Thursday, September 26, 2013

Why are we using uranium instead of thorium for nuclear power?

Many years ago, during the Nixon Administration, a precipitous decision was made: whether to use uranium light water reactors or to use thorium molten salt reactors. Some might say that the decision was based on the need for atom bomb materials, and in many ways, they would be right.

Kirk Sorensen, a former NASA engineer, has been researching the potential of thorium as a source of nuclear energy. He happened upon documentation in government archives that describe a working molten salt reactor using thorium as fuel, back in the 1950s and 1960s. The Oak Ridge National Laboratory ran a thorium molten salt reactor for more than 22,000 hours (a bit less than 3 years), before it was shut down. He explains many of the benefits of thorium based power in 5 minutes here

Sorensen found audio recordings from the Nixon administration regarding the subject of nuclear power. In this presentation, at about 12 minutes into it, we hear Nixon marshalling forces to put a uranium nuclear power plant in California to create jobs. The competing project used thorium and was based in Tennessee. Nixon had powerful alliances that wanted a power plant in California to ensure his re-election to office and they were successful in meeting their objectives.

With uranium reactors, it's relatively easy to extract bomb materials from the reaction products. That's not so true of thorium. Bomb materials are extremely difficult to extract from the thorium fuel cycle.

While it's possible that in the main, nuclear fuel for bombs was a primary consideration in the choice of uranium nuclear reactors, evidence presented by Sorensen indicate that a much larger consideration was to put jobs in California to assist Nixon in a future re-election campaign. Seems like just a political decision, right? No big deal?

What are the implications of this decision? Three big implications come to mind. Chernobyl, Three Mile Island and Fukushima, three of the biggest nuclear reactor accidents in my memory. Had we been using thorium molten salt reactors, none of these accidents could have happened.

The thorium molten salt reactor, by design, cannot have a runaway reaction. The molten salt is kept in a reaction vessel by a drain with a frozen plug. A fan blowing on the plug keeps the plug frozen. If something goes wrong, the plug melts and all the reacting materials are drained into passive cooling tanks.

The Liquid Flouride Thorium Reactor produces less than 1% of the waste that a uranium reactor makes. The radioactivity from that waste lasts only 300 years compared to 10,000 plus years for uranium waste. Waste from uranium reactors can be reprocessed in thorium reactors, too.

Thorium reactors are about 300 times more efficient than uranium reactors. One ton of thorium can replace 31 billion barrels of oil. Think about that. The US has giant reserves of thorium and could become completely energy independent. Our dependence on foreign oil goes away, almost completely. Our need to maintain bases all over the world to protect the oil supply goes away. 9/11? Wouldn't have happened if we used thorium for fuel.

The energy density of thorium is so high that a small ball of thorium in your hand is enough for your entire lifetime energy needs. Thorium radioactivity is not nearly as dangerous as uranium. Thorium can be mined straight from the ground and needs no extensive processing to get the right isotope as with uranium.

Now that I've seen what happened, it is astounding to me that one man could set us on a course so completely wrong. It doesn't matter if he's liberal or conservative, Democrat or Republican. What matters now is that we change course for our kids.

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