In part three, I talked about just how inefficient the early nuclear weapons were, and how the discovery of adding fusionable hydrogen isotopes to the equation resulted in boosted fission weapons that were many times more powerful than the fission weapons alone. Well, scientists weren’t finished improving on the destructive power contained in those little atoms.
In the early 1950’s, a nuclear physicist by the name of Edward Teller had been working on an idea he’d discussed a decade earlier with famed Italian physicist Enrico Fermi, the same physicist who proposed The Fermi Paradox. If you’ve never heard of the Fermi Paradox, it’s a fascinating subject that has nothing at all to do with nuclear weapons, but rather with the question of where the hell are all the alien civilizations. The most incredible article I’ve seen dealing with that can be found at one of my favorite websites HERE.
Now, if you clicked on that link and just got stuck in a Fermi Paradox internet black hole for the last few hours, I can’t blame you, and welcome back. Enrico Fermi was much better known as one of the preeminent nuclear physicists of his day, and he had the idea of developing a fusion weapon that was triggered by a fission reaction. When Edward Teller realized that actually seemed to be able to work with the boosted fission weapons they’d developed and tested, he went to work developing a multi-stage nuclear weapon where the first stage would be a standard fission chain reaction, and the second, completely separate stage would contain a fusion reaction, ready to be touched off by the fission reaction. His work was aided by Stanislaw Ulam who came up with the idea of separating the two stages of the bomb, and the Teller-Ulam configuration that is still the design used in today’s thermonuclear weapons, was born.
The key to making the two stages work was X-rays.
X-rays had been studied for many years prior to the discovery of nuclear fission, and it was no surprise to anybody that the fissioning of a heavy atom produced extremely powerful X-rays. Teller and Ulam knew that if they could harness the power of those X-rays, they would provide enough pressure to implode the secondary device which contained the hydrogen-based fuel. Compressing the secondary would cause the hydrogen fuel to undergo fusion, which would release tremendous amounts of energy.
Before I go into the details of exactly how this works, I want to discuss something I found interesting and fascinating. First of all, the exact processes and designs of nuclear weapons are top-secret in every country that has them. Nobody wants the information getting out to rogue states or terrorist cells that may use the info to create their own nuclear weapons, something that most can agree would be a disaster. Some would consider that to have already happened, what with North Korea having successfully detonated several nuclear bombs, and Iran having shown they were well on their way to developing them, if they aren’t secretly still working on it.
What’s interesting about the top-secret nature of nuclear weapons though, is that nuclear information in the United States is what’s known as “born secret.” That means it’s so top-secret, that even if you come up with information about how they work all on your own, it automatically falls under the top-secret classification. There’s a lot of information out there about exactly how nuclear weapons work, but a lot of the intricate design detail that’s published is speculation. If I was to speculate about non-published information regarding nuclear weapon design, and I was correct, I could actually be arrested and charged with Treason for spilling the secrets in this blog.
Now, I’m not so vain and arrogant as to think that I could actually succeed in spilling top-secret information about nuclear weapon design through speculation about the unknown aspects of it, so don’t think I’m saying that. Nuclear scientists have done plenty of that, and I’ll simply report on what the leading nuclear physicists who are not directly involved in the manufacture of nuclear weapons think about exactly how they work. They’ve already done the spilling of the secrets, so I don’t have to be the first. Even though I just may have some ideas that I’ve never seen published…
So here’s exactly how (hypothetically of course) the Teller-Ulam configuration works.
- We’ll start with the primary, a boosted fission device. Into a hollowed-out sphere of plutonium-239 (and some plutonium-240) is fitted a neutron generator and a mixture of tritium and deuterium gases. Around the plutonium is a sheet of beryllium designed to reflect neutrons back into the reaction, and surrounding that is a tamper made from aluminum or some other light metal, possibly beryllium itself in some designs. High explosive lenses, exactingly milled into shapes very similar to the hexagons and pentagons that make up a soccer ball, tightly surround the plutonium package.
- The explosive lenses are triggered in an exacting and carefully calculated pattern to create a perfectly shaped blast wave. If this blast wave isn’t perfect, critical chain-reaction fissions will not be achieved and the weapon will “fizzle” and be a dud. The mighty blast wave compresses the tamper, which compresses the plutonium-239 to between 1/3 and 1/5 its original diameter. At the same time, the neutron generator inside is activated and begins shooting free neutrons into the tritium and deuterium (hydrogen isotope gases), which are condensed and heated by the compression of the cavity.
- The hydrogen gases undergo fusion from the pressure, heat, and free neutron bombardment, generating an even larger amount of free neutrons as the hydrogen isotopes are converted to helium-4, a free neutron, and energy. In the meantime, the plutonium has begun to undergo fission and a chain reaction of fissions has begun which is aided by the free neutrons from the boosted hydrogen isotopes which are now undergoing fusion.
- As this begins, X-rays are produced from the atomic nucleus of the fissioning plutonium. These X-rays shoot out at near the speed of light, which is about 100 times faster than the explosion that is brewing in the now critically fissioning plutonium, and plenty fast enough to reach the secondary before the explosion itself does. (We’re talking in terms of nanoseconds and milliseconds here. Billionths of a second and millionths of a second, with a total time of the entire device in the thousandths of a second, or microseconds.)
- The secondary device is both a fusion and fission bomb and it nests in a cavity, known as a hohlraum, which is a cavity that is in perfect equilibrium with regard to radiation. This is actually the most closely guarded secret of thermonuclear weapon design because the secondary has to be compressed perfectly symmetrically without the use of the exacting conventional explosive lenses, and through only the use of X-rays. What happens is, the bomb casing is lined with a metal meant to channel (without absorbing) the X-rays directly to the secondary housing. This housing is encapsulated in a polystyrene foam that fills the entire bomb compartment encasing the secondary, and when the X-rays hit the foam, the tremendous energy they carry converts the polystyrene into a plasma nearly instantaneously.
- I found a lot of information that stated the pressure of the plasma itself compresses the secondary device, but that’s not actually true, and seems to be a common misconception. Incredibly, and nearly inconceivably, it’s the ablation of the plasma that compresses the secondary. Ablation means that the polystyrene foam is heated so quickly by the X-rays, that as it converts to plasma, it vaporizes away from the casing that houses the secondary with such force that the vaporizing mechanism itself causes the secondary to implode. This secondary housing is either a cylinder or a sphere, and the ablation process causes it to implode to about 1/10th of its original diameter, (if it’s a sphere; 1/30th the original diameter in the case of a cylinder design) making it 1000 times denser than it previously was. And the container is made from uranium that’s about 1 inch thick! Just to be clear, X-rays and ablation alone cause this tremendous implosion of the secondary housing, nothing else. Incredible.
- Inside the secondary is the fusion fuel, along with a plutonium-239 “spark plug.” Much like the spark plug in a car, the plutonium-239 rod is designed to spark the fusion process of the secondary, and to aid in free neutron generation, which assists the fusion of the hydrogen isotopes inside.
- For the fusion fuel of the secondary, a solid (powder) called lithium-deuteride is used. This is a mixture of lithium and deuterium, which, since lithium is a solid, allows the mixture itself to be a solid instead of a gas or liquid, which makes it much easier to maintain than when it’s a mixture of deuterium and tritium like you find in the primary. Lithium is number 3 on the periodic table, with an atomic weight of 7, which means it contains 3 protons and 4 neutrons. For the lithium-deuteride, it’s actually the lithium isotope called lithium-6 that’s used, and when it undergoes fusion, the lithium-deuteride converts to tritium and deuterium, which, as we know from our discussion of primaries, converts to helium-4 and a free neutron, and, of course, copious amounts of energy.
- The spark plug, which as mentioned, is plutonium-239, also undergoes fission while the lithium-deuteride is undergoing fusion, and that adds to the yield of the secondary. As it goes critical, the expanding explosion from the primary boosted fission stage reaches the secondary, and they combine to form a big boom.
How big? The first bomb created with the Teller-Ulam design was known as Ivy Mike. It was detonated on November 1st, 1952 at Enewetak Atoll in the Pacific Ocean. It had a blast yield of 10.4 megatons. That’s 20 times bigger than the previous largest bomb ever detonated.
Up to now, we’ve been discussing weapons with blast yields in the kilotons, or thousands of tons of TNT. The prefix mega means million. So, Ivy Mike had a blast yield of 10.4 million metric tons of TNT. For anybody struggling with the math, that’s almost 23 billion pounds of TNT.
As unfathomable as that amount of blast power is, the Teller-Ulam configuration allows for much bigger blast yields. By simply adding more secondary devices symmetrically around the casing, you can harness the X-rays from the primary through an arbitrary number of secondary devices, each contributing to the blast yield. It also has the theoretical potential to use X-rays from the secondary to ignite a tertiary stage which would be another fission stage, for a fission-fusion-fission bomb. Theoretical bomb yields of 100 megatons are deemed possible, though testing that large a bomb comes with enormous complications.
The Teller-Ulam configuration developed in 1951 is basically the same design used in today’s weapons. The hydrogen isotopes of the primary and the secondary devices give these bombs the names hydrogen bomb and thermonuclear weapon as opposed to atom bomb and nuclear weapon that describe single stage configurations.
Here’s a good but simple representation of what the Teller-Ulam design looks like.
Incidentally, the largest thermonuclear device ever detonated was by the Soviet Union on October 30th, 1961 over the island of Novaya Zemlya near the arctic circle. The bomb was known as Tsar Bomba, and it was a monster. The blast yield was somewhere between 50 and 58 megatons, depending on which source you check. This Discovery Channel video has a few errors, but does a good job of showing the destructive power of Tsar Bomba. It had a total destruction radius of 15-20 miles. That’s a circle with a total destruction diameter of 30-40 miles. Plenty to completely annihilate most major cities with a single bomb. Of course, the bomb was so large that only one could fit on the bomber, and only then by making special modifications that had the Tsar hanging out of the bomb bay doors for the duration of the flight. The drag and lack of maneuverability of that plane would have made it effectively useless against the air defenses of the United States, then or now.
Which brings us to what really matters when it comes to nuclear weapons, and that is delivering them to the target. It doesn’t make much sense to build a nuclear weapon so big that you have to modify a bomber with the weapon hanging out the bomb bay doors, creating a radar cross section the size of Manhattan. What matters is making weapons as powerful as possible while still being able to mount them on Intercontinental Ballistic Missiles, or ICBMs. That required a miniaturization program, keeping all of the design components of the Teller-Ulam configuration and keeping the yield to a satisfactory level.
To give an idea of how difficult this was, the first deployable United States hydrogen bombs, tested again at Bikini Atoll in what was called Operation Castle, were getting yields of around 15 megatons, and were considered extremely compact for their time. Yet they still weighed upwards of 23,000 pounds and were about twelve-feet long. The lithium-deuteride fusion fuel in the secondary device itself weighed 880 pounds. That’s a huge secondary, and difficult to maintain and deploy. Not to mention the yield of 15 megatons was unnecessarily large. Cities are only so big, right?
So weapons had to be made small enough to fit onto missiles, and that was accomplished very quickly. Both the U.S. and the U.S.S.R. were throwing enough money into the nuclear arms race to ensure the scientists had everything they needed to make it happen, and it took just a few years before we began to see deployable nuclear weapons with yields in the megaton range.
It would take another 3 parts to this blog to discuss all the aspects and designs of ICBMs, so I’m not going to do it. However, North Korea now has ICBMs capable of delivering a nuclear weapon, and North Korea’s capabilities are actually the subject of this blog, so we need to talk just a little about them. Here are the basics:
- The IC in ICBM stands for Intercontinental, which means the missile is capable of spanning the long distances between continents to deliver its payload. This is accomplished by launching the missile out of the atmosphere and into sub-orbital flight where it doesn’t have to deal with atmospheric pressures that would cause enormous fuel burn.
- The B stands for Ballistic, and that basically means that the missile is thrust upwards into an arc and then allowed to enter an unpowered and unguided trajectory back to the target established during guidance of the initial portion of the flight. Much of the flight of the missile occurs out of the atmosphere in a sub-orbital flight trajectory in space. The M in ICBM stands for missile which means… well, if you don’t know what a missile is, ask the person reading this to you.
- An ICBM can have a range upwards of 8000 miles in the case of the only current United States ICBM, the LGM-30 Minuteman III. North Korea’s only true ICBM is known as the Hwasong-14, and it’s thought to have a range of approximately 5000-6000 miles.
- The incredibly fast speed attained by a ballistic missile (up to mach 23 for the Minuteman III), due to its travel through space with no atmospheric drag to slow it, makes it difficult to intercept. It’s short travel time, around 30 minutes for its maximum range, means decisions on what to do if one is launched need to come quickly from command and control units.
- ICBMs can be stored and launched from missile silos, from submarines (where they’re actually known as SLBMs, submarine-launched ballistic missiles, usually with a much shorter range), from mobile rail launchers on trains, or from heavy trucks, such as this one.
Russian mobile missile truck –
- Each ICBM can carry multiple warheads known as MIRVs, or Multiple Independently targetable Reentry Vehicles. These are independent thermonuclear devices that all ride together into the sub-orbital flight portion of the ICBM, and then are released to reenter the atmosphere, each on its own trajectory toward a unique target. The United States doesn’t use MIRVs on its Minuteman III missiles due to requirements from the START II nuclear treaty with Russia, but its SLBM, the Trident II does carry up to 14 independent nuclear warheads on each missile.
Trident II SLBM launch from a submarine
Nine MIRVs mounted on an ICBM platform.
MIRV testing with tracers following the individual flight paths of the inert warheads.
Note: North Korea does not deploy any MIRVs on any of its ICBMs or SLBMs. Their SLBMs have failed numerous launch tests and are not thought to be ready for action at this time. We’ll talk a lot more about that in part five.
One of the greatest fears of the cold war was ICBM launched nuclear weapons. Not only had miniaturization of the Teller-Ulam design made it possible to launch nuclear warheads over the great distance from the Soviet Union to the United States, but both America and the USSR had developed enough warheads and missiles to completely annihilate one another. This is not the case with North Korea, and we’ll soon discuss exactly what they’re currently capable of.
The current thermonuclear warheads mounted on the ICBMs of the United States are known as the W87. They were originally designed in 1982 and mounted on Peacekeeper ICBMs, each of which could hold 12 W87s as MIRVs. They’re now mounted singly on the much smaller Minuteman III, and they’ve been upgraded with all the modern safety features that keep them from detonating accidentally. The yield of each warhead is 475 kilotons, making them significantly smaller with regard to yield than the megaton weapons that have to be delivered via bomber, such as the B83 which, at a maximum yield of 1.2 megatons is the largest yield weapon currently in the U.S. arsenal.
A W88 warhead, very similar in configuration and yield to the W87, By Dan Stober and Ian Hoffman, adapted by User:HowardMorland [CC BY-SA 2.5 (http://creativecommons.org/licenses/by-sa/2.5)%5D, via Wikimedia Commons
The B83, like most modern nuclear gravity bombs, has what’s known as dial-a-yield, which lets the operator choose the blast yield they want to achieve. This allows the bombs to be used for numerous different options. The yield is controlled by a simple dial on the outside, which, on the inside is effected by a few different options such as limiting the amount of boosted fission fuel enters the chamber, or by shutting down the secondary completely, making the device a primary fission bomb only. For the B83, the yield at the low end of the dial is classified but is reported to be in the “low kiloton range” whatever that means.
The United States has created nuclear bombs with very small yields. The Davy Crockett was developed in the late 1950s as a troop weapon, meant to accompany ground troops into battle. It was a tactical nuclear recoilless gun that was mounted on a tripod and had a range of between 1.2 miles and 2.5 miles. They could be mounted on an armored personnel carrier, or even a Jeep, and though it doesn’t seem that you’d want to be less than two miles from a nuclear explosion, that distance was perfectly safe for the yield of these nuclear weapons. They had variable yields of between 10 and 20 tons of TNT. Not kilotons…tons. The yields of the Davy Crockett were comparable to yields of several large conventional bombs of the day, but in a package that weighed only around 50 pounds.
Not only are low-yield nuclear weapons like the Davy Crockett able to be safely deployed from a short distance, but they are often safe even when they are detonated directly above a person. And, even when the blast yield is much greater than the 20 ton yield of the Davy Crockett. To show just how safe these weapons are, in 1954 the Air Force got five volunteers to stand directly under a 2-kiloton nuclear blast from an air-to-air nuclear rocket. Keep in mind, this blast yield is 100 times that of the Davy Crockett weapon, and it detonates only two miles from the officers, directly above them. Check out this video of these clearly low IQ volunteers.
The point of these last two examples is to indicate that while nuclear weapons can be absolutely devastating, and are designed primarily for that purpose, there are some that could absolutely be used in place of, and more effectively than, conventional bombs. Let me give an example.
On April 13, 2017, the United States conducted an airstrike on Nangarhar Province in eastern Afghanistan. The target of the airstrike was a network of underground tunnels being used by ISIS in Afghanistan, tunnels that were originally constructed for the Mujahedeen during the Russian war in Afghanistan.
Multiple attempts had been made to destroy the tunnel network through bombing runs and drone strikes, and they’d been unsuccessful. That’s when the military made the decision to deploy the GBU-43/B Massive Ordnance Air Blast, commonly known as the MOAB, with the nickname, Mother Of All Bombs.
The MOAB has an explosive yield of 11 tons of TNT, which puts it on par with the yield of the Davy Crockett nuclear weapon. Except the Davy Crockett weighed 51 pounds, and could be fired from a Jeep. The MOAB weighs over 21,000 pounds and needs to be delivered by a heavy bomber.
Russia has a conventional bomb much larger even than MOAB. Known as FOAB, the Father Of All Bombs, it’s a thermobaric weapon, meaning it pulls in oxygen from the surrounding air to generate an intense, high temperature explosion. Its blast yield is 44 tons, four times larger than MOAB, and the total weight of the bomb is just under 16,000 pounds.
There are of course, many critics of the use of weapons such as MOAB and FOAB that can cause indiscriminate and unintentional killing of civilians due to their large blast radii. But, when used cautiously, they can also be very effective weapons, succeeding where other bombs had failed. MOAB destroyed the tunnel system and killed a reported 94 ISIS fighters, including 4 commanders. There were some reports that two civilians may have also been killed, but overall, it was considered a very successful deployment. So, what would have been the difference if we’d used a low-yield tactical nuke such as the Davy Crockett in its place?
As far as yield, number of deaths, and probably even radioactive fall-out, next to nothing. The difference would have been the fact that it was a nuclear weapon, and that would have resulted in catastrophic consequences for the United States, numerous treaty violations, and an international incident on a scale previously unprecedented. But why? For what? Using MOAB is effectively the same thing as using a low-yield tactical nuke with one exception—MOAB uses conventional explosives instead of nuclear explosives.
The purpose of this paper thus far has been to show how nuclear weapons were developed and how they work today, and to show that the fears surrounding them are vastly overrated, and to do that, we need to talk about peaceful uses of nuclear weapons.
Nuclear weapons themselves are not inherently bad. They are inherently neutral, and can be used for both evil purposes and for good purposes. A nuclear explosion might be necessary someday to move an asteroid or comet out of its flight path to keep it from striking the earth. Nuclear pulse propulsion is a hypothetical method of using nuclear explosions to power the thrust of a spacecraft. Operation Plowshare in the 1960s and 70s detonated 27 nuclear devices for peaceful purposes. Most were experimental, and results were mixed. The ground explosions caused large amounts of radioactive fallout and contaminated water supplies which caused protesting and eventually brought the program to a halt.
The Comprehensive Nuclear-Test-Ban Treaty of 1996 prohibits all nuclear explosions, regardless of their purpose, and that brought a halt to all potential “good” uses of the explosive power. But should it have? At the time, I would say yes. The radioactive fallout of these ground bursts, even the peaceful ones, were causing environmental damages that will last for decades or longer. But, just as the treaty was being signed, scientists were making great strides toward clean nuclear weapons.
Clean nuclear weapons make use of the explosive power of the fusion stage of the weapon, and attempt to get rid of the radioactive metals of the fission stage. In theory, a complete fusion bomb would be potentially more powerful than the fission/fusion bombs of today, with complete control over the desired yield, and no radioactive fallout at all, which would allow clean surface and subsurface detonations.
In the 1970s, the Soviet Union attempted to create a canal joining two rivers. It was called the Pechora-Kama Canal, and they detonated three 15-kiloton weapons, each of which was reported to be 98% fusion and only 2% fission. This still wasn’t enough to avoid radioactive fallout though, as there is still some evidence today of radiation from the blasts. The danger is small, and people visit and live in the area without problem, but to ever have a peaceful nuclear program again would require 100% clean fusion bombs.
We’ll never be able to develop a pure fusion weapon with the current test ban treaties though, because development advances are only theory if the weapon can’t be tested and studied. And the Comprehensive Nuclear-Test-Ban Treaty prohibits all explosions of any type of nuclear device, fission or fusion, clean or dirty. That needs to be changed if we want to be able to ever harness the power of a clean nuclear detonation and use it for good.
On the flip side of the good of nuclear weapons, there have been some bad as well. Cobalt bombs, or salted bombs could be used for radiological warfare, designed to intentionally contaminate an explosion site with radiation, the sole purpose being to not allow humans to wait out the fallout in a bomb shelter. With a half-life of 5.27 years, the fallout of cobalt-60 would be dangerous for more than five decades using the 10 half-lives rule. This fear is what has driven many apocalyptic movies where you see radioactive wastelands. A nice plot for a movie, though there’s no evidence that any countries have actually produced and ever planned to use such weapons, although there is speculation that Russia did indeed have plans for similar devices, and may have even built some.
Another type of “bad” nuclear device, as I mentioned earlier, is the neutron bomb. A neutron bomb does the opposite of what most thermonuclear devices do; instead of trying to harvest the free neutrons and direct them back into the critical mass, the neutron bomb encourages their release out of the bomb. The casing of the bomb is made from depleted uranium, lead, or steel, all of which are translucent to neutrons. The explosion itself, without the addition of the free neutrons, is usually quite small, a fizzle compared to the explosions of today, but free neutrons are deadly to living beings. The massive neutron burst, which races ahead of the explosion, kills any humans or animals around. This type of bomb could be exploded above the heads of enemy troops, killing every person within a mile radius, but leaving the area fairly untouched by explosion. The neutrons are absorbed quickly into the atmosphere, and friendly troops could move right in.
With a neutron’s ability to pass right through steel and armor, even troops inside tanks or other armored vehicles would be killed immediately by the neutron bursts. An extremely effective but controversial bomb. If you’re interested in reading more about it, Wikipedia actually has a very informative page regarding the neutron bomb.
The radioactive fallout of conventional nuclear weapons is what led to their downfall, and rightfully so, considering the apparent complete lack of empathy employed by the superpowers during their production and testing in the 50s and 60s. The Nevada Test Site, which oversaw the detonations of 100 atmospheric thermonuclear devices (and an additional 828 underground detonations) often failed to completely consider fallout, or didn’t care to warn residents who were downwind of the explosions. This caused numerous and marked increases in cancers such as leukemia, bone cancer, brain tumors, and thyroid cancer in residents of St. George, Utah from the mid-50s into the 1980s, and caused a “significant excess of leukemia deaths” in children under 14 years of age. To date, nearly $2 billion has been paid out in compensation claims.
It is the combination of the real fears of nuclear annihilation from the Soviet Union during the cold war, in addition to the radioactive fallout experienced in the 100 above-ground tests at the Nevada Test Site and the atmospheric and ground tests at various atolls in the Pacific that have given nuclear weapons the chilling and almost universally feared name they have today. But, in my opinion, they don’t need to be so chilling. Conventional bombs are big enough today that they can compete with some of the smaller yield devices, and, clean nuclear bombs are a real possibility, with many, many uses that would greatly enhance the efficiency of any operation involving earth moving, mining, and tunnel drilling, as well as opening up possible space travel improvements. In order for this to ever happen, humankind needs to adjust its fears of the word, “nuclear.”
In part five of this paper, I’ll discuss North Korea’s specific nuclear program, what kinds of bombs they have, what types of delivery vehicles they have for those bombs, and how much fear Americans (and the rest of the world) should have about those bombs. I’ll also post the full bibliography and sourcing for this article.