The Ultimate Guide to Nuclear Weapons

as the blazing mid-day sun scorched the new mexico desert america's scientific elite gathered together to watch the assembly and installation of a strange-looking device the machine oppenheimer teller and fermi were there to see was code named gadget a two meter metal sphere that seemed to be growing cables from every orifice beneath its steel outer shell layers of explosive lenses and a uranium tamper sat a small core of just six kilograms of plutonium this grapefruit-sized metal sphere was enough to set the world on fire as the sweat drench team watched gadget was winched up a 100 foot tower the gravity of the moment was felt by all the culmination of the work of some 130 000 people over three years and billions of dollars of investment was slowly ascending that tower to everyone's horror gadget became unhinged and nearly fell but disaster was averted when a member of the crew stabilized it if the device failed much of that effort would have been for naught if it worked the most harrowing war in human history might be finally brought to an end the time for detonation was set at 4 am monday july the 16th 1945 however as hour approached a nearby thunderstorm delayed the test until 5 30. to cut the tension fermi began taking bets on whether or not the bomb would ignite the atmosphere and if so whether it would merely destroy new mexico or destroy the world oppenheimer was happy to wage 10 against george kistiakowski's entire month's pay that the bomb would not work at all as the final minutes ticked down most observers lay down on the desert floor to shield themselves from the blast despite the fact that the observation area was several miles from ground zero at precisely 5 30 the pitch black darkness was illuminated by a blinding light so bright that even to look at it would mean near certain blindness witnesses describe the surrounding hills as being as perfectly illuminated as if it were lit by the midday sun as the brilliant white light receded to a fiery orange the crowd rose to view a mile wide fireball rise silently into the desert sky beneath it a stem of dust and debris connected the rising cloud to the earth below the iconic phenomenon of a nuclear explosion as the onlookers began to cheer the shock wave reached them a deafening blast that carried loose paper several meters away the blast was so powerful that it knocked over a 200 tonne steel container that was over half a mile from ground zero oppenheimer one of the leading scientists in the manhattan project later recalling the moment quoted the hindu sacred text the bhagavad-gita now i am become death the destroyer of worlds humanity had now entered the nuclear era the power unleashed by the gadget device was preposterous despite only weighing a few tons in total with a core of just six kilograms of plutonium the trinity test unleashed an energy equivalent to twenty four thousand eight hundred tons of tri nitro toluene or tnt to put that into perspective an iron duke class battleship displaced around twenty five thousand tons of water at a light load in order to achieve the same energy release one would have to amass a pile of high explosives that weighed as much as a world war one super dreadnought battleship but how could such a thing even be possible what kind of demon hid inside that 6-inch sphere of radioactive metal that could destroy a whole city to understand nuclear weapons and what makes them so unfathomably powerful we have to not only examine how they work and how they kill but the fundamental constituents of matter and energy human warfare has been dominated by explosives for over 500 years black powder a combination of sulfur saltpeter and charcoal revolutionized combat allowing for the dominance of firearms and artillery the foundational arms of armies to this day black powder releases energy by rearranging chemical bonds it contains both fuel and oxygen which are both stored in solid form when ignited both are released simultaneously allowing an extremely rapid combustion to occur without the inclusion of external oxygen from the atmosphere this is called a deflagration this process rapidly converts all of the solid to a gas which as gases are far less dense than a solid generates a small area of extremely high pressure and temperature given the fact that a local area of high pressure will always move towards equilibrium this highly compressed hot gas expands extremely rapidly generating a highly destructive blast wave this phenomenon is exacerbated by explosives that combust at supersonic speed which are called high explosives c4 and tnt are two famous high explosives in simple terms chemical explosives rely upon the energy stored in chemical bonds chemistry is driven by the interactions of different molecules which are nothing more than the arrangements of different chemical elements such as carbon or oxygen that are bonded together in certain well-defined ways the smallest chemical element is an atom which are bonded together to form all of the molecules of the universe chemical bonds are driven by the interaction of an atom's electrons if two atoms share a value called electronegativity they will share electrons forming a covalent bond atoms with high electronegativity can become attracted to each other if they are of different electrical charge which creates ionic bonds typical high explosives leverage chemical reactions like combustion to unleash the energy stored in these chemical bonds by rearranging the molecular structure extremely rapidly nuclear energy is very different rather than relying upon the rearrangement of chemical bonds nuclear reactions leverage the forces that bind atoms together as stated previously molecules are arrangements of atoms however atoms themselves are simply arrangements of subatomic particles that are bound by their own nuclear forces an atom is made up of three foundational constituents protons and neutrons which are bonded to form a nucleus and electrons which orbit around the nucleus this view of the atom is highly simplified as according to quantum mechanics the electrons do not orbit the nucleus but rather exist in a cloud of possible locations that are governed by a wave function but for our purposes this newtonian view of the atom will suffice within the nucleus the protons and neutrons are composed of a more fundamental element called a quark three in each the proton which contains two up quarks and one down quark is positively charged the neutron as the name suggests has no charge and is therefore neutral and is composed of two down quarks and one up quark electrons are negatively charged the simplest atom is hydrogen which has a nucleus containing a single proton as the nucleus is charged it will attract a single electron making the atom as a whole electrically neutral the different chemical elements like helium oxygen iron and carbon are simply defined by the number of protons that are in the nucleus helium has two protons oxygen has eight the higher the atomic number the more protons an atom contains in addition to protons the nucleus of an atom can contain differing numbers of neutrons as neutrons are neutral the number of these has no effect on chemical reactions this means that a single chemical element like hydrogen can have different masses by having different numbers of neutrons accompanying the proton for example deuterium is simply hydrogen with one additional neutron and tritium is hydrogen with two neutrons water that is composed of oxygen and deuterium is called heavy water for this reason oxygen as an example has three primary isotopes the most common of which is oxygen 16 which contains eight protons like all oxygen atoms and eight neutrons unlike the bonds of chemistry that rely on electromagnetism the nucleus is held together by the strong nuclear force one of the four primary forces of nature this is the interaction that binds up and down quarks together and this force leaks out of the protons and neutrons to bind them as well the strong force is strong really strong over the size of an atomic nucleus it is 137 times stronger than electromagnetism it is much stronger than that within a proton or a neutron but much of this force is cancelled out within the particle itself and thus only a small residual amount escapes to bind the atomic nucleus together despite its strength the strong force is extremely short-ranged subatomic particles will only feel its effect if they are extremely close together just as chemical explosives leverage chemical reactions like combustion nuclear explosives rely on nuclear reactions sometimes one chemical element will change into something else when this happens by itself we call this process decay generally speaking atoms will always change into something more stable and in undergoing that transformation they will release radiation this is why this process is called radioactive decay there are two other relevant nuclear reactions fission and fusion fission occurs when a very heavy atom such as uranium splits into smaller pieces usually two halves each of which will now become a new lighter atom when a heavy atom undergoes fission it releases a significant amount of energy in the form of radiation and kinetic energy fission can be triggered by hitting a heavy atom with a neutron however it can also occur spontaneously as a result of radioactive decay the other type of nuclear reaction is fusion this occurs when two very light atoms such as hydrogen fuse together to form something heavier such as helium in order for fusion to occur the two atomic nuclei have to get close enough to feel the strong force's attraction but in order to do so they have to overcome the electromagnetic repulsion felt by two bodies of the same charge this means enormous temperatures and pressures are required to initiate fusion this reaction also releases vast amounts of energy and it is the very mechanism that powers the sun so by rearranging subatomic particles to create new atoms rather than rearranging atoms to create new molecules nuclear explosives leverage a force of nature that is well over 100 times stronger than their chemical counterparts when we account for just how many more atoms there are than molecules this leads to reactions that are tens of thousands of times more energetic as an example of just how much energy is released in a nuclear reaction if just one kilogram of uranium undergoes complete fission this will release the same energy as 17.5 kilotons of tnt because of how difficult it is to initiate fusion the first nuclear bombs relied purely on fission as a nuclear reaction nuclear energy whether it is released in a nuclear reactor or an atom bomb rests on the fact that when some atoms undergo fission they release more neutrons than they absorb if enough neutrons are released this allows the possibility of a chain reaction one atom is hit by a neutron and splits releasing two more neutrons if these hit another nucleus these will in turn undergo fission releasing four additional neutrons which can then go on and hit more atoms this is called a chain or self-sustaining reaction a nuclear power plant is simply a very well controlled chain reaction that occurs very slowly releasing energy in a predictable and manageable way but when this chain reaction occurs in a highly compressed pit of fissile material it can happen extremely quickly releasing an ungodly amount of energy in the process nevertheless there are a few problems the first issue is the fact that there are very few chemical elements that can sustain a chain reaction or to be more precise only a small number of isotopes of these few chemical elements uranium is the heaviest natural chemical element that is reasonably abundant on earth but the vast majority of it is incapable of sustaining a chain reaction over 99 of all known uranium deposits are u-238 which can undergo fission if hit with a fast neutron but won't release enough neutrons to sustain a chain reaction the only naturally occurring fissile isotope is u-235 which accounts for just 0.72 percent of all uranium these two isotopes are evenly mixed throughout the world uranium deposits the reason there is so much less u-235 the new 238 is because it has a significantly shorter half-life making it a little more radioactive most of it has simply decayed extracting u-235 from u-238 a process called enrichment is an extremely difficult engineering challenge because both are isotopes of uranium you cannot use chemistry to do it generally speaking enrichment processes rely on the minute difference in weight between the two isotopes in order to separate them in 1944 uranium tetrachloride a chemically stable form of uranium was heated until it formed gas ionized and then spun in an electromagnetic field the heavier u-238 ions would then be pushed to the outer edge of the container separating the isotopes gaseous diffusion was another method utilized but today centrifuges are used for this purpose enrichment is an expensive and extremely time consuming process in order to achieve a nuclear detonation the fuel has to be enriched to 90 percent uranium-235 which means removing the vast majority of the u-238 from uranium ore the waste product of this process which is just u-238 is called depleted uranium because of its immense density and low radioactivity depleted uranium makes excellent armor and armor penetrators this whole process made up the vast majority of the manhattan project's cost over 30 000 people worked at the massive enrichment plant at oak ridge tennessee and after two years of effort they only had enough u-235 to make a single nuclear weapon nonetheless there are other ways to create fissile material although uranium is the heaviest widely occurring natural element that exists on earth heavier atoms can be created in a nuclear reactor these elements are called transuranics and include neptunium plutonium americium californium and even einsteinium which was named after albert einstein some of these heavier elements which contain more protons than uranium can sustain a fission chain reaction in exactly the same way as u-235 and it is for this reason that plutonium has become famous reactive fuel has to be enriched in the same way as the uranium used in a nuclear weapon but to a much lower degree in fact some reactor fuel may only contain five percent u-235 meaning the majority of the fuel is still u-238 when a nuclear reactor is operational and fission is occurring copious amounts of neutrons are produced occasionally one of these will hit a u-238 atom and when this happens there is a reasonably good chance that said neutron will simply be captured because we just added an additional neutron to the nucleus this creates an isotope called u-239 but u-239 is very unstable it rapidly undergoes a pair of base decays in which one of the atom's neutrons turns into a proton emitting an electron in the process as this changes the number of protons a heavier element is created first u-239 changes into neptunium-239 which then rapidly undergoes the same process and decays into plutonium-239 all of these isotopes have the same mass it's just that the numbers of protons and neutrons have changed creating plutonium in a nuclear reactor essentially alleviated the requirement to undertake extremely difficult and expensive isotopic separation because plutonium is a different chemical element it can be separated from the uranium fuel by a simple chemical reaction greatly reducing the cost of nuclear weapon production plutonium-239 is also a superior fissile material compared to u-235 it has a higher chance of undergoing a fission when hit with a neutron and releases more neutrons per fission meaning you need much less to achieve critical mass the only issue with plutonium is an isotope called plutonium-240 which can be created when plutonium-239 absorbs a neutron plutonium-240 is a poison for nuclear weapons it is highly radioactive making it dangerous to work with it is also prone to spontaneous fission making a weapon likely to detonate with a sub-optimal yield something called a fizzle for this reason weapons-grade plutonium is defined by the amount of plutonium-240 it contains below seven percent for military purposes typically spent fuel that has been in a nuclear reactor for three years will contain around 40 plutonium-240 making it very unsuited to use in nuclear weapons military breeder reactors will typically only expose the fuel for three months limiting plutonium-240 production the tendency of even a small amount of plutonium-240 to create a fizzle event has significant consequences for nuclear weapon design a key concept to understand in nuclear engineering is something called a critical mass in essence this is the amount of fissionable material required to achieve a chain reaction basically even if you successfully start a fission or one just happens due to decay and two or three neutrons are released if there aren't enough other nuclei around the chances of getting another hit will be less than one making a chain reaction impossible this is called a subcritical mass however if you pile up enough visual material in one place the chances of getting a hit with each neutron release will be greater than one simply because there are more fissile atoms around meaning for every fission event you get at least one other fission for u-235 a critical mass for a sphere at normal density is about 47 kilograms in weight for plutonium-239 the same sphere needs to be about 10 kilograms there are two primary methods by which a critical mass can be reduced the first is by using neutron reflectors if you surround the core with a substance that will cause neutrons to bounce off it like graphite you effectively double the chance that any neutron will hit an atomic nucleus before it escapes the other way to reduce the critical mass is by compressing the material if you bring the uranium or plutonium atoms closer together effectively making the material look thicker to a neutron you also increase the chances of scoring a hit in the simplest of terms nuclear weapons work by taking a sub-critical mass of fissile material and making it critical as fast as possible obviously if one were simply to make a critical mass by piling up enough u-235 you would not accomplish anything other than your own annihilation there are a couple of ways to do this the first is to take two subcritical masses that are large enough that they would be critical if they were in the same place and simply bring them together this was the design used by the hiroshima bomb the first nuclear weapon used in war code named little boy this device used a gun barrel to bring two chunks of highly enriched uranium together inside the bomb sat a smooth bore artillery barrel that was 1.8 meters long and 165 millimeters or six and a half inches wide at one end sat the target a small four inch wide and seven inch higher cylinder of highly enriched uranium that weighs some 25 kilograms at the other end in front of a high explosive charge was the projectile a cup-shaped mass of uranium that was backed by a tungsten carbide pusher when the weapon was detonated the explosive charge accelerated the 38 kilogram projectile down the barrel at several hundred meters per second the target and projectile were designed so one would fit inside the other rapidly creating a supercritical mass at the base of the weapon the uranium target was surrounded by a tungsten carbide tamper a tamper is a critical element in nuclear weapon design essentially just a very dense material that surrounds the core a tamper significantly improves the efficiency of their weapon by slowing down its expansion during detonation allowing for additional chain reactions before the bomb blows itself to pieces this tungsten carbide tamper also acted as a neutron reflector the gun type is by far the most simple form of nuclear weapon design it is essentially foolproof it was deemed to be so reliable that no full scale test of the little boy weapon was required although there was only enough weapons-grade uranium for a single device anyway an indication of just how difficult uranium enrichment is nonetheless this kind of design has many significant limitations the first is its very low efficiency despite being accelerated down the barrel at hundreds of metres per second it is very hard to avoid the initiation of the nuclear detonation before the two halves have completely integrated a key challenge in nuclear weapon design is the fact that a supercritical mass will instantly want to blow itself to pieces stopping the chain reaction if this happens too quickly the yield will be low causing a fizzle even in the most efficient weapons only a fraction of the fuel undergoes fission the problem with the gun type weapon is fission will virtually always initiate too early leading to low yields little boy contained 64 kilograms of fissile material nearly three critical masses when you account for neutron reflection yet only one kilogram of uranium actually underwent fission generating a yield of some 16 kilotons this issue also means a gun type design is unsuited to plutonium even weapons-grade plutonium contains a small amount of plutonium-240 because this isotope constantly emits significant levels of neutron radiation it will almost certainly cause a fizzle leading to a very low yield to avoid these limitations the manhattan project scientists leverage the other way you can safely turn a subcritical mass of plutonium supercritical compression but how do you highly compress one of the densest metals that exist well you can use high explosives basically if you take a sphere of plutonium and surround it with a larger sphere of explosives you can compress the metal enough to make it supercritical but this is far more difficult than it seems firstly you have to use something called an explosive lens which is a specially shaped blend of different explosive compounds that is designed to focus the shock wave in the same way as an optical lens focuses light the plutonium core has to be surrounded by these lenses which all have to be detonated within milliseconds of each other if the detonation is not nearly simultaneous the core will not be sufficiently compressed leading to a fizzle or even a non-detonation the electronic requirements of an implosion design were absolutely state of the art in 1945 it was just barely possible given the technology of the age the gadget device which was all but identical to the fat man bomb dropped on nagasaki was a highly complex machine at its core was a plutonium pit that was just over nine centimeters or three inches in diameter and weighed 6.1 kilograms made up of two hemispheres the plutonium pit contained a small initiator at its center an urchin made of beryllium and polonium this initiator would release a powerful burst of neutrons when crushed aiding in the detonation process encasing the pit was a 13 centimeter thick tamper that weighed some 111 kilograms unlike the little boy weapon which could not permit any stray neutrons near the target this tamper was made out of depleted uranium not only would this very dense metal slow down the explosion but u-238 is also capable of undergoing fission if struck by a high energy neutron meaning the bomb as a whole would have a greater yield in fact about 30 of the total energy came from the fission of the uranium tamper outside of this metal sphere 32 explosive lenses were arranged to form an even larger 1.5 meter sphere when triggered the weapons electronics initiate the explosive lenses through exploding wire detonators which had to be invented for the project as the nearly two tons of high explosives detonate a supersonic blast front is formed and focused by the shape of the charges compressing the plutonium pit with the core rapidly becoming supercritical it is showered by neutrons from the initiator at its center which augment the constantly occurring natural fissions these reactions happen extremely quickly a generation of fissions occur roughly 100 millionth of a second or 0.01 microseconds from a single neutron it will take 51 generations of fission reactions to generate a 0.1 kiloton yield however because of the exponential growth in the number of neutrons with the number of reactions more than doubling every generation 100 kilotons is achieved in just 58 generations this means that the vast majority of the energy generated is released in the last seven generations or about .07 of a microsecond at this point despite the influence of the heavy tamper the temperatures inside the weapon are so high that the atoms of plutonium begin to move away from each other at tremendous speed ending the reaction the fat man proved to be a far superior weapon designed to the little boy despite using just six kilograms of fissile material compared to 64 which was the much easier to produce plutonium-239 it generated a significantly larger yield of just over 20 kilotons about one kilogram of plutonium underwent fission generating a yield of roughly 15 kilotons achieving a 16 efficiency this was the same amount as little boy however that weapon utilized 10 times more fissile material additionally the ability to use a depleted uranium tamper added another five to seven kilotons the little boy was also a seriously unsafe weapon once the cordart charge was loaded if it detonated for any reason a full yield explosion would inevitably result additionally as there were two subcritical cores present even if the bomb was dropped from an altitude of 15 000 feet without being armed the impact of hitting the ground would have been enough to cause a serious nuclear detonation a similar threat was present when flying over water the sheer volume of fissile material nearly three critical masses meant that if seawater entered the weapon it would act as a moderator slowing down the neutrons and making fission more probable this alone could make the weapon super critical none of these issues were present with the fat man design even if one or more of the explosive lenses exploded prematurely this would not cause a nuclear detonation only the very precise simultaneous detonation of all 32 lenses would generate the required compression of the pit this is basically impossible unless you mean to do it additionally because this simply isn't a critical mass of plutonium unless it is compressed none of the other risks are really a factor in essence the implosion mechanism remains the same for all modern nuclear weapons to this day the fat man design became the mainstay of the first generation of both american and soviet nuclear weapons as the first soviet bomb was based on technical information provided to the kgb by los alamos scientist klaus fuchs and was thus a direct copy this design led to the mark iii and mark iv freefall bombs which could achieve yields of between 1 and 30 kilotons depending on the type and size of the pit installed in the weapon by the early 1950s research began into incorporating the fusion reaction into nuclear weapon design even in the 21st century a fusion reaction is extremely difficult to initiate and sustain but with working fission weapons the requisite temperatures and pressures could now be reached one of the first ways this new reaction was implemented was through a process called boosting a term coined by edward teller in this process a very small amount of heavy hydrogen isotopes tritium and deuterium were injected into the centre of an enriched uranium pit of an implosion bomb when the fission reaction began the deuterium and tritium were exposed to unimaginable pressure enough to initiate fusion converting both into helium-4 the additional blast yield from this reaction was minimal however the deuterium tritium reaction releases a vast number of fast neutrons with this shower of additional neutrons flowing through the core the number of fissions that occurred before the bomb blew itself to pieces was vastly increased this improved the efficiency of the weapon doubling the amount of material that actually underwent fission the boosting technique was first tested during operation greenhouse in 1951 shot item was the first demonstration of a boosted weapon just via this technique the yield of the bomb was doubled to 45.5 kilotons with the success of the greenhouse item test which had demonstrated that the detonation of an atom bomb could produce the required conditions to initiate nuclear fusion work began on a device that could create fusion on a much larger scale fusion is a highly attractive nuclear reaction wait for weight the fusion of deuterium nuclei produces nearly three times as much energy as the fission of uranium or plutonium the critical development was the immensely high temperatures generated by a runaway chain reaction this is why devices that generate large fusion reactions through high temperatures are called thermonuclear weapons the more colloquial name is the hydrogen bomb as the ordinary fusion fuels deuterium and tritium are isotopes of hydrogen by 1952 work was well underway on the development of a thermonuclear device the main challenge was developing a form of deuterium and tritium that was stable in a solid form as both are gases at normal temperatures and pressures edward teller known as the father of the hydrogen bomb and other scientists at the u.s atomic energy commission decided upon a proof of concept his configuration for a thermonuclear weapon called a tele-ulam design uses the energy of a fission bomb the primary to compress and heat the secondary a container of fission fuel the immense heat generated in the secondary then causes a large number of fusion reactions to occur greatly increasing the yield of the weapon because the fusion reactions generate neutrons of extremely high energy these can be used to initiate fission in u-238 meaning a tamper made out of natural uranium will increase the blast yield further therefore most hydrogen bombs are more correctly described as fission fusion fission weapons typically fission and fusion account for roughly equal amounts of the yield the exact process which leads to the compression of the secondary is still a matter of conjecture but the most likely explanation is tamper ablation when the primary detonates an enormous amount of high energy x and gamma ray radiation is released this heats the outer shell of the tamper to such a high temperature that it evaporates which accelerates the tamper inward compressing the fusion fuel the first major challenge in the development of the hydrogen bomb was the hydrogen itself deuterium and tritium are gases and tritium is both radioactive and has a reasonably short half-life but for a proof of concept it was decided to simply use liquid deuterium which had to be cooled to cryogenic temperatures the first shot of operation ivy undertaken in the pacific proving ground the ib mic device was therefore not a deliverable weapon it weighed some 74 metric tons the device was encased in a six metre high two meter wide steel tube with 30 centimeter thick walls this assembly which itself weighed some 49 tonnes would then be filled with liquid deuterium at the top of the tube sat the fission primary the mach 5 fission bomb a more efficient version of the fatman device with a composite plutonium uranium pit the primary and liquid deuterium were separated inside the device itself with the secondary surrounded by 4.5 tons of natural uranium which acted as a tamper to support the refrigeration equipment a 3 000 kilowatt power plant was installed and the whole assembly was housed in a 20 meter high building called the shot cab it really was more of a nuclear installation than a nuclear weapon the energy released by ivy mike was truly terrifying mere moments after detonation a three mile or five kilometer wide fireball engulfed the test island triggering lightning strikes and sending detectable shock waves around the earth the mushroom cloud rose to an altitude of 50 000 feet in just 90 seconds on board ship the observers from the naval task force were shocked by the heat radiated from the fireball one described it as frightening despite being stationed some 40 miles away 30 minutes after detonation the diameter of the mushroom cloud was 60 miles and it only stopped rising once it hit the tropopause at an altitude of 120 000 feet all that was left of the test site was a 1.9 kilometer wide crater later calculations placed the yield produced by ivy mike at 10.4 megatons of tnt ten million four hundred 000 tons of tri nitro toluene to put that into perspective the great pyramid of giza weighs approximately 2.3 million tons thus to make an explosion as powerful as mike you would need to make four piles of high explosive as large as the great pyramid humanity truly had entered a terrifying new technological age with this horrifying demonstration of the destructive potential of thermonuclear weapons the species itself now possessed the technology required to commit autogenocide but iv mike was never really designed to be a deliverable weapon and although a number of weapons were jury rigged together called the mark 16 nuclear bomb these were immensely impractical somehow a solid fusion fuel had to be developed in order to allow for the deployment of practical deliverable thermonuclear weapons an answer was found in the chemical element lithium it was well known that when the isotope lithium-6 is hit with a neutron it can undergo fission it is the only light element which can do so but the energy released in this process is much smaller than uranium but of more interest is lithium-6's fission products helium and tritium the ability to create tritium by exposing lithium-6 to the intense neutron radiation of a fission bomb detonation was the key breakthrough in hydrogen bomb design all that was required to sustain fusion was the deuterium which was simply chemically bonded to the lithium atom to create lithium deuteride much like lithium hydride lithium deuteride is a stable inert inorganic solid at room temperature it has a melting point of nearly 700 degrees celsius and is not radioactive just as black powder contains everything required for a deflagration in a single stable solid both the oxidizer and the fuel so had teller's team forged a fuel that contained deuterium and tritium in a solid inert form the first test of a solid-fueled thermonuclear device was set for march the 1st 1951. codenamed castle bravo the shot would be detonated at the pacific proving ground on bikini atoll the device itself called the shrimp was much smaller than the ivy mic design it weighed just over 10 tons the fission primary was a variant of the compact mark 7 bomb which when boosted produced a yield of 60 kilotons the secondary was formed by a cylinder of lithium deuteride containing both a fission spark plug at its center and a natural uranium tamper surrounding the fusion fuel the spark plug was a critical element in achieving a good fusion burn essentially a rod of weapons-grade plutonium as this underwent compression it would become critical creating a fission explosion within the fusion fuel this would act as a source of internal pressure compressing the fuel against the imploding tamper and showering the lithium with high energy neutrons this whole assembly was housed in a radiation case a one inch thick solid aluminium cylinder the radiation case was designed to reflect the initial burst of x-rays confining it for as long as possible and directing its energy towards the fusion secondary the space between the primary and secondary was filled with a form of polystyrene foam which would instantly turn into a low z plasma allowing for a smooth transfer medium for the x-ray radiation the yield of the weapon was designed to be about 5 megatons however castle bravo seriously over-performed lithium has two stable isotopes lithium-6 and lithium-7 lithium-7 is by far the most common on earth and it made up about 60 of the lithium in the fuel under normal circumstances when hit with a neutron a lithium-7 atom will absorb it and decay into beryllium-8 adding nothing to the reaction what no one knew at the time was that when hit by neutrons with the kind of energies present in a nuclear detonation lithium-7 will also undergo fission producing both tritium and more neutrons this caused a cascade of effects as the lithium-7 as well as the lithium-6 began to produce tritium the total amount of fusion reactions more than doubled greatly increasing the amount of energy released additionally the higher neutron flux caused by the fission of the lithium-7 and the additional fusion reactions bombarded the uranium tamper with far more neutrons than expected which led to much more fission in all these processes generated a yield of 15 megatons quite literally 1 000 times as powerful as the little boy bomb dropped on hiroshima as soon as the device was detonated the control crew knew something went wrong the shot was fired from a concrete bunker located on any island at the other end of the atoll some 38 kilometers away when the ground shock hit it was so powerful that standing was impossible as a result of the overpressure water surged out of the toilet and behind the control panel the fireball was unimaginably huge measured at some seven kilometers in diameter it was so bright that it was instantly visible on neighbouring wrong lap atoll on board the japanese trawler fukuyumaru one of the sailors remarked that the sun rises in the west around the control bunker all above ground buildings had been flattened by the blast wave as onlookers on board the navy task force watched the colossal mushroom cloud rose rapidly into the sky ballooning to over 100 kilometers in diameter soon it began to snow the tiny white flakes of ash raining down on them and geiger counters rapidly clicking the task force steams south at full speed castle brabo was a particularly dirty bomb producing extremely high levels of fallout for reasons that will be described later the combination of high levels of fission in the uranium tamper and sea level detonation generated a massive and deadly fallout plume this was complicated by a misreading of high level winds in the control bunker the scientific team led by dr felt soon began to detect an alarmingly rapid increase in radiation levels outside as the radioactive ash began to fall around them like a heavy snowfall radiation levels inside the bunker began to rise despite being in a concrete building the team was forced to move from room to room to find one with safe radiation levels they were all forced to cram into a data processing room that happened to have a large amount of sand above it about 12 hours later once the outdoor radiation levels had dropped significantly the team were rescued by a helicopter none received a dangerous level of radiation exposure about an hour after the blast radiation levels were so high that anyone outside would have received a fatal dose as the deadly cloud was blown to the east the japanese fishermen on board fukuyumaru had no idea of the dangerous situation they were now in blanketed by fallout all received a dangerous dose of radiation inducing burns and radiation sickness one sailor died the test forced the evacuation of several neighboring atolls despite the dangerous over-performance of the device castle bravo was a foundational step in thermonuclear weapon development not only was a solid field hydrogen bomb now technologically demonstrated but the possibility of using the much more common lithium-7 isotope as a fusion fuel had been discovered something that would have remained a mystery without a full-scale test within months the united states had fielded a number of operational multi-megaton thermonuclear devices beginning with the mark 17 and mark 24 freefall bombs the latter of which demonstrated a yield of just over 13 megatons despite its high yield the mark 24 weighed a colossal 19 tons severely complicating delivery essentially only the american super heavy bombers could employ the weapon the american family tree of super hydrogen bombs reached its apogee with the b-41 a three-stage weapon the 10-ton b-41 had a maximum yield of 25 megatons almost twice the energy achieved by castle bravo the weapon entered service in 1963. as much as the americans had been the pioneers of hydrogen bomb development it was the soviets who took the super yield thermonuclear weapon to its zenith castle bravo was a two-stage device meaning a boosted fission primary bomb was used to compress a fusion secondary stage this is the foundational design for all thermonuclear weapons nevertheless there is no reason why you cannot add a third stage for even more yield in a three-stage design a fission primary compresses the fusion secondary which then compresses another fusion stage this design was realized in project 202 which had a stated objective of developing a deliverable nuclear device with a yield of 100 megatons this device was known to its developers as the tsar bomber or the emperor of bombs tsar bomber had three stages the first was a fission bomb the second stage actually contained a pair of small fusion charges which were placed around the massive tertiary stage given how large the third stage was more energy was required to compress it to the requisite temperatures than the fission primary could provide the second stage by itself had a yield of around 1.5 megatons the detonation of the two secondary stages would provide so much radiation pressure that this would ignite the massive third stage lithium deuteroid was also used as a solid fuel tsar bomber had two yield settings depending on the configuration of the third stage tamper if this tamper were made of lead or another nuclear passive material the yield would be about 50 megatons however if the third stage's tamper was replaced with uranium-238 the yield was predicted to double it was decided to test the device in 1961. because of the potential for massive radioactive fallout the lower yield configuration was selected in any case the possibility of the delivery aircraft escaping a 100 megaton detonation was questionable the most remarkable thing about tsar bomba was the fact that it was air deliverable just in order to fit the 27 tonne device the tupolev tu-95 had to have its bombay doors and fuselage tanks removed still this feat stands testament to the skill and ingenuity of soviet engineering on october 17 the aircraft took off from its base on the kohler peninsula and headed for the arctic island of nevada zelmia after slowly climbing to an altitude of 34 000 ft by 1120 the target area came into view when released from the bomber the weapon deployed a large parachute a necessity if the crew were to have any chance of survival at 11 13 at a height of 4 000 meters detonation was initiated instantly a five mile wide fireball lit up the morning sky the blast wave was so powerful that it circled the earth three times severni an uninhabited village was flattened by the blast wave it was 55 kilometers from ground zero the device produced so much thermal radiation that it would have inflicted third degree burns on any exposed individual at a range of 100 kilometers despite the colossal yield of the weapon and the gigantic 95 kilometer wide mushroom cloud radioactive fallout was minimal in fact radiation levels were so low that within just two hours of the blast test crew were able to walk around ground zero this low radioactive impact and the marked difference to castle bravo are due to both the low levels of fission in the weapon and the use of an air burst these effects will be addressed in greater detail later as impressive as these mega hydrogen bombs are they really were not all that useful tsar bomber was never a practical weapon of war even the american 25 megaton b-41 which was the most efficient nuclear bomb in history when mass and yield are considered weighed some 4 500 kilograms realistically a 10 plus megaton explosion is really overkill for virtually all situations in which one might want to use a nuclear weapon and the costs you pay in mass and its impact on delivery systems are substantial most of these super hydrogen bombs had short service lives thus in the late 1960s and 1970s the emphasis of nuclear weapon design changed substantially it was realized that if you could use a thermonuclear reaction to make large bombs unfathomably powerful you could also use the same technology to make nuclear weapons much smaller and lighter while still having very significant yields for example the mark 13 bomb a fission weapon provided a yield of 30 kilotons it weighed just under 3 000 kilograms or 6 600 pounds but by utilizing the additional yield generated by a thermonuclear reaction the w58 warhead had an estimated yield of 200 kilotons despite weighing just 117 kilograms or 257 pounds about as heavy as a large man the w58 was just one metre in length this miniaturization meant that many more weapons could be delivered by a single system but it wasn't just thermonuclear weapons that underwent a process of miniaturization within the first five years of nuclear weapon development much smaller yield devices were produced for example the very early mark iv bomb which still used much of fat man's fundamental design had several low yield variants including one and eight kilotons this lower yield was achieved by utilizing a smaller plutonium pit both the soviets and americans quickly realized the limitations of high-yield weapons in battlefield applications when using a nuclear device tactically meaning targeting an enemy's military forces whilst they are deployed and therefore actually in the battle space lower yield weapons are far more useful even 20 or 30 kilotons may pose significant risks of not only collateral damage to nearby civilian infrastructure and population but your own forces the thing about battle is typically friendly formations will be operating in close proximity to the enemy making a one megaton weapon essentially useless this led to a divide between tactical and strategic nuclear weapons in simple terms tactical weapons are designed to be used on the battlefield to engage military targets in close proximity to your own forces they are designed to win battles strategic nuclear weapons were designed to destroy your enemy's ability to wage war itself either by destroying their critical military infrastructure in their home area or at the most extreme case by striking their population centers and economic assets in the early to mid cold war tactical nuclear weapons were generally speaking smaller lighter devices with a yield that was less than 20 or 30 kilotons although when defining a nuclear weapon as tactical or strategic there is no hard line when it comes to yield some weapons can serve in both roles what really makes tactical weapons different is their method of delivery modern battle is fluid opportunities for the employment of a nuclear weapon on the battlefield may be fleeting as an example as a nato corps commander you may only have an hour or two's warning that the soviet armoured division has concentrated its forces for an attack therefore these small light weapons with low enough yield that they can safely be employed in close proximity to your own forces need to be delivered by systems that are flexible and responsive icbms generally speaking are not great delivery systems for tactical weapons because of the complex command and control arrangements that makes platforms like tactical fighters short-range ballistic missiles and artillery perfect delivery systems for tactical nuclear weapons the most famous tactical nuclear weapon is probably atomic annie an 11-inch artillery system that fired a 15 kiloton warhead tested during operation upshot knothole grabel annie produced some of the most iconic nuclear test footage ever made once you imagine the possibility of a tactical nuclear war where both sides refrain from striking each other's major cities or critical infrastructure then the utility of nuclear weapons on the battlefield becomes readily apparent because of their very large area of effect in comparison to conventional explosives even low-yield nuclear weapons can be of great utility simply by improving the accuracy of your systems or rather by mitigating a lack of accuracy obviously the impact of a 10 or 15 kiloton blast on a land battle is not hard to appreciate but nuclear weapons are just as useful in air or naval battle take submarine warfare as an example if you have detected a submarine but you have not been able to fix or track it meaning you know it's there but you don't know exactly where it is you can't engage it effectively with conventional weapons but if you have a nuclear depth charge like the 10 kiloton w44 nuclear asrock you will likely sink any submarine in a 3 000 meter radius the same principle applies to surface-to-air missiles hitting a high-flying bomber is difficult with 1960s error technology especially considering their defensive electronic warfare capability now imagine trying to stop dozens of them all of which may be carrying nuclear weapons well if you equip your nike hercules with that 20 kiloton nuclear warhead you only have to get a single missile within a thousand meters of the formation perhaps the most iconic tactical nuclear weapon was the m28 davy crockett weapon system one of the smallest nuclear weapons ever fielded essentially a nuclear recoilless rifle the davy crockett had a range of about two miles or three kilometers it fired the m388 nuclear round the warhead weighed just 34 kilograms it was about the size of a large briefcase or watermelon a pure fission weapon when detonated the m388 provided a yield of 22 tons of tnt equivalent as with all low yield nuclear weapons for reasons that will be discussed later the bomb's radiation was its most lethal feature specifically its neutron flux all personnel within a 150 meter radius would have become instant radiation casualties with most dying within a period of minutes outside of that lethal radius radiation casualties would reduce with distance although many within 200 meters would have died later from radiation exposure blast effects would have been substantial over a 100 meter radius the weapon was designed to be used in key defensive areas such as the folded gap davy crockett batteries would saturate these natural choke points with small nuclear blasts creating a radioactive barrier through which soviet forces would have to pass the miniaturization of nuclear weapons which was the prevalent trend throughout the last half of the cold war also led to the development of variable yield devices commonly called dialer yields this feature allows the user to drastically change the explosive power of the weapon with the mere flick of a switch the second generation of nuclear weapons such as the mark iv also had multiple different yields but these were determined by the size of the plutonium pit that was physically placed in the bomb prior to delivery but the development of small thermonuclear devices allowed for much more flexibility take the american b61 freefall nuclear bomb depending on the model the b61 has a number of different possible yields ranging from 0.3 of a kiloton to 400 kilotons for example the mod 3 bomb reportedly has 4 yield settings 0.3 1.5 10 and 170 kilotons to change the yield all an operator has to do is adjust the settings of the weapon prior to the mission no internal components have to be replaced dialer yield works by deliberately causing the weapon to malfunction at different stages of the process or in other words by intentionally causing a fizzle for the mod 3 bomb the full yield is 170 kilotons but we can surmise that the 10 kiloton setting is simply the yield produced by the fission primary by changing the internal geometry of the weapon the secondary will not be properly compressed preventing ignition the lower settings are achieved by intentionally causing the primary to fizzle either by not boosting the weapon or by varying the neutron reflectors and ignition timing to only generate a partial detonation this allows for great flexibility in the utilization of a nuclear stockpile a single weapon such as the sub 1000 pound b61 can be used to strike many different kinds of targets which require different yields this makes them useful in both the tactical and strategic roles most modern nuclear weapons include a variable yield function both the united states and soviet union invested heavily in tactical nuclear weapons which made up a large portion of their massive 30 000 weapon plus stockpiles nevertheless many have argued that even the smallest use of nuclear arms would inevitably result in total nuclear annihilation meaning a tactical nuclear war is quite literally impossible however the inevitability or not of this proposition remains unsolved obviously the employment of small yield tactical nuclear weapons against military targets poses a very significant risk of escalation to the strategic level nonetheless like many things in history perhaps we should not treat this kind of escalation as inevitable historically there have been other norms that have held in war during the second world war all of the major powers possessed vast chemical weapon stockpiles by the development of nerve agents like sarin germany had achieved a technological lead although britain had large stockpiles of mustard gas despite the ability of both sides to use chemical weapons on enemy population centers and despite the fact that all sides were engaged in a total war one in which national survival was at stake neither the germans nor the western allies nor the soviets employed these devastating weapons indeed although there were instances of chemical weapon attacks on the chinese chemical weapons were not used in the pacific theater either even though japanese and german cities were being turned into rubble by allied bombers they still refrained from using this most terrible of weapons for fear of retaliation in kind when it came to chemical weapons a form of mutually assured destruction existed this historical episode should guide us when we consider the employment of nuclear weapons clearly if the major powers could refrain from employing chemical weapons in a total war then we should conclude that it is at least possible for a war between nato and the soviet union to have involved only a limited nuclear exchange certainly both powers had to be prepared for that possibility which is why they invested so heavily in low-yield tactical weapons in many ways the ballistic missile revolutionized the nuclear bomb at least in the strategic role indeed an evaluation of the nuclear weapon itself is incomplete without considering its method of delivery after all a 100 megaton hydrogen bomb is perfectly useless if it cannot be delivered to the target throughout the first decade of the nuclear age the immense weight and size of nuclear weapons meant the heavy bomber was the only practical delivery system giving the united states a significant advantage throughout the 1950s nonetheless the soviets were about to change the game on the 12th of september 1960 the r7a was declared operational with a total range of over 9500 kilometers this liquid-fueled rocket could launch a nuclear weapon directly from the soviet union to north america the intercontinental ballistic missile was born by the mid-1960s both the united states and soviet union had a significant icbm capability especially with the introduction of the american minuteman 1 solid fuel missile in 1962 and the soviet r-16 a few months earlier both powers were now faced with the possibility of a massed intercontinental ballistic missile strike within 40 minutes from the order to launch dozens of thermonuclear warheads could be impacting all over the country this was especially concerning if an enemy launched an attack on your nuclear capability with such unimaginable offensive firepower available your entire nuclear arsenal could be wiped out in a matter of hours strategic bomber air bases icbm missile silos command-and-control facilities and nuclear stockpiles these could all be struck with three to five megaton nuclear weapons in a matter of minutes such an operation is called a counter force nuclear strike and icbms made it a realistic possibility such a capability was very destabilizing if either side thought they had a realistic chance of effectively crippling the other's nuclear capability the chances of a nuclear war grew substantially in essence the icbm incentivized both sides to strike first although our counterforce strike somehow seems less morally challenging than targeting enemy population centers which is called a counter value attack the level of collateral damage would still be enormous striking enemy missile silos which are hardened underground structures requires powerful surface bursts in the united states these are located in montana colorado and north dakota the resulting fallout which would disproportionately impact the midwest would lead to millions of casualties this threat of a successful counterforce nuclear attack carried out by intercontinental ballistic missiles led to the development of something called the nuclear triad although the origin of the nuclear triad can certainly be partially explained by inter-service rivalry as both the u.s navy and u.s air force fought for the primacy of their own nuclear delivery systems it soon became the cornerstone of u.s strategic deterrence the u.s nuclear triad included icbms that were fast and accurate strategic bombers that were flexible and nuclear submarines that were survivable the primary idea was to ensure that a soviet counterforce strike would not be successful by diversifying launch platforms and keeping both submarines and bombers constantly deployed to fulfill this requirement throughout the 1960s u.s strategic air command kept 12 flights of nuclear-armed b-52s constantly airborne code-named operation chrome dome this ensured that even if air bases were struck by icbms a significant amount of strategic air power would be able to rapidly respond it also improved the united states first strike capability the final element in the nuclear triad were the united states navy's george washington class nuclear submarines which deployed the polaris ballistic missile with a range of nearly 5 000 kilometers and equipped with three w-58 200 kiloton warheads each polaris missile could devastate the city however the weapon lacked the accuracy to hit point targets with a circular error probable of some 900 meters this meant the polaris was only really a counter value weapon designed to target enemy population centers making it a second strike weapon having three 200 kiloton w58 warheads allowed for much greater destruction of value targets than the single w47 600 kiloton device this is because of the way blast scales which is different to the destructive radius blast energy is expanded in three dimensions but a city is basically a two-dimensional object therefore by hitting a soft target like a city with three smaller warheads a far greater area will be subjected to higher blast overpressures increasing the total damage inflicted in effect a larger area would be closer to one of the three smaller epicentres with such a capability hidden under the oceans a first strike would hopefully be perpetually deterred because of their inherent stealth and survivability the ballistic missile submarine remains the premier arm of strategic nuclear deterrent the united states russia china great britain france and india currently deploy nuclear weapons on ballistic missile nuclear submarines with the next generation of missiles such as trident they also became a potent first strike weapon the trident d5 has a range of more than 12 000 kilometers and delivers a payload of 14 warheads or dummies over that distance although it is limited to 8 warheads by treaty currently armed with the 475 kiloton w88 nuclear warhead the trident can attack eight individual target sites over a very wide area perhaps a thousand kilometers this is called a multiple independent reentry vehicle or mirv capability and it is the current state of the art in ballistic missile nuclear delivery systems russia china great britain and france field merv capable systems with the gps guided mark v re-entry vehicle the weapon has a cep of just 90 meters making it 10 times more accurate than polaris each ohio class submarine deploys 24 trident ballistic missiles which could potentially field 192 w88 warheads providing a combined yield of 91 megatons although in reality the smaller 100 kiloton w76 is probably deployed in large numbers there are 14 ohio-class ssbns currently operational russia has a comparable capability with its typhoon and borree classes it is a truly awesome and terrifying concentration of destructive potential with these capabilities in place a mutually assured destruction exists between the major nuclear powers as ballistic missile submarines have made a completely successful counterforce strike almost impossible any large-scale nuclear attack will always be able to be met in kind and by this means peace can be maintained but only at the end of a loaded gun even at its currently reduced levels a mass strike by russia's high readiness nuclear forces on the united states would inflict approximately 100 million casualties so what actually happens when a nuclear device is detonated let's imagine a one megaton nuclear bomb is triggered a few thousand metres above the earth's surface as the detonation system triggers the fission primary the plutonium pit is highly compressed making it supercritical the immense energy released by the primary compresses the secondary leading to both fusion in the lithium-deuteride fuel and fission in the uranium tamper as explained previously the initiation of a nuclear chain reaction in a weapon generates a vast amount of energy in a small concentration of matter this leads to the near instantaneous generation of extremely high temperatures and pressure at the moment of detonation conditions within the bomb itself are analogous to the center of the sun tens of millions of degrees and over one million atmospheres of pressure the extreme temperature instantly vaporizes the bomb and all of its components including the uranium or plutonium casing and fission products these gaseous weapon products contain a vast amount of kinetic energy and begin expanding at extremely high velocity because of the temperature of the weapon components within less than a tenth of a millionth of a second they will begin to emit copious amounts of high-energy electromagnetic radiation primarily in the form of x-rays and gamma rays this wavelength of electromagnetic radiation is absorbed rapidly by the atmosphere this initial burst of x-ray radiation may only travel a few hundred meters the process of x-ray absorption rapidly heats the air to a point that it begins to radiate forming a spherical area of luminescent air and gaseous weapon debris anything within this region will be vaporized this area is called the fireball the fireball itself is so hot that it releases vast amounts of energy as ultraviolet visible and infrared light this is why nuclear explosions have their trademark bright white flash which is a way you can distinguish a nuclear detonation from a very large conventional explosion at just one millisecond after our one megaton detonation the fireball will be so luminous that it will appear brighter than the noon sun to observe as 100 kilometers away the radiant heat emitted by the fireball is enough to cause third degree burns and start fires at several tens of kilometers the size of the fireball and the total amount of thermal energy released is directly proportionate to the weapon's yield as the fireball is formed it rapidly expands until it eventually reaches its maximum diameter which is determined by its temperature this extremely rapid expansion combined with the very high temperature generates a wall of highly compressed air that radiates out from the explosion traveling faster than the speed of sound this wall of high pressure air is called the blast front or blast wave any above ground structures will experience immense pressure as the blast wave passes over them as any difference in air pressure between different parts of the structure will exert a force on the structure as a whole this means buildings can be demolished just by the passage of the blast wave itself if the pressure is high enough at the front of this blast wave is an area of peak over pressure after which the air pressure drops off substantially the passage of the blast wave is accompanied by very strong winds first emanating out from the epicenter and then as an area of negative pressure follows the blast wave towards it the strength of the wind is proportional to the level of peak overpressure it is important to note that these winds are local and therefore do not contain any radioactive material as the blast front radiates out from the fireball it steadily loses strength blast effects and the high speed winds that are generated by a nuclear detonation in the lower atmosphere are the primary mechanism by which nuclear weapons kill people and destroy things as the fireball reaches its maximum radius it instantly begins to rise just like a hot air balloon there is a substantial difference in pressure between the fireball itself and the cool air surrounds it which causes it to rapidly ascend as the sphere rises it cools allowing the vaporized material to condense to form a cloud containing small particles of weapon debris including highly radioactive fission products and water vapor as this spherical cloud rises the outer edges drag on the atmosphere slowing them down this causes the cloud to change shape from a sphere to a toroid or donut as it ascends this cloud undergoes a violent horizontal circulation which generates a strong updraft at its center these powerful winds suck dirt and debris up from the surface connecting the rising cloud to the ground giving rise to the iconic image of the nuclear age the mushroom cloud the huge temperature differences between the cloud and the atmosphere will cause it to reach an enormous height potentially one hundred thousand feet and increase to a very large size the highly radioactive fission products and other elements of the bomb are all contained within the head of the mushroom cloud generally speaking these vaporized weapon debris can dense into tiny particles by themselves they will be elevated into the stratosphere and dispersed over a large area diluting their effect for example because both detonations were air bursts not a single injury was sustained from nuclear fallout in both the hiroshima and nagasaki nuclear attacks however if the fireball comes in contact with the earth's surface large amounts of dirt dust and rock will also be vaporized and mixed into the fireball itself when these condense into solids they form much heavier objects to which the highly radioactive fission products become attached when the updraft weakens as the cloud cools these heavy pieces of debris fall back to earth in concentrated areas we call this phenomenon nuclear fallout nuclear detonations can also induce powerful disruptions in electric and magnetic fields which although harmless to biology can negatively impact unshielded electronics this phenomenon is called an electromagnetic pulse or emp for detonations near the earth's surface this effect is caused by an area of intense ionization near the burst which generates powerful electric currents in both the air and ground this causes a significant drop in electromagnetic field strength which is the most powerful near the burst with a reasonably high yield the range at which an emp has an appreciable effect will be below the destructive radius of heat and blast nonetheless for low yield weapons the emp may outrange the blast effect the impact of an emp generated in the upper atmosphere is far more significant when detonated at an altitude of 300 000 feet or more the intense x-ray and gamma-ray flux travels much farther before the radiation is absorbed by the atmosphere the process by which x-rays are attenuated by the atmosphere is called photoelectric absorption where the oxygen atoms in the upper atmosphere absorb an x-ray photon and then emit an electron this causes a rain of electrons to shower the earth's surface which generates a brief but intense electromagnetic field that can generate a charge in unshielded electrical conductors damaging delicate electronics over a vast area computers are particularly vulnerable to emp effects in essence nuclear weapons release their energy in four ways blast radiant heat initial radiation which is defined as radiation given off by the weapon in the first minute after detonation and residual radiation about 50 percent of the energy is converted to blast 35 is emitted as thermal radiation which is primarily ultraviolet to infrared light 5 as initial radiation and 10 percent as residual radiation obviously these numbers describe a detonation in the lower atmosphere as most of the weapons energy is converted into the blast wave and the majority of human structures and vehicles are most susceptible to blast effects maximizing the blast pressure is a key principle in nuclear weapon employment the blast itself is best described as a very short but intense region of overpressure it is essentially a wall of highly compressed air which is followed by steadily decreasing pressure levels after its passing including an area of negative pressure where air is being sucked back towards ground zero the passage of the blast front is accompanied by very strong winds which can be almost 300 miles per hour with a peak over pressure of 10 psi the higher the peak overpressure the faster the blast front will move it can travel at several times the speed of sound in a high energy detonation although as peak overpressure drops with distance so does the speed maximizing blast pressure is the primary reason why air bursts are utilized if detonated above a target rather than on it very little of the blast energy will be transmitted to the ground additionally when a nuclear weapon detonates in an air burst a larger area will be subjected to the blast front if the height of the air burst and the yields are carefully managed then a number of blast phenomena can be leveraged to greatly increase the power of the blast wave the first is something called a mux stem upon detonation the blast front radiates out from the fireball in all three dimensions when it strikes the ground it is reflected creating a second blast front that also radiates out in three dimensions as the two blast waves move away from ground zero the reflected wave begins to overtake the incident or original blast wave when this happens there is an area close to the surface where both blast waves merge into one more powerful blast front this area is called the mac stem which will produce significantly greater overpressure the second blast phenomenon provided by an air burst is something called a precursor discovered in the grable shot of operation upshot knothole made famous by the use of artillery as a nuclear delivery system the low blast height and dusty desert environment led to the formation of a superheated layer of air right on the surface the lower air density allowed for the formation of a precursor wave that traveled in front of the mac stem this reduced the peak overpressure of the blast wave that greatly increased the dynamic pressure meaning more powerful winds this greatly increased the damage to drag sensitive targets generally speaking if you are attacking a soft target such as a city or a military formation air bursts are preferred nonetheless there are many scenarios which require a surface burst hardened targets such as bunkers or hardened concrete buildings can withstand relatively high overpressures especially if a facility is housed underground for an underground bunker or missile silo the thermal radiation and overpressure of a nearby air burst may not pose a substantial threat nevertheless these structures are vulnerable to energy transfer through the earth itself referred to as a shock front as opposed to a blast front whenever a nuclear weapon is detonated on the surface just below it or at a low enough altitude that the fireball comes into contact with the ground this is called a surface burst surface bursts will tend to leave craters when a weapon's energy is transferred to the earth directly this induces an effect that is very similar to a major earthquake at least in the local vicinity this can cause the internal collapse of deep underground facilities and if close enough to the surface to be within the volume of the crater they will be annihilated a similar utilization of blast energy can be leveraged underwater just as with conventional explosives water is an excellent conduit for kinetic energy in water the shock front behaves very similarly to the blast front in air radiating out in all directions however with an underwater burst the peak overpressure will not diminish with time in the same way as in air this gives an underwater burst a much greater range of effect in terms of shock and blast for example at a range of 1000 meters from a 100 kiloton burst the peak over pressure and air might be 5 pounds per square inch in water at the same range it will be 2 700 psi this makes underwater bursts especially deadly to submarines as noted earlier in an air burst almost half of the bomb's energy will be released as heat or thermal radiation this is caused by both the absorption of x-ray radiation by the atmosphere and the massive kinetic energy of the bomb products which serve to heat a spherical region of air until it becomes incandescent this is the fireball the fireball gives off an extremely large amount of thermal radiation but the total amount will depend on the burst height with an air burst illuminating the largest area the yield of the weapon the distance from ground zero and to some extent the atmospheric conditions the fireball emits energy in the ultraviolet visible and infrared spectrums although the ultraviolet is mostly absorbed by the atmosphere the thermal energy drops with distance in a one megaton air burst everything within a 10 mile or 16 kilometer radius would receive three calories per cubic centimeter of exposure enough to cause moderate flash burns and ignite some material closer in at a range of five miles that exposure climbs to 25 calories per cubic centimeter this thermal radiation has two destructive effects the first is its impact on people anyone who is directly exposed to the fireball and within a dangerous range will receive potentially fatal burns if someone is close enough to the burst they may well be vaporized the second destructive effect is fire exposed flammable materials will ignite if they absorb enough thermal radiation when combined with the destructive impact of the blast these fires can lead to a firestorm amongst the rubble and destroyed buildings in hiroshima the little boy caused a comparable amount of fire damage as a conventional bomber strike with about 1 000 tons of incendiary bombs when you consider how low the yield was the destructive potential due to fire alone is readily apparent about five percent of the bomb's energy is released in something called the initial radiation meaning the ionizing radiation released by the weapon in the first minute after detonation the reason one minute is the appropriate time period for describing the initial radiation effect is simply because the mushroom cloud will be high enough that no radiation will reach the ground after 60 seconds this is true for all yields as hotter mushroom clouds rise faster technically ultraviolet and infrared light are forms of radiation but they are not ionizing radiation meaning they lack the energy to ionize atoms and therefore alter chemical bonds ionizing radiation can cause significant damage to living cells leading to radiation poisoning a higher risk of cancer and even death depending on the dose there are four kinds of ionizing radiation alpha particles which are essentially just the nucleus of a helium-4 atom beta particles which are high energy electrons or positrons neutrons and gamma rays alpha and beta particles have a very short range in air and thus none of this form of radiation will reach the ground from an air burst this leaves us with two forms of relevant initial radiation the first are gamma rays basically light with photons of extremely high energy gamma rays are emitted in the initial reaction itself and by nuclear processes that occur immediately after it they are also released by the rapid decay of fission products in the mushroom cloud itself the second form of relevant initial radiation are neutrons the fission and fusion reactions themselves generate a vast neutron flux which radiates out in all directions both gamma ray and neutron exposure are extremely dangerous to humans at high doses in general terms for a typical high-yield device the gamma-ray emission will far exceed that of neutrons which account for only about one percent of the bomb's total energy both gamma rays and neutrons are very difficult to shield against for example at a distance of 1 mile or 1.6 kilometers from a 1 megaton air burst the initial radiation dose would probably prove fatal to the majority of humans that were protected by 24 inches of concrete more than enough to shield them from thermal radiation at that range in comparison to gamma rays neutrons have one important feature that can make other materials radioactive when exposed to a neutron flux some of the atoms on the target material will capture a neutron creating a heavier isotope these are generally unstable and will undergo radioactive decay emitting gamma radiation or alpha and beta particles with all that being said in a high-yield nuclear detonation the initial radiation is very unlikely to cause large-scale injuries or death that is because both gamma rays and neutrons are absorbed by the atmosphere at a much higher rate than thermal radiation or blast giving them a much shorter range as an example in order to receive a dangerous dose of 300 rads of initial radiation from a 1 megaton air burst a person will have to be 3000 meters away from ground zero at that range they will be receiving 1 000 calories per cubic centimeter of thermal radiation 30 times the level at which burns can occur and experience peak over pressure of 10 psi enough to destroy reinforced concrete buildings in essence for a high yield burst with the exception of individuals who are heavily shielded if you are close enough to the fireball to receive a dangerous dose of initial radiation you have almost certainly being killed by heat and blast this relationship is inverse for lower yield weapons however for the 15 kiloton burst experienced by hiroshima the 300 rad radiation dose occurs at 1 600 meters at that range blast pressure is only 3 psi which may heavily damage residential structures but is unlikely to induce widespread fatalities this explains the high number of radiation casualties at hiroshima for very low yield weapons in the one kiloton range the range at which initial radiation poses a threat is far higher than blast pressure roughly double there are some nuclear weapons in which the initial radiation is designed to be the primary destructive mechanism these are called enhanced radiation weapons or more colloquially a neutron bomb these weapons are designed to minimize blast yield and maximize the neutron flux therefore minimizing the blast and heat effects this is achieved by minimizing the amount of fission in the weapon and using pure deuterium and tritium in the secondary rather than lithium deuteride this creates a larger pulse of neutrons whilst keeping the blast radian heat and residual radiation at the lowest possible levels that being said neutron bombs are still nuclear weapons with explosive yields in the one kiloton range in fact enhanced radiation weapons are only possible in reasonably low yield devices as mentioned earlier because the scaling laws are different at yields above 10 kilotons blast and heat will dominate initial radiation no matter how much the initial neutron flux is enhanced there is a very widely held misconception about enhanced radiation weapons that they are designed to kill people whilst keeping infrastructure intact whilst this is technically true people often envisage this as a particularly ghoulish weapon that is designed to kill all the people in a city whilst leaving the infrastructure in place so those economic assets can be utilized profitably at a later date ironically enough enhanced radiation weapons were specifically designed to minimize civilian casualties in a large-scale european conflict throughout the last half of the cold war nato relied heavily on low-yield nuclear weapons to offset the material superiority of the warsaw pact which outnumbered them more than three to one in the forward area the soviet army was one of the most mechanized armies in history at its peak the soviet union fielded over 15 000 main battle tanks in the events of a limited nuclear war nato planned to use low-yield tactical weapons to break up mass concentrations of soviet armor apart from the risk of nuclear escalation there were two major problems with the use of tactical nuclear weapons the first is the protection armored fighting vehicles provide against both heat and blast in a british nuclear test in australia a tank was only lightly damaged when exposed to a 9 kiloton air burst at a range of just 500 meters its engine only stopped running when it ran out of fuel this means initial radiation is by far the most effective way to kill a tank however as discussed previously initial radiation has a much shorter range than blast and heat meaning in order to achieve a reasonable lethal radius of neutron radiation enough to break up a mass soviet tank attack you need a high yield in excess of 10 kilotons the second major problem with the use of tactical nuclear weapons was the fact that such a war was going to take place in west germany a staunch nato partner the use of conventional nuclear weapons with yields large enough to be effective against soviet armoured formations would wreak utter destruction upon germany with the countryside devastated by blast heat and fallout the neutron bomb was specifically designed to minimize this collateral damage in essence it maintained the neutron flux of a 10 kiloton weapon whilst reducing the blast yield to one kiloton and greatly limiting residual radiation once exposed to a sufficient amount of neutron radiation a tank will become radioactive through neutron activation making it a lethal environment for the crew the very limited range and tendency to make objects radioactive by neutron activation are two reasons why enhanced radiation weapons are unsuited to attacks against civilian targets despite the widely circulating myths and cliches about them the neutron bomb was absolutely designed to be used on the battlefield the last form of energy released by a nuclear weapon is residual radiation better known as fallout residual radiation accounts for about 10 of the bomb's total energy it takes two primary forms in a surface or very low altitude burst the ground around the fireball will undergo neutron activation in the same way as a tank making the area surrounding ground zero radioactive nevertheless the most significant and dangerous element of residual radiation are the fission products when uranium and plutonium undergo fission they split into a wide variety of new atoms more than 300 isotopes of 36 different chemical elements roughly 2 ounces of fission products are produced per kiloton meaning pounds or 56 kilograms for a 1 megaton blast the majority of these are unstable and will rapidly change into other more stable elements we call this process decay and in order to change from one thing into another the atom has to give off energy in the form of radiation a simple rule of decay is the shorter the half-life of an isotope the more radioactive it is the implication of this rule is that fission products produced by the bomb will be most radioactive immediately after detonation however as the most radioactive elements decay the most quickly the radiation levels will also rapidly abate this makes fusion a much cleaner process as the primary product of fusion is helium-4 which is stable and not radioactive nonetheless there is a period of hours where fallout poses an extremely significant radiological risk calculations have shown that if the fission products of a one kiloton fission explosion were evenly distributed over a flat area of one square mile one hour after detonation an exposed person would receive a dose of 2400 rads per hour meaning a potentially lethal dose of 400 rads will be incurred in just 8 minutes this level of radiation falls very rapidly however 24 hours after detonation when most of the short half-life elements have decayed radiation levels will have dropped approximately by a factor of 2 000. if the radiation exposure was 1 000 rads per hour one hour after detonation by 24 hours it will have dropped to just 23 rads per hour and at hour 48 radiation levels will be as low as 10 rads per hour this rate of decay has several implications firstly it explains why air bursts do not produce significant amounts of risk due to residual radiation the fission products are vaporized in the initial explosion and are carried up into the upper atmosphere by the mushroom cloud when these condense back into solid matter they form tiny invisible particles that are very light which are carried up into the stratosphere and diluted over a very large area some may circumnavigate the planet unless brought to ground in the immediate vicinity of the blast by rain or snow these particles remain airborne for a very long time potentially weeks to months meaning that when they eventually come to ground they will not only be in very tiny concentrations but will have decayed into more stable and less radioactive elements this is called the late fallout no fallout injuries were sustained in either nagasaki or hiroshima there are some minor cancer risks from long-lived fission products like strontium-90 which can be ingested through the food chain but compared to the early fallout these are insignificant surface bursts however are quite a different story when the fireball touches the earth's surface or is very close to it all of the material excavated in crater formation becomes vaporized along with the weapon debris in the castle bravo shot this included half a million tons of coral sand additionally as the mushroom cloud is generated at a lower altitude a large amount of debris is sucked up into the fireball by the updraft in a similar process to the formation of raindrops as the mushroom cloud cools the vaporized fission products condense around small particles of dust and debris this is in addition to the surface material which was also vaporized which when mixed with the bomb debris condenses to form a composite solid material these processes form much larger macroscopic particles that fall to ground quickly and in the immediate area that can be as large as two millimeters across the heaviest particles will begin falling to earth before the mushroom cloud has reached its maximum height meaning the highest levels of radiation will be deposited reasonably close to ground zero nevertheless as witnessed in the castle bravo fallout incident the fallout pattern can extend a very significant distance depositing potential lethal levels of radioactive material as far as 220 statute miles or 350 kilometers down range with less dangerous but substantial fallout as far as 300 miles away the size of the fallout pattern is dependent upon high level winds but will generally take on a cigar shape despite the very large area contaminated by castle bravo as the control team on nu demonstrated if individuals can take shelter for as little as 6 to 12 hours the radiation hazard posed by even large fallout events can be survived although potentially several months may be required until the area can be permanently habited again there is a type of nuclear device that is designed to enhance the fallout it generates which is called a salted bomb the main idea of this weapon is to enhance hazardous fallout by producing very specific radioactive isotopes the most famous of which is cobalt 60 which has a half-life of just over 5 years which could be produced by replacing the uranium tamper with one made of typical cobalt 59 when exposed to the intense neutron flux much of the cobalt 59 would absorb a neutron creating cobalt 60 which is radioactive a beta and gamma emitter cobalt 60 would produce far less radiation than a more typical mix of fission products only equalizing after six months of decay however after that time cobalt contamination would maintain much higher levels of radioactivity which will continue to pose a danger to humans for decades the exact degree of radiological hazard would depend on the concentration of contamination and in the early hours after a nuclear strike the fallout from a cobalt bomb would actually be far less dangerous than a regular thermonuclear device apart from one attempt to use cobalt as a radio chemical tracer in a british nuclear test no such weapon has ever been fielded so given what we now understand about the effects of nuclear weapons what would happen if we detonated a one megaton nuclear device in an air burst over a city firstly as the fireball grew to its maximum diameter the city as a whole would be scorched by thermal radiation directly under the fireball exposed individuals may well be vaporized by the colossal initial temperatures within 11 kilometers anyone outside will receive third degree burns almost all fatal at a distance of 14 kilometers those become second degree burns including flash blindness which drops to first degree or flash burns at a radius of 16 kilometers all exposed paper and leaves will ignite at a range of 15 kilometers with wood buildings and trees combusting with intent as fires begin to ignite and any exposed individuals are burned by the intense thermal radiation the blast wave emanates out from the fireball as infrared energy travels at the speed of light the thermal effects will be felt long before the blast front arrives at 2 300 meters the peak overpressure is 20 psi even the most heavily reinforced concrete structures are destroyed and fatalities are nearly universal wind speeds here are over 800 kilometers or 500 miles per hour at 3 600 meters it has dropped to 10 psi enough to heavily damage reinforced concrete structures and flatten regular buildings most people are killed the blast wave is still producing 5 psi of over pressure at a range of 5.6 kilometers followed by wind speeds in excess of 250 kilometers per hour that is enough to destroy most buildings causing significant casualties this drops to 3 psi at 7.7 kilometers heavily damaging residential homes finally at 16 kilometers the blast wave is now one psi enough to shutter windows the radiation casualties of the blast would have been minor anyone within 1800 metres of the epicentre would have received a fatal dose of neutron radiation but if one were that close they also would have experienced an absolutely fatal 25 psi peak overpressure and temperatures in the thousands of degrees celsius as the mushroom cloud quickly rises into the stratosphere it takes all of the weapon debris and fission products with it leaving no persistent radiation apart from neutron activation around ground zero that will abate reasonably quickly all buildings within a 15 kilometer radius have been heavily damaged and those within 600 meters of the blast absolutely flattened countless fires have been ignited in the outer areas where the blast pressures were below 3 psi and most buildings are intact these can be relatively easily extinguished by survivors but this is impossible closer towards the epicenter the combination of rubble destroyed homes and hundreds of fires is perhaps a perfect condition for a firestorm if the weather conditions are conducive we should expect extensive uncontrolled fires to rage within the 15 kilometer radius with the rubble and devastation preventing effective firefighting if this weapon were detonated over a city the size of boston montreal or melbourne casualties would far exceed one million now i am become death the destroyer of worlds krishna's words immortalised to western ears by oppenheimer's infamous quote underlying the terrifying power of nuclear weapons for nearly a century now the human race has possessed the power to destroy itself the immense destructive power bottled up in the smallest of objects the atomic nucleus and the weapon that leverages that power the atomic bomb have long been a subject of fear and fascination their awesome power and even macabre beauty contains an allure that is felt by many as much as the stupendous spectacle of a nuclear detonation contains a certain kind of wondrous splendor we must not forget just how much death and destruction this technology is capable of inflicting on the human race it really is a weapon like no other nonetheless and as counter-intuitive as it may seem there is a very serious argument that nuclear weapons may have actually made the world a better place the century before the invention of the atom bomb was the bloodiest in human history marked by two global conflicts that inflicted untold suffering in fact the second of those wars was brought to a close at least partially by the use of nuclear arms as close as we came to nuclear annihilation during the cold war judgment day did not come and given the immense geopolitical and ideological tension between nato and the warsaw pact without the eternal fear of nuclear hellfire one has to wonder how likely a third orgy of violence would have been almost inevitable in my view as much as anything can be in history in fact one could also make the argument that nuclear weapons are no longer really a weapon of war the immense destructive potential of nuclear arms have for nearly a century induced a kind of self-deterrence raising the threshold for their use to such a high level that they have become irrelevant in the actual wars that raged in the cold war period and those that continue to be fought today nuclear weapons have shown themselves to be a tool of statecraft a weapon of diplomacy rather than battle through their awesome destructive potential they shape the behaviour of other powers indeed their primary role in the 21st century has been relegating to deterring a nuclear attack by other nuclear powers and ensuring the survival of the state against conventional threats of the greatest strategic danger such as invasion that seems to be the kind of stasis we are now in for better or worse we all live in the nuclear age these weapons are with us now we cannot put this genie back in the bottle or to mix metaphors we cannot un-eat the forbidden fruit furthermore given the fact that this technology is approaching its 100th birthday can we really expect to perpetually prevent those who desire nuclear weapons from developing them limiting the risks is perhaps the best we can hope to achieve the course we choose when it comes to this most destructive of technologies may very well decide the fate of our species but whatever path we walk down it is in all of our interests that the nuclear bomb remains a tool of statecraft it must never become a weapon of war again

Channel: hypohystericalhistory

Views: 1,265,338

Keywords:

Id: 8uIPQBOCJ64

Length: 102min 38sec (6158 seconds)

Published: Mon Apr 18 2022

Reddit Comments

[u/HaloArtificials]

Sigh…

UNZIPS

[u/zzGravity]

Amazing video... thanks for the link :)

[u/aBakersDozenSoft]

Check out Scott Manely’s “going nuclear “ series on YouTube. Very very good.

[u/rjanderson8]

Great video thanks for it!