April 26, 2012

Power Up: Nuclear

The pros and cons of a nuclear power plant.

Shelby: In 1979, a near-disaster at a nuclear power plant in Pennsylvania stopped all new construction of nuclear reactors in the U.S. Thirty years later, regulators have approved plans for the first new nuclear power plant in a generation. But why is nuclear energy so controversial?

In today’s Power Up segment, we take a closer look.

There was even a near disaster in the U.S. in 1979 which lead to a public backlash against nuclear power. To some, the nuclear power plant is a symbol of humanity’s greatest fears. A disaster could have major consequences for the world. But for others, nuclear energy represents one of humanity’s greatest hopes, providing vast amounts of cheap, clean and reliable energy. Supporters say that atomic energy could free us from dependence on fossil fuels and save the world from climate change. A lot of that atomic energy is already being produced right here in the United States. In fact, the U.S. is the world’s top creator of nuclear power, and it currently provides about one fifth of our nation’s electricity.

But what happens inside a nuclear power plant? We visited the Palo Verde nuclear generating station in Arizona to learn more. Palo Verde is home to three of the country’s 104 nuclear reactors and is the largest power producer of any kind in the United States.

At capacity, the plant can produce more than 4,000 megawatts of electricity, enough to power 1.3 billion cell phones!

First of all, what is nuclear power?

“Nuclear power is a way that we make energy using uranium.”

Shelby: Uranium is a radioactive element that is the key to creating nuclear energy.

“The uranium is mined from the ground, and it then gets processed into what are called fuel pellets.”

Shelby: Those fuel pellets are about as tiny as the top of your pinky. This one is just a sample, but it is the same size as the real deal.

Ok, so here at the energy information center, we just learned that a pellet of uranium fuel this size is the equivalent of three barrels of oil, or one ton of coal! That is one of the big advantages of nuclear power. It does not emit CO2 or other greenhouse gasses like plants powered by fossil fuels. It is also considered to be cheaper since a little uranium goes a long way.

But how do those little pellets create so much power in the first place? Well, the pellets are stacked in metal tubes and placed inside a reactor core. There, they undergo a powerful process called nuclear fission, where splitting one atom causes it to crash into others in a chain reaction that puts off energy. That energy heats water to produce steam, which powers a generator to create electricity.

The reactor core, where all of that fission takes place, is protected by a large dome called a containment structure. We got to see one up close.

“They have an elevator here that can go up and down.”

Shelby: Elizabeth says these structures were made to withstand big disasters, like a jet crash or tornado wind speeds up to 300 miles per hour. They are supposed to contain the release of radiation — something that can be extremely dangerous to humans.

Elizabeth: Radiation is very good at damaging DNA, which is the basis of how cells divide in our body.

Shelby: Radiation occurs naturally, and we are exposed to low doses of it when we sit in the sun, get an X-ray, or even eat a banana. But high doses of radiation can be deadly, and long-term exposure can also lead to cancer, which Dr. David Brenner says is the biggest concern.

Dr. David Brenner: The bigger the dose, the bigger the risk. The smaller the dose, the smaller the risk. It doesn’t happen overnight. Ten, twenty, thirty years after the exposure is when the cancer might appear.

Shelby: That is why nuclear power, and the high levels of radiation that come with it, are controversial.

And another big concern is the radioactive waste that is left behind after the fission process. Those used fuel rods give off heat and radiation for years.

“So what ends up happening, the fuel is used for about 18 months. And then we unload the reactor core into what’s called the spent fuel pool building.”

Shelby: Most nuclear power plants use water to cool the radioactive rods. Then, some load the rods into dry storage casks like these, where they continue to cool and decay down for years.

So, why is it important to cool these rods and these materials?

“The heat that’s given off, if we didn’t cool it, it would eventually raise up and it would start to melt the fuel pellet. Once it’s in a melted state, it’s a lot more difficult to control. So, the cooling, it is allowing us to control it for years and years and years.”

Shelby: Elizabeth and other supporters of nuclear power say that nuclear energy can be produced in a safe way. But critics point to disasters, like what happened in Japan last year and in the Ukraine back in the 1980s, where dangerous levels of radiation did leak, devastating the environment and threatening peoples’ health. And after a near disaster in the U.S. in 1979, public backlash stopped any new nuclear plants from being built. But supporters say with the right protection, nuclear power is safe.

“Based upon our preparedness and on expertise and equipment, personnel, no, it won’t happen here. But when you take a look at the simple things going wrong over there in Japan, that’s disturbing.”

Shelby: The risks have at least nine countries looking to ban nuclear power altogether. But despite the recent nuclear crisis in Japan, there are plans to build more reactors in the U.S., and it is estimated that 4 to 6 new units may come on line by 2020.

Shelby Holliday, Channel One News.



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