How High-level Nuclear Waste Works

What exactly is high-level nuclear waste, and how are we dealing with it today? In this episode, Marshall breaks down the techniques used to store high-level nuclear waste.

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Episode Transcript

Speaker 1 (00:00):
Welcome to Brainstuff from house stuff works dot com, where
smart happens Him Marshall Brain with today's question, what is
high level nuclear waste and how are we dealing with
it today. Let's imagine that you own a nuclear power plant.

(00:23):
You're in a pretty good position these days because compared
to a coal fired power plant, your operation is very green.
You're producing lots of reliable electricity without releasing any carbon
dioxide into the atmosphere. You don't release any other pollutants
like sulfur or mercury into the atmosphere either, and you
also are not creating huge quantities of coal ash, which

(00:47):
at many power plants ends up being stored in immense lagoons.
These lagoons raise a lot of questions in terms of
long term stability, especially during floods. So as a nuclear
power plant operator, you are feeling pretty good. There is
in fact, only one fly in your ointment at the moment.
That fly is called high level nuclear waste, and it

(01:10):
appears every time you need to refuel your reactor. In fact,
the fly grows a little bigger with each refueling. Let's
take a look at how this high level nuclear waste works. First,
little background The goal of a nuclear reactor is to
create heat so that it can produce steam that drives
a generator. The nuclear fuel in the reactor creates the

(01:31):
heat through nuclear fission. The fuel consists of a mixture
of uranium two thirty five about four percent mixed with
uranium two thirty eight and other elements. The uranium two
thirty five is the actual fuel for the reactor. Each
fuel pellet containing the U two thirty five is very small,
about the size of your little toe, but it contains

(01:53):
the equivalent heat of perhaps a ton of coal. A
typical reactor contains several tons of these all it's arranged
in rods that fill the reactor core. The YouTube thirty
five sitting in the core undergoes a fission process. In
this process, it creates a tremendous amount of heat. In
a nuclear bomb, this heat is all released in less

(02:15):
than a second to create a gigantic explosion. In a
nuclear reactor, the heat is released gradually over the course
of a year or two to boil water that drives
the electric generators. At the end of that year or two,
the reactor shuts down for a month for refueling, and
the fly in the ointment appears, between one quarter and
one third of the fuel in the core is removed

(02:37):
and replaced with fresh fuel rods. Several tons of highly
radioactive material, also known as spent fuel or high level
nuclear waste, now has to be managed. The spent fuel
is still quite hot. It's so hot that it must
be stored in a spent fuel pool. It's like a
gigantic swimming pool fifty ft deep. The water is there

(03:00):
to absorb the heat. The depth of the water protects
people against the radioactivity of the fuel and also provides
a margin of safety. After several years in the pool,
the spent fuel has cooled enough to be manageable outside
of the spent fuel pool. However, it's still highly radioactive
and dangerous. In fact, it'll be highly radioactive and dangerous

(03:23):
for thousands and thousands of years. In the ideal case,
one of two things would happen at this point. One
possibility is recycling. A recycling facility could reprocess the spent
fuel to extract the usable uranium two thirty five and
the plutonium. It could then create a new fuel and
do so economically. However, in the United States, we do

(03:46):
not recycle nuclear fuel right now. The other option would
be to move the now cooled spent fuel into permanent storage.
The goal would be to keep it away from people
for thousands and thousands of years. The Yuck Amount Facility
in Nevada was the proposed site for such long term storage,
but that idea has been abandoned for now. So at

(04:07):
the moment, nuclear power plants store their cooled spent fuel
their high level nuclear waste in containers called dry casks.
These are typically strong steel cylinders that are then surrounded
in concrete. The combination of steel and concrete provides a
secure container and protection from the radioactivity of the spent

(04:28):
fuel inside the cask. These casks are stored on concrete
pads outside the reactor facility and will remain there until
the United States comes up with a better long term
solution for high level nuclear waste. Be sure to check
out our new video podcast, Stuff from the Future. Join
House to Work staff as we explore the most promising

(04:49):
and perplexing possibilities of tomorrow. The House to Worts I
find app has arrived. Download it today on iTunes.