Last week I mentioned that this week I’d be writing about thorium nuclear reactors.  I wasn’t sure if anyone would be interested, but I noted a few positive comments about the subject and nothing negative.  I do realize that my readers realized that the alternative to me writing about thorium nuclear reactors was a semi-veiled threat that I’d write about sex or politics if you didn’t approve.

Thorium, it has the symbol, “Th” and the atomic number 90.  It is weakly radioactive and has a number of isotopes, the most stable of which has a half-life of 14.05 billion years and eventually decades into Pb (lead).  No idea what that all means, but it sure sounds impressive.  You likely know that 14.05 billion years is about the age of the age of the universe so thorium has been around a long time and isn’t leaving anytime soon.

Interestingly we’ve know about thorium since 1828 when mineralogist Morten Thrane Esmark and chemist Jons Jacob Berzelius discovered and identified the element, naming it after Thor, the Norse god of thunder.  So far I haven’t discovered anything to indicate that thorium has ever gone, boom, and likely is too soft a metal to be used in a hammer.  We should think of another name for it.

The first use of thorium was as a light source in gas mantles.  You know, those little white sock like things that you put in to your camping gas lantern.  Yup, they have a little radioactive material in them.  Thorium has also been used in TIG welding, but currently thorium is being phased out of use. TIG welding is an interesting subject, but beyond the scope of this post.

Nuclear scientist, Edward Teller, was among the first to suggest that thorium could be used in a nuclear reactor.  Teller is known as “the father of the hydrogen bomb,” although he thought the title was in bad taste.  Still Teller knew his way around radioactive things so I’ll take his word on it.

I just want you to know that I’ve done extensive research on this – watched a YouTube video and read the Wikipedia article – so I know almost nothing about what I’m taking about here.  During these internet times that makes me an expert.  After all, I’ve done my own research.

Turns out that thorium is a fertile rather than fissile material.  I know I’d rather be described as fertile rather than fissile.  Fissile basically means that a material can do the nuclear reaction thing – like blowing up or producing heat, while fertile materials can be converted into fissile materials by absorbing neutrons.

Confused? Me too, but that’s what it says on wikipedia so it must be right.

There are a lot of long, complex chemical reaction charts on the wikipedia page that describe what is going on and I’ll try to summarize in simple terms:

First get a bunch of thorium and expose it to some neutrons and magically thorium becomes uranium-233, a fissile material.  This uranium then starts doing the nuclear fission thing of splitting atoms and creating heat and excess neutrons which converts more of the thorium into uranium.  You don’t get an explosion, just lots of heat that you can use to boil water to make steam to turn an electric turbine.  Along the way, you’ll also make some other isotopes of uranium and plutonium.  I had to mention plutonium because it’s in the title of this post.

This whole process is used in a breeder reactor, which is why you have to start with something fertile …

What really bothers me about nuclear power is that after all the wildly advanced science that goes into this, you end up boiling water.  Seriously? We do all this complicated splitting atoms, recombining them, moving neutrons, emitting beta particles and frying things with gamma rays and what do we end up with? Steam.

I’ve got a tea kettle that can do that and it has a much shorter wikipedia page.

Still, a lot of people are excited about thorium nuclear reactors as they have a number of great advantages over conventional light water reactors:

1. There is about three times more thorium on the planet than uranium.
2. The byproducts of a thorium reactor are difficult to make into a bomb, unlike a conventional reactor that can make lots of bombs.
3. There is much less nuclear waste as almost all of it gets consumed and it’s radioactive for a much shorter time – 100 to 1,000 years compared to 10,000+ years for a standard uranium reactor.
4. When used in a molten salt reactor, thorium can’t melt down like a uranium reactor so it’s far safer than current reactors.
5. Mining thorium is safer than mining uranium.
6. It could provide an abundant and safe energy source replacing oil and coal as part of a low carbon future.

There are a few disadvantages:

1. It could be expensive. Very expensive
2. The government will be a big pain about licensing a thorium reactor.  Face it the, government’s job is to say, “no” not “yes.”  (today’s political statement).
3. It’s still mostly experimental and the few commercial reactors proposed are still in the planning stage with the US government saying it needs more money to study it.
4. Thorium reactors do make some uranium-232 which emits gamma rays, which could cause the creation of many, many Bruce Banners – aka The Incredible Hulk.

So there you go – every thing I know about thorium.  It’s a promising energy source and could be the bridge fuel we use until scientists come with a practical fusion reactor, which I’m told is only 20 years away, like it has been for the last 50 years.

Check in next week for another enlightening and edgy essay.