There are, in turn, two basic approaches to ICF.  In one, referred to as direct drive, the target material is directly illuminated by the laser beams.  In the other, indirect drive, the target is placed inside a small container, or “hohlraum,” with entrance holes for the laser beams.  These are aimed at the inside walls of the hohlraum, where they are absorbed, producing x-rays which then compress and ignite the target.  The NIF currently uses the latter approach.

The NIF was completed and became operational in 2009.  Since that time, the amount of news coming out of the facility about the progress of experiments has been disturbingly slight.  That is not a good thing.  If everything were working as planned, a full schedule of ignition experiments would be underway as I write this.  Instead, the facility is idle.  The results of the first experimental campaign, announced in January, sounded positive.  The NIF had operated at a large fraction of its design energy output of 1.8 Megajoules.  Surrogate targets had been successfully compressed to very high densities in symmetric implosions, as required for fusion.  However, on reading the tea leaves, things did not seem quite so rosy.  Very high levels of laser plasma interaction (LPI) had been observed.  In such complex scattering interactions, laser light can be scattered out of the hohlraum, or in other undesired directions, and hot electrons can be generated, wreaking havoc with the implosion process by preheating the target.  We were assured that ways had been found to control the excess LPI, and even turn it to advantage in controlling the symmetry of the implosion.  However, such “tuning” with LPI had not been foreseen at the time the facility was designed, and little detail was provided on how the necessary delicate, time-dependent shaping of the laser pulses would be achieved under such conditions.

After a long pause, another series of “integrated” experiments was announced in October.  Even less information was released on this occasion.  We were informed that symmetric implosions had been achieved, and that, “From both a system integration and from a physics point of view, this experiment was outstanding,”  Since then, nothing.  

It’s hard to imagine that the outlook is really as rosy as the above statement would imply.  The NIF was designed for a much higher shot rate.  If it sat idle through much of 2010, there must be a reason.  It could be that damage to the laser optics has been unexpectedly high.  This would not be surprising.  Delicate crystals are used at the end of the chain of laser optics to triple the frequency of the laser light, and, given that the output energy of the facility is more than an order of magnitude larger than that of its next largest competitor, damage may have occurred in unexpected ways, as it did on Nova, the NIF’s predecessor at Livermore.  LPI may, in fact, be more serious, more difficult to control, and more damaging than the optimistic accounts in January implied.  Unexpected physics may be occurring in the absorption of laser light at the hohlraum walls.  Whatever the problem, Livermore would be well advised to be forthcoming about it in its press releases.  After all, the NIF will achieve ignition or not, regardless of how well the PR is managed.

All this seems very discouraging for the scientists who have devoted their careers to the quest for fusion energy, not to mention the stewards of the nation’s nuclear weapons stockpile, whose needs the NIF was actually built to address.  In the end, these apparent startup problems may be overcome, and ignition achieved after all.  However, I rather doubt it, unless perhaps Livermore comes up with an alternative to its indirect drive approach.

…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.

The byline claims that, “Thorium has nearly 200 times the energy content of uranium,” a statement I will assume reflects the ignorance of the writer rather than any outright attempt to deceive. She cites physicist Carlo Rubbia as the source, but if he ever said anything of the sort, he was making some very “special” assumptions about the energy conversion process that she didn’t quite understand. I assume it must have had something to do with his insanely dangerous subcritical reactor scheme, in which case the necessary assumptions to get a factor of 200 would have necessarily been very “special” indeed. Thorium cannot sustain the nuclear chain reaction needed to produce energy on its own. It must first be transmuted to an isotope of uranium with the atomic weight of 233 (U233) by absorbing a neutron. Strictly speaking, then, the above statement is nonsense, because the “energy content” of thorium actually comes from a form of uranium, U233, which can sustain a chain reaction on its own. However, let’s be charitable and compare natural thorium and natural uranium as both come out of the ground when mined. 

As I’ve already pointed out, thorium cannot be directly used in a nuclear reactor on its own.  Natural uranium actually can.  It consists mostly of an isotope of uranium with an atomic weight of 238 (U238), but also a bit over 0.7% of a lighter isotope with an atomic weight of 235 (U235).  U238, like thorium, is unable to support a nuclear chain reaction on its own, but U235, like U233, can.  Technically speaking, what that means is that, when the nucleus of an atom of U233 or U235 absorbs a neutron, enough energy is released to cause the nucleus to split, or fission.  When U238 or natural thorium (Th232) absorbs a neutron, energy is also released, but not enough to cause fission.  Instead, they become U239 and Th233, which eventually decay to produce U233 and plutonium 239 (Pu239) respectively. 

Let’s try to compare apples and apples, and assume that enough neutrons are around to convert all the Th232 to U233, and all the U238 to Pu239.  In that case we are left with a lump of pure U233 derived from the natural thorium and a mixture of about 99.3% Pu239 and 0.7% U235 from the natural uranium.  In the first case, the fission of each atom of U233 will release, on average, 200.1 million electron volts (MeV) of energy that can potentially be converted to heat in a nuclear reactor.  In the second, each atom of U235 will release, on average, 202.5 Mev, and each atom of Pu239 211.5 Mev of energy.  In other words, the potential energy release from natural thorium is actually about equal to that of natural uranium. 

Unfortunately, the “factor of 200″ isn’t the only glaring mistake in the paper.  The author repeats the familiar yarn about how uranium was chosen over thorium for power production because it produced plutonium needed for nuclear weapons as a byproduct.  In fact, uranium would have been the obvious choice even if weapons production had not been a factor.  As pointed out earlier, natural uranium can sustain a chain reaction in a reactor on its own, and thorium can’t.  Natural uranium can be enriched in U235 to make more efficient and smaller reactors.  Thorium can’t be ”enriched” in that way at all.  Thorium breeders produce U232, a highly radioactive and dangerous isotope, which can’t be conveniently separated from U233, complicating the thorium fuel cycle.  Finally, the plutonium that comes out of nuclear reactors designed for power production, known as “reactor grade” plutonium, contains significant quantities of heavier isotopes of plutonium in addition to Pu239, making it unsuitable for weapons production.

Apparently the author gleaned some further disinformation for  Seth Grae, CEO of Lightbridge, a Virginia-based company promoting thorium power.  He supposedly told her that U233 produced in thorium breeders “fissions almost instantaneously.”  In fact, the probability that it will fission is entirely comparable to that of U235 or Pu239, and it will not fission any more “instantaneously” than other isotopes.  Why Grae felt compelled to feed her this fable is beyond me, as “instantaneous” fission isn’t necessary to prevent diversion of U233 as a weapons material.  Unlike plutonium, it can be “denatured” by mixing it with U238, from which it cannot be chemically separated.

It’s a mystery to me why so much nonsense is persistently associated with discussions of thorium, a potential source of energy that has a lot going for it.  It has several very significant advantages over the alternative uranium/plutonium breeder technology, such as not producing significant quantities of plutonium and other heavy actinides, less danger that materials produced in the fuel cycle will be diverted for weapons purposes if the technology is done right, and the ability to operate in a more easily controlled “thermal” neutron environment.  I can only suggest that people who write popular science articles about nuclear energy take the time to educate themselves about the subject.  Tried and true old textbooks like Introduction to Nuclear Engineering and Introduction to Nuclear Reactor Theory by John Lamarsh have been around for years, don’t require an advanced math background, and should be readable by any intelligent person with a high school education.

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.

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.

But I digress. Of course, there is also Japanese officialdom. Ever since the end of the war, they have been busy rationalizing, relativizing, and generally seeking to consign to oblivion such horrific crimes as the rape of Nanking, the deliberate slaughter of the civilian population of Manila (in both of which cities more civilians died than in Hiroshima), the Bataan Death March, the deliberate starving and murder of prisoners, the wholesale rape of a generation of Korean women,

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germ warfare experiments with human guinea pigs, etc., etc. The bomb has always been their most effective foil for diverting attention from their country’s criminal past. Other than that, there are the legions of Ameria-haters worldwide for whom the United States is well-suited for the role of “out-group,” satisfying the universal need wired in the human brain for an evil enemy.

It is usually easy to identify historical revisionists.  They tip their hands by insisting on a version of reality that allows no room for doubt, and that neatly fits their ideological preconceptions.  In this case, for example, in spite of the undeniable coincidence of the atomic bombing and the surrender of Japan, they insist that there was absolutely no connection, and that the bombing had nothing at all to do with the Japanese decision to capitulate.  Obviously, especially in view of the careful destruction of relevant documents by Japanese officials, it is irrational to claim that it has absolutely been proved that the bombing and the surrender were purely coincidental, and the former’s contribution to the latter was trivial at best.  That, however, is precisely what the revisionists claim.  Look at their books and essays, and you will also find that they invariably leave out salient facts that don’t fit the altered reality they are trying to construct, and that other facts are “reinterpreted” to give them a significance they don’t deserve. 

Readers who have been around long enough may recall a previous round of Hiroshima revisionism on the occasion of the 50th anniversary of the bombing back in 1995.  Earlier in the year, officials at the Smithsonian Institution, a magnet for leftist academics whose tastes run to interpreting all American history as the story of an oppressor’s playground on which a series of invariably  pure, noble and morally immaculate classes of victims were brutalized by an invariably greedy, selfish, and evil ruling class, had attempted to introduce the now familiar adjustments to reality in conjuction with the Institution’s planned display of the Enola Gay.  Fortunately, enough people with firsthand knowledge of what really happened and who objected to the bowdlerization of history, were around at the time to mount an effective resistance to the fabricators.  Now most of the eyewitnesses have passed from the scene.  It is, therefore, all the more important that the critical source material relating to the atomic bombing be preserved and made easily accessible. 

Revisionists of one stripe or another will always be with us.  At different times and in different places, they have succeeded in constructing alternate realities in spite of the existence of a far greater volume and variety of source material than exists in the case of the atomic bombing of Japan.  Schools in much of the US South, for example, raised generations of students who firmly believed that the Civil War “really” occurred for any number of reasons besides slavery, in spite of overwhelming evidence documenting that the leaders of the South believed it was about slavery, the leaders of the North believed it was about slavery, the populations in both sections believed it was about slavery, and foreign observers were unanimous in confirming that it was about slavery.  Today Holocaust deniers control the public narrative in much of the Middle East.  In both of those cases, the source material available to document what really happened was orders of magnitude larger than what remains pertinent to the atomic bombing of Japan.  The Hiroshima revisionists would seem to have a much easier task.  The amount of documentation it will be necessary for them to drop down the “memory hole” is a great deal smaller, and their attempts to construct a mythical reality may consequently turn out to be a great deal more successful than those of the Iranian theocracy, or the “Southern heritage” crowd.

History can and will be falsified.  In the case of Hiroshima, those who are attempting to revise it are influential and determined.  The antidote to revisionism is the preservation of facts.  The truth is important.  One must hope that enough facts about the atomic bombing of Japan will be preserved to give future generations at least a fighting chance of finding it.

UPDATE: This article by Richard B. Frank (hattip ChicagoBoyz), entitled “Why Truman Dropped the Bomb, which appeared in the Weekly Standard in 2005, is a must read for those seeking the facts about the atomic bombing of Japan.  Money quote: 

There are a good many more points that now extend our understanding beyond the debates of 1995. But it is clear that all three of the critics’ central premises are wrong. The Japanese did not see their situation as catastrophically hopeless. They were not seeking to surrender, but pursuing a negotiated end to the war that preserved the old order in Japan, not just a figurehead emperor. Finally, thanks to radio intelligence, American leaders, far from knowing that peace was at hand, understood–as one analytical piece in the “Magic” Far East Summary stated in July 1945, after a review of both the military and diplomatic intercepts–that “until the Japanese leaders realize that an invasion can not be repelled, there is little likelihood that they will accept any peace terms satisfactory to the Allies.” This cannot be improved upon as a succinct and accurate summary of the military and diplomatic realities of the summer of 1945.

Y-12 Nuclear Facility

As for the article’s assertion that we are “falling behind” other nations in this regard, I rather doubt it, especially if the source of the information is a United States senator from a state that would benefit directly from the proposed work. In fact, we’ve already undertaken some significant upgrades, and I know of no factual basis at the moment for the claim that other nations have done more, or are ahead of us in this regard. The case for upgrading our weapons infrastructure can stand on its own merits, based on the need to maintain the safety and reliability of the existing stockpile. There’s no need to invoke an imaginery “modernization gap.”

If anyone around today lives to see the dawn of the era of fusion energy, it will probably be because some exceptionally clever researcher has hoodwinked Mother Nature and discovered how to finesse his way past the Coulomb barrier that usually keeps atomic nuclei too far apart to come within the range of the fusion-enabling strong force. Several promising candidates are already in the field, and one of them, Tri-Alpha Energy, has apparently managed to attract $50 million in private research funding. The company hasn’t revealed the nature of its approach, but it is apparently inspired by the work of Prof. Norman Rostoker of UC Irvine. One can get a broad hint from this paper co-authored by Rostoker and Tri-Alpha entitled, “Colliding Beam Fusion Reactors.” Rostoker is an emeritus professor who has been publishing papers since the 50′s, some co-authored with fusion superstars such as Nicholas Krall and Marshall Rosenbluth. Octogenarian physicists don’t often pull off such miracles, but you never know.

If he or someone else ever does manage to pull the fusion rabbit out of the hat, it would potentially put an end to our worries about energy for a very long time. It could also enable pure fusion weapons. Let’s keep our fingers crossed that it doesn’t.

Fusion Reaction

Overall, this form of MAD is a good thing. The sanctimonious, condescending attitude of the journalists of yesteryear was getting very old by the time Rush Limbaugh finally appeared on the scene. However, it does have its drawbacks, in the form of increasing levels of political polarization and the associated pious posing on both the right and the left. Indeed, when it comes to the ostentatious striking of sanctimonious public poses, the right has, at long last, achieved parity with the left. Reasoned debate becomes difficult when both sides are only interested in occupying the moral high ground.

Consider, for example, the right’s overwrought response to the latest Nuclear Posture Review (NPR). The NPR is a document submitted to Congress each year by the Department of Defense setting forth what the role of nuclear weapons in U.S. security strategy should be. The latest version contains a watered down “no first use” provision according to which we won’t respond with nuclear weapons even if attacked with chemical and biological weapons, with the caveat that for nations that don’t play according to the Nuclear Nonproliferation Treaty, everything is still on the table. Some of the other more significant provisions include:

• The United States will not conduct nuclear testing, and will seek ratification and entry into force of the Comprehensive Nuclear Test Ban Treaty.

• The United States will not develop new nuclear warheads. Life Extension Programs (LEPs) will use only nuclear components based on previously tested designs, and will not support new military missions or provide for new military capabilities.

• The Administration will study options for ensuring the safety, security, and reliability of nuclear warheads on a case-by-case basis, consistent with the congressionally mandated Stockpile Management Plan. The full range of LEP approaches will be considered: refurbishment of existing warheads, reuse of nuclear components from different warheads, and replacement of nuclear components.

The response Tunku Daravarajan at The Daily Beast:

I despair of this latest episode of gestural theater designed to make the U.S. look exquisitely reasonable (should we call it “Jimmy-Cartesian”?), but which in truth results in the U.S. looking flaccid, or worse, complacent. After all, who gains from a presidential posture that has, in effect, stigmatized our most potent deterrent? In terms of foreign policy—or, better put, foreign clout—the U.S. is going through a startling period of auto-emasculation.

and from Roger Simon at PajamasMedia:

Like some looney member of Code Pink, our president is abandoning the nuclear deterrent adhered to by every American president since Truman. And he is doing it in a manner that makes absolutely no sense… What are we to make of this and the man who is adopting this policy? Does he hate us? Does he hate this country? What would he do if there was, for example, a massive small pox attack on the U.S.? Send in the infantry? Call in the Marines? Try to reason with whoever did it and recommend they negotiate as the fatal disease spreads to millions of people?… Now I detest nuclear weapons as much as the next person, but this approach seems — I hate to repeat myself, but I will — deranged.

Now let’s think about this for a moment. Suppose, just for the sake of argument, that the ultimate reason for having a nuclear arsenal in the first place is to protect our security. What if Tunku and Roger, being human, and therefore not infallible, are wrong? What if, just hypothetically, the policy set forth in the NPR really will make us more safe, and the policy they prefer less safe. They have not limited themselves to a reasoned response to the NPR, setting forth, in their opinions, why they think it will not enhance our safety. Rather, they have villified the people who support it, accusing them, not only of being wrong, but of being crazy. When you demonize people, you make it very difficult for them to respond to your objections in a reasoned manner. Being human, they are more likely to strike back, trading tit for tat. I would even go so far as to say that, in some cases, that is the only rational way to respond. It seems rather obvious that convergence to correct policy decisions is not a likely outcome of this process of mutual demonization.

That is the reason that, as I have maintained elsewhere, when it comes to policy decisions as weighty as those relating to nuclear policy, moralistic posing, with all the associated pushing of emotional hot buttons, should be set aside in favor of some semblance of rational discussion. The goal here, I assume, is to survive. Let us, then, dispassionately consider what we should best do in order to survive.

According to Steve Schippert ant Liberty Pundits, the NPR not only does not serve that goal but is, in fact, pointless.  In his words:

There is none, really. Not beyond rhetoric and “historic” moments and – dare the Los Angeles Times say it – a “manifesto.”

No point at all – but for one critical aspect lost in all of the arguing back and forth. Clarity is dead. Nuance and the foolish self-assurance of perceived superior intellectual and/or moral capacity have rightly replaced clear understanding.

Admitting in advance my own fallibility, I beg to differ. In the first place, we have kept the nuclear genie in the bottle now for going on 65 years. I am far from believing that an all out nuclear exchange would result in the extinction of humanity, or anything close to it. It is, nevertheless, an understatement to say that it would be extremely destructive. That being the case, it would be well if, to the extent possible, we maintained a taboo on the first use of nuclear weapons.

Any first user of nuclear weapons likely would become and, it seems to me, should become, an international pariah. Roger paints a nightmare scenario in which millions of people are dying in a biological attack while our hands are tied. Given the known effects of the releases of biological and chemical agents to date, the chances of something like that happening are vanishingly small. If it did, the NPR would become a moot point, just as all our loud protestations against unrestricted submarine warfare prior to our entry into WWI became a moot point for our own submarine forces in the Pacific after Pearl Harbor. A far more likely first use scenario would be an attempt at eliminating enemy stocks of biological or chemical weapons with a nuclear bunker buster, either preemptively or after an ineffective and very ill-considered attack on the United States with such weapons. This kind of first use would be very attractive to many in the nuclear weapons community. It would, however, do anything but promote our national security. Rather, it would end the taboo on the use of nuclear weapons, greatly increasing the chances that we, in turn, would become the victims of a really devastating attack, not with ineffective chemical or biological agents, but with nuclear weapons.

I also agree with the other sections of the NPR that are major departures from past policy, or, at least, have been represented as such. One of these is the provision that the United States will not conduct nuclear testing. Again, there are many in the weapons community who would love to resume testing, basing their arguments on insuring the reliability of the stockpile. It would also help the national weapons laboratories solve the demographic problem they face with the retirement or impending retirement of most of the physicists and other technical experts who have actually taken part in nuclear tests, and the difficulty of attracting talented scientists to careers as custodians of an aging pile of nuclear weapons. It would also play directly into the hands of our enemies.

The United States has a huge advantage over potential nuclear rivals in its possession of above ground experimental facilities (known in the business as AGEX) second to none in the world. From the massive National Ignition Facility, with its ability to focus 192 powerful laser beams on a tiny point, to the Z pulsed power machine capable of producing bursts of X-rays at levels far beyond those of any comparable facility on the planet, to a host of other smaller but still highly impressive and technologically advanced experimental facilities, we can approach the physical conditions that exist within exploding nuclear devices more closely and for longer periods of time than any other nation can even dream of. To resume nuclear testing would be to stupidly throw away this huge advantage. At the same time, it would give our enemies all the moral authority they needed to resume testing or develop nuclear weapons themselves.

The decision to set in concrete in the NPR the decision not to develop new nuclear weapons is also a good one. The idea that the United States would do such a thing is anything but implausible. On the contrary, the National Nuclear Security Administration has been agitating for years to get the go-ahead to build the Reliable Replacement Warhead. When Congress wisely told them, not only no, but hell no, they kept up the pressure regardless. Congress has taken a lot of bad raps lately. They deserve a lot of credit for derailing NNSA’s determination to go ahead with the RRW. In the first place, the weapons in our stockpile are not fragile and unreliable. Any enemy that assumed so would be making a very grave mistake. In the second, if we developed the RRW, the pressure to test it would likely become irresistible. The idea of developing a nuclear weapon without testing it would never have passed the “ho-ho” test at the weapons labs back in the 70′s and 80′s. The claim that we wouldn’t need to test the RRW is likely wishful thinking. Again, all the objections to a resumption of nuclear testing I have cited above would apply. Finally, by building a new type of nuclear weapon we would once again sacrifice the moral high ground, handing our enemies all the justification they needed for building new weapons themselves. Again, we would sacrifice major advantages, simply to acquire a weapon that would be somewhat cheaper to maintain than those in the existing stockpile. For obvious reasons, the weapons designers at the labs would love it. For the rest of us, it would make no sense at all.

I am hardly in favor of unilateral nuclear disarmament. On the contrary, I am in favor of maintaining a powerful arsenal and assuring that the resources we need to keep it safe and reliable will always be available. However, the latest NPR is a reasoned response to the nuclear myopia that would have us sacrifice real advantages in return for extremely dubious returns. As such, it deserves our support.

In inertial confinement fusion, or ICF, the target, a thin, spherical shell containing a mixture of deuterium and tritium, two heavy isotopes of hydrogen, is first compressed and imploded to very high densities.  A series of converging shocks then create a “hot spot” in the center of the compressed material, setting off fusion reactions which release enough energy to set off a ”burn wave.”  This wave propagates out through the remaining fuel material, heating it to fusion energies as well.  The process is known as inertial confinement fusion because it takes place so fast (on the order of a nanosecond) that the material’s own inertia holds it in place long enough for the fusion reactions to occur.  There are two basic approaches; direct drive, in which the laser beams hit the fusion target directly, and indirect drive, the process that will be used in the upcoming Livermore ignition experiments, in which the beams are shot into a hollow can or “hohlraum,” producing x-rays when they hit the inner walls.  These x-rays then implode and ignite the target.  

A potential problem that must be overcome in ICF is known as laser plasma interactions (LPI).  These are parasitic interactions which can soak up laser energy and quench the fusion process.  According to the Livermore paper, special grids at the hohlraum entrance holes were used in the latest experiments, allowing the use of LPI to “tweak” the incoming beams, steering them to just the right spots.  This recent (and elegant) innovation allows the exploitation of a process that has always been considered a major headache in the past to actually improve the chances of achieving igntion.

The BBC and Spiegel both have articles about the latest experiments today, conflating the energy and military applications of the NIF as usual.  According to the Spiegel article, for example, it will be necessary for the lasers in a fusion reactor to hit the target ten times a second, whereas hours are necessary between shots at the NIF.  The reason, of course, is that the NIF was never designed as an energy project, but is being funded by the National Nuclear Security Administration (NNSA) to conduct nuclear weapons experiments.  If ignition is achieved, the prospects for fusion energy will certainly be improved, but the prospects aren’t nearly as bright as the press releases from LLNL would imply.  It will still be necessary to overcome a great number of scientific and engineering hurdles before the process can ever become useful and economical as a source of energy.

I am not optimistic about the success of the upcoming experiments.  I suspect it will be too difficult to achieve the fine beam energy balance and symmetry that will be necessary to ignite the central “hot spot.”  It will take more than one converging shock to do the job.  Several will be necessary, moving inward through the target material at just the right speed to converge at a small spot at the center.  If they really pull it off, I will be surprised, but will be more than happy to eat crow.  A lot of very talented scientists have dedicated their careers to the quest for fusion, and I’m keeping my fingers crossed for them. 

Even if these ignition experiments fail, it won’t mean the end for fusion by a long shot.  We know we can achieve the high fuel densities needed for inertial fusion, and there are other ways of creating the “hot spot” needed to achieve ignition, such as “fast ignitor.”  Other approaches to fusion keep showing up in the scientific literature, and I can’t help but think that, eventually, one of them will succeed.