Green to the Core?
Date: Saturday, November 19, 2005 @ 22:40:22 UTC
Topic: General



How I tried to stop worrying and love nuclear power
by JUDITH LEWIS (LA Weekly)

Nothing in life is to be feared; it is only to be understood. - Marie Curie

[Extracts] ...Even plutonium, one of the world’s most toxic materials, emits only alpha particles, which can be blocked by paper, a thin sheet of aluminum or even your skin. “As long as you don’t ingest or inhale [them],” Golden says, “alpha particles can’t hurt you.” Or, in the words of Elena Filatova, the intrepid Ukrainian motorcyclist who documented Chernobyl’s dead zone in photographs, “You can play billiard balls with pure plutonium. Just don’t swallow it by mistake.”


Back in the learning laboratory at San Onofre, where I’ve come on my own open-minded journey to test my assumptions about nuclear power, Golden holds up a small vial of yellow powder: uranium oxide, or yellowcake uranium, milled and refined — the substance at the heart of the current CIA leak investigation. Before its atoms’ energy can be harnessed, uranium oxide has to be enriched, by centrifuge or by being turned into a gas and passed through a series of membranes, a process called “gaseous diffusion.” Uranium comes out of the ground only .7 percent uranium-235 (or U-235); fueling a light-water reactor like San Onofre’s requires a concentration of 4.7 percent U-235. Using a mock-up of a reactor core that stands at the front of the room — a contraption that looks like the inside of a miniature pipe organ — Golden demonstrates how uranium pellets the size of baby fingertips fill the core’s 236 zirconium tubes, which are then bundled together in a fuel assembly.

..He accuses the nuclear industry of “falling down on the job” by keeping so many secrets about its world, and holds that if the American public, like the more nuclear-friendly French, knew all the facts — what happens when atoms split, how unstable nuclides decay, how uranium is enriched and waste is transported — nuclear energy might be more popular with the American public. “Most Americans think they know about radiation because of Chernobyl, science fiction or the three-eyed fish in The Simpsons,” he says. “So as a country, we are phobic about radiation.”...

... Of course, the U-235 that fuels San Onofre is highly fissile: When one of its atoms absorbs an extra neutron, its nucleus splits and forms other nuclides, including radio­active versions of strontium, cesium and iodine, along with plutonium. It also lets loose more neutrons to hit other U-235 atoms, provoking a chain reaction of fission events. Fission generates heat, which in a light-water reactor turns water into steam. Maintaining the right balance of fission events — keeping the reactor at a “critical” state — is a tricky process. If too many neutrons fly around splitting atoms, the core gets too hot, in which case operators insert control rods made of boron and silver into the fuel assembly to slow or stop the chain reaction and avert a meltdown. If it doesn’t stay hot enough, the core loses power, provoking a different set of events that can lead to an equally disastrous loss of control. If the reactor drifts in either direction, or if for some reason the core loses too much water — which cools the core at the same rate it transfers heat — a partial or complete meltdown could result. In the early days of nuclear power, many people feared that once a meltdown was in process, it would continue to melt through the Earth’s core from North America all the way to China: the “China Syndrome” of the movie’s title....

... “Our core is only a 12-foot cube,” Golden says, “yet it powers 1.2 million homes for four years before you ever need to refuel.” The trillions of fissile atoms in one tiny uranium pellet yield enough energy to replace 150 gallons of gas, 1,780 pounds of coal, 16,000 cubic feet of natural gas and two and a half tons of wood. And they do so without adding an ounce of greenhouse gases to the atmosphere. It is widely accepted that one nuclear power plant spares the atmosphere the emissions of 93 million cars...

“How it could be possible that the worst nuclear power plant accident in history, releasing between 100 and 200 million curies of radiation into the environment, could produce positive ecological consequences?” the official wanted to know.

“The answer was simple,” the men concluded. “Humans have evacuated the contaminated zone.” It’s not that radiation hasn’t harmed the animals — the mice in the freakishly abundant new wilderness show profound genetic mutations — it’s just that “the benefit of excluding humans from this highly contaminated ecosystem appears to outweigh significantly any negative cost associated with Chernobyl radiation.”

Nuclear power may change the world after all...

Sourse: http://www.laweekly.com/ink/05/51/features-lewis.php






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