1 00:00:00,520 --> 00:00:03,600 Speaker 1: Welcome to brain Stuff from house stuff works dot com, 2 00:00:03,600 --> 00:00:14,680 Speaker 1: where smart happens. Hi am ourshall brain with today's question, 3 00:00:15,160 --> 00:00:19,720 Speaker 1: what the heck happened with Japan's nuclear power plants this weekend? 4 00:00:20,560 --> 00:00:24,920 Speaker 1: As you'll recall, Japan had its giant earthquake and tsunami 5 00:00:25,040 --> 00:00:29,280 Speaker 1: last Friday, and right after the earthquake, everything looked pretty 6 00:00:29,360 --> 00:00:32,040 Speaker 1: much fine as far as the nuclear power plants were concerned. 7 00:00:32,280 --> 00:00:36,000 Speaker 1: The New York Times ran a story about how everything 8 00:00:36,080 --> 00:00:39,360 Speaker 1: looked good. There were no major problems. The reactor hadn't 9 00:00:39,360 --> 00:00:43,120 Speaker 1: cracked or you know, fallen over anything because of the earthquake, 10 00:00:43,360 --> 00:00:47,400 Speaker 1: and it looked really good. But then by Saturday, things 11 00:00:47,440 --> 00:00:49,519 Speaker 1: had taken a turn for the worst, so there were 12 00:00:49,560 --> 00:00:53,120 Speaker 1: reactor buildings exploding. There was all kinds of talk about 13 00:00:53,240 --> 00:00:56,760 Speaker 1: meltdowns and China syndrome and all this other stuff. So 14 00:00:56,880 --> 00:00:59,520 Speaker 1: when you think about it, a nuclear power plant is 15 00:00:59,560 --> 00:01:03,840 Speaker 1: supposed us to be one of the most amazingly engineered, 16 00:01:04,240 --> 00:01:08,959 Speaker 1: super wonderful things in the world. With umpteen levels of redundancy, 17 00:01:09,000 --> 00:01:13,160 Speaker 1: and every single contingency thought about and poured over and 18 00:01:13,280 --> 00:01:17,640 Speaker 1: inspected both nationally and internationally, there should have been nothing 19 00:01:17,680 --> 00:01:20,800 Speaker 1: that could go wrong in Japan's nuclear power plants, and 20 00:01:20,880 --> 00:01:23,800 Speaker 1: yet it did. So what happened and how did things 21 00:01:23,880 --> 00:01:29,080 Speaker 1: go from being really quite stable to completely unstable and 22 00:01:29,560 --> 00:01:32,039 Speaker 1: leading to some of the worst nuclear accidents ever to 23 00:01:32,080 --> 00:01:34,640 Speaker 1: occur on the planet. So let's take a look at 24 00:01:34,680 --> 00:01:37,959 Speaker 1: what happened step by step, because it really is an 25 00:01:38,000 --> 00:01:41,560 Speaker 1: interesting story and it shows how even when something is 26 00:01:41,680 --> 00:01:45,520 Speaker 1: engineered to the highest levels and given multiple layers of 27 00:01:45,560 --> 00:01:49,720 Speaker 1: redundancy and so on, things can still go sour. In 28 00:01:49,800 --> 00:01:54,400 Speaker 1: step one, the earthquake happened, and this was fine. The 29 00:01:54,480 --> 00:01:57,440 Speaker 1: four reactors that were nearest the epicenter of the earthquake 30 00:01:57,600 --> 00:02:00,440 Speaker 1: detected the earthquake and they shut down automatic, just like 31 00:02:00,480 --> 00:02:03,200 Speaker 1: they were supposed to. So what does shut down mean? 32 00:02:03,560 --> 00:02:06,040 Speaker 1: If you were to look inside these nuclear reactors, you 33 00:02:06,080 --> 00:02:09,880 Speaker 1: would see fuel rods filled with nuclear fuel little pellets 34 00:02:09,880 --> 00:02:13,399 Speaker 1: about the size of your little finger that are arranged 35 00:02:13,440 --> 00:02:18,600 Speaker 1: in these rods and collected together in bundles, and the 36 00:02:18,600 --> 00:02:23,880 Speaker 1: control rods moved down between the rods to absorb neutrons 37 00:02:23,919 --> 00:02:27,680 Speaker 1: that are coming out of the uranium atoms in the fuel. 38 00:02:27,919 --> 00:02:31,480 Speaker 1: And once you absorb the neutrons, you basically quench or 39 00:02:31,600 --> 00:02:35,200 Speaker 1: stop the nuclear reaction. That's creating the heat that's creating 40 00:02:35,240 --> 00:02:38,639 Speaker 1: the steam that's creating the electricity for the power plant. 41 00:02:38,760 --> 00:02:41,960 Speaker 1: So they automatically shut down the control rods moved into 42 00:02:41,960 --> 00:02:46,080 Speaker 1: the reactor core, absorbed all the neutrons quen the reaction. 43 00:02:46,120 --> 00:02:48,920 Speaker 1: Now there's still some, well not some, a lot of 44 00:02:49,040 --> 00:02:54,200 Speaker 1: residual heat in that reactor core, both from other radioactive 45 00:02:54,240 --> 00:02:58,040 Speaker 1: elements of short life that are in the core before 46 00:02:58,080 --> 00:03:01,600 Speaker 1: it's quenched, and also just the heat that had accumulated. 47 00:03:01,680 --> 00:03:04,600 Speaker 1: You can't have a gigawatt power plant with you know, 48 00:03:04,840 --> 00:03:07,040 Speaker 1: a light bulb as that. Here, you have a giant 49 00:03:07,240 --> 00:03:10,359 Speaker 1: mass of something that's hot and it's it's itself is 50 00:03:10,360 --> 00:03:13,679 Speaker 1: going to take time to cool down. So the earthquake happened, 51 00:03:13,720 --> 00:03:17,040 Speaker 1: nothing happened to the buildings. They were engineered properly and 52 00:03:17,040 --> 00:03:20,680 Speaker 1: and sustained no damage in the earthquake. The reactors shut 53 00:03:20,720 --> 00:03:23,399 Speaker 1: down and everything was fine. So now you have these 54 00:03:23,440 --> 00:03:28,080 Speaker 1: big nuclear reactors which are in the process of cooling down, 55 00:03:28,120 --> 00:03:31,000 Speaker 1: which is gonna take some time. And during that cooling 56 00:03:31,040 --> 00:03:36,480 Speaker 1: down process you need to circulate cooling water through the cores. Unfortunately, 57 00:03:36,920 --> 00:03:40,160 Speaker 1: the power grid wasn't in such great shape and so 58 00:03:40,360 --> 00:03:43,760 Speaker 1: power failed to the nuclear power plants, and you would 59 00:03:43,760 --> 00:03:46,240 Speaker 1: think this wouldn't be the big problem, since they are 60 00:03:46,320 --> 00:03:49,640 Speaker 1: power plants after all, but they had been shut down automatically, 61 00:03:49,640 --> 00:03:53,720 Speaker 1: so they aren't producing electricity. So in this situation where 62 00:03:53,720 --> 00:03:57,520 Speaker 1: your nuclear power plant is shut down and you have 63 00:03:57,680 --> 00:04:01,280 Speaker 1: lost the connection to the power grid, what they've got 64 00:04:01,600 --> 00:04:06,920 Speaker 1: is on site backup diesel generators. So these diesel generators 65 00:04:07,120 --> 00:04:10,080 Speaker 1: fired up to provide power that would run the pumps 66 00:04:10,120 --> 00:04:14,280 Speaker 1: that would keep these cores cool. That system worked properly 67 00:04:14,320 --> 00:04:18,719 Speaker 1: and everything was fine until the tsunami hit. And normally 68 00:04:19,040 --> 00:04:21,560 Speaker 1: a tsunami hitting a nuclear power plant wouldn't be a 69 00:04:21,560 --> 00:04:25,200 Speaker 1: big deal because they know about tsunamis and had designed 70 00:04:25,200 --> 00:04:28,440 Speaker 1: against them. But they had not expected this big of 71 00:04:28,440 --> 00:04:32,120 Speaker 1: a tsunami, so when it hit, it basically inundated the 72 00:04:32,160 --> 00:04:36,200 Speaker 1: diesel generators, all of them, and took them out of service. 73 00:04:36,520 --> 00:04:39,160 Speaker 1: Now you could argue that the engineers should have put 74 00:04:39,160 --> 00:04:41,600 Speaker 1: the diesel generators up higher so they couldn't have gotten 75 00:04:41,680 --> 00:04:43,880 Speaker 1: hit by a tsunami, or they should have made the 76 00:04:43,920 --> 00:04:47,760 Speaker 1: diesel generators submersible so even if the tsunami came, they 77 00:04:47,760 --> 00:04:52,240 Speaker 1: could run submerged and keep power going. But neither of 78 00:04:52,279 --> 00:04:55,919 Speaker 1: those things happened, so the diesel generators failed. Now, in 79 00:04:55,960 --> 00:05:00,000 Speaker 1: a nuclear power plant, there's another backup system which involve 80 00:05:00,000 --> 00:05:04,200 Speaker 1: alves batteries, and batteries are there in case the diesel 81 00:05:04,240 --> 00:05:08,039 Speaker 1: generators fail so that you have time to get some 82 00:05:08,160 --> 00:05:12,640 Speaker 1: kind of additional backup plan in place. But these are batteries. 83 00:05:12,680 --> 00:05:16,080 Speaker 1: Think about how batteries are in your life. They're always 84 00:05:16,120 --> 00:05:20,280 Speaker 1: going dead, they never last long enough. If they're fully charged, 85 00:05:20,560 --> 00:05:23,719 Speaker 1: you're you're still subconsciously thinking about them going dead. And 86 00:05:23,880 --> 00:05:26,360 Speaker 1: batteries at a nuclear power plant are no different. These 87 00:05:26,400 --> 00:05:29,440 Speaker 1: were designed to have a lifespan of about eight hours. 88 00:05:29,760 --> 00:05:33,520 Speaker 1: So the batteries are circulating cooling water through the cores 89 00:05:33,560 --> 00:05:37,240 Speaker 1: and everything's fine, And meanwhile the engineers are trucking in 90 00:05:37,760 --> 00:05:42,039 Speaker 1: backup backup diesel generators to puck into the nuclear power 91 00:05:42,040 --> 00:05:45,039 Speaker 1: plants and fire them up. But when these when these 92 00:05:45,080 --> 00:05:49,600 Speaker 1: backup backup generators arrived, apparently they had the wrong plugs 93 00:05:49,600 --> 00:05:52,960 Speaker 1: on them. They weren't quite compatible with the nuclear power plant, 94 00:05:53,040 --> 00:05:56,920 Speaker 1: according to some reports, and they couldn't just be hooked 95 00:05:56,920 --> 00:05:59,920 Speaker 1: in instantly, which meant that the batteries went dead. And 96 00:06:00,080 --> 00:06:03,680 Speaker 1: this is where things started to come unraveled without cooling 97 00:06:03,760 --> 00:06:08,279 Speaker 1: water circulating through the core, the reactor core starts to 98 00:06:08,400 --> 00:06:11,120 Speaker 1: heat up and it starts to boil the cooling water, 99 00:06:11,440 --> 00:06:15,640 Speaker 1: and as that water boils off, it starts to lower 100 00:06:15,720 --> 00:06:19,320 Speaker 1: the level of water in the reactor core, causing some 101 00:06:19,520 --> 00:06:22,919 Speaker 1: of the clear fuel rods to not be submerged in 102 00:06:23,000 --> 00:06:27,720 Speaker 1: water anymore. At this point, the fuel rods overheated and cracked, 103 00:06:27,720 --> 00:06:31,240 Speaker 1: allowing water to get into the very very hot nuclear 104 00:06:31,320 --> 00:06:35,160 Speaker 1: pellets and you get dissociation of the water molecules and 105 00:06:35,240 --> 00:06:38,320 Speaker 1: the production of hydrogen. It builds up in pressure and 106 00:06:38,360 --> 00:06:41,400 Speaker 1: it has to be vented off, and that normally wouldn't 107 00:06:41,400 --> 00:06:44,400 Speaker 1: be a problem. Factories vent gases all the time, but 108 00:06:44,520 --> 00:06:47,200 Speaker 1: for some reason, when they vented off a large quantity 109 00:06:47,200 --> 00:06:51,440 Speaker 1: of hydrogen gas, it ignited and exploded, and this caused 110 00:06:51,560 --> 00:06:55,960 Speaker 1: the building around the reactor vessel to disintegrate. Basically, the 111 00:06:55,960 --> 00:06:59,120 Speaker 1: whole top of it was blown off by the hydrogen explosion. 112 00:06:59,160 --> 00:07:04,080 Speaker 1: And this occurred multiple times, apparently at multiple plants. Now, 113 00:07:04,120 --> 00:07:07,600 Speaker 1: if this process had been allowed to continue, the process 114 00:07:07,640 --> 00:07:10,600 Speaker 1: of boiling the cooling water off and exposing more and 115 00:07:10,640 --> 00:07:13,000 Speaker 1: more of the core, things would have gone from bad 116 00:07:13,080 --> 00:07:16,240 Speaker 1: to worse because eventually the nuclear fuel pellets would get 117 00:07:16,280 --> 00:07:18,640 Speaker 1: so hot that they would melt. And this is where 118 00:07:18,760 --> 00:07:22,160 Speaker 1: the word meltdown comes from. The idea that the nuclear 119 00:07:22,200 --> 00:07:26,360 Speaker 1: fuel heats up, melts and becomes what one article termed 120 00:07:26,480 --> 00:07:29,960 Speaker 1: radioactive lava that flows to the bottom of the reactor 121 00:07:30,040 --> 00:07:33,760 Speaker 1: vessel and potentially each through it and ends up in 122 00:07:33,800 --> 00:07:37,400 Speaker 1: the floor of the reactor containment building. To prevent that 123 00:07:37,600 --> 00:07:41,160 Speaker 1: from happening. To prevent a meltdown, the technicians in Japan 124 00:07:41,360 --> 00:07:46,040 Speaker 1: decided to start pumping seawater into the reactors. And this 125 00:07:46,640 --> 00:07:50,720 Speaker 1: is largely a desperation measure because the seawater ruins the 126 00:07:50,760 --> 00:07:53,960 Speaker 1: reactor and you're not ever going to be able to 127 00:07:53,960 --> 00:07:55,760 Speaker 1: to fix it. You're gonna have to scrap the whole 128 00:07:55,760 --> 00:07:59,840 Speaker 1: thing and start over. So they start pumping seawater in 129 00:08:00,480 --> 00:08:03,480 Speaker 1: and that prevents a meltdown. Long term, that's going to 130 00:08:03,600 --> 00:08:07,280 Speaker 1: have some serious consequences for the whole nuclear industry in 131 00:08:07,360 --> 00:08:11,720 Speaker 1: Japan and for the Japanese Power Group, because nuclear power 132 00:08:11,760 --> 00:08:15,400 Speaker 1: is an important part of the power system in Japan. 133 00:08:15,560 --> 00:08:17,880 Speaker 1: It makes up you know, these failed reactors make up 134 00:08:17,960 --> 00:08:22,880 Speaker 1: something like fifteen percent of the whole electricity generating capacity 135 00:08:22,880 --> 00:08:26,240 Speaker 1: of the country and that's a big loss for a 136 00:08:26,320 --> 00:08:29,640 Speaker 1: country to sustain and will have to be replaced both 137 00:08:29,680 --> 00:08:32,720 Speaker 1: short term and long term. So what does this whole 138 00:08:32,760 --> 00:08:36,680 Speaker 1: episode mean in real terms? That depends on how you 139 00:08:36,720 --> 00:08:40,240 Speaker 1: want to spin it. So if you don't like nuclear power, 140 00:08:40,760 --> 00:08:44,280 Speaker 1: the way you spin this is you say, look, these 141 00:08:44,400 --> 00:08:48,160 Speaker 1: terrible things happened. These were supposed to be well engineered systems, 142 00:08:48,200 --> 00:08:51,680 Speaker 1: but clearly they were not. There was radiation that was 143 00:08:51,920 --> 00:08:55,520 Speaker 1: released into the environment, there were explosions, there could have 144 00:08:55,640 --> 00:08:59,800 Speaker 1: been a meltdown. Things just did not go as we 145 00:08:59,800 --> 00:09:02,240 Speaker 1: were are told they were go. Would go in an 146 00:09:02,240 --> 00:09:05,920 Speaker 1: engineer system like this, Nuclear power should not be allowed 147 00:09:06,000 --> 00:09:09,360 Speaker 1: anywhere on the planet. If you're pro nuclear, you'd spin 148 00:09:09,440 --> 00:09:12,520 Speaker 1: it the other way. You'd say, well, these reactors were 149 00:09:12,600 --> 00:09:17,080 Speaker 1: designed and engineered with redundant systems and with procedures to 150 00:09:17,200 --> 00:09:20,960 Speaker 1: handle just about any possible scenarios. So a lot of 151 00:09:20,960 --> 00:09:25,000 Speaker 1: stuff went wrong, and yet in the big picture, nothing 152 00:09:25,160 --> 00:09:30,080 Speaker 1: seriously dangerous happened as a result of the problems that occurred. So, yes, 153 00:09:30,160 --> 00:09:33,560 Speaker 1: a little bit of radiation was leaked into the atmosphere, 154 00:09:33,600 --> 00:09:36,560 Speaker 1: but most of it is harmless, very short lived, and 155 00:09:36,640 --> 00:09:40,320 Speaker 1: that which wasn't completely harmless happened to blow out to see, 156 00:09:40,360 --> 00:09:43,960 Speaker 1: so it wasn't affecting any major population areas or anything 157 00:09:43,960 --> 00:09:46,960 Speaker 1: like that. And there were no meltdowns and there were 158 00:09:47,400 --> 00:09:51,880 Speaker 1: no you know, radioactive explosions like we had at Chernobyl, 159 00:09:52,320 --> 00:09:55,520 Speaker 1: So nothing really bad happened. And even if the meltdown 160 00:09:55,559 --> 00:09:57,800 Speaker 1: had occurred, it would have been okay because it would 161 00:09:57,800 --> 00:10:00,400 Speaker 1: have been contained within the containment build thing and it 162 00:10:00,440 --> 00:10:03,320 Speaker 1: wouldn't have been any big deal. You can kind of 163 00:10:03,400 --> 00:10:07,040 Speaker 1: pick how you want to personally spend this event, whether 164 00:10:07,120 --> 00:10:09,920 Speaker 1: you want to be pro nuclear or anti nuclear, or 165 00:10:10,040 --> 00:10:14,960 Speaker 1: somewhere in between. Be sure to check out our new 166 00:10:15,040 --> 00:10:18,800 Speaker 1: video podcast, Stuff from the Future. Join how Stuffwork staff 167 00:10:18,800 --> 00:10:22,679 Speaker 1: as we explore the most promising and perplexing possibilities of tomorrow. 168 00:10:24,160 --> 00:10:26,680 Speaker 1: The House Stuff Works I Find app has arrived. Download 169 00:10:26,760 --> 00:10:28,199 Speaker 1: it today on iTunes