 0:19:46.640 --> 0:19:50.800 then just let the UH reaction go to full full blast. 0:19:52.280 --> 0:19:56.200 Cadmium and boron are two elements that are very good 0:19:56.240 --> 0:19:59.560 at absorbing stray neutrons, and you may have heard about 0:19:59.560 --> 0:20:04.120 born being introduced into the Japanese facility along with sea water. 0:20:04.520 --> 0:20:07.480 We'll talk about that in a minute too, um, but 0:20:07.520 --> 0:20:10.400 those are those are also uh, those are useful because 0:20:10.400 --> 0:20:14.760 they're basically fighting over who gets the stray neutrons and 0:20:14.760 --> 0:20:17.960 that just slows everything down and helps right keep it 0:20:18.000 --> 0:20:21.280 under control. Now, inside this nuclear reactor, you also have 0:20:21.320 --> 0:20:24.639 to have coolant because and actually the coolant is what 0:20:24.760 --> 0:20:28.159 heats up to go and then usually you have a 0:20:28.320 --> 0:20:31.240 you have a coolant that then runs through another system 0:20:31.320 --> 0:20:34.399 that will heat up water and the water becomes steam 0:20:34.400 --> 0:20:37.680 and that's what drives the turbine. Some nuclear power plants, 0:20:37.720 --> 0:20:41.000 and these are the ones that are kind of particularly dangerous, 0:20:41.760 --> 0:20:45.359 have the coolant system also driving the turbine, which means 0:20:45.400 --> 0:20:50.240 that you have radioactive material pushing that turbine because the 0:20:51.200 --> 0:20:55.160 coolant that encounters the actual rods is going to pick 0:20:55.240 --> 0:20:59.520 up radioactive material itself, will become radioactive. It's gonna have 0:20:59.600 --> 0:21:02.879 radioacti particles running through that cooling system. So most of 0:21:02.880 --> 0:21:06.520 these cooling systems are are self contained and they do 0:21:06.600 --> 0:21:11.120 not cross over into the water system that drives the turbine. 0:21:11.160 --> 0:21:13.239 They just they just you can think of it as 0:21:13.280 --> 0:21:16.680 it runs up against the water system, and the heat 0:21:16.800 --> 0:21:20.840 from the cooling system is what generates the steam in 0:21:20.880 --> 0:21:24.880 the water system. Um. So, but you have to have that. 0:21:25.040 --> 0:21:28.680 If you don't have that again, the uh, the core 0:21:28.800 --> 0:21:31.760 can reach a temperature that's so high that the uranium 0:21:31.760 --> 0:21:35.840 begins to melt. And there there's a lot of scary 0:21:37.320 --> 0:21:39.720 guesswork as to what would happen if you had a 0:21:39.720 --> 0:21:43.400 true meltdown, like a full on meltdown to the point 0:21:43.440 --> 0:21:46.720 where we're not really sure if the material would get 0:21:46.760 --> 0:21:50.000 so hot, like the reaction would continue to a point 0:21:50.000 --> 0:21:53.679 where it would just burn right through the reactor. Um 0:21:53.720 --> 0:21:57.199 that's a theoretical possibility, although we haven't actually seen that 0:21:57.240 --> 0:22:00.920 happen in real life yet, Thank goodness us that's true. Well, 0:22:00.960 --> 0:22:05.960 the the movie The China Syndrome is about that, and 0:22:06.359 --> 0:22:11.399 I think most scientists would probably tell you that that's 0:22:12.000 --> 0:22:15.639 a bit hysterical for what might actually happen. Uh. The 0:22:15.880 --> 0:22:20.639 the premise being that the core melts down, the fuel 0:22:21.320 --> 0:22:24.600 is melting, and it melts all the way through the 0:22:24.600 --> 0:22:27.240 center of the Earth again, from the United States to China, 0:22:27.359 --> 0:22:30.119 all the way through the the Earth that might be 0:22:30.160 --> 0:22:33.000 a little I think that's probably I mean, I'm not 0:22:33.040 --> 0:22:35.919 a scientist obviously, but I think that's a little extreme. 0:22:35.920 --> 0:22:38.960 I would definitely call that the worst case scenario. Yeah, 0:22:39.160 --> 0:22:42.040 I don't I don't know that it could actually go 0:22:42.280 --> 0:22:45.399 that far. But yes, that that is an exaggeration of 0:22:45.440 --> 0:22:47.760 what Jonathan's talking about, the idea that it would melt 0:22:47.880 --> 0:22:54.320 through the reactor. So the the problems that we could 0:22:54.359 --> 0:22:58.200 conceivably face with a nuclear power plant would involve something 0:22:58.240 --> 0:23:01.240 going wrong with the ability to insert or remove the 0:23:01.280 --> 0:23:04.320 control rods, really to insert them, because because if they're 0:23:04.359 --> 0:23:07.200 stuck there, all you really have is a dead nuclear 0:23:07.200 --> 0:23:09.320 power plan. And yes, that is terrible and that it's 0:23:09.359 --> 0:23:12.880 gonna cost billions of dollars to fix, but it doesn't 0:23:13.160 --> 0:23:17.439 pose an immediate threat to the surrounding area. UM. You 0:23:17.520 --> 0:23:20.320 also have the problem with if if the water system, 0:23:20.480 --> 0:23:23.600 if the cooling system is UH in any way compromised, 0:23:23.640 --> 0:23:26.679 then you have the chance of the nuclear reactor overheating, 0:23:27.040 --> 0:23:30.680 which unfortunately we have seen happen before, and that can 0:23:30.720 --> 0:23:35.360 cause UH massive problems down the line. Now, what happened 0:23:35.400 --> 0:23:41.960 with Japan is that the earthquake actually did not UH 0:23:42.119 --> 0:23:45.320 did not damage the reactors to the point where they 0:23:45.320 --> 0:23:48.320 were inoperable. In fact, what happened was that the control 0:23:48.400 --> 0:23:51.639 rods descended, as they should have in that instance to 0:23:51.840 --> 0:23:56.400 control that reaction. But again there's decay heat. It's not 0:23:56.520 --> 0:23:59.560 like it can shut it off immediately. It's just that 0:24:00.040 --> 0:24:05.359 the reaction is no longer continuing, right, but still generating heat. Right. UM. 0:24:05.400 --> 0:24:10.240 Another thing to consider with regard to the Japanese reactor 0:24:10.640 --> 0:24:15.760 is that, uh, there were containment devices set up. When 0:24:15.800 --> 0:24:18.360 you build a nuclear power plant like this, this light 0:24:18.359 --> 0:24:24.240 water plant, UM, it is ideal to build a containment 0:24:24.400 --> 0:24:28.840 area around the reactor course. UM. This is usually made 0:24:28.880 --> 0:24:33.200 with concrete, UH, very thick concrete in the case of 0:24:33.600 --> 0:24:39.000 the Japanese plant, UM, which for has has so far 0:24:39.080 --> 0:24:41.880