Let me start out with a story. This is the nucleus of a helium atom. I imagine a few of us have opened up the small end of a balloon and sucked a few of these down. Anybody ever realize that when you’re sucking down helium you’re actually sucking down nuclear waste from millions of years ago inside the earth? I shocked a reporter the other day by telling her that.
Helium has four nucleons in its nucleus. It has two protons and two neutrons. And somewhere in the last hundred years, somebody figured out that every time a nuclear decay takes place, it throws out one of these helium nuclei. It throws it out and it loses four mass numbers. And so, by implication, they figured out that there’s probably four different chains that matter can follow when it decays.
And they looked in nature, and sure enough, they found one of them, it was uranium-235, and every time it decays it loses four numbers. You can see, one, two, three, four, and it gets to the end at a mass number of 207. And they looked for another one and they found uranium-238, and it dropped by four each time until it reached 206. And they found thorium, and it dropped by four, until it reached 208. And then there was this one, and nobody could find it. It was the–I don’t know what to call it–it was the other one. The one of the four that was extinct on Earth.
And there was a fellow named Glenn Seaborg who was a famous chemist in California, and this is during the Manhattan Project, and he said, “you know what, I want to find out if we can make something that lives in this chain that nobody’s looked for before.” And so he had a grad student named John Gofman, and he told John Gofman to go and bombard thorium with neutrons. He said, “Let’s see if we can make something that lives in this chain.” And they made uranium-233 from thorium.
And Seaborg, he was a really smart guy. He was very intuitive about how things might work, and he said to Gofman “you know what–let’s go see if uranium-233 will fission. Let’s see if it will split if we hit it with a neutron.” And sure enough, it turns out that it did split. It turns out that you can turn thorium into thorium-233 and then it will decay and ultimately end up as uranium-233.
Now, to most of us non-physicists in the world, this would seem like one of those interesting little facts that doesn’t really make a whole lot of difference. But Glenn Seaborg wasn’t one of these kind of guys. He was a brilliant mind. He was a guy who could see way down the road. And when he figured out that thorium would turn into uranium-233 and fission, and had certain properties, he turned to Gofman and said “we’ve just made a fifty-quadrillion dollar discovery.”
Because the implications of what he’d figured out was that billions of years ago, a supernova that created all the matter that now forms our planet and the solar system and the Sun and everything else, had locked up in the form of thorium a vast amount of energy. A staggering amount of energy, that had been waiting for five billion years for us to figure out what it means and what it can do. And on that day, when Gofman and Seaborg made their realization about the properties of thorium, they opened up a future for us that I think even now we are just beginning to dimly realize.
It’s a future that means that we can have the energy we need to make our society work, literally, for the foreseeable horizon of humanity, millions of years into the future, and it’s based on the fact that uranium-233 and thorium have properties that allow them to be burned indefinitely in reactors that are not terribly dissimilar from the kinds we have now, what a nuclear engineer would call a “thermal-spectrum reactor”. This is a really big deal, but as I said, dimly appreciated; even today, there are few people, even within the nuclear engineering community, that appreciate the implications that Gofman and Seaborg grasped fifty years ago in that laboratory in California.
But back in the Fifties it was a little better grasped than it is now. We had luminaries like Eugene Wigner and Alvin Weinberg who were actively trying to develop thorium reactors that could take advantage of Seaborg’s discovery in order to provide clean and abundant power for society. They actually convinced our government to stockpile thorium–a large stockpile because they saw it being of such important value and strategic to the future of our country, that they were able to convince them to purchase about 3200 tonnes of thorium. Well, many years later we apparently forgot what that thorium was for because we turned around and buried it in the desert of Nevada. Right there is the best thorium mine in the world–3200 tonnes of thorium, buried in a 12-foot deep ditch out at the Nevada Test Site. This picture was taken in 2005; the thorium is in barrels inside those cargo containers. So why should we care about what’s sitting in a ditch in Nevada?
Well, you’re going to get my opinion.