There Has Just Got To Be A Better Way

Anyone who has the lightest familiarity with nuclear power knows that it is impossible to steal fuel from an operating reactor. Even assuming a terrorist knew how to shut it down, there is still the problem of very high level radiation within the reactor core that would be fatal in a matter of minutes for anyone who attempted to break in. (Our brave terrorist - pardon the oxymoron - would find this a very unpleasant way to enter paradise.)

The same goes for hijacking the spent-fuel truck or train on the way to the reprocessing plant. After storage for at least five years at the power plant site, the "spent" fuel is still highly radioactive and thermally quite hot. Hijacking 44,000-pound fuel containers - designed to smash into a concrete wall at 60 mph or fall onto a spike from thirty feet without rupturing - is a bit difficult to do surreptitiously.

This leaves us with raiding the reprocessing plant (bad idea) or stealing the fuel from shipments to the power plant (best bet). Assuming that the militants can make off with a huge truck, monitored as all valuable shipments are with global positioning electronics and probably guarded, and that no one notices this cargo with the huge radioactive symbols all over it, the hijackers must plan ahead to make sure their plutonium reclamation plant is near by. Typically the price tag on such a facility is in the hundreds of millions, or billions of dollars - and, of course, they've got to hide this construction from the prying eyes of swarms of government inspectors looking for something to inspect... or, even more difficult to avoid, the office-supply salesmen in the four surrounding counties.

Assuming the truck is hijacked and taken to the secret $100 million facility, the problems are just starting for our ill-intentioned thieves. Now they must cut up the fuel assemblies and dissolve them in nitric acid. After that, the chemical processes to separate the plutonium from the uranium are devilishly tricky - in part because an almost-certainly fatal criticality accident can occur quite easily when the plutonium is in a liquid form. But let's assume that our "clever" terrorists are successful in refining out the plutonium and have shaped it for a bomb. Two big problems:

The first is obtaining the explosive charges necessary to "implode" a sphere of plutonium in on itself - essentially taking a hollow globe and compressing it down to a golf or tennis-ball-sized solid... well, almost solid. Regular explosive won't work, as the charge must have different characteristics as it "burns" to maintain the shape of the shock wave that is doing the compressing. Then there is the matter of the initiator, or trigger - the device that produces a stream of neutrons to start the reaction inside a one-tenth microsecond envelope when they are needed. This was considered by the Manhattan Project team (approximately 130,000 personnel, including arguably the best physicists and engineers in the world) as one of the most difficult items to design. Polonium 210 and beryllium must be mixed thoroughly - but this must occur within the aforementioned 0.0000001-second time frame. But let's suppose they are able to do all this. Sorry, still no cigar.

For you see, problem two, the plutonium they liberated from the Imperialist Yankee Running Dogs is not suitable for making a decent bomb. Since BWR and PWR reactors "burn" fuel slowly, Pu239 is created not only from the U238, but also from the Pu240 isotope. While not a fissionable isotope (which wouldn't make much difference in small concentrations), it is a spontaneous neutron emitter, which bodes ill for aspiring bomb makers. Even a very small amount of Pu240 is sufficient to throw off the timing of the necessary bomb reaction by starting it before the implosion is complete - causing the bomb to fizzle. Oh, you'll get an explosion of sorts - perhaps sufficient to flatten a city block or two - but not as awful as what you could do with ammonium nitrate and a little fuel oil, a la Oklahoma City. (The 1947 Texas City blast - where 512 were killed - was also a fertilizer explosion, which didn't require any plutonium at all.)

Terrorists are, in my mind, among the most despicable of humankind. But this isn't to say they are stupid. If they want to kill people and spread fear, there are a lot of easier ways to do this, and they know it. Poisoning the water supply, blasting a hole in a dam, setting oil storage facilities afire when the wind is blowing toward a heavily populated area - the list goes on and on. But building a dud bomb from hijacked plutonium isn't one of them.

Energy Sources for the Future - Take Your (Limited) Choices

Fossil fuels will be around as long as mankind, but there is historical reason to believe that they - like whale oil and placer gold - will be diminishing in economically recoverable supplies. "Renewable sources" - such as solar, wind, hydro, tidal, geothermal and chicken manure energies - are frankly just not going to fill the bill when it comes to an industrial economy with billions of people requiring an ever-increasing supply of energy. [For instance, energy-balance calculations reveal that the energy cost of building a solar plant exceeds the energy it is expected to capture and utilize over a forty-year lifetime.]

Fusion, as noted, would be wonderful... if it is possible as a source, and if we have the ability to develop it in the next twenty generations. Which leaves us with one proven source of sufficient energy for the world during the next several millennia: nuclear fission. There are, as far as is known today - and we know quite a bit - only three choices for fissionable materials:

Number 1: Uranium 235. This is the granddad of fission. It naturally occurs as 0.7% of the element found on Earth, and - if economically recoverable supplies are considered - is probably good for powering the world's energy needs for the next century or so. Many observers say forty years, but "Julian Simon's Law" would no doubt govern this commodity also. [Simon, Julian. The Ultimate Resource, Princeton University Press, Princeton, 1996.]

Number 2: Plutonium 239. Easily "bred" from common uranium 238, transmutation of existing stockpiles should last several hundred years at present use rates. But as Dr. Cohen points out in The Nuclear Energy Option, with breeder technology it becomes economical to separate uranium from sea water - where there are some 2 trillion curies - allowing man all the energy he needs until the sun burns out in 4 or 5 billion years.

Number 3: Uranium 233. This is the sleeper. When thorium 232 is exposed to neutrons, as in the transmutation of U238 to Pu239, another miraculous thing happens. Dirt becomes and incredible energy source. As mentioned in chapter 1, the Earth's surface averages 2.5 tons of thorium in the first foot of each square mile of area. The late Dr. Edward Teller was a strong advocate of thorium transmutation using a CANDU-type heavy-water reactor. His design would allow plentiful and inexpensive thorium to be entered in one side of the reactor, converted slowly to U232, which would be fissioned for power, with the "really spent" fuel exiting from the other side months or years later. He calculates this would give earthlings sufficient energy to provide for the next seven ice ages. [Teller is known as the "Father of the H-bomb" - but more accurately described as the defender of the free world from Soviet totalitarianism. See "CANDU Is Really Remarkable," Power Projections, May 1980.]

Add this to Dr. Cohen's four or five billion years, and we're really starting to talk about some time.

Power Reactors

In the United States, power reactors are entirely of the PWR (pressurized water reactor) or the BWR (boiling water reactor) types. In both cases, water is used as the coolant and the moderator, which provides a very interesting advantage that probably no one has bothered to mention to you: If the coolant is lost, the chain reaction stops. Depending on the length of time the fuel has been producing power, the fuel rods may or may not be thermally and radioactively "hot" from the daughters of the fissioning process. Even in the worst case, the heat generated is no more than 1% or 2% of that during normal operation. This is why the "disaster" at Three Mile Island didn't really happen - except in the minds of the uninformed.

While the Japanese installed the first Advanced Boiling Water Reactor (ABWR) in 1996, none of the new, modular designs have seen the light of day in this country. Not only have we been blinded by the non-threat of low-level radiation, but the cost of building a nuclear plant has escalated by a factor of seventeen, after considering inflation - mostly from construction delays caused by environmentalist lawsuits. (The above-mentioned Japanese ABSR plant took fifty-two months to build - compared with more than eleven years for the most recent plant in the United States.) I would say the new designs are even safer than the old - but how do you get safer than no deaths, no injuries, and no negative effects to the public from several thousand reactor years of operation with thousands of gigawatt-hours of life-enhancing electrical energy having been generated? [Some of the media scream "disaster" when ten gallons of water with 1/80 the radioactivity of salad oil leak out in the process of heating and otherwise providing life-giving energy to an entire city. Why doesn't it make front-page news when some one falls off the roof to his death trying to clean the solar collector - which provides a few puny kilowatts of solar energy for warming the hot water... when the sun is shining?]

Nonetheless, neither the PWR or BWR has much promise for miniaturization and "local" use as - by nature - they operate with high-power densities, which have the potential to cause a messy and expensive loss-of-coolant accident. They also require pumps, back-up pumps, and relatively elaborate controls.

All of these U.S. power reactors use enriched uranium as a fuel, as do reactors in France (where 80% of the electrical power comes from nuclear energy), Japan, England, and most other countries. The enrichment process starts with natural uranium, which is dissolved in acid to produce uranium hexafluoride gas. This ultra-corrosive gas is then pumped thousands of times through membranes where the lighter U235 passes through just a little bit easier than the U238. For power reactors, the U235 is enriched from 0.7% to about 3.5%, which takes not only lots of time but considerable energy. ["Bomb grade" U235 must be enriched to 90% - an extremely difficult process. Thank goodness, or any crackpot might be able to do it.)]

Enter the Atom

Let's return for a short graduate course from Hormesis U. about "splitting the atom."

We've already seen that U238 is an isotope of uranium with a half-life of 4.5 billion years. [I realize I said I was going to refer to isotopes in the form of 238U or uranium 238. But U235 and U238 are such commonly used abbreviations to denote these isotopes that I will be using them in this chapter.]

With a lump of this element and the proper instruments, you would find there is another isotope, U235, which amounts to only 0.7% of the total mass. Yet it is this tiny fraction that makes uranium the tremendous source of safe and reliable energy - not to mention the fearful master - that it has become.

U235, like its more plentiful sibling, is an alpha emitter - but has a considerably shorter half-life... a mere 3,800,000 years, meaning that it was considerably more plentiful a billion or so years ago. [U235 is sometimes referred to as "actinium" or "uranoactinium."] It, along with plutonium 239 and U233, are the only isotopes that are fissionable - a phenomenon described below.

Under normal conditions, we can expect to see a U235 atom occasionally decay into an isotope of thorium and a helium nucleus (an alpha particle) similar to all radioactive isotopes experiencing alpha decay. ["Occasionally" takes on a new meaning in the atomic world. Our roughly penny-sized gram of U235 would experience approximately 80,000 nuclear disintegrations per second.]

But let us suppose that a stray neutron smacks into the nucleus of an unsuspecting U235 atom. If the energy of the neutron is within a certain range, our U235 target atom fissions, that is, breaks into pieces. [This was first observed by an unbelieving Lise Meitner in December 1938. She had observed barium, with an atomic number of 56, arising when she bombarded "actinium" with neutrons.]

It usually splits into two roughly equal parts, and most important, ejects about two neutrons. Obviously no atom could eject or emit about two neutrons, but, on average, that is what a fissioning U235 atom sends out of its nucleus.

Imagine, then, one of these neutrons hitting another U235 atom, which emits two neutrons with at least one of these splitting another atom... and so on, and so on. As you have no doubt already figured out, this is what is known as a chain reaction. When the ratio of fissioned atoms in successive generations is equal to one - that is, when one splitting atom causes exactly one more to split - the reaction is said to go critical. What happens to the other neutrons? They either escape from the volume of uranium, or they are absorbed - either unintentionally by structural material, or purposely by control rods made of boron, aluminum, cadmium, or several other neutron-absorbing materials - in order to keep the reaction under control (that is, to keep it from going super-critical). Does a super-critical reaction cause a bomb-like explosion? Not at all; if it did, bomb development by the Manhattan project would have been relatively simple rather than requiring the best theoretical physics minds on two continents. But super-criticality is no picnic. It causes rapid rises in fission reactions, leading to very high temperatures that cause structural damage, torrents of neutrons, and "steam explosions." Bad, yes, but still light years away from the mushroom-shaped cloud.

Let's look at a few different types of reactors, with an eye for those that might allow decentralization of electric power generation.