TORONTO, ONTARIO - Earlier this year, this blog featured the thorium reactor as a potential alternative for improved nuclear power in the future. While no "expose"-type publication has come out, the quiet consensus from nuclear professionals expressed in letters to the editor is that the promise of the thorium reactor as a panacea for the recognized issues with nuclear technology is oversold. It might be modestly harder to get nuclear weapons fuel from a thorium reactor, but it's still possible, and the other purported savings in waste are not especially significant, and the higher abundance of thorium is not especially relevant when breeder reactors can make enough of their own fuel for any degree of anticipated demand yet forecast.
Instead, an older article in Technology Review magazine touts the traveling wave reactor as a much more likely way to move nuclear energy forward toward a less expensive and and safer future. Also boasting its own Wikipedia page, the traveling wave reactor differs from current nuclear plants in that it does not require enriched uranium, and the fission reaction occurs in a specific moving zone (hence the name "traveling wave") instead of through the entire core of the reactor.
The traveling wave reactor isn't a panacea, either. It probably requires about 10% enriched uranium (U-235) to start a fission reaction. However, once the chain reaction is started, it can be sustained with depleted uranium (U-238), and most theoreticians believe that a single fueling could quite possibly last 60 years or more, contrasted with 2-3 years using conventional technology. Right there, proliferation concerns would be diminished, as there would be no materials being removed from the reactor that could be diverted, and since the fuel is no longer (mostly) enriched, there is a lesser need for materials that could be diverted.
Another potential issue is that the reactor would have to be cooled by liquid sodium and operate at 550 C, instead of the 330 C typical of current reactors. However, that doesn't automatically mean lower safety; assuming proper reactor design and cooling systems the danger might not be significantly different.
To this point, most of the work on traveling wave reactors has been at the behest of venture capital firm Intellectual Ventures. Unlike the thorium advocates, they don't view it as a short-term technology, but one that may take hold if an expansion of nuclear power takes place in the United States, what it calls a "nuclear renaissance."
Somehow, I suspect nuclear critics would find a different word than "renaissance," and it will take a lot more than an oil spill to push the world toward traveling wave reactors.
Showing posts with label nuclear proliferation. Show all posts
Showing posts with label nuclear proliferation. Show all posts
Thursday, June 3, 2010
Tuesday, January 26, 2010
Politics: Thorium
TORONTO, ONTARIO - By some accounts, the world's current problems of energy production and nuclear proliferation could be solved by a Norse god. Okay, not exactly the Norse god of thunder, Thor, but the chemical element named in his honor, thorium. A fair number of scientists believe that relatively-abundant thorium can create power using a cycle that is useless for nuclear weapons and produces much less toxic waste than the currently-employed nuclear reactors.
Quite a number of thorium-advocacy web sites can be found on the Internet; just look at the links list in the left panel at the Thorium Energy Alliance web site. The sites all tell a compelling story. By most estimates (though nobody seems to be certain), thorium is at least four times as common in the earth's crust as uranium, and has the advantage of being commonly found in a single isotope, thus not requiring much purification. Thorium itself is not fissile, or spontaneously useful as an energy source, but if it is bombarded with neutrons, it can be cheaply converted to uranium-233, which is a very useful nuclear fuel. While uranium-233 can be used in nuclear bombs in pure form, in the thorium fuel cycle (especially if properly designed), it is contaminated with other isotopes and hence cannot be easily extracted to use in weapons. Plus, the decay products of the reaction are such that the waste remains radioactive for only a couple hundred years, instead of tens of thousands.
The groups would have it appear that thorium solves pretty much all the problems associated with nuclear power. The fuel is more common and easy to process. The waste produced is not nearly as dangerous and decay on a time scale in which we have confidence in our own engineering. Concerns about nuclear weapons proliferation are much diminished (if not gone entirely) from diverted materials. Furthermore, most proposed thorium cycles could not "melt down" in the way that other nuclear reactors have done. So why don't we use it?
In the early nuclear era, the answer actually had a bit to do with the weapons capability--the United States and the Soviet Union both wanted to invest in technology that would allow them to build their stockpiles. However, the most compelling reason right from the start was that there was more knowledge about uranium and plutonium, so the least risky way to proceed was to build on that knowledge.
There has been some exploration along the way, including experiments in Canada in the 1960's and more recently in India. In 2008, US Senators Harry Reid (D-Nevada) and Orrin Hatch (R-Utah) introduced a bill to fund more research in the United States, but that bill never made it to the floor, a victim of focus on immediate economic matters and that fall's election.
Assuming the promise of thorium comes even close to being realized, whatever nation does the work to commercialize the technology economically will be well-positioned in the coming century. As India and Russia start to put money into thorium, it behooves the rest of the world not to be left behind.
Quite a number of thorium-advocacy web sites can be found on the Internet; just look at the links list in the left panel at the Thorium Energy Alliance web site. The sites all tell a compelling story. By most estimates (though nobody seems to be certain), thorium is at least four times as common in the earth's crust as uranium, and has the advantage of being commonly found in a single isotope, thus not requiring much purification. Thorium itself is not fissile, or spontaneously useful as an energy source, but if it is bombarded with neutrons, it can be cheaply converted to uranium-233, which is a very useful nuclear fuel. While uranium-233 can be used in nuclear bombs in pure form, in the thorium fuel cycle (especially if properly designed), it is contaminated with other isotopes and hence cannot be easily extracted to use in weapons. Plus, the decay products of the reaction are such that the waste remains radioactive for only a couple hundred years, instead of tens of thousands.
The groups would have it appear that thorium solves pretty much all the problems associated with nuclear power. The fuel is more common and easy to process. The waste produced is not nearly as dangerous and decay on a time scale in which we have confidence in our own engineering. Concerns about nuclear weapons proliferation are much diminished (if not gone entirely) from diverted materials. Furthermore, most proposed thorium cycles could not "melt down" in the way that other nuclear reactors have done. So why don't we use it?
In the early nuclear era, the answer actually had a bit to do with the weapons capability--the United States and the Soviet Union both wanted to invest in technology that would allow them to build their stockpiles. However, the most compelling reason right from the start was that there was more knowledge about uranium and plutonium, so the least risky way to proceed was to build on that knowledge.
There has been some exploration along the way, including experiments in Canada in the 1960's and more recently in India. In 2008, US Senators Harry Reid (D-Nevada) and Orrin Hatch (R-Utah) introduced a bill to fund more research in the United States, but that bill never made it to the floor, a victim of focus on immediate economic matters and that fall's election.
Assuming the promise of thorium comes even close to being realized, whatever nation does the work to commercialize the technology economically will be well-positioned in the coming century. As India and Russia start to put money into thorium, it behooves the rest of the world not to be left behind.
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