WEBVTT - How High-level Nuclear Waste Works

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<v Speaker 1>Welcome to Brainstuff from house stuff works dot com, where

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<v Speaker 1>smart happens Him Marshall Brain with today's question, what is

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<v Speaker 1>high level nuclear waste and how are we dealing with

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<v Speaker 1>it today. Let's imagine that you own a nuclear power plant.

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<v Speaker 1>You're in a pretty good position these days because compared

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<v Speaker 1>to a coal fired power plant, your operation is very green.

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<v Speaker 1>You're producing lots of reliable electricity without releasing any carbon

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<v Speaker 1>dioxide into the atmosphere. You don't release any other pollutants

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<v Speaker 1>like sulfur or mercury into the atmosphere either, and you

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<v Speaker 1>also are not creating huge quantities of coal ash, which

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<v Speaker 1>at many power plants ends up being stored in immense lagoons.

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<v Speaker 1>These lagoons raise a lot of questions in terms of

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<v Speaker 1>long term stability, especially during floods. So as a nuclear

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<v Speaker 1>power plant operator, you are feeling pretty good. There is

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<v Speaker 1>in fact, only one fly in your ointment at the moment.

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<v Speaker 1>That fly is called high level nuclear waste, and it

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<v Speaker 1>appears every time you need to refuel your reactor. In fact,

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<v Speaker 1>the fly grows a little bigger with each refueling. Let's

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<v Speaker 1>take a look at how this high level nuclear waste works. First,

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<v Speaker 1>little background The goal of a nuclear reactor is to

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<v Speaker 1>create heat so that it can produce steam that drives

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<v Speaker 1>a generator. The nuclear fuel in the reactor creates the

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<v Speaker 1>heat through nuclear fission. The fuel consists of a mixture

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<v Speaker 1>of uranium two thirty five about four percent mixed with

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<v Speaker 1>uranium two thirty eight and other elements. The uranium two

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<v Speaker 1>thirty five is the actual fuel for the reactor. Each

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<v Speaker 1>fuel pellet containing the U two thirty five is very small,

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<v Speaker 1>about the size of your little toe, but it contains

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<v Speaker 1>the equivalent heat of perhaps a ton of coal. A

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<v Speaker 1>typical reactor contains several tons of these all it's arranged

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<v Speaker 1>in rods that fill the reactor core. The YouTube thirty

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<v Speaker 1>five sitting in the core undergoes a fission process. In

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<v Speaker 1>this process, it creates a tremendous amount of heat. In

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<v Speaker 1>a nuclear bomb, this heat is all released in less

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<v Speaker 1>than a second to create a gigantic explosion. In a

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<v Speaker 1>nuclear reactor, the heat is released gradually over the course

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<v Speaker 1>of a year or two to boil water that drives

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<v Speaker 1>the electric generators. At the end of that year or two,

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<v Speaker 1>the reactor shuts down for a month for refueling, and

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<v Speaker 1>the fly in the ointment appears, between one quarter and

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<v Speaker 1>one third of the fuel in the core is removed

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<v Speaker 1>and replaced with fresh fuel rods. Several tons of highly

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<v Speaker 1>radioactive material, also known as spent fuel or high level

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<v Speaker 1>nuclear waste, now has to be managed. The spent fuel

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<v Speaker 1>is still quite hot. It's so hot that it must

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<v Speaker 1>be stored in a spent fuel pool. It's like a

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<v Speaker 1>gigantic swimming pool fifty ft deep. The water is there

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<v Speaker 1>to absorb the heat. The depth of the water protects

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<v Speaker 1>people against the radioactivity of the fuel and also provides

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<v Speaker 1>a margin of safety. After several years in the pool,

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<v Speaker 1>the spent fuel has cooled enough to be manageable outside

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<v Speaker 1>of the spent fuel pool. However, it's still highly radioactive

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<v Speaker 1>and dangerous. In fact, it'll be highly radioactive and dangerous

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<v Speaker 1>for thousands and thousands of years. In the ideal case,

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<v Speaker 1>one of two things would happen at this point. One

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<v Speaker 1>possibility is recycling. A recycling facility could reprocess the spent

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<v Speaker 1>fuel to extract the usable uranium two thirty five and

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<v Speaker 1>the plutonium. It could then create a new fuel and

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<v Speaker 1>do so economically. However, in the United States, we do

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<v Speaker 1>not recycle nuclear fuel right now. The other option would

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<v Speaker 1>be to move the now cooled spent fuel into permanent storage.

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<v Speaker 1>The goal would be to keep it away from people

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<v Speaker 1>for thousands and thousands of years. The Yuck Amount Facility

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<v Speaker 1>in Nevada was the proposed site for such long term storage,

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<v Speaker 1>but that idea has been abandoned for now. So at

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<v Speaker 1>the moment, nuclear power plants store their cooled spent fuel

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<v Speaker 1>their high level nuclear waste in containers called dry casks.

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<v Speaker 1>These are typically strong steel cylinders that are then surrounded

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<v Speaker 1>in concrete. The combination of steel and concrete provides a

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<v Speaker 1>secure container and protection from the radioactivity of the spent

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<v Speaker 1>fuel inside the cask. These casks are stored on concrete

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<v Speaker 1>pads outside the reactor facility and will remain there until

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<v Speaker 1>the United States comes up with a better long term

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<v Speaker 1>solution for high level nuclear waste. Be sure to check

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<v Speaker 1>out our new video podcast, Stuff from the Future. Join

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