Thorium: Wired Magazine Muddies the Water

Glenn Reynolds at Instapundit recently linked to an article by Richard Martin in Wired Magazine entitled, ‘Uranium is so Last Century:  Enter Thorium, the New Green Nuke.”  I cringed when I read it.  I suspect serious advocates of thorium did as well.  It was a piece of scientific wowserism of a sort that has been the bane of nuclear power in the past, and that its advocates would do well to steer clear of in the future.  It evoked a romantic world of thorium “revolutionaries” doing battle with the dinosaurs of conventional nuclear power.  Things aren’t quite that black and white in the real world.  Thorium breeders deserve fair consideration, not hype, as does nuclear power in general.  There are many good reasons to prefer it to its alternatives as a source of energy.  It doesn’t take a genius to understand those reasons, assuming one approaches the subject with a mind that isn’t made up in advance, and is willing to devote a reasonable amount of time to acquire a basic understanding of the technology.  Martin would be well advised to do so before writing his next article on the subject. 

In the first place, thorium is not a replacement for uranium, as implied by the title of the Wired article.  Rather, the point of putting it in nuclear reactors is to breed uranium, which remains the actual fuel material, albeit in the form of isotope U233 rather than U235.  Thus, when Martin writes things like,

Those technologies are still based on uranium, however, and will be beset by the same problems that have dogged the nuclear industry since the 1960s. It is only thorium… that can move the country toward a new era of safe, clean, affordable energy.

in comparing thorium reactors to their more conventional alternatives, it is evident he doesn’t know what he is talking about.  Referring to the physicist Alvin Weinberg, he tells us,

Weinberg and his men proved the efficacy of thorium reactors in hundreds of tests at Oak Ridge from the ’50s through the early ’70s. But thorium hit a dead end. Locked in a struggle with a nuclear- armed Soviet Union, the US government in the ’60s chose to build uranium-fueled reactors — in part because they produce plutonium that can be refined into weapons-grade material. The course of the nuclear industry was set for the next four decades, and thorium power became one of the great what-if technologies of the 20th century.

With all due respect to Weinberg, a brilliant scientist whose work remains as relevant to conventional reactors as to their thorium cousins, this picture of thorium knights in shining armor doing battle with the dark forces of the nuclear weapons establishment is certainly romantic, but it leaves out some rather salient facts.  In the first place, conventional power reactors do not even produce weapons grade plutonium, which contains a high concentration of plutonium 239.  Special reactors that run for a much shorter period of time are used for that purpose.    Furthermore, thorium is not a nuclear fuel.  A reactor using thorium alone would never work because thorium is not a fissile material.  In other words, unlike, for example, uranium 235 or plutonium 239, it cannot sustain a nuclear chain reaction.  The point of putting it in nuclear reactors is to breed uranium 233, another isotope that is fissile.  We began producing nuclear power with conventional nuclear reactors based on uranium 235 rather than thorium breeders because of their simplicity, not because of their usefulness as sources of bomb material.  The fuel needed to run them is available in nature as one of the isotopes in mined uranium, and doesn’t depend on a complex breeding cycle for its production.  There are other drawbacks to thorium breeders that Martin doesn’t mention in his article.  For example, in addition to uranium 233, they produce significant quantities of uranium 232, a short lived isotope with some nasty, highly radioactive daughters.  Separating it from U233 was out of the question, and its presence makes the production and handling of nuclear fuel elements a great deal more difficult. 

I’m certainly no opponent of thorium breeders.  In fact, I think we should be aggressively developing the technology.  However, before writing articles about the subject, it can’t hurt to have some idea what you’re talking about.  There are no lack of good articles about the subject on the Web within easy reach of anyone who can use Google.

The Iranian Bomb: Guessing the Date

According to the latest estimate by Israeli intelligence, Iran is capable of building a bomb by 2011. These estimates always beg the question of what kind of bomb one is talking about. In fact, Iran will have a perfectly adequate bomb or, more accurately, nuclear device, the moment it has enough bomb grade plutonium or uranium to assemble a critical mass. In the first place, it does not take a great deal of technical finesse to build a gun assembled atomic bomb. In the second, Iran needn’t bother, because, if she were really determined to carry out a nuclear attack, something much more crude would be more attractive from her point of view. By “crude” I mean, for example, a suicide bomber equipped with two subcritical masses that, when combined, would form a critical mass. This could be done by dropping one subcritical mass on top of another, or simply slapping them together. Unlike something as sophisticated as the device dropped on Hiroshima, such a “bomb” would preserve plausible denial for Iran. Even if the material could be traced to one of her reactors, she could claim that it had been stolen or diverted by terrorists. If assembled in the middle of a large city, it may not produce the familiar mushroom cloud, but it would certainly produce a radioactive mess that would inspire terror, likely cost billions to clean up, be much less likely to provoke nuclear retaliation than a high yield bomb, and spare Iran immediate relegation to the status of an international pariah for having once again unleashed the nuclear genie, committing mass murder in the process.

In a word, once Iran has sufficient special nuclear material to make a bomb, it will no longer be necessary to speculate about how long it will take her to build one. She will have the “bomb” the moment she has enough material to assemble a critical mass.

Jon Kyl and the Resumption of Nuclear Testing

In a recent article in the Wall Street Journal, Arizona Senator Jon Kyl called for a resumption of nuclear testing. Such a step would be both unnecessary and a potentially disastrous threat to our national security.

I am no pacifist, and I favor maintaining a strong and credible nuclear deterrent. It is for that very reason that I oppose a resumption of nuclear testing. It would in no way strengthen us. Rather, it would promote nuclear proliferation and result in a weakening of the nuclear posture of the United States vis-à-vis its potential nuclear armed opponents.

Obviously, Senator Kyl has heard some of these arguments, but they somehow don’t seem to sink in. He notes in his article that, “There’s a related theory, which is that the U.S. has to ratify the CTBT if it wants to have any credibility or leadership on nonproliferation,” but then dismisses these arguments with the claim that, “Aside from the fact that countries will act in their best interest whether or not the U.S. ‘leads’ them, no one can legitimately question U.S. commitment on proliferation issues.” I, for one, would question the U.S. commitment on proliferation issues if we resumed testing, whether Kyl considered it legitimate or not, and I would hardly be alone in that conclusion. Beyond that, his assertion that other countries will act in their own best interests ignores the reality that the actions of the United States can have a substantial bearing on what those best interests happen to be, particularly in matters relating to nuclear proliferation. Take, for example, Iran. If she tests a nuclear device after her oft-repeated denial of any desire to do so, she will become an international pariah, and likely subject herself to severe economic sanctions. She will also provide moral backing to those in Israel and the United States who advocate an attack on her nuclear facilities, greatly increasing the chances that one will occur. However, if she tested a nuclear device after the United States had resumed testing its own weapons, she could and would portray it as a legitimate act that had been forced on her by the actions of her enemies. The idea that the path chosen by the United States would have “no bearing” on her national interests is absurd.

Kyl cites the danger that clandestine nuclear tests cannot be verified and other nations will be able to test on the sly. To “prove” this dubious assertion, he notes that monitoring systems “failed to collect necessary radioactive gases and particulates to prove that a test had occurred” following the latest test by North Korea. In fact, seismic devices did detect it, in spite of the fact that its estimated yield was only a few kilotons. I have heard no credible argument to the effect that major nuclear powers could substantially enhance the power of their arsenals vis-à-vis the United States with clandestine tests that had a significant chance of going undetected. If anyone who actually knows what they’re talking about cares to make such an argument, let them put their cards on the table.

The part of Kyl’s argument that is likely to carry the most weight is the contention that there are serious concerns about the aging and reliability of our arsenal. To bolster his argument, he cites the testimony of C. Paul Robinson, former Director of Sandia National Laboratories, before the House Armed Services Committee last year. In fact, this testimony is very interesting in its own right, and, among other things has a direct bearing on the issue of the Reliable Replacement Warhead (RRW), which was promoted by the Bush Administration, but wisely rejected by Congress. It’s exactly what one might have expected to hear from a weaponeer at Los Alamos if one were transported back in time to the 1970’s or 80’s. In fact, that’s exactly what Robinson was at the time. In those days, the suggestion that a substantially new weapon could become part of the arsenal without previous testing would never have passed the “ho-ho” test.

Referring to his position on nuclear testing at the time that the Stockpile Stewardship program was first formulated in the early 90’s, Robinson said,

I will repeat only a few of the words that most of us with responsibilities for U.S. warheads said at the time—e.g. that “there is no precedent for such complex technological devices to be depended on unless they were periodically tested” and that “fielding of first-of-a-kind new devices without testing would be the most stressful challenge.”

Note the direct reference to a “first-of-a-kind” device here. The only such device anyone has seriously discussed building since the end of testing in 1992 is the RRW. Robinson goes on,

But in other areas we are just as uncertain today. My belief is that most weapons designers have less confidence about making changes to their designs than they had in the past. I particularly found the recent colloquy between the JASON group and the lab designers most curious —as they each speculated over the difficulties of fielding designs under the contemplated Reliable Replacement Weapon (RRW) effort. Although you will doubtless find a spectrum of views at the labs, my take is that uncertainties will necessarily (and quite naturally) grow over time for several of our systems.

Here again, although he speaks of other systems in general, Robinson specifically refers to the RRW as a system that it will be particularly problematic to introduce to the arsenal without testing. It is the only one he could be referring to when he cites the concerns of weapons designers about “making changes to their designs.” In spite of this, after an interesting bit on the genesis of the RRW concept, Robinson makes a remarkable intellectual double back flip a few sentences later:

After some discussion, the key idea of the RRW then emerged —that if we incorporated designs of “different genetic diversity” in each leg of the TRIAD, there would be a much lowered likelihood that all would fail at the same time from a common problem. Yet from what I’ve read, the Congressional support for the idea has been less than lukewarm —as evidenced by your canceling of the RRW funding, with some suggesting that the labs might be trying to “create new designs that would necessitate underground testing” in order to field the RRW. I assure you that this suggestion is just not true. RRW was conceived to lessen the likelihood that testing would be needed. At the very least I must conclude that “there has been a significant failure to communicate”, and I believe we must not let such misunderstandings perpetuate, when there is so much at stake.

This remarkable juxtaposition of the contradictory assertions that 1) new designs must be tested, but 2) the RRW will reduce the need for testing, is difficult to explain as other than a variant of Orwellian “doublethink” inspired by the need to stay “on message” on both the need to build the RRW and the necessity of resuming testing. In other words, Robinson and some of his fellow weaponeers at the National Labs want to have their cake and eat it too.

As is abundantly clear from Kyl’s article, there is no lack of people, both inside and outside the weapons labs, who want to resume nuclear testing. Trust me, if the RRW is built, it will result in a ratcheting up of the pressure to do so many fold. This is one of those rare instances when Congress actually got it right. Let’s forget about the RRW.

What, then, of the general assertion that testing is required because “concerns about aging and reliability have only grown?” In fact, if we stop hankering after the RRW and devote our attention to maintaining the weapons we already have, there is no credible reason to believe that they will not work as advertised. Let those who would maintain otherwise drop their vague assertions, put their cards on the table, and explain exactly what failure modes they are referring to. The weapons in our arsenal are robust, and any opponent who assumed otherwise would be making a very disastrous mistake.

Assuming, then, that we can really dismiss the negative political effects of resuming nuclear testing as Senator Kyl does with a cavalier wave of the hand, what would be the advantages of doing so? Surely, if we took the lead, the other nuclear powers would resume testing as well. The science of nuclear weapons has reached a high level of maturity in both the United States and Russia. It is much more likely that a resumption of testing will enable countries that have joined the nuclear club more recently to substantially improve their weapons designs than it will countries that have already developed highly sophisticated weapons. At the same time, it will negate the vast advantage we currently hold in possessing by far the most capable experimental facilities for validating nuclear weapons physics of any nation on earth. The experimental assets represented by Z facility at Sandia, the National Ignition Facility at Livermore, and a host of others give us a major leg up over the rest of the world in approaching the conditions that exist in nuclear weapons and investigating the relevant physics. When combined with our superiority in supercomputing power, they insure us a decisive advantage that it would be positively foolhardy for us to cast away with a resumption of testing.

Why then, the persistent pressure to resume testing? Once can only speculate. In Senator Kyl’s case, perhaps the increasing unsuitability of the Nevada Test Site as Las Vegas continues to sprawl in its direction may play a role. There are attractive alternative sites in his own state of Arizona that could potentially create many new jobs. As for the weapons designers, their lives were a lot more interesting during the era of nuclear testing. I suspect many of them would prefer a return to those “golden days of yesteryear” to their current role as custodians of an aging stockpile. These, however, are considerations that should not and cannot be allowed to play any role in our decision to resume testing or not.

Our weapons are reliable, and can be maintained with confidence. Let us preserve our advantage, and refrain from foolishly throwing it away with a resumption of nuclear testing.

Nuclear Strategery

Jonathan Tepperman has an interesting post on the Newsweek site entitled, “Why Obama should Learn to Love the Bomb.” According to Tepperman, “A growing and compelling body of research suggests that nuclear weapons may not, in fact, make the world more dangerous, as Obama and most people assume.” Yes, and there was “a growing and compelling body of research” in 1914 that suggested the great powers were so economically dependent on each other they would never risk going to war. Tepperman continues, “The argument that nuclear weapons can be agents of peace as well as destruction rests on two deceptively simple observations. First, nuclear weapons have not been used since 1945. Second, there’s never been a nuclear, or even a nonnuclear, war between two states that possess them.” That’s true, and the argument that possession of nuclear weapons reduces the chances of war between states that possess them is certainly plausible. However, the fact that, for example, there was never a nuclear exchange between the United States and the Soviet Union does not mean that the risk of such an exchange was zero. It is more likely that we dodged a bullet.

An all out conventional war between India and Pakistan would certainly result in great loss of life. An all out nuclear war would be, according to Tepperman, less likely. It would also be more costly in terms of loss of life, not to mention economic damage. Perhaps, then, a reasonable metric for assessing whether nuclear weapons make us more or less secure would be risk of war times likely human and economic cost. The problem with such a neat formula is that it would be impossible to predict or to agree on the magnitude of the different factors. For example, it was widely assumed during the cold war that a general nuclear exchange would result in the annihilation of the populations of the US and Soviet Union. However, I doubt the leaders on either side really believed that. Various attempts were made to calculate likely outcomes, but they were generally flawed by the ideological predispositions of those making the estimates.

Let’s consider what else Tepperman has to say:

Even the craziest tin-pot dictator is forced to accept that war with a nuclear state is unwinnable and thus not worth the effort. As (Berkeley Professor Kenneth) Waltz puts it, “Why fight if you can’t win and might lose everything?”

I’m not so sure that the craziest tin-pot dictator would come to such a logical conclusion. However, the statement as it stands is almost irrelevant. I suspect a nuclear exchange is far more likely to result from a miscalculation, accident, or loss of control to a rogue actor than any premeditated, deliberate attack.

Meanwhile, the nuclear powers have scrupulously avoided direct combat, and there’s very good reason to think they always will. There have been some near misses, but a close look at these cases is fundamentally reassuring—because in each instance, very different leaders all came to the same safe conclusion.

This is wrong on the face of it. Always is a long time. As long as there are nuclear weapons, there will be a finite risk of a nuclear exchange. Therefore, if states with nuclear arsenals continue to exist into the indefinite future, there will eventually be a nuclear exchange. The question is not whether it will happen, because it certainly will. The question is whether its cost, when it does happen, will be greater or less than the cost of the, presumably more frequent, conventional wars that would have occurred in the absence of nuclear arsenals. Similarly, as long as sufficient special nuclear material (SNM), such as U235 or Pu239, exists to make nuclear weapons, there will be a finite risk of it falling into the hands of non-state actors, or terrorists if you will. From this we must conclude that a terrorist nuclear attack is also inevitable. It is not a question of if. It is a question of when. It may be tomorrow, or it may be a thousand years from now, but it will happen. I rather suspect it will be sooner rather than later.

…in 1957, Mao blithely declared that a nuclear war with America wouldn’t be so bad because even “if half of mankind died … the whole world would become socialist.” Pyongyang and Tehran support terrorism—but so did Moscow and Beijing. And as for seeming suicidal, Michael Desch of the University of Notre Dame points out that Stalin and Mao are the real record holders here: both were responsible for the deaths of some 20 million of their own citizens. Yet when push came to shove, their regimes balked at nuclear suicide, and so would today’s international bogeymen.

That is an unwarranted assumption. In any case, as noted above, it is irrelevant, because the nuclear danger from accident or miscalculation is far greater than that from deliberate use.

Even if the Pakistani state did collapse entirely—the nightmare scenario—the chance of a Taliban bomb would still be remote. Desch argues that the idea that terrorists “could use these weapons radically underestimates the difficulty of actually operating a modern nuclear arsenal. These things need constant maintenance and they’re very easy to disable. So the idea that these things could be stuffed into a gunnysack and smuggled across the Rio Grande is preposterous.

Here, Tepperman’s “expert,” Michael Desch of Notre Dame, doesn’t know what he’s talking about. One wonders what sort of “constant maintenance” he has in mind. The basic design principles of both gun and implosion type weapons are well known. They certainly require maintenance occasionally, but “constant maintenance?” I think not. Any non-state actor gaining possession of an intact nuke will have plenty of time to use it. The idea that nukes are easy to disable is also poppycock. You can make the firing set as clever as you please, but the SNM would still be there. If you didn’t have an explosives guy capable of jury rigging the device, you could still simply cannibalize the material from two nukes and make a simple, but very effective device. Recall that our physicists were so confident that the gun type Little Boy would work that it was dropped without prior testing. The computer modeling tools available to anyone now are infinitely better than the rudimentary mathematical tools they had then. Building a crude bomb is simply not that difficult. As for smuggling the weapon in a gunnysack, Tepperman is right. A terrorist would have to be brain dead to even attempt it. Unfortunately, smuggling a complete weapon is completely unnecessary. It would be much simpler, and just as effective, to smuggle the SNM in small bits, and assemble it into a weapon at the target. The chances that we will be able to detect any of the material before the weapon actually goes off are virtually nil.

The risk of an arms race—with, say, other Persian Gulf states rushing to build a bomb after Iran got one—is a bit harder to dispel. Once again, however, history is instructive. “In 64 years, the most nuclear-weapons states we’ve ever had is 12,” says Waltz. “Now with North Korea we’re at nine. That’s not proliferation; that’s spread at glacial pace.” Nuclear weapons are so controversial and expensive that only countries that deem them absolutely critical to their survival go through the extreme trouble of acquiring them. That’s why South Africa, Ukraine, Belarus, and Kazakhstan voluntarily gave theirs up in the early ’90s, and why other countries like Brazil and Argentina dropped nascent programs.

Perhaps. However, I do not find the existence of a maximum of 12 nuclear states as comforting as Tepperman.

Put this all together and nuclear weapons start to seem a lot less frightening. So why have so few people in Washington recognized this? Most of us suffer from what Desch calls a nuclear phobia, an irrational fear that’s grounded in good evidence—nuclear weapons are terrifying—but that keeps us from making clear, coldblooded calculations about just how dangerous possessing them actually is. The logic of nuclear peace rests on a scary bargain: you accept a small chance that something extremely bad will happen in exchange for a much bigger chance that something very bad—conventional war—won’t happen. This may well be a rational bet to take, especially if that first risk is very small indeed. But it’s a tough case to make to the public.

Here, Tepperman makes some good points. The real issue is one of risk. Unfortunately, for the reasons cited above, I rather suspect he is seriously underestimating it. Be that as it may, assuming one can really get a good handle on the actual risk, what he says makes sense.

Given this reality, Washington would be wiser to focus on making the world we actually live in—the nuclear world—safer. This involves several steps, few of which the Obama administration has mentioned but which it should emphasize in its Nuclear Posture Review due at the end of the year. To start, the logic of deterrence works only if everybody knows who has a nuclear arsenal and thus can’t be attacked—as Peter Sellers puts it in Stanley Kubrick’s Dr. Strangelove, “The whole point of a Doomsday Machine is lost if you keep it a secret!”

Probably true. Unilateral nuclear disarmament would certainly be suicidal. Reducing our arsenal to the point that potential enemies might find the risk of retaliation acceptable is almost equally so.

Chris Bodenner at Sully’s blog thinks a piece by Peter Scoblic at TNR’s website “scalpels” Tepperman’s piece. I think not. It’s more in the pious platitude here, anecdotal evidence there, preaching a foregone conclusion to the choir style that has become the stock in trade at TNR lately. They have seen better days (when Sully was editor, in fact. He has seen better days, too). One hopes the better days will return.

Nuclear Power: Thoughts on Thorium

Rod Adams has an interesting post on thorium power over at Atomic Insights. I tend to think that nuclear power is more environmentally benign than the alternatives, such as paving thousands of square kilometers of our environmentally fragile desert southwest with solar collectors. If we do restart the nuclear industry, it will also make a lot more sense to build breeders of the type mentioned in Rod’s post, which produce more fuel than they consume during operation, than to just burn up all the uranium 235 we can find in natural uranium.

There are two basic breeder reactor fuel cycles. In the first, uranium 238, which makes up 99.3% of natural uranium, is converted to plutonium 239. In the second thorium 232, which is more abundant than natural uranium, is converted to uranium 233. Both are fissile reactor fuels. Both can also be used to make nuclear weapons. If we breed either of these isotopes, it is essential that we be sure of one thing; that they never fall into the wrong hands, either now or in 10,000 years from now. For that reason, it seems to me that thorium breeders are the better of the two options.

As noted above, both types of breeders would produce fissile material that could be used to make a bomb. In both cases, the material could be separated from spent fuel using relatively straightforward chemical methods. However, spent reactor fuel remains highly radioactive for many years after it is removed from a reactor core. It would be lethal to work with without highly specialized equipment unlikely to be available to other than technically advanced states. In the case of thorium breeders, however, the fissile uranium 233 would be contaminated with uranium 232, a short-lived, highly radioactive isotope that could not be separated from the U233, making it even more difficult to work with than plutonium.

In both cases, the levels of radioactivity of the spent fuel would decay exponentially over time, gradually making it easier to handle the material. Eventually, it would become possible for non-state actors to separate the bomb-grade material. It is immaterial whether this happens in a thousand years, or ten thousand years. We cannot simply put such material in a nuclear storage facility and leave it for future generations to deal with. In the case of plutonium, the only way to reliably eliminate it, other than, perhaps, rocketing it into the sun, would be to burn all of it up. However, in the case of U233, it could be “denatured” by mixing it with large amounts of non-fissile U238, rendering it, for all practical purposes, as difficult to convert to a weapon as natural uranium.

Rapid Response to Terrorist Nuclear Attack

I wish I were seeing a lot more articles like this one (hat tip Instapundit) that appeared in New Scientist, concerning preparedness for a terrorist attack with homemade nuclear weapons. I also wish the political powers that be would take them seriously. The nuclear attacks on Japan were not an historical anomaly. Nuclear weapons will be used again. The only question is when. “When” may well be when terrorists with the will to launch a nuclear attack acquire enough of the special nuclear material, in the form of plutonium or uranium, necessary to make a bomb. Once they have it, it is certain they will be able to make an effective nuclear device. The only question is how effective. On the low end of the spectrum, they could make a super dirty bomb by simply assembling a critical mass. On the high end, they could build a device with an explosive yield equal to or greater than that of the weapon dropped on Hiroshima. Regardless, when an attack occurs, we should be prepared to act swiftly and effectively, because thousands or tens of thousands of lives may be hanging in the balance.

Many of those whose lives could be saved by an effective rapid response will be those suffering from radiation poisoning. The effects of radiation poisoning are described here, and additional information on effects, symptoms, treatment, etc., may be found here, here and here. Note that death from radiation poisoning usually occurs because radiation damage renders our cells incapable of reproducing. This is especially critical in the case of cells that normally reproduce rapidly, such as white blood cells, or the cells lining our gut. If they are unable to reproduce, the number of these cells in our body may become depleted, typically in a matter of a few weeks, to the point that we succumb to infection and other secondary effects of their loss. As noted here, without treatment, “Total body exposure of 400 roentgens (or 4 Gy) causes radiation sickness and death in half the individuals.” However, the effectiveness of the techniques we have developed to treat radiation poisoning has increased very substantially in the last few decades. Using these techniques, victims might be stabilized and kept alive during the few critical weeks needed for their cells to recover the ability to reproduce. A great many of those who would have died could be saved. Related information may be found in the links noted above, as well as here, and much additional information may be found on the web. In short, if we respond effectively, we will be able to save a great many lives of those who would have been written off as hopeless cases 20 years ago. We must be prepared.

Good people are working on these problems in government agencies, universities, technical societies, etc. We need to listen to them, recognize the urgency of the problem, take action, and be ready.

Plutonium and the Return to Nuclear Power

I’m on board when it comes to restarting the nuclear industry – with reservations. What’s not to like? No carbon footprint. Less release of dangerous radionuclides into the atmosphere than coal plants. No need to pave thousands of square miles of environmentally fragile desert with solar collectors, windmills, and similar “environmentally friendly” and “sustainable” energy sources.

There is one big potential problem, though. When you burn uranium in a conventional nuclear reactor, you breed plutonium. The spent fuel rods currently stored on site at every nuclear plant in the country are laced with the stuff. You don’t need fancy centrifuges or gas diffusion plants to separate the plutonium. Any reasonably skilled chemist could do it. Once you’ve separated the plutonium, you have the one key ingredient you need to make a nuclear weapon. Oh, I know, it won’t be weapons grade plutonium, but no matter. The United States conducted a successful nuclear test with reactor grade plutonium.

Why, you ask, haven’t terrorists already stolen a batch of fuel rods if it’s so simple. Well, at the moment, the problem is that they’re so highly radioactive that bad actors would probably fry themselves before they could do any damage. They won’t stay that way, though. The radionuclides that make fuel rods so “hot” when it comes to emitting radiation have a certain half life. They decay, and become less radioactive at an exponential rate. At some point, they will become safe enough to handle, even without specialized equipment. The exact time will depend on the material configuration of the fuel rods when they were produced, and the degree of risk the person handling them is willing to take. True, we’re probably talking hundreds or thousands of years in the future, but beyond what date can we ignore the welfare of future generations? When does it become OK to subject them to the risk of nuclear annihilation?

Fortunately, there are solutions to the problem. One is fuel recycling, in which the plutonium from spent rods would be extracted and recycled into new fuel rods. An even better one is building breeder reactors to go along with the recycling. The problem with conventional reactors is that they use up the U235 in natural uranium as fuel. Unfortunately, only seven tenths of one percent of natural uranium is isotope 235, and the rest is 238. Depleted uranium is mostly U238, being what’s left over when the U235 is separated.

With breeder reactors, the U238 can be gradually converted into plutonium 239, a reactor fuel. In that way, a much greater percentage of the natural uranium could be converted to energy, greatly extending the time available to us for figuring out what to do when that fuel supply runs out. Alternatively, thorium, which can be converted into U233, another fissile material, could be used in the breeders. U233 has the very significant advantage of not being chemically separable from other uranium isotopes, and would, therefore be much more difficult to weaponize than plutonium.

Plutonium-based energy production is not benign. It would require tight security standards at every step along the fuel chain. But, then again, no known method of producing energy is benign, including the “environmentally friendly” ones noted above. If the choice were mine to make, I think I would agree with the guys over at Atomic Insights.

Meanwhile, it strikes me as a little crazy that we are gratuitously pumping potentially energy rich depleted uranium slugs out of the barrels of gatling guns. If we really start running out of energy, others might notice there are better uses for the stuff as well.

Nuclear Terrorism and Nuclear Smuggling: Will Portal Radiation Detectors Save Us?

Well, no. Not if you’re talking about interdicting a nuclear weapon or its components. The syllogism works like this: 1) Anyone with enough Special Nuclear Material (SNM) to assemble a bomb would have to be brain dead to try to tote it through a radiation portal. 2) Anyone clever enough to acquire enough SNM to make a bomb is not brain dead. 3) Therefore, anyone with enough SNM to make a bomb will not attempt to carry it through a radiation portal. (Apropos SNM, the image to the left shows a guy holding a plutonium “button.” He probably wouldn’t do that if it were radioactive enough to kill him outright.)

The location of radiation portals and their approximate performance parameters are easily accessible to potential nuclear smugglers at any of a host of “intelligence” websites online. The question then becomes, can they avoid passing them? Of course! How many of the millions of illegal immigrants currently in the country do you suppose passed through radiation portals? There are a virtually infinite number of ways to smuggle SNM into the country that don’t involve passing through radiation detectors, ranging from slingshots to personal submarines. The unclassified amounts of SNM deemed sufficient for a nuclear explosive device are 25 kilograms of highly enriched uranium, or 4 kilograms of weapons grade plutonium. However, there’s no need whatsoever to smuggle such large quantities all at once. Terrorists could “smuggle by components.” In other words, they could simply smuggle the SNM into the country bit by bit until they had enough for a weapon.

By the way, dear reader, if you are one of those whose tastes run to calculating how much SNM it would “really” take to make a bomb, here’s some advice for you: Don’t do it! In general, don’t try to impress everyone with how clever you are by speculating on the design details of nuclear weapons. You will take yourself right out of the dialogue, because anyone who really knows anything about such matters is liable to have a “Q” security clearance, and, according to DOE guidelines, will be unable to comment on whatever brilliant conclusions you’ve come to on the subject.

In fact, it is absolutely unnecessary to wander into classified territory in discussions of nuclear terrorism, or at least into the classified territory relating to the design of nuclear weapons. Once upon a time, the National Weapons Laboratories and others used to (and maybe still do) come up with silly menageries of “threat objects” to “help” the radiation portal operators focus in on what to look for. Of course, the radiation signature of such “threat objects” can vary over a wide range depending on what kind of shielding and other objects surround it, and even in which direction the “threat object” is pointing when it passes through the portal. Other than that, there are an infinite variety of potentially lethal weapon configurations that are quite different from those in whatever menagerie you happen to consult.

Look, the “threat object” is SNM. That’s what terrorists have to have to assemble a nuclear device, and that’s what you have to look for, period. Do they have to smuggle it in 4 kg or 25 kg chunks? No! Depending on how patient they are, they can smuggle in bits as small as they please, and then assemble them at the target. Would it be hard for them to assemble a weapon at the target. Well, much has been said about the great technical virtuosity terrorists must have to assemble a nuclear weapon. Here’s the reality:

1. Take two chunks of SNM, well separated, that, when combined, form a critical mass.
2. Put one of the chunks on the ground.
3. Climb up a medium size step ladder with the other chunk.
4. Take careful aim.
5. Drop the chunk you’re carrying on top of the other chunk.

Not exactly rocket science, is it? Now, this admittedly rather crude nuclear weapon isn’t going to outperform Fat Man, but, before the critical mass you’ve just created disassembles because of its own energy release, it will create a radioactive mess, paralyze all economic activity for a while in the surrounding area, and have a huge psychological impact. That may be just the result that potential terrorists have in mind. Why sacrifice the good will of potential sympathizers and collaborators by vaporizing hundreds of thousands of people? Why risk getting caught with the SNM while you try to figure out how to put together a high yield weapon? Furthermore, to assemble such a weapon at the target, you don’t have to bring in all the SNM at once. You can transport it in arbitrarily small chunks.

In a word, anyone who gains possession of SNM to begin with will not be deterred or stopped by radiation portals. In the first place, there’s no need whatsoever for them to go through the portal to begin with. However, if they insist on taking risks, they can spoof the radiation detectors by surrounding the SNM with appropriate shielding, or putting it next to a medical radioisotope or other innocent radiating material, or the SNM can be carried through in small enough bits to avoid detection.

The ineffectiveness of radiation portals will become increasingly obvious as more and more nuclear smugglers are caught. I an not aware of a single incident to date in which SNM smugglers were stopped by radiation detectors. The ones that have been caught tend not to be top drawer professional smugglers, but unsophisticated crooks who happened to have access for one reason or another. They were stopped, not by radiation detectors, but by good intelligence and police work. I suspect this pattern will continue into the future.

Does all this mean that all our attempts to detect illicit radioactive materials are a waste of time and money? I think not. In the first place, SNM is not the only kind of radioactive material the portals can detect. They have successfully detected scrap metal contaminated with radioactive waste, commercial radioisotopes without proper documentation, etc. As we build more of them, and devote more funding to their development, radiation detectors will become better and cheaper, perhaps to the point that a more effective detection strategy becomes feasible. Then, of course, there is a political side of the question to consider. If a smuggled nuclear device really does go off in a US city, how would you assess the chances of reelection of an Administration that had made a deliberate decision to discontinue funding of radiation portals?

The North Korean Nuke: Design for Delivery?

North and South Korea at Night

“If they had gone with the “fail safe” WWII design, it would probably mean it was too heavy to mount on a missile. They would be making a political bomb that would undoubtedly use a lot of high explosive to ensure it got a good compression of the plutonium pit. The 4 KT bomb, however, might very well fit on a DPRK missile. If they have stayed with this design, it probably indicates that weaponizing it is even more important than ensuring a successful test.”

Here’s something appeared in the UK’s “Guardian” a year ago that adds plausibility to that conjecture:

“Blueprints for a sophisticated and compact nuclear warhead have been found in the computers of the world’s most notorious nuclear-smuggling racket, according to a leading US researcher.

“The digital designs, found in heavily encrypted computer files in Switzerland, are believed to be in the possession of the US authorities and of the International Atomic Energy Agency, in Vienna, but investigators fear they could have been extensively copied and sold to “rogue” states via the nuclear black market.

“David Albright, a physicist, former UN weapons inspector and authority on the nuclear smuggling ring run by the Pakistani metallurgist Abdul Qadeer Khan, said the “construction plans” included previously undisclosed designs for a compact warhead that could fit on Iran’s (or North Korea’s, ed.) medium-range ballistic missiles.”

Read the whole thing. It begs the question of how we should respond if the North Korean leadership really is crazy enough to hit us, or one of our allies, with a weaponized nuke. Annihilate a population of slaves for the crimes of their leaders? We were ready to do that in the Cold War. Twenty years later, do we still really need to kill 10 or 20 million innocent Koreans to “make an example?” I’d hate to have to make that decision, because the answer may be yes.

Iran, Nuclear Weapons, and the “Hiroshima Fallacy”

A while back, I posted an article over at Davids Medienkritik about the “Hiroshima fallacy,” the notion that an effective nuclear weapon must necessarily have a yield approaching that of the device dropped on Hiroshima. This assumption is, of course, absurd. For example, all a terrorist needs to do to have a highly effective nuclear device is to drop one chunk of fissile material on top of another to form a critical mass. Whether it explodes or not is a moot point. It will certainly produce a radioactive mess, likely to cost millions if not billions to decontaminate. A few bloggers noticed (for example, here and here), but, in general, outside of a few people who know better, when it comes to nuclear proliferation, the world continues to keep its collective head deeply buried in the sand.

According to the conventional wisdom, a nuclear weapon is an extremely complicated device, requiring technological and scientific skill, not to mention economic infrastructure, only available to a nation state. In fact, the only thing that needs to be available is special nuclear material (SNM), typically in the form of either highly enriched uranium (HEU) or weapons grade plutonium. Whether or not Iran is really seeking to acquire nuclear weapons or not, its nuclear program must be seen in that context.

There is an interesting article on the subject over at Wikipedia, although, as usual, it is subject to change from day to day depending on the political predilections of the last one to post. It appears that, as this post is written, many of the incorrigibly optimistic are convinced that Iran is not enriching uranium beyond the level required for the production of nuclear power, and, therefore, poses no nuclear threat. Unfortunately, once one of those nuclear reactors is run for a relatively short period, it produces enough plutonium to produce a bomb, and no high-tech centrifuges are needed to separate it. All it takes is someone with a reasonalble level of skill as a chemist.

As in the case of North Korea, I have no brilliant suggestions about how to deal with the Iranian threat or the problem of proliferation in general. I merely point out that the problem is growing worse, that tons of SNM are out there, and that, eventually, enough of it will get in the wrong hands to make a bomb. Whether the “wrong hands” are those of a rogue nation or a terrorist organization, the result will be as devastating as it is inevitable. It is merely a question of when.