WEBVTT - What Is Chernobyl's Elephant's Foot Made Of?

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<v Speaker 1>Welcome to Brainstuff, a production of iHeartRadio, Hey brain Stuff

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<v Speaker 1>Lauren Vogelbaum here. April of nineteen eighty six saw the

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<v Speaker 1>accident at the Chernobyl nuclear power plant in Ukraine. Eight

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<v Speaker 1>months later, workers who entered a corridor beneath the damaged

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<v Speaker 1>Number four reactor discovered a startling phenomenon. Some sort of

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<v Speaker 1>black lava had flowed out from the reactor core, as

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<v Speaker 1>if it had been some kind of human made volcano.

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<v Speaker 1>One of the hardened masses was particularly startling, and the

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<v Speaker 1>crew nicknamed it the elephant's foot because it had flowed

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<v Speaker 1>into a massive, wrinkled shape resembling an elephant's foot. Sensors

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<v Speaker 1>told the workers that the lava formation was so highly

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<v Speaker 1>radioactive that it would take just five minutes for a

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<v Speaker 1>person to get a lethal amount of exposure from it.

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<v Speaker 1>A decade later, the US Department of Energy's International Nuclear

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<v Speaker 1>Safety Project, which elected hundreds of pictures of Chernobyl, obtained

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<v Speaker 1>several images of the elephant's foot, which was estimated to

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<v Speaker 1>weigh about two tons. Since then, the elephant's foot, which

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<v Speaker 1>is known as a lava like fuel containing material or LFCM,

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<v Speaker 1>has remained macabre object of fascination, but what is it?

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<v Speaker 1>Because the elephant's foot was so radioactive, scientists at the

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<v Speaker 1>time used a camera on a wheel to photograph it.

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<v Speaker 1>A few researchers got close enough to take samples for analysis.

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<v Speaker 1>What they found was that the elephant's foot was not

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<v Speaker 1>the remnants of nuclear fuel, or not nuclear fuel alone.

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<v Speaker 1>Experts explained that the elephant's foot is composed of a

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<v Speaker 1>rare substance called korium, which is produced in a nuclear

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<v Speaker 1>accident when the nuclear fuel and parts of the reactor

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<v Speaker 1>core structures overheat and melt together, forming a mixture. A

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<v Speaker 1>Quorium has only formed on its own five times in history,

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<v Speaker 1>a once during a three mile island accident in Pennsylvania

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<v Speaker 1>in nineteen seventy nine, once at Chernobyl, and three times

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<v Speaker 1>at the Fukushima plant disaster in Japan in twenty eleven.

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<v Speaker 1>For the article this episode is based on How Stuff Works,

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<v Speaker 1>spoke by email with Edwin Lyman, director of Nuclear power

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<v Speaker 1>Safety for the Union of Concerned Scientists. He said, if

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<v Speaker 1>a core melt cannot be terminated, then eventually the molten

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<v Speaker 1>mass will flow downward to the bottom of the reactor

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<v Speaker 1>vessel and melt through with a contribution of additional molten

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<v Speaker 1>materials dropping to the floor of the containment. The hot

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<v Speaker 1>molten mass will then react with the concrete floor of

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<v Speaker 1>the containment if there is one, again changing the composition

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<v Speaker 1>of the melt. Depending on the type of reactor, the

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<v Speaker 1>melt can spread and melt through the containment walls, or

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<v Speaker 1>continue to melt through the floor, eventually infiltrating groundwater. This

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<v Speaker 1>is what happened at Fukushima. When the melt cools sufficiently,

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<v Speaker 1>it will harden into a hard rock like material. How

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<v Speaker 1>stuff works also spoke by email with Mitchell T. Farmer,

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<v Speaker 1>a veteran nuclear engineer and program manager at the Argonne

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<v Speaker 1>National Laboratory. He explained the quorium looks quote a lot

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<v Speaker 1>like lava, a blackish oxide material that gets very viscous

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<v Speaker 1>as it cools down, flowing like sticky molten glass. The

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<v Speaker 1>composition of a particular quorium flow and thus its appearance,

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<v Speaker 1>will vary based on what materials melt together to make it.

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<v Speaker 1>For example, the elephant's foot has a brownish hue that

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<v Speaker 1>comes from concrete made with a lot of silica, basically glass.

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<v Speaker 1>A part of it is always going to be uranium oxide. Fuel.

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<v Speaker 1>Other ingredients include the fuel's coating, typically an alloy of

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<v Speaker 1>zirconium called circuloi, and structural materials, which are mostly stainless

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<v Speaker 1>steel composed of iron. A farmer said, depending on when

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<v Speaker 1>water is resupplied to cool the quorium, the quorium composition

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<v Speaker 1>can evolve in time As steam boils off. The steam

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<v Speaker 1>can react with metals in the quorium, azirconium and steel

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<v Speaker 1>to produce hydrogen gas, the effects of which you saw

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<v Speaker 1>during the reactor accidents at Houkshima. The oxidized materials in

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<v Speaker 1>the quorium are converted to oxides, causing the composition to change.

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<v Speaker 1>But if the quorium isn't cooled, it will move down

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<v Speaker 1>through the reactor vessel, melting more structural steel along the way,

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<v Speaker 1>which causes even more changes in its composition. A farmer said.

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<v Speaker 1>If still under cooled, the quorium can eventually melt through

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<v Speaker 1>the steel reactor vessel and drop down onto the concrete

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<v Speaker 1>floor of containment. This happened all three reactors of Fukushima.

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<v Speaker 1>The concrete that comes in contact with the quorium will

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<v Speaker 1>eventually heat up and begin to melt. Once the concrete melts, concrete,

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<v Speaker 1>oxides typically known as slag, are introduced into the melt,

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<v Speaker 1>which causes the composition to evolve even further. The melting

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<v Speaker 1>the concrete also releases steam and carbon dioxide, which continue

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<v Speaker 1>to react with metals in the melt to produce hydrogen

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<v Speaker 1>and carbon monoxide, causing still more changes in the quorium's composition.

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<v Speaker 1>The resulting mess that created Elephant's Foot is extremely dangerous. Generally,

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<v Speaker 1>quorium is much more hazardous than undamaged spent fuel because

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<v Speaker 1>it's in a potentially unstable state that's more difficult to handle, package,

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<v Speaker 1>and store. A lineman said to the extent that quorium

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<v Speaker 1>retains highly radioactive fission products plutonium and core materials that

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<v Speaker 1>have become radioactive a quorium will have a high dose

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<v Speaker 1>rate and remain extremely hazardous many decades or even centuries

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<v Speaker 1>to come, and although it should be contained, doing so

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<v Speaker 1>could be hazardous in itself. That's because very hard, solidified

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<v Speaker 1>quorium like that of the elephant's foot would have to

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<v Speaker 1>be broken up to remove it from damaged reactors. Lyman

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<v Speaker 1>said that will generate radioactive dust and increase hazards to

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<v Speaker 1>workers and possibly the environment, but what's even more worrisome

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<v Speaker 1>is that scientists don't know how quorium might behave over

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<v Speaker 1>the long term, of like when it's stored at a

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<v Speaker 1>nuclear waste repository. What they do know is the quorium

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<v Speaker 1>of the elephant's foot is likely not as active as

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<v Speaker 1>it was, and that is cooling down on its own

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<v Speaker 1>and will continue to cool but it is still melting

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<v Speaker 1>down and remains highly radioactive. In twenty sixteen, the new

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<v Speaker 1>safe confinement shield, a giant structure of steel and concrete,

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<v Speaker 1>was slid over Chernobyl to prevent any more radiation leaks

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<v Speaker 1>from the nuclear power plant. Another steel structure was built

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<v Speaker 1>within this containment shield to support the decaying concrete sarcophagus

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<v Speaker 1>in Chernobyl's reactor number four. The new safe confinement would

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<v Speaker 1>ideally help prevent a massive cloud of uranium dust from

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<v Speaker 1>dispersing into the air in the case of an explosion

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<v Speaker 1>in room three oh five to two. Room three oh

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<v Speaker 1>five to two was directly under the number four reactor

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<v Speaker 1>core and has been showing signs of increased neutron emissions

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<v Speaker 1>since twenty sixteen. It's totally inaccessible to humans because of

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<v Speaker 1>the deadly radiation levels and as fascinating as it is,

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<v Speaker 1>nobody wants to see another elephant's foot. A farmer has

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<v Speaker 1>spent most of his career studying nuclear accidents and working

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<v Speaker 1>with quorium in an effort to develop ways for plant

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<v Speaker 1>operators to terminate an accident, how much water to inject

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<v Speaker 1>and where to inject it, and how fast water can

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<v Speaker 1>cool the quorium and stabilize it. He said, we do

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<v Speaker 1>large experiments in which we produce quorium with the real materials,

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<v Speaker 1>but we use electrical heating to simulate decay heat instead

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<v Speaker 1>of decay heating itself. We focused most of our work

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<v Speaker 1>on studying the efficiency of water addition in quenching and

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<v Speaker 1>cooling quorum for various quoreum compositions. Thus, we are doing

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<v Speaker 1>research on accident mitigation. The other end of it is

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<v Speaker 1>accident prevention, and this is a principal focus area for

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<v Speaker 1>the nuclear industry. Today's episode is based on the article

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<v Speaker 1>Chernobyl's Elephant's foot is a toxic massive quorum on HowStuffWorks

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<v Speaker 1>dot Com, written by Patrick J. Kiger. Brainstuff is production

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<v Speaker 1>of My Heart Radio in partnership with how stuffworks dot Com,

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<v Speaker 1>and it is produced by Tyler Klang. For more podcasts

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<v Speaker 1>from my heart Radio, visit the iHeartRadio app, Apple Podcasts,

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