1 00:00:01,840 --> 00:00:07,560 Speaker 1: Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff 2 00:00:07,600 --> 00:00:12,920 Speaker 1: Lauren Vogelbaum here. April of nineteen eighty six saw the 3 00:00:12,960 --> 00:00:17,160 Speaker 1: accident at the Chernobyl nuclear power plant in Ukraine. Eight 4 00:00:17,160 --> 00:00:20,639 Speaker 1: months later, workers who entered a corridor beneath the damaged 5 00:00:20,720 --> 00:00:25,520 Speaker 1: Number four reactor discovered a startling phenomenon. Some sort of 6 00:00:25,560 --> 00:00:28,960 Speaker 1: black lava had flowed out from the reactor core, as 7 00:00:28,960 --> 00:00:31,240 Speaker 1: if it had been some kind of human made volcano. 8 00:00:32,320 --> 00:00:35,760 Speaker 1: One of the hardened masses was particularly startling, and the 9 00:00:35,800 --> 00:00:38,920 Speaker 1: crew nicknamed it the elephant's foot because it had flowed 10 00:00:38,960 --> 00:00:45,400 Speaker 1: into a massive, wrinkled shape resembling an elephant's foot. Sensors 11 00:00:45,440 --> 00:00:48,240 Speaker 1: told the workers that the lava formation was so highly 12 00:00:48,320 --> 00:00:50,960 Speaker 1: radioactive that it would take just five minutes for a 13 00:00:51,000 --> 00:00:53,519 Speaker 1: person to get a lethal amount of exposure from it. 14 00:00:55,240 --> 00:00:58,640 Speaker 1: A decade later, the US Department of Energy's International Nuclear 15 00:00:58,680 --> 00:01:02,640 Speaker 1: Safety Project, which elected hundreds of pictures of Chernobyl, obtained 16 00:01:02,680 --> 00:01:05,760 Speaker 1: several images of the elephant's foot, which was estimated to 17 00:01:05,800 --> 00:01:10,840 Speaker 1: weigh about two tons. Since then, the elephant's foot, which 18 00:01:10,880 --> 00:01:14,720 Speaker 1: is known as a lava like fuel containing material or LFCM, 19 00:01:15,200 --> 00:01:19,880 Speaker 1: has remained macabre object of fascination, but what is it? 20 00:01:21,959 --> 00:01:25,440 Speaker 1: Because the elephant's foot was so radioactive, scientists at the 21 00:01:25,480 --> 00:01:27,920 Speaker 1: time used a camera on a wheel to photograph it. 22 00:01:28,560 --> 00:01:31,840 Speaker 1: A few researchers got close enough to take samples for analysis. 23 00:01:32,760 --> 00:01:35,080 Speaker 1: What they found was that the elephant's foot was not 24 00:01:35,200 --> 00:01:39,480 Speaker 1: the remnants of nuclear fuel, or not nuclear fuel alone. 25 00:01:41,200 --> 00:01:43,920 Speaker 1: Experts explained that the elephant's foot is composed of a 26 00:01:44,000 --> 00:01:47,280 Speaker 1: rare substance called korium, which is produced in a nuclear 27 00:01:47,319 --> 00:01:50,080 Speaker 1: accident when the nuclear fuel and parts of the reactor 28 00:01:50,120 --> 00:01:55,320 Speaker 1: core structures overheat and melt together, forming a mixture. A 29 00:01:55,440 --> 00:01:58,800 Speaker 1: Quorium has only formed on its own five times in history, 30 00:01:59,240 --> 00:02:02,200 Speaker 1: a once during a three mile island accident in Pennsylvania 31 00:02:02,280 --> 00:02:05,720 Speaker 1: in nineteen seventy nine, once at Chernobyl, and three times 32 00:02:05,760 --> 00:02:08,800 Speaker 1: at the Fukushima plant disaster in Japan in twenty eleven. 33 00:02:11,000 --> 00:02:13,560 Speaker 1: For the article this episode is based on How Stuff Works, 34 00:02:13,560 --> 00:02:16,960 Speaker 1: spoke by email with Edwin Lyman, director of Nuclear power 35 00:02:16,960 --> 00:02:21,400 Speaker 1: Safety for the Union of Concerned Scientists. He said, if 36 00:02:21,440 --> 00:02:24,680 Speaker 1: a core melt cannot be terminated, then eventually the molten 37 00:02:24,720 --> 00:02:27,160 Speaker 1: mass will flow downward to the bottom of the reactor 38 00:02:27,240 --> 00:02:30,639 Speaker 1: vessel and melt through with a contribution of additional molten 39 00:02:30,680 --> 00:02:34,360 Speaker 1: materials dropping to the floor of the containment. The hot 40 00:02:34,400 --> 00:02:36,960 Speaker 1: molten mass will then react with the concrete floor of 41 00:02:36,960 --> 00:02:40,240 Speaker 1: the containment if there is one, again changing the composition 42 00:02:40,360 --> 00:02:43,760 Speaker 1: of the melt. Depending on the type of reactor, the 43 00:02:43,760 --> 00:02:46,680 Speaker 1: melt can spread and melt through the containment walls, or 44 00:02:46,800 --> 00:02:51,000 Speaker 1: continue to melt through the floor, eventually infiltrating groundwater. This 45 00:02:51,040 --> 00:02:54,640 Speaker 1: is what happened at Fukushima. When the melt cools sufficiently, 46 00:02:54,840 --> 00:03:00,600 Speaker 1: it will harden into a hard rock like material. How 47 00:03:00,600 --> 00:03:03,720 Speaker 1: stuff works also spoke by email with Mitchell T. Farmer, 48 00:03:03,880 --> 00:03:07,400 Speaker 1: a veteran nuclear engineer and program manager at the Argonne 49 00:03:07,480 --> 00:03:12,359 Speaker 1: National Laboratory. He explained the quorium looks quote a lot 50 00:03:12,520 --> 00:03:16,320 Speaker 1: like lava, a blackish oxide material that gets very viscous 51 00:03:16,360 --> 00:03:21,960 Speaker 1: as it cools down, flowing like sticky molten glass. The 52 00:03:22,080 --> 00:03:26,080 Speaker 1: composition of a particular quorium flow and thus its appearance, 53 00:03:26,360 --> 00:03:29,520 Speaker 1: will vary based on what materials melt together to make it. 54 00:03:30,440 --> 00:03:33,400 Speaker 1: For example, the elephant's foot has a brownish hue that 55 00:03:33,520 --> 00:03:37,640 Speaker 1: comes from concrete made with a lot of silica, basically glass. 56 00:03:38,120 --> 00:03:41,080 Speaker 1: A part of it is always going to be uranium oxide. Fuel. 57 00:03:41,920 --> 00:03:45,600 Speaker 1: Other ingredients include the fuel's coating, typically an alloy of 58 00:03:45,680 --> 00:03:50,520 Speaker 1: zirconium called circuloi, and structural materials, which are mostly stainless 59 00:03:50,520 --> 00:03:55,839 Speaker 1: steel composed of iron. A farmer said, depending on when 60 00:03:55,920 --> 00:03:59,720 Speaker 1: water is resupplied to cool the quorium, the quorium composition 61 00:03:59,800 --> 00:04:04,040 Speaker 1: can evolve in time As steam boils off. The steam 62 00:04:04,080 --> 00:04:07,440 Speaker 1: can react with metals in the quorium, azirconium and steel 63 00:04:07,600 --> 00:04:10,600 Speaker 1: to produce hydrogen gas, the effects of which you saw 64 00:04:10,720 --> 00:04:14,960 Speaker 1: during the reactor accidents at Houkshima. The oxidized materials in 65 00:04:14,960 --> 00:04:19,080 Speaker 1: the quorium are converted to oxides, causing the composition to change. 66 00:04:20,839 --> 00:04:23,400 Speaker 1: But if the quorium isn't cooled, it will move down 67 00:04:23,440 --> 00:04:27,000 Speaker 1: through the reactor vessel, melting more structural steel along the way, 68 00:04:27,279 --> 00:04:31,400 Speaker 1: which causes even more changes in its composition. A farmer said. 69 00:04:31,880 --> 00:04:35,120 Speaker 1: If still under cooled, the quorium can eventually melt through 70 00:04:35,160 --> 00:04:38,040 Speaker 1: the steel reactor vessel and drop down onto the concrete 71 00:04:38,040 --> 00:04:42,279 Speaker 1: floor of containment. This happened all three reactors of Fukushima. 72 00:04:44,720 --> 00:04:47,120 Speaker 1: The concrete that comes in contact with the quorium will 73 00:04:47,120 --> 00:04:51,960 Speaker 1: eventually heat up and begin to melt. Once the concrete melts, concrete, 74 00:04:52,000 --> 00:04:55,599 Speaker 1: oxides typically known as slag, are introduced into the melt, 75 00:04:55,839 --> 00:04:59,880 Speaker 1: which causes the composition to evolve even further. The melting 76 00:05:00,000 --> 00:05:04,120 Speaker 1: the concrete also releases steam and carbon dioxide, which continue 77 00:05:04,160 --> 00:05:06,760 Speaker 1: to react with metals in the melt to produce hydrogen 78 00:05:06,880 --> 00:05:11,320 Speaker 1: and carbon monoxide, causing still more changes in the quorium's composition. 79 00:05:13,160 --> 00:05:18,840 Speaker 1: The resulting mess that created Elephant's Foot is extremely dangerous. Generally, 80 00:05:19,040 --> 00:05:23,000 Speaker 1: quorium is much more hazardous than undamaged spent fuel because 81 00:05:23,080 --> 00:05:27,599 Speaker 1: it's in a potentially unstable state that's more difficult to handle, package, 82 00:05:27,640 --> 00:05:32,440 Speaker 1: and store. A lineman said to the extent that quorium 83 00:05:32,480 --> 00:05:37,200 Speaker 1: retains highly radioactive fission products plutonium and core materials that 84 00:05:37,240 --> 00:05:40,640 Speaker 1: have become radioactive a quorium will have a high dose 85 00:05:40,760 --> 00:05:45,160 Speaker 1: rate and remain extremely hazardous many decades or even centuries 86 00:05:45,160 --> 00:05:50,760 Speaker 1: to come, and although it should be contained, doing so 87 00:05:50,960 --> 00:05:55,480 Speaker 1: could be hazardous in itself. That's because very hard, solidified 88 00:05:55,520 --> 00:05:58,599 Speaker 1: quorium like that of the elephant's foot would have to 89 00:05:58,600 --> 00:06:02,520 Speaker 1: be broken up to remove it from damaged reactors. Lyman 90 00:06:02,640 --> 00:06:06,560 Speaker 1: said that will generate radioactive dust and increase hazards to 91 00:06:06,600 --> 00:06:11,560 Speaker 1: workers and possibly the environment, but what's even more worrisome 92 00:06:11,720 --> 00:06:14,720 Speaker 1: is that scientists don't know how quorium might behave over 93 00:06:14,760 --> 00:06:17,120 Speaker 1: the long term, of like when it's stored at a 94 00:06:17,200 --> 00:06:21,080 Speaker 1: nuclear waste repository. What they do know is the quorium 95 00:06:21,080 --> 00:06:23,600 Speaker 1: of the elephant's foot is likely not as active as 96 00:06:23,600 --> 00:06:26,560 Speaker 1: it was, and that is cooling down on its own 97 00:06:26,960 --> 00:06:30,640 Speaker 1: and will continue to cool but it is still melting 98 00:06:30,720 --> 00:06:37,640 Speaker 1: down and remains highly radioactive. In twenty sixteen, the new 99 00:06:37,680 --> 00:06:41,680 Speaker 1: safe confinement shield, a giant structure of steel and concrete, 100 00:06:42,000 --> 00:06:45,360 Speaker 1: was slid over Chernobyl to prevent any more radiation leaks 101 00:06:45,400 --> 00:06:49,320 Speaker 1: from the nuclear power plant. Another steel structure was built 102 00:06:49,320 --> 00:06:53,279 Speaker 1: within this containment shield to support the decaying concrete sarcophagus 103 00:06:53,279 --> 00:06:58,160 Speaker 1: in Chernobyl's reactor number four. The new safe confinement would 104 00:06:58,360 --> 00:07:01,640 Speaker 1: ideally help prevent a massive cloud of uranium dust from 105 00:07:01,640 --> 00:07:04,040 Speaker 1: dispersing into the air in the case of an explosion 106 00:07:04,200 --> 00:07:07,359 Speaker 1: in room three oh five to two. Room three oh 107 00:07:07,440 --> 00:07:10,320 Speaker 1: five to two was directly under the number four reactor 108 00:07:10,360 --> 00:07:13,880 Speaker 1: core and has been showing signs of increased neutron emissions 109 00:07:13,880 --> 00:07:18,560 Speaker 1: since twenty sixteen. It's totally inaccessible to humans because of 110 00:07:18,600 --> 00:07:23,840 Speaker 1: the deadly radiation levels and as fascinating as it is, 111 00:07:24,160 --> 00:07:27,960 Speaker 1: nobody wants to see another elephant's foot. A farmer has 112 00:07:28,000 --> 00:07:31,280 Speaker 1: spent most of his career studying nuclear accidents and working 113 00:07:31,280 --> 00:07:33,800 Speaker 1: with quorium in an effort to develop ways for plant 114 00:07:33,800 --> 00:07:37,480 Speaker 1: operators to terminate an accident, how much water to inject 115 00:07:37,480 --> 00:07:40,360 Speaker 1: and where to inject it, and how fast water can 116 00:07:40,440 --> 00:07:44,920 Speaker 1: cool the quorium and stabilize it. He said, we do 117 00:07:45,080 --> 00:07:48,960 Speaker 1: large experiments in which we produce quorium with the real materials, 118 00:07:49,320 --> 00:07:53,000 Speaker 1: but we use electrical heating to simulate decay heat instead 119 00:07:53,000 --> 00:07:56,800 Speaker 1: of decay heating itself. We focused most of our work 120 00:07:56,800 --> 00:07:59,920 Speaker 1: on studying the efficiency of water addition in quenching and 121 00:08:00,160 --> 00:08:05,360 Speaker 1: cooling quorum for various quoreum compositions. Thus, we are doing 122 00:08:05,400 --> 00:08:08,920 Speaker 1: research on accident mitigation. The other end of it is 123 00:08:09,000 --> 00:08:12,600 Speaker 1: accident prevention, and this is a principal focus area for 124 00:08:12,640 --> 00:08:20,240 Speaker 1: the nuclear industry. Today's episode is based on the article 125 00:08:20,360 --> 00:08:24,200 Speaker 1: Chernobyl's Elephant's foot is a toxic massive quorum on HowStuffWorks 126 00:08:24,200 --> 00:08:27,480 Speaker 1: dot Com, written by Patrick J. Kiger. Brainstuff is production 127 00:08:27,480 --> 00:08:29,920 Speaker 1: of My Heart Radio in partnership with how stuffworks dot Com, 128 00:08:29,960 --> 00:08:32,800 Speaker 1: and it is produced by Tyler Klang. For more podcasts 129 00:08:32,800 --> 00:08:35,959 Speaker 1: from my heart Radio, visit the iHeartRadio app, Apple Podcasts, 130 00:08:36,040 --> 00:08:37,840 Speaker 1: or wherever you listen to your favorite shows.