Center for a New American Security

As we have posted on this blog before, the Navy has long been researching greener technologies for its transportation needs, proposing everything from seawater-based fuels in its fighter jets to biodiesels in its ground vehicles. Now one Congressman is commissioning a study to examine the implications of mixing thorium into the nuclear Navy fleet’s reactor fuel, instead of relying strictly on uranium and plutonium.

In June, Congressman Joe Sestak (D, PA) – a retired rear admiral – authored a bill (pdf) requesting a study of thorium-liquid-fueled nuclear reactors and their potential as propulsion systems for the Navy (see pp. 282 through 285). Sestak’s legislation made it into the fiscal year 2010 National Defense Authorization Act, so the study could theoretically begin as early as next year if the bill passes intact. This research is particularly relevant in light of the 2008 NDAA requirement (pdf again) that new major combat ships be built with integrated nuclear propulsion systems.

The proposed study would build on a long line of research into thorium’s practical uses. Thorium is a radioactive metal that is found in nature in far greater quantities than uranium. Although not fissile on its own, it can be added to certain reactors and used to “breed” uranium-233. This uranium can then be used as a nuclear power source. Used in a naval context, thorium would carry all the risks associated with nuclear power, including the possibility of disaster and subsequent environmental damage. But thorium-generated energy would also carry all of the benefits of nuclear power, offering a carbon-free alternative to petroleum-based fuel sources. Thorium proponents also note that thorium reactions produce less nuclear waste and do not create usable plutonium as a by-product, thus reducing proliferation worries. Thorium has been successfully used for commercial purposes (pdf) in limited quantities, notably in the Shippingport plant in Pennsylvania, but the military has not explored thorium in much depth, as far as we know publicly.

The biggest obstacle to thorium’s use as a nuclear fuel is its availability. Although it is three times as common as uranium in nature, no mines currently dig primarily for thorium. It is usually produced in mining operations for uranium and rare earth elements instead. Large deposits are found in Australia and India, but the potential size of U.S. thorium reserves has attracted interest from a variety of U.S. politicians. The Lemhi Pass (another pdf) area of Idaho is especially rich with thorium, and has the largest proven reserves in the United States. A Utah-based corporation owns this land, but it could take years for proper mining and transport infrastructure to be built. A positive result from the DOD study would surely increase interest and investment in domestic thorium mining.

But there may be political problems with Congressman Sestak’s proposal. The thorium fuel study was featured only in the version of the 2010 NDAA passed by the House of Representatives, not the Senate version. Right now, the 2010 NDAA  is awaiting review by the Armed Services committees of both houses, which should reconvene this fall to reconcile the differences between the two versions of the bill. The fate of the thorium study is uncertain, but the prospects look bright given the political interest in thorium-fueled nuclear power. If the proposal survives in its current House form, the Secretary of Defense and the Chairman of the Joint Chiefs of Staff will be required to submit their report to relevant Congressional committees by February 1, 2011. And we at the Natural Security Blog will be watching to see what happens.