Nuclear terrorism – Helian Unbound

Polyanna Pinker’s Power Profundities

Recently Steven Pinker, public intellectual and author of a “history” of the Blank Slate debacle that was largely a fairy tale but at least drew attention to the fact that it happened, has been dabbling in something entirely different. Inspired by the latest UN Jeremiad against climate change, he has embraced nuclear power. In a series of tweets, he has endorsed articles advocating expanded reliance on nuclear power, such as one that recently turned up at Huffpo cleverly entitled “If We’re Going To Save the Planet, We’ve Got To Use the Nuclear Option.” As things now stand, that would be a dangerous, wasteful, and generally ill-advised idea.

I say “as things now stand.” I’m certainly not opposed to nuclear power. I’m just opposed to the way it would be implemented if we suddenly decided to build a bevy of new nukes given current economic realities. The new reactors would probably look like the AP1000 models recently abandoned in South Carolina. Such reactors would use only a fraction of the available energy in their nuclear fuel, and would produce far larger amounts of long-lived radioactive waste than necessary. They are, however, cheaper than alternatives that could avoid both problems using proven technologies. Given the small number of players capable of coming up with the capital necessary to build even these inferior reactors, there is little chance that more rational alternatives will be chosen until alternative sources of energy become a great deal more expensive, or government steps in to subsidize them. Until that happens, we are better off doing without new nuclear reactors.

As noted above, the reasons for this have to do with the efficient utilization of nuclear fuel, and the generation of radioactive waste. In nature there is only one potential nuclear fuel – Uranium 235, or U235. U235 is “fissile,” meaning it may fission if it encounters a neutron no matter how slow that neutron happens to be traveling. As a result, it can sustain a nuclear chain reaction, which is the source of nuclear energy. Unfortunately, natural uranium consists of only 0.7 percent U235. The rest is a heavier isotope – U238. U238 is “fissionable.” In other words, it will fission, but only if it is struck by a very energetic neutron. It cannot sustain a fission chain reaction by itself. However, if U238 absorbs a neutron, it becomes the isotope U239, which quickly decays to neptunium 239, which, in turn, quickly decays to plutonium 239. Plutonium 239 is fissile. It follows that if all the U238 in natural uranium could be converted to Pu239 in this way, it could release vastly more energy than the tiny amount of U235 alone. This is not possible in conventional reactors such as the AP1000 mentioned above. A certain amount of plutonium is produced and burned in the fuel elements of such reactors, but the amount is very small compared to the amount of available U238. In addition, other transuranic elements, such as americium and curium, which are produced in such reactors, along with various isotopes of plutonium, would remain dangerously radioactive for thousands of years.

These problems could be avoided by building fast breeder reactors. In conventional reactors, neutrons are “thermalized” to low energies, where the probability that they will react with a fuel nucleus are greatly increased. The neutron spectrum in “fast” reactors is significantly hotter but, as a result, more neutrons are produced, on average, in each encounter. More neutrons means that more Pu239 can be produced without quenching the fission chain reaction. It also means that the dangerous transuranic elements referred to above, as well as long lived fission products that are the source of the most long-lived and dangerous radioactive isotopes in nuclear waste, could be destroyed via fission or transmutation. As a result, the residual radioactivity resulting from running such a nuclear reactor for, say 30 years, would drop below that released into the environment by a coal plant of comparable size in 300 to 500 years, as opposed to the thousands of years it would take for conventional reactors. And, yes, radioactivity is released by coal plants, because coal contains several parts per million each of radioactive uranium and thorium. Meanwhile, a far higher percentage of the U238 in natural uranium would be converted to Pu239, resulting in a far more efficient utilization of the fuel material.

An even better alternative might be molten salt reactors. In such reactors, the critical mass would be in liquid form, and would include thorium 232 (Th232) in addition to a fissile isotope. When Th232 absorbs a neutron, it decays into U233, another fissile material. Such reactors could run at a lower neutron “temperature” than plutonium breeders, and would be easier to control as a result. The liquid core would also greatly reduce the danger of a nuclear accident. If it became too hot, it could simply be decanted into a holding pan where it would immediately become subcritical. Thorium is more abundant than uranium in nature, so the “fuel” material would be cheaper.

Consider the above in the context of the present. Instead of extracting the vast amounts of energy locked up in U238, or “depleted” uranium, we use it for tank armor and armor piercing munitions. In addition to this incredibly stupid waste of potentially vast energy resources, we dispose of huge amounts of it as “radioactive waste.” Instead of treasuring our huge stores of plutonium as sources of carbon-free energy, we busy ourselves thinking up clever ways to render them “safe” for burial in waste dumps. It won’t work. Plutonium can never be made “safe” in this way. Pu239 has a half-live of about 25,000 years. It will always be possible to extract it chemically from whatever material we choose to mix it with. Even if it is “reactor grade,” including other isotopes of plutonium such as Pu240, it will still be extremely dangerous – difficult to make into a bomb, to be sure, but easy to assemble into a critical mass that could potentially result in radioactive contamination of large areas. Carefully monitored breeder reactors are the only way of avoiding these problems.

According to the Huffpo article referenced above,

Doesn’t nuclear power contribute to nuclear weapons proliferation? No. Weapons programs do not depend on civilian nuclear power, which operates under stringent international safeguards.

Really? Will the “stringent international safeguards” last for the 25,000 years it takes for even half the plutonium waste produced by conventional reactors to decay? I would advise anyone who thinks it is impossible to fabricate this waste into a bomb, no matter what combination of isotopes it contains, to take an elementary course in nuclear engineering. The only way to avoid this problem is to burn all the plutonium in breeder reactors. Predictably, the article doesn’t even mention the incredible wastefulness of current reactors, or the existence of breeder technology.

It’s nice that a few leftist “progressives” have finally noticed that their narrative on nuclear power has been controlled by imbeciles for the last half a century. I heartily concur that nuclear energy is a potent tool for reducing carbon and other greenhouse gas emissions. I simply suggest that, if we decide to return to nuclear, we either provide the subsidies necessary to implement rational nuclear technologies now, or wait until it becomes economically feasible to implement them.

START and the Resurrection of the Reliable Replacement Warhead

The Reliable Replacement Warhead is a really bad idea that never seems to go away. Congress has wisely condemned it, and it was explicitly rejected in the nation’s latest Nuclear Posture Review, but now the RRW has popped up again, artificially linked to the New Start arms control treaty, in a couple of opeds, one in the New York Times by former UN ambassador John Bolton, and another in the Wall Street Journal by R. James Woolsey, former arms control negotiator and Director of the CIA. Bolton writes, “Congress should pass a new law financing the testing and development of new warhead designs before approving New Start,” and Woolsey chimes in,

…the administration needs to commit to replacing and modernizing our aging nuclear infrastructure as well as the bombers, submarines and ballistic missiles – and the warheads on them – that provide our ultimate guarantee of national security. The Senate’s resolution of ratification should, for example, require the president to commit to specific modernization plans so we can be sure these programs will have his full support. The administration has particularly resisted warhead modernization, beginning with its Nuclear Posture Review last year. This led 10 former directors of the nation’s nuclear weapons labs to write to the secretaries of Defense and Energy urging them to revisit that misguided policy. The secretaries should commit to doing so.

In fact, one hopes they have enough sense not to follow that advice. What Bolton and Woolsey are referring to when they speak of “modernizing” weapons isn’t the continued refurbishment of old weapons, or the adding of new conventional packaging around them, as in the case of the B61-11, to make them more effective for earth penetration or some other specific mission. They are speaking of a new design of the nuclear device itself. At the moment, the RRW is the only player in that game.

Going ahead with the RRW would be self-destructive at a number of levels. In the first place, it’s unnecessary. There is no reason to doubt the safety and reliability of the existing weapons in our arsenal, nor our ability to maintain them into the indefinite future. A reason given for building the RRW is that low yield versions could be designed that would be “more effective deterrents,” because enemies would consider it a lot more likely that we would actually use such a weapon against them, as opposed to our existing high yield weapons. The problem with that logic is that they would be right. Given the alacrity with which we went to war in Iraq, it is not hard to imagine that we would be sorely tempted to use a mini-nuke to take out, say, a buried and/or hardened enemy bunker suspected of containing WMD’s. Any US first use of nuclear weapons, for whatever reason, and regardless of the chances of “collateral damage,” would be a disastrous mistake. It would let the nuclear genie out of the bottle once again, serving as a perfect pretense for the use of nuclear weapons by others, and particularly by terrorists against us. Those who think the Maginot line of nuclear detectors we are installing at our ports, or the imaginary difficulty of mastering the necessary technology, will protect us from such an eventuality, are gravely mistaken.

The building of a new weapon design would also provide a fine excuse for others to modernize their own arsenals. It is hard to imagine how this could work to the advantage of the United States. Our nuclear technology is mature, and it would simply give the lesser nuclear powers a chance to catch up with us. More importantly, it would almost inevitably imply a return to nuclear testing, thereby negating a tremendous advantage we now hold over every other nuclear power, namely, our above ground experimental (AGEX) capability. In the National Ignition Facility at Lawrence Livermore National Laboratory, the Z pulsed power machine at Sandia, the DAHRT radiographic test facility at Los Alamos, and a host of other experimental facilities, we possess an ability to study the physics that occurs in conditions near those in nuclear detonations that no other country comes close to matching. It would be utterly pointless to throw that advantage away in order to build a new nuclear weapon we don’t need.

It does not surprise me that 10 former directors of the nation’s nuclear weapons laboratories signed a letter calling on the Secretaries of Energy and Defense to revisit our RRW policy. It would certainly serve the interests of the nuclear weapons laboratories. It is much easier to attract talented physicists to an active testing program than to serve as custodians of an aging stockpile, and new designs would mean new money, and the removal of any perceived existential threats to one or more of the existing labs on the basis of their redundancy. The problem is that it would not serve the interests of the country.

Let the RRW stay buried. The nuclear genie will return soon enough as it is.

A Nuclear 9/11: Can we Defeat Nuclear Terrorism by Securing the Ports?

In a word, no. Anyone who wants to smuggle the key ingredients (highly enriched uranium or weapons grade plutonium, otherwise known as special nuclear material, or SNM) needed to make a nuclear weapon into this country can easily do so, and the installation of any combination of the most sophisticated radiation dectection devices on the planet at our ports will do nothing to alter the fact. The idea that lots of expensive detection equipment at our ports, or any other ports, will significantly reduce the terrorist nuclear danger is based on a fallacy: that terrorists capable of securing enough SNM to build a bomb will be brain dead. They would have to be brain dead to try to sneak SNM past sophisticated detectors when there are a virtually unlimited number of ways one could get it into the country without taking that risk. It’s not necessary to smuggle a nuclear weapon in one piece. It could be brought in broken down into small components and assembled at the target. The SNM could be smuggled across our borders in pieces small enough to be virtually undetectable by backpackers, on commercially available mini-submarines, light aircraft, small pleasure boats, or what have you. The SNM could then be assembled and easily fabricated into any desired weapons configuration in place. The whole debate about defeating nuclear terrorism sounds like it’s being conducted in a lunatic asylum.

For example, The Daily Caller (hattip Instapundit) cites a GAO report to the effect that, ”

The nation’s ports and border crossings remain vulnerable to a nuclear 9/11 despite a $4 billion investment since 2005 by the Department of Homeland Security (DHS) on a number of programs aimed at preventing nuclear smuggling around the world.

Senators similarly admonished DHS in a recent Senate hearing for failing to uphold its end of the bargain with the American people.

“Terrorists have made clear their desire to secure a nuclear weapon,” Maine Republican Sen. Susan Collins said at the Sept. 15 hearing. “Given this stark reality, we must ask: what has the department done to defend against nuclear terrorism on American soil? The answer, unfortunately, is not enough… not nearly enough.”

The Domestic Nuclear Detection Office (DNDO), responsible for the domestic aspect of DHS’s nuclear terror deterrence, received approximately half of the $4 billion investment, which it spent deploying over 1,400 radiation monitors at the nation’s seaports and border crossings in conjunction with U.S. Customs and Border Protection.

But these radiation monitors have a serious flaw: they can only detect radiation from lightly shielded radiation sources.

The only problem is that spending billions more to fix this “flaw” won’t help, unless you happen to have invested your nest egg in detection equipment. The article continues,

The GAO report uncovered a bureaucratic nightmare involving DNDO and U.S. Customs and Border Protection, which resulted in the failure to properly develop and deploy detection equipment that could detect radiation from heavily shielded sources.

DNDO began working shortly after its founding in April 2005 on what it called the Cargo Advanced Automated Radiography System (CAARS) and the Advanced Spectroscopic Portal (ASP) ̶ intended to automatically detect radiation from heavily shielded sources in a user-friendly fashion in order to screen cargo containers in the nation’s ports and border crossings.

In the first place, radiation detection equipment doesn’t come in just two flavors; “good for heavily shielded sources” and “not good for heavily shielded sources.” There are a great number of different types, all with their own strengths and weaknesses in terms of sensitivity, energy resolution, etc. In the second place, it doesn’t matter what kind are installed at the ports, because terrorists will simply bypass them. The whole port security paradigm is based on the premise that our opponents, in spite of their ability to acquire SNM in the first place, will be bone stupid. They won’t, and there are much more effective ways to spend all the money we are throwing down this particular rathole.

The article goes on to cite Cato Institute budget analyst Tad DeHaven, who plays a familiar broken record to demagogue the sheep:

They are not subject to market forces and other controls, so they can screw up federal money,” DeHaven said. “There are not going to be any angry shareholders, and in most cases you are not going to lose your job, so the incentives for the federal government to efficiently and effectively procure goods … are poor.”

One wonders if he reallly gets paid to churn out such hackneyed stuff. Tell me, Tad, do you actually know anything about the people who work for DNDO? Did it ever occur to you that many of them might be ex-military, that they might be highly motivated and dedicated to their country’s welfare, and that it’s not out of the question that they care a great deal about working to “efficiently and effectively procure goods”? You might actually try meeting and talking to some of them. They work just down the street from you. Did it ever occur to you that the problem might not be their lack of patriotism and dedication, but the fact that they’ve been given an impossible task? And BTW, no, I don’t work for DNDO or DHS.

The article concludes in a somewhat more sober vein,

Heritage Foundation homeland security analyst Jena Baker-McNeill instead blames Congress for setting what she sees as an unrealistic goal of inspecting every container that passes through the nation’s ports and border crossings. Congress imposed the goal for political reasons without considering its practical implications, she said. Baker-McNeill believes more emphasis should have been placed on increased intelligence aimed at intercepting nuclear smugglers abroad due to the volume of cargo that enters the country and limited resources.

It seems to me Ms. Baker-McNeill might be on to something. If we’re going to spend money to defeat nuclear terrorism, I suspect it will be much better spent on finding ways to keep terrorists from getting their hands on SNM in the first place. Once they do, we can install the most efficient radiation detectors with the most clever software ever devised at all our ports, and it won’t deter them in the slightest. We will only have bought ourselves a dangerous sense of false security.

Subcritical Thorium Reactors: Dr. Rubbia’s Really Bad Idea

The Telegraph (hattip Insty) turned the hype level to max in a recent article about the potential of thorium reactors. According to the headline, “Obama could kill fossil fuels overnight with a nuclear dash for thorium.” Against all odds, this is to happen in three to five years with a “new Manhattan Project,” and a “silver bullet” in the form of a new generation of thorium reactors. The author is so vague about the technologies he’s describing that it’s hard to avoid the conclusion that he simply doesn’t know what he’s talking about, and couldn’t be bothered to spend a few minutes with Google to find out. I’ll try to translate.

It’s claimed that thorium “eats its own waste.” In fact, thorium is very promising as a future source of energy, but this is nonsense. Apparently it’s based on the fact that certain types of thorium reactors actually could burn their own fuel material, as well as plutonium scavenged from conventional reactor waste and other transuranics, much more completely than alternative designs. This is certainly an advantage, but the fission products (lighter elements left over from the splitting of uranium and plutonium) would still be highly radioactive, and would certainly qualify as waste. Such claims are so obviously spurious that they play into the hands of opponents of nuclear power.

It is also claimed that “all (thorium) is potentially usable as fuel, compared to just 0.7% for uranium.” In fact, thorium is not a fissile material, meaning that, unlike uranium 235 (U235), which is the 0.7% of natural uranium the author is referring to, it cannot sustain a nuclear chain reaction on its own. It must first be converted to a lighter isotope of uranium, U233, which is fissile. In fact, the U238 that makes up most of the rest of the leftover 99.3% percent of natural uranium is “potentially usable as fuel” in that sense as well, by conversion to plutonium 239, also a fissile material.

The author is vague about exactly what kind of reactors he is referring to, lumping Dr. Carlo Rubbia’s subcritical design, which depends on a proton accelerator to provide enough neutrons to keep the fission process going, and molten fluoride salt reactors, which do not necessarily require such an accelerator. He claims that, “Thorium-fluoride reactors can operate at atmospheric temperature,” which they certainly could not if the goal were to generate electric power. I suspect that what he means here is that, unlike plutonium breeders, which require a high energy neutron spectrum to produce more fuel than they consume, thorium breeders could potentially use “thermal” neutrons that have been slowed to the point that their average energy, when converted to a “temperature,” would be much closer to that of the other material in the reactor core.

In any case, the design he seems to be so excited about is Dr. Rubbia’s “energy amplifier,” which, as noted above, would be subcritical, requiring a powerful, high current proton accelerator to keep the fission process going. It would do this via spallation, a process in which a copious source of the neutrons required to keep the reaction going would be provided via interaction of the protons with heavy nuclei such as lead, or thorium itself. This is the process used to produce neutrons at the Oak Ridge Spallation Neutron Source. Such reactors could easily be “turned off” by simply shutting down the source of neutrons. However, the idea that they would be inherently “safer” is dangerously inaccurate. In fact, they would be an ideal path to covert acquisition of nuclear weapons. Thorium reactors work by transmuting thorium into U233, which is the isotope that fissions to produce the lion’s share of the energy. It is also an isotope that, like U235 and Pu239, can be used to make nuclear bombs.

The article downplays this risk as follows:

After the Manhattan Project, US physicists in the late 1940s were tempted by thorium for use in civil reactors. It has a higher neutron yield per neutron absorbed. It does not require isotope separation, a big cost saving. But by then America needed the plutonium residue from uranium to build bombs.

“They were really going after the weapons,” said Professor Egil Lillestol, a world authority on the thorium fuel-cycle at CERN. “It is almost impossible make nuclear weapons out of thorium because it is too difficult to handle. It wouldn’t be worth trying.” It emits too many high (energy) gamma rays.

What Lillestol is referring to is the fact that, in addition to U233, thorium reactors also produce a certain amount of U232, a highly radioactive isotope of uranium with a half life of 68.9 years whose decay does, indeed, release potentially deadly gamma rays. It would be extremely difficult, if not impossible, to remove it from the U233, and, if enough of it were present, it would certainly complicate the task of building a bomb. The key phrase here is “if enough of it were present.” Thorium enthusiasts like Lillestol never seem to do the math. In fact, as can be seen here, even conventional thorium breeders could be designed to produce U233 sufficiently free of U232 to allow workers to fabricate a weapon without serious danger of receiving a lethal dose of gamma rays. However, large concentrations of highly radioactive fission products would make it very difficult to surreptitiously extract the uranium, and it would also be possible to mix the fuel material with natural or depleted uranium, reducing the isotopic concentration of U233 below that necessary to make a bomb.

With subcritical reactors of the type proposed by Rubbia, the problem of making a bomb gets a whole lot easier. Rogue state actors, and even terrorists groups if we “succeed” in coming up with a sufficiently inexpensive design for high energy proton accelerators, could easily modify them to produce virtually pure U233, operating small facilities that it would be next to impossible for international monitors to detect. There are two possible pathways for the production of U232 from thorium, both of which involve a reaction in which a neutron knocks two neutrons out of a heavy nucleus of Th232 or U233. Those reactions can’t occur unless the initial neutron is carrying a lot of energy as can be seen in figure 8 of the article linked above, the threshold is around 6 million electron volts (MeV). That means that, in order to produce virtually pure U233, all that’s necessary is to slow the incoming spallation neutrons below that energy. That’s easily done. Imagine two billiard balls on a table. If you hit one as hard as you can at the other one, what happens when they collide? If your aim was true, the first ball stops, transferring all its energy to the second one. The same thing can be done with neutrons. Pass the source neutrons through a layer of material full of light atoms such as paraffin or heavy water, and they will bounce off the light nuclei, losing energy in the process, until they eventually become “thermalized,” with virtually none of them having energies above 6 MeV. If such low energy neutrons were then passed on to a subcritical core, they would produce U233 with almost no U232 contamination.

It gets worse. Unlike Pu239, U233 does not emit a lot of spontaneous neutrons. That means it can be used to make a simple gun-type nuclear weapon with little fear that a stray neutron will cause it to fizzle before optimum criticality is reached. And, by the way, a lot less of it would be needed than would be required for a similar weapon using U235, the fissile material in the bomb that destroyed Hiroshima.

We’re quite capable of blowing ourselves up without Rubbia’s subcritical reactors. Let’s not make it any easier than it already is. Thorium reactors have many potential advantages over other potential sources of energy, including wind and solar. However, if we’re going to do thorium, let’s do it right.

UPDATE: Steven Den Beste gets it right at Hot Air. His commenters throw out the usual red herrings about the US choosing U235 and Pu239 over U233 in the Manhattan Project (for good reasons that had nothing to do with U233’s suitability as a bomb material) and the grossly exaggerated and misunderstood problem with U232. You don’t have to be a nuclear engineer to see through these fallacious arguments. The relevant information is all out there on the web, it’s not classified, and it can be understood by any bright high school student who takes the time to get the facts.

The Case of the Contraband Uranium

It appears that authorities in Moldova seized about four pounds of contraband uranium and arrested several suspects. The material in question turned out to be the isotope uranium 238 (U238), meaning that, unlike the fissile isotope U235, it couldn’t be used to make a bomb. Maybe it’s just me, but it seems that whenever I have personal knowledge of what happened in an incident that makes the news, or expertise regarding its subject, the mainstream media, with their layers of editors and fact checkers, manage to botch the story. For example, CNN uncritically quotes Kirill Motspan, a spokesman for Moldova’s Interior Ministry as saying that, “…it was his understanding that 1 kilo of uranium costs $6.3 million on the black market and that is what the smugglers were expecting to get.” I seriously doubt that Motspan meant just any uranium, and especially not U238. If that were the case, the guys who fly A10 Warthog ground support planes armed with Gatling guns that pump out rounds that contain just under a pound each of the stuff at 4,200 rounds per minute must be using caddies to recover them. He was probably referring to uranium highly enriched in isotope 235, which can be used to make a bomb. In other words, the smugglers were intending to snooker their customers. Anyone can Google the fact that natural uranium, which contains at least a little (about 0.71%) U235, is currently selling for just under $50 per pound.

Not to be outdone, the Telegraph reports that the material seized was “enriched uranium.” Since the caption of the figure that appears in the article notes that the material was U238, commonly referred to as depleted uranium, none of their “fact checkers” apparently has a clue what they’re talking about.

BTW, have you noticed that whenever contraband radioactive and special nuclear material is seized, its usually due to good old fashioned police work, and not to those snazzy new radiation detectors that are being installed hand over fist at ports and border crossings? That’s not a coincidence.

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.

thorium

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.