The ups and downs of nuclear power
With renewed momentum but no plans to store its waste, American nuclear energy sits in limbo.
By Robynne BoydThu, Mar 12 2009 at 5:00 AM EST
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Nuclear energy is a radioactive topic. Depending whom you talk to, it's either a clean, sustainable fuel source providing ample homespun electricity, or an expensive, dirty and dangerous gamble as outdated as the Cold War. This debate's roots run deep, having electrified conversation since the nuclear-energy boom of the 1970s, when most of America's nuclear plants rose from the gravel and began churning out power for the growing population. The average nuclear reactor produces enough electricity each year to power 740,000 households (equivalent to 13.7 million barrels of oil).
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How does nuclear power work?
A nuclear power plant works in much the same was as any power plant: It burns fuel to produce heat. The heat is transformed into steam, which rotates the blades of a turbine. This movement is converted into electricity and sent to homes and businesses via high-voltage wires. The only difference with nuclear energy is that the fuel is uranium (as opposed to coal or petroleum), and the heat originates from fission — the process of splitting a uranium atom.
During fission, a neutron (part of an atom's nucleus that has no charge) hits a uranium atom, causing it to divide in two and release a cloud of radiation and heat. More neutrons are also released, which then split more uranium atoms, triggering a chain reaction of energy production. This process occurs inside the plant's reactor, which is submerged in water. The water turns to steam as fission occurs.
What is uranium and where does it come from?
Uranium is a common metal found all over the globe. But the type used in nuclear power plants — U-235 — is much more rare. After it's extracted from the Earth's crust, U-235 is processed into fuel capsules and placed end-to-end in a fuel rod inside the nuclear reactor.
Do all nuclear reactors work the same way?
Two types of reactors are used in the United States: boiling-water reactors and pressurized-water reactors. The latter are more common (the country has 35 boiling-water reactors and 69 pressurized-water reactors) since they use a simpler design and are thus considered safer.
In a boiling-water reactor, the water surrounding the reactor core boils and turns to steam as the uranium atoms split. In a pressurized-water reactor, the steam is generated in a separate piece of equipment, called the steam generator. The water in the reactor core is kept under pressure until it reaches the steam generator, where it then boils and turns to gas. The unused steam travels into a condenser where it liquefies and is pumped back to the reactor vessel.
How much does it cost?
The cost of building a nuclear power plant varies widely, but a 2008 study indicated it's risen significantly in recent years, about 130 percent since 2000. A new plant may cost somewhere between $6 billion and $8 billion to build — a price heavily subsidized by the federal government.
What are the environmental concerns?
Global warming has been the major impetus behind nuclear energy's renaissance. Since nuclear power doesn't release CO2 during the generation process, many people consider it "clean." According to the Nuclear Energy Institute, geothermal energy is the only form of electricity production that has a lower carbon footprint than nuclear. There are, however, carbon emissions associated with mining uranium and building each plant.
Low carbon emissions give nuclear energy an outwardly "green" appearance, yet the intractable problem of how to dispose of its radioactive waste continues to tarnish its image. Exhausted fuel rods contain radioactive material that can take thousands of years to become inert. Only temporary storage for these rods exists; they're placed inside pools of water or steel or concrete containers at hundreds of sites around the country. The U.S. Department of Energy had planned since 1987 to store radioactive waste at Yucca Mountain, a ridge of volcanic rock about 100 miles northwest of Las Vegas, but controversy has loomed ever since, due largely to the waste's long-term radioactivity. The Obama administration may have driven the final nail into Yucca's coffin in early March, when it cut its funding — reigniting the debate over what to do with radioactive waste.
© 2009 MNN Holding Co. LLC
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Comments
Ashton V.
Today 04:51 AM
Nuclear energy is known as a dangerous kind of energy, which is harmful to human. Well though the purpose is for good it would be better to have the safe alternatives in producing energy substitute to oil. Your credit rating is one of the most important things, as dumb as it seems. It pays to keep it in the 700 range, and it will pay off the sooner you get it heading in that direction. Every now and again, everyone encounters a financial crisis and is in need of emergency funds. In that.... More
Zack
03/14/2009 23:03 PM
I'd just like to point out that, under normal circumstances, does not come into contact with any radioactive material. The water is placed around the reactor, not mixed in with the fuel rods. Also, the containers that are used to store the spent fuel are only sometimes put into water. Again, the water doesn't come into contact with any radioactive material.
Guest
03/17/2009 12:25 PM
Also, in PWR reactors, the water in the reactor (primary water) never leaves the containment building, a 3 foot thick concrete structure lined with stainless steel. The steam generator, which is also in the containment building, pipes the hot primary water through small tubes in a pool of water (secondary water). The secondary water is what turns to steam and continues through the secondary loop which includes the turbine, condenser, etc... The water in the reactor is radiated, but does not.... More
Anonymous
03/12/2009 20:28 PM
The cost of a nuclear plant varies enormously - Japan recently completed a plant at around $2000 per kilowatthour, or roughly $2 billion for the plant, as opposed to the $6 to $8 billion quoted in the article.
Actually, claiming a certain price for a nuclear plant is absurd- there are several technological generations of plant design currently available. And the costs differ considerably. Nor are there "any massive federal subsidies" available for nuclear power. Loan guarantees are the.... More
Eileen McCabe
03/12/2009 14:08 PM
A clarification: I did not post as anonymous. I am Eileen McCabe, and with the Green Party of Utah
Eileen McCabe
03/12/2009 14:07 PM
While this article does mention nuclear waste, it glosses over some of the other unsavory aspects of nuclear power.
URANIUM: using traditional methods, huge amounts of rock must be mines and milled in order to extract tiny amounts of uranium. The piles of discarded rock, tailings remain in piles where it has been mined, some near water sources like the Colorado river decades later. Newer methods such as ISL inject soda solution into suitable rock formations through wells, but run the risk of.... More
