Uranium Is So Last Century — Enter Thorium, the New Green Nuke

Full Article:

http://www.wired.com/magazine/2009/12/ff_new_nukes/

Hi-lites:

Named for the Norse god of thunder, thorium is a lustrous silvery-white metal. It’s only slightly radioactive; you could carry a lump of it in your pocket without harm. On the periodic table of elements, it’s found in the bottom row, along with other dense, radioactive substances — including uranium and plutonium — known as actinides.

Uranium is currently the actinide of choice for the industry, used (sometimes with a little plutonium) in 100 percent of the world’s commercial reactors. But it’s a problematic fuel. In most reactors, sustaining a chain reaction requires extremely rare uranium-235, which must be purified, or enriched, from far more common U-238. The reactors also leave behind plutonium-239, itself radioactive (and useful to technologically sophisticated organizations bent on making bombs). And conventional uranium-fueled reactors require lots of engineering, including neutron-absorbing control rods to damp the reaction and gargantuan pressurized vessels to move water through the reactor core. If something goes kerflooey, the surrounding countryside gets blanketed with radioactivity (think Chernobyl). Even if things go well, toxic waste is left over.

When he took over as head of Oak Ridge in 1955, Alvin Weinberg realized that thorium by itself could start to solve these problems. It’s abundant — the US has at least 175,000 tons of the stuff — and doesn’t require costly processing. It is also extraordinarily efficient as a nuclear fuel. As it decays in a reactor core, its byproducts produce more neutrons per collision than conventional fuel. The more neutrons per collision, the more energy generated, the less total fuel consumed, and the less radioactive nastiness left behind.

After it has been used as fuel for power plants, the element leaves behind minuscule amounts of waste. And that waste needs to be stored for only a few hundred years, not a few hundred thousand like other nuclear byproducts. Because it’s so plentiful in nature, it’s virtually inexhaustible. It’s also one of only a few substances that acts as a thermal breeder, in theory creating enough new fuel as it breaks down to sustain a high-temperature chain reaction indefinitely. And it would be virtually impossible for the byproducts of a thorium reactor to be used by terrorists or anyone else to make nuclear weapons.

A Scientist, His Work and a Climate Reckoning

Original Article:

http://www.nytimes.com/2010/12/22/science/earth/22carbon.html?pagewanted=1&_r=1&hp

Snippets:

Fossil fuel emissions, they say, are like a runaway train, hurtling the world’s citizens toward a stone wall — a carbon dioxide level that, over time, will cause profound changes.

The risks include melting ice sheets, rising seas, more droughts and heat waves, more flash floods, worse storms, extinction of many plants and animals, depletion of sea life and — perhaps most important — difficulty in producing an adequate supply of food. Many of these changes are taking place at a modest level already, the scientists say, but are expected to intensify....

In an interview on the Scripps campus in La Jolla, Ralph Keeling calculated that the carbon dioxide level at Mauna Loa was likely to surpass 400 by May 2014, a sort of odometer moment in mankind’s alteration of the atmosphere.

“We’re going to race through 400 like we didn’t see it go by,” Dr. Keeling said....

Moreover, scientists say that an increase of five or six degrees is a mildly optimistic outlook. They cannot rule out an increase as high as 18 degrees Fahrenheit, which would transform the planet.

“When I go see things with my children, I let them know they might not be around when they’re older,” he said. “ ‘Go enjoy these beautiful forests before they disappear. Go enjoy the glaciers in these parks because they won’t be around.’ It’s basically taking note of what we have, and appreciating it, and saying goodbye to it.”