Problems with new nuclear

Scientific American talks about the problems with fast neutron reactors.

I haven't paid much attention to the issues with this type of reactor, which are supposed to help with reducing the disposal problem. But combining sodium and nuclear reactors not only sounds dangerous; it's been proved dangerous:

The most prevalent type of fast-neutron reactor, so-called because the neutrons used to initiate the fission chain reaction are traveling faster than neutrons moderated by water in conventional nuclear reactors, operate at temperatures as high as 550 degrees Celsius and use liquid sodium instead of water as a coolant. Sodium burns explosively when exposed to either air or water, necessitating elaborate safety controls. Nevertheless, as far back as 1951 at Idaho National Laboratory, such a sodium-cooled fast-neutron reactor produced electricity.

But attempts to make that technology commercial have largely failed, mostly because of difficulties with controlling sodium fires and the steam generators that transfer heat from the sodium to water. Japan's Monju sodium-cooled fast neutron reactor caught fire in 1995—and has just received permission to resume operation this month after years of technical difficulties in repairing it, along with legal challenges to its restart. The French Superphenix sodium-cooled fast-neutron reactor operated successfully for more than a decade—but only produced electricity 7 percent of the time, "one of the lowest load factors in nuclear history," said nuclear consultant Mycle Schneider, an IPFM member during the call. An accident at the plant cost one engineer his life and injured four other people when a leftover tank with roughly 100 kilograms of sodium residue exploded, according to Schneider.

It's not like they haven't tried to improve them:

As far back as 1956, Adm. Hyman Rickover, who oversaw both the Navy's nuclear-propulsion efforts as well as the dawn of the civilian nuclear power industry, cited such sodium-cooled fast-neutron reactors as "expensive to build, complex to operate, susceptible to prolonged shutdown as a result of even minor malfunctions, and difficult and time-consuming to repair." That judgment remains despite six decades and $100 billion of global effort, according to physicist Michael Dittmar of the Swiss Federal Institute of Technology in Zurich who wrote, "ideas about near-future commercial fission breeder reactors are nothing but wishful thinking" in a November 2009 analysis.

"For that $100 billion we did learn some things," remarked physicist Thomas Cochran of the Natural Resources Defense Council, an environmental group, during the IPFM call. "We learned that fast reactors were going to cost substantially more than light-water reactors…[and]…that, relative to thermal reactors, they're not very reliable."

The article goes on to note that Bill Gates has been promoting a new type of reactor, the travelling wave reactor, which would have cores that contain fuel for 30 years. Trouble is, the materials needed for that aren't developed yet.

Thorium breeder reactors get a bit of a pessimistic hit too:

Wrapping highly fissile plutonium in a thorium blanket could produce enough nuclear fuel indefinitely, according to the vision laid out by the architect of India's nuclear program, physicist Homi J. Bhabha, in 1954. The Indian government is currently building such a prototype fast breeder reactor, despite limited success with a precursor, said Princeton physicist M. V. Ramana during the IPFM call. "The cost of electricity is 80 percent higher than from heavy-water reactors," he added. Uranium prices would need to increase 15-fold from current levels of roughly $80 per kilogram to make it economically attractive.

Nothing with nuclear is terribly easy, it seems.

It's also interesting to note that a French nuclear company has bought a major US solar thermal company. Maybe it pays to diversify.