We hear a great deal these days of something called tritium. We hear that we’re in danger of running out of it because of the closure of plants that manufacture it, and that if we do run out we will not be able to explode our hydrogen-bombs at need. We will be engaging in involuntary unilateral nuclear disarmament.
But what is tritium and why is it necessary? Isn’t the stuff that operates a hydrogen bomb hydrogen? Isn’t that why it’s called a hydrogen bomb?
Yes, but tritium is a form of hydrogen.
Hydrogen comes in three forms. The atoms of ordinary hydrogen consist of a tiny nucleus made up of one proton, with an electron circling it. All hydrogen atoms have exactly one proton in the nucleus, but some have one or two neutrons in addition. A neutron is as heavy as a proton, but does riot affect the chemical nature of the atom.
Thus, an ordinary hydrogen atom, with just a proton in the nucleus, is hydrogen-1. A hydrogen with two particles in its nucleus, a proton and a neutron, is twice as heavy, so it is hydrogen-2. A hydrogen with a proton and two neutrons in the nucleus is three times as heavy, so it is hydrogen-3. Hydro gen-2 is sometimes called deuterium from a Greek word meaning “second” because it is the second of the three hydrogens. Similarly, hydrogen-3 is called “tritium” from the Greek word meaning “third.”
Hydrogen can be made to undergo fusion. Its small atoms can be mashed together under enormous heat and pressure to form larger atoms, releasing vast energies in the process.
Hydrogen-1 fuses with great difficulty. It does so in the sun, but we can’t duplicate the extreme conditions at the sun’s center here on Earth. Hydrogen-2 fuses more easily, and hydrogen-3 fuses most easily of all.
Therefore, if we want a hydrogen bomb, we would want to use hydrogen-2, rather than hydrogen-1, and hydrogen-3 (tritium), most of all — but there’s a catch. Out of every 100,000 atoms of hydrogen that exist on earth, 99,985 are hydrogen-1 and 15 are hydrogen-2. That isn’t too bad. There’s so much hydrogen in the oceans and hydrogen-2 is so easy to separate, we can have tons of it, if we wish. However, hydrogen-2 by itself is still not easy enough to fuse for our purposes. We need at least some hydrogen-3, and that exists in nature only in insignificant traces. It simply cannot be obtained in useful amounts.
Why is that? Hydrogen-1 and hydrogen-2 are stable. They will retain their identity for eons. Hydrogen-3, however, is radioactive. It breaks down into helium-3 (which is virtually useless in fusion reactions) at such a rate that in 12½ years, half of any amount of tritium has decayed away. Any tritium that once existed on earth in times past is therefore long gone. The only reason that even traces exist today is that some atoms of tritium are constantly being formed in the atmosphere by cosmic rays.
Scientists, however, learned how to make tritium themselves by means of certain nuclear reactions, and huge plants were built-in which those nuclear reactions could be carried out. Not enough tritium is formed to make hydrogen bombs of tritium only, but enough can be formed so that a little tritium can be added to deuterium to act as a detonator, to get fusion started. The heat of the initial fusion will keep things going in the rest of the deuterium.
But the tritium-making plants must remain in operation for as long as we want to have hydrogen bombs, for the tritium they make steadily decays, and there’s nothing we can do about that. We must form tritium at the same rate that it decays so that we always have enough for our hydrogen bomb arsenal. The trouble is that the tritium-making plants are old, obsolete and unsafe; they leak radioactivity into the environment; and they form radioactive wastes that have been disposed off carelessly. For years, this has been kept secret and nothing important was done about it — a matter of US national security.
The secret has leaked out, however, and people object to being exposed to radiation poisoning, to cancer, birth defects and death, even for the sake of “national security”. The tritium-making plants have therefore been shut down. To repair them and make them even minimally safe will cost many billions of dollars and many years of time. To build new and better plants may take even more money and more years. Meanwhile the tritium we have is slowly breaking down, and that’s the situation we’re in.
Why weren’t the plants kept in repair replaced bit by bit, in the course of time? We presume because the government had other things it would rather spend the money on, and that it could always hide the flaws and dangers of the situation behind the smoke screen of “national security”.
It’s depressing. How many other flaws, how many other causes of ruin, does the US Government hide with the cry of “national security”?
Photo by Teravolt at English Wikipedia, CC BY 3.0, Link