To many nuclear optimists, thorium represents the next big thing. Supporters of the nuclear fuel named after a Norse god point to thorium's many advantages: First, because it's not fissile, there is no threat of a thorium reactor meltdown. Second, because it doesn't produce plutonium, it's very difficult to produce a nuclear weapon from thorium. Third, because it's four times as plentiful as uranium, there is less chance of running out. And finally, because it's lighter than uranium, thorium produces less nuclear waste.

Given all these compelling qualities, many countries have dedicated significant resources to making thorium power a reality. India, for example, has put many of its best scientists on the project with an official goal of producing a thorium prototype by 2016. China, meanwhile, has dedicated at least $350 million and at least 140 PHD's to its own efforts.  

With such great potential and the intellectual firepower behind it, some think that thorium will be a threat to uranium. If thorium replaces uranium, uranium miners such as CamecoRio Tinto, and Denison Mines will have much more serious problems to worry about rather than just idle Japanese reactors. So far, though, almost no one talks about thorium as a plausible threat to the uranium industry today.

Here are two reasons why most people don't believe thorium is a threat.

Many nuclear reactors using uranium will still be operating 
First, although it costs a lot to build a nuclear power plant, once those fixed costs are accounted for, the variable cost of operating a nuclear power plant is actually quite low. According to some experts, the variable cost of nuclear is only around 2 cents per kilowatt hour versus the 6 cents per kilowatt hour of fixed costs.

Because the variable costs of nuclear reactors are so low, many nuclear reactors currently using uranium will continue operating until they're decommissioned, even in the event that thorium reactors do become practical. That wide base of operating nuclear reactors using uranium will provide the uranium mining industry with a steady source of demand for many years afterwards.

Formidable technological challenge
Second, for all of thorium's promises, the technology is extremely difficult to develop. The United States, for example, spent decades working on making thorium power a reality at Oak Ridge National Laboratory, but had nothing to show for the research.

Because the United States failed, it may take China and India a significant amount of time to make thorium work. Most experts, in fact, believe that it may take the nations a decade or more.  

The bottom line
Given all its compelling qualities, thorium reactors will eventually be developed. In an energy-starved world where global warming is becoming a bigger and bigger problem, and events like Fukushima occur more frequently than they should, countries like China and India can't afford to not develop thorium reactors. But given thorium's formidable technological challenges, it may take at least a decade or more for the technology to become feasible. Until that time, uranium miners have other things to worry about.

Jay Yao has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.