[ExI] Could Thorium solve our energy problem?

[John Clark]

On Jul 11, 2010, at 4:47 PM, Ryan Rawson wrote:

> Wired had an article about Thorium reactors, most if it has been
> already stated here:
> 
> http://www.wired.com/magazine/2009/12/ff_new_nukes/

From the article:

>> The real action, though, is in India and China, both of which need to satisfy an immense and growing demand for electricity. The world’s largest source of thorium, India, doesn’t have any commercial thorium reactors yet. But it has announced plans to increase its nuclear power capacity: 

In addition to India and China France is working on Thorium reactors, but for some reason they are all using solid fuel not liquid. I think that is foolish, they're just accustomed to solid fuel and don't want to try something new.

>> Critics point out that thorium’s biggest advantage — its high efficiency — actually presents challenges.

That remark strikes me as a rather foolish thing to say.

>>  Since the reaction is sustained for a very long time, the fuel needs special containers that are extremely durable and can stand up to corrosive salts. 
 
Fluoride salts are not corrosive, they are very stable for the same reason Teflon, another Florine compound, is stable. Florine is the most chemically reactive element known so when it reacts with something it releases a lot of energy, if you want to change that compound you must supply the same amount of energy and that isn't easy.  

The following is not from the main article but from the comment section by people I don't know:

>> Liquid fluoride thorium reactors are literally one of the top approaches for U-233 weapons material production

Untrue. Thorium reactors are not as neutron rich as the reactors we use today, it produces enough neutrons for a chain reaction but just barely; so if you start to siphon off more than trivial amounts of U-233 fuel for clandestine sinister purposes the reaction will stop and the reactor will shut down. People tend to notice that sort of thing.

And there is no "top approach" for making weapons out of U-233, nobody is approaching it at all. If you want to blow somebody up in a nuclear way there are much easier and better ways to go about it.

>> the US has detonated a number of U-233 weapons tests.

There is an internet rumor that the USA did it once sometime in the 1950's, I've never been able to confirm it. I think it unlikely, if there was a facility large enough to produce that much U-233 you'd think it would have shown up somewhere on the radar screen by now. 

>>  U-233 has nearly as low a critical mass as plutonium

U-233 critical mass is in fact 60% higher than Plutonium so you'd need more of it and it's neutron density due to spontaneous fissions is 3 times as high so it would be harder to prevent pre-detonation.  Both these facts mean that making a bomb from U-233 would be harder than making one from Plutonium which would be harder than making one from U-235. And this is ignoring the rather important fact that you'd need a two inch thick tuxedo made of lead if you expected to finish making the bomb before you died from gamma radiation. 

>>  and especially if produced in a continuous process avoiding much U-234 contamination it will be a easy to handle and fabricate material, much less tricky than Plutonium.

That is total disinformation. First of all the contaminate you have to worry about is U-232 not U-234 and despite what is said above nobody knows of a way to produce industrial quantities of U-233 for use in a bomb without that contaminant that would make it so radioactive it would be suicidal to work with, detrimental to other bomb components and easy to detect. 

 John K Clark

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