A thermonuclear weapon is a second-generation nuclear weapon design using a secondary nuclear fusion stage consisting of implosion tamper, fusion fuel, and spark plug which is bombarded by the energy released by the detonation of a primary nuclear fission bomb within, compressing the fuel material (tritium, deuterium or lithium deuteride) and causing a fusion reaction. Some advanced designs use produced by this second stage to ignite a third fast fission or fusion stage. The fission bomb and fusion fuel are placed near each other in a special radiation-reflecting container called a radiation case that is designed to contain x-rays for as long as possible. The result is greatly increased explosive power when compared to single-stage fission weapons. The device is colloquially referred to as a hydrogen bomb or, an H-bomb, because it employs the fusion of isotopes of hydrogen.The misleading term "hydrogen bomb" was already in wide public use before fission product fallout from the Castle Bravo test in 1954 revealed the extent to which the design relies on fission.
The Ivy Mike was carried out by the United States in 1952; the concept has since been employed by most of the world's nuclear powers in the design of their weapons.From National Public Radio Talk of the Nation, November 8, 2005, Siegfried Hecker of Los Alamos, "the hydrogen bomb – that is, a two-stage thermonuclear device, as we referred to it – is indeed the principal part of the U.S. arsenal, as it is of the Russian arsenal." The modern design of all thermonuclear weapons in the United States is known as the Teller–Ulam configuration for its two chief contributors, Edward Teller and Stanislaw Ulam, who developed it in 1951 on the Nuclear Non-Proliferation Institute website. This is the original classified paper by Teller and Ulam proposing staged implosion. This declassified version is heavily redacted, leaving only a few paragraphs. for the United States, with certain concepts developed with the contribution of John von Neumann. Similar devices were developed by the Soviet Union, United Kingdom, France, and China.
As thermonuclear weapons represent the most efficient design for weapon energy yield in weapons with yields above , virtually all the nuclear weapons of this size deployed by the five nuclear-weapon states under the Non-Proliferation Treaty today are thermonuclear weapons using the Teller–Ulam design. "So far as is known all high yield nuclear weapons today (>50 kt or so) use this design."
The radiation implosion mechanism exploits the temperature difference between the secondary stage's hot, surrounding radiation channel and its relatively cool interior. This temperature difference is briefly maintained by a massive heat barrier called the "pusher"/"tamper", which also serves as an implosion tamper, increasing and prolonging the compression of the secondary. If made of uranium, enriched uranium or plutonium, it can capture produced by the fusion reaction and undergo fission itself, increasing the overall explosive yield. In addition to that, some designs also make the radiation case out of a fissile material that undergoes fission. As a result, such bombs get a third fission stage, and the majority of current Teller–Ulam are fission-fusion-fission weapons. Fission of the tamper or radiation case is the main contribution to the total yield and produces radioactive fission product /ref>
Detailed knowledge of fission and fusion weapons is classified to some degree in virtually every industrialized nation. In the United States, such knowledge can by default be classified as "Restricted Data", even if it is created by persons who are not government employees or associated with weapons programs, in a legal doctrine known as "born secret" (though the constitutional standing of the doctrine has been at times called into question; see United States v. Progressive, Inc.). Born secret is rarely invoked for cases of private speculation. The official policy of the United States Department of Energy has been not to acknowledge the leaking of design information, as such acknowledgment would potentially validate the information as accurate. In a small number of prior cases, the U.S. government has attempted to prior restraint, with limited success. According to the New York Times, physicist Kenneth Ford defied government orders to remove classified information from his book, Building the H Bomb: A Personal History. Ford claims he used only pre-existing information and even submitted a manuscript to the government, which wanted to remove entire sections of the book for concern that foreign nations could use the information.
Though large quantities of vague data have been officially released, and larger quantities of vague data have been unofficially leaked by former bomb designers, most public descriptions of nuclear weapon design details rely to some degree on speculation, reverse engineering from known information, or comparison with similar fields of physics (inertial confinement fusion is the primary example). Such processes have resulted in a body of unclassified knowledge about nuclear bombs that is generally consistent with official unclassified information releases, related physics, and is thought to be internally consistent, though there are some points of interpretation that are still considered open. The state of public knowledge about the Teller–Ulam design has been mostly shaped from a few specific incidents outlined in a section below.
Surrounding the other components is a hohlraum or radiation case, a container that traps the first stage or primary's energy inside temporarily. The outside of this radiation case, which is also normally the outside casing of the bomb, is the only direct visual evidence publicly available of any thermonuclear bomb component's configuration. Numerous photographs of various thermonuclear bomb exteriors have been declassified.
The primary is thought to be a standard implosion method fission bomb, though likely with a plutonium pit boosted by small amounts of fusion fuel (usually 50/50% deuterium/tritium gas) for extra efficiency; the fusion fuel releases excess when heated and compressed, inducing additional fission. When fired, the plutonium-239 (Pu-239) or uranium-235 (U-235) core would be compressed to a smaller sphere by special layers of conventional arranged around it in an explosive lens pattern, initiating the nuclear chain reaction that powers the conventional "atomic bomb".
The secondary is usually shown as a column of fusion fuel and other components wrapped in many layers. Around the column is first a "pusher-tamper", a heavy layer of uranium-238 (U-238) or lead that helps compress the fusion fuel (and, in the case of uranium, may eventually undergo fission itself). Inside this is the fusion fuel itself, usually a form of lithium deuteride, which is used because it is easier to weaponize than liquefied tritium/deuterium gas. This dry fuel, when bombarded by , produces tritium, a heavy isotope of hydrogen which can undergo nuclear fusion, along with the deuterium present in the mixture. (See the article on nuclear fusion for a more detailed technical discussion of fusion reactions.) Inside the layer of fuel is the "spark plug", a hollow column of fissile material (plutonium-239 or uranium-235) often boosted by deuterium gas. The spark plug, when compressed, can itself undergo nuclear fission (because of the shape, it is not a critical mass without compression). The tertiary, if one is present, would be set below the secondary and probably be made up of the same materials.
Separating the secondary from the primary is the interstage. The fissioning primary produces four types of energy: 1) expanding hot gases from high explosive charges that implode the primary; 2) superheated plasma that was originally the bomb's fissile material and its tamper; 3) the electromagnetic radiation; and 4) the from the primary's nuclear detonation. The interstage is responsible for accurately modulating the transfer of energy from the primary to the secondary. It must direct the hot gases, plasma, electromagnetic radiation and neutrons toward the right place at the right time. Less than optimal interstage designs have resulted in the secondary failing to work entirely on multiple shots, known as a "fissile fizzle". The Castle Koon shot of Operation Castle is a good example; a small flaw allowed the neutron flux from the primary to prematurely begin heating the secondary, weakening the compression enough to prevent any fusion.
There is very little detailed information in the open literature about the mechanism of the interstage. One of the best sources is a simplified diagram of a British thermonuclear weapon similar to the American W80 warhead. It was released by Greenpeace in a report titled "Dual Use Nuclear Technology". A cleaned up version: The major components and their arrangement are in the diagram, though details are almost absent; what scattered details it does include likely have intentional omissions or inaccuracies. They are labeled "End-cap and Neutron Focus Lens" and "Reflector Wrap"; the former channels neutrons to the U-235/Pu-239 Spark Plug while the latter refers to an X-ray reflector; typically a cylinder made out of an X-ray opaque material such as uranium with the primary and secondary at either end. It does not reflect like a mirror; instead, it gets heated to a high temperature by the X-ray flux from the primary, then it emits more evenly spread X-rays that travel to the secondary, causing what is known as radiation implosion. In Ivy Mike, gold was used as a coating over the uranium to enhance the blackbody effect.
The first U.S. government document to mention the interstage was only recently released to the public promoting the 2004 initiation of the Reliable Replacement Warhead Program. A graphic includes blurbs describing the potential advantage of a RRW on a part by part level, with the interstage blurb saying a new design would replace "toxic, brittle material" and "expensive 'special' material... which unique facilities". "Improved Security, Safety & Manufacturability of the Reliable Replacement Warhead" , NNSA March 2007. The "toxic, brittle material" is widely assumed to be beryllium which fits that description and would also moderate the neutron flux from the primary. Some material to absorb and re-radiate the X-rays in a particular manner may also be used. A 1976 drawing that depicts an interstage that absorbs and re-radiates X-rays. From Howard Morland, "The Article", Cardozo Law Review, March 2005, p 1374.
Candidates for the "special material" are polystyrene and a substance called "FOGBANK", an unclassified codename. FOGBANK's composition is classified, though aerogel has been suggested as a possibility. It was first used in thermonuclear weapons with the W-76 thermonuclear warhead, and produced at a plant in the Y-12 Complex at Oak Ridge, Tennessee for use in the W-76. Production of FOGBANK lapsed after the W-76 production run ended. The W-76 Life Extension Program required more FOGBANK to be made. This was complicated by the fact that the original FOGBANK's properties weren't fully documented, so a massive effort was mounted to re-invent the process. An impurity crucial to the properties of the old FOGBANK was omitted during the new process. Only close analysis of new and old batches revealed the nature of that impurity. The manufacturing process used acetonitrile as a solvent, which led to at least three evacuations of the FOGBANK plant in 2006. Widely used in the petroleum and pharmaceutical industries, acetonitrile is flammable and toxic. Y-12 is the sole producer of FOGBANK. Speculation on Fogbank, Arms Control Wonk
Thermonuclear weapons may or may not use a boosted primary stage, use different types of fusion fuel, and may surround the fusion fuel with beryllium (or another neutron reflecting material) instead of depleted uranium to prevent early premature fission from occurring before the secondary is optimally compressed.
For two thermonuclear bombs for which the general size and primary characteristics are well understood, the Ivy Mike test bomb and the modern W-80 cruise missile warhead variant of the W-61 design, the radiation pressure was calculated to be 73 million bar (atmospheres) (7.3 tera- Pa) for the Ivy Mike design and 1,400 million bar (140 TPa) for the W-80.
The sequence of firing the weapon (with the foam) would be as follows:
This would complete the fission-fusion-fission sequence. Fusion, unlike fission, is relatively "clean"—it releases energy but no harmful radioactive products or large amounts of nuclear fallout. The fission reactions though, especially the last fission reaction, release a tremendous amount of fission products and fallout. If the last fission stage is omitted, by replacing the uranium tamper with one made of lead, for example, the overall explosive force is reduced by approximately half but the amount of fallout is relatively low. The neutron bomb is a hydrogen bomb with an intentionally thin tamper, allowing as much radiation as possible to escape.
[[Image:BombH explosion.svg|center|frame|Foam plasma mechanism firing sequence.
Current technical criticisms of the idea of "foam plasma pressure" focus on unclassified analysis from similar high energy physics fields that indicate that the pressure produced by such a plasma would only be a small multiplier of the basic photon pressure within the radiation case, and also that the known foam materials intrinsically have a very low absorption efficiency of the gamma ray and X-ray radiation from the primary. Most of the energy produced would be absorbed by either the walls of the radiation case or the tamper around the secondary. Analyzing the effects of that absorbed energy led to the third mechanism: ablation.
Rough calculations for the basic ablation effect are relatively simple: the energy from the primary is distributed evenly onto all of the surfaces within the outer radiation case, with the components coming to a thermal equilibrium, and the effects of that thermal energy are then analyzed. The energy is mostly deposited within about one X-ray Optical depth of the tamper/pusher outer surface, and the temperature of that layer can then be calculated. The velocity at which the surface then expands outwards is calculated and, from a basic Newtonian momentum balance, the velocity at which the rest of the tamper implodes inwards.
Applying the more detailed form of those calculations to the Ivy Mike device yields vaporized pusher gas expansion velocity of 290 kilometers per second and an implosion velocity of perhaps 400 kilometers per second if 3/4 of the total tamper/pusher mass is ablated off, the most energy efficient proportion. For the W-80 the gas expansion velocity is roughly 410 kilometers per second and the implosion velocity 570 kilometers per second. The pressure due to the ablating material is calculated to be 5.3 billion bar (530 tera- Pa) in the Ivy Mike device and 64 billion bar (6.4 Peta- Pa) in the W-80 device.
The calculated ablation pressure is one order of magnitude greater than the higher proposed plasma pressures and nearly two orders of magnitude greater than calculated radiation pressure. No mechanism to avoid the absorption of energy into the radiation case wall and the secondary tamper has been suggested, making ablation apparently unavoidable. The other mechanisms appear to be unneeded.
United States Department of Defense official declassification reports indicate that foamed plastic materials are or may be used in radiation case liners, and despite the low direct plasma pressure they may be of use in delaying the ablation until energy has distributed evenly and a sufficient fraction has reached the secondary's tamper/pusher.
Richard Rhodes' book Dark Sun stated that a layer of plastic foam was fixed to the lead liner of the inside of the Ivy Mike steel casing using copper nails. Rhodes quotes several designers of that bomb explaining that the plastic foam layer inside the outer case is to delay ablation and thus recoil of the outer case: if the foam were not there, metal would ablate from the inside of the outer case with a large impulse, causing the casing to recoil outwards rapidly. The purpose of the casing is to contain the explosion for as long as possible, allowing as much X-ray ablation of the metallic surface of the secondary stage as possible, so it compresses the secondary efficiently, maximizing the fusion yield. Plastic foam has a low density, so causes a smaller impulse when it ablates than metal does.
Two special variations exist that will be discussed in a subsequent section: the cryogenics cooled liquid deuterium device used for the Ivy Mike test, and the putative design of the W88 nuclear warhead—a small, MIRVed version of the Teller–Ulam configuration with a spheroid (Oval or watermelon shaped) primary and an elliptical secondary.
Most bombs do not apparently have tertiary "stages"—that is, third compression stage(s), which are additional fusion stages compressed by a previous fusion stage. (The fissioning of the last blanket of uranium, which provides about half the yield in large bombs, does not count as a "stage" in this terminology.)
The U.S. tested three-stage bombs in several explosions (see Operation Redwing) but is thought to have fielded only one such tertiary model, i.e., a bomb in which a fission stage, followed by a fusion stage, finally compresses yet another fusion stage. This U.S. design was the heavy but highly efficient (i.e., nuclear weapon yield per unit bomb weight) 25 Mt B41 nuclear bomb. The Soviet Union is thought to have used multiple stages (including more than one tertiary fusion stage) in their 50 megaton (100 Mt in intended use) Tsar Bomba (however, as with other bombs, the fissionable jacket could be replaced with lead in such a bomb, and in this one, for demonstration, it was). If any hydrogen bombs have been made from configurations other than those based on the Teller–Ulam design, the fact of it is not publicly known. (A possible exception to this is the Soviet early Sloika design).
In essence, the Teller–Ulam configuration relies on at least two instances of implosion occurring: first, the conventional (chemical) explosives in the primary would compress the fissile core, resulting in a fission explosion many times more powerful than that which chemical explosives could achieve alone (first stage). Second, the radiation from the fissioning of the primary would be used to compress and ignite the secondary fusion stage, resulting in a fusion explosion many times more powerful than the fission explosion alone. This chain of compression could conceivably be continued with an arbitrary number of tertiary fusion stages, each igniting more fusion fuel in the next stage
As discussed above, for destruction of cities and non-hardened targets, breaking the mass of a single missile payload down into smaller MIRV bombs, in order to spread the energy of the explosions into a "pancake" area, is far more efficient in terms of area-destruction per unit of bomb energy. This also applies to single bombs deliverable by cruise missile or other system, such as a bomber, resulting in most operational warheads in the U.S. program having yields of less than 500 kilotons.
Stanislaw Ulam, a co-worker of Teller, made the first key conceptual leaps towards a workable fusion design. Ulam's two innovations that rendered the fusion bomb practical were that compression of the thermonuclear fuel before extreme heating was a practical path towards the conditions needed for fusion, and the idea of staging or placing a separate thermonuclear component outside a fission primary component, and somehow using the primary to compress the secondary. Teller then realized that the gamma and X-ray radiation produced in the primary could transfer enough energy into the secondary to create a successful implosion and fusion burn, if the whole assembly was wrapped in a hohlraum or radiation case. Teller and his various proponents and detractors later disputed the degree to which Ulam had contributed to the theories underlying this mechanism. Indeed, shortly before his death, and in a last-ditch effort to discredit Ulam's contributions, Teller claimed that one of his own "graduate students" had proposed the mechanism.
The "George" shot of Operation Greenhouse of 9 May 1951 tested the basic concept for the first time on a very small scale. As the first successful (uncontrolled) release of nuclear fusion energy, which made up a small fraction of the 225 kt total yield, it raised expectations to a near certainty that the concept would work.
On November 1, 1952, the Teller–Ulam configuration was tested at full scale in the "Ivy Mike" shot at an island in the Enewetak Atoll, with a yield of 10.4 TNT equivalent (over 450 times more powerful than the bomb dropped on Nagasaki during World War II). The device, dubbed the Sausage, used an extra-large fission bomb as a "trigger" and liquid deuterium—kept in its liquid state by 20 (18 ) of Cryogenics equipment—as its fusion fuel, and weighed around 80 short tons (70 metric tons) altogether.
The liquid deuterium fuel of Ivy Mike was impractical for a deployable weapon, and the next advance was to use a solid lithium hydride fusion fuel instead. In 1954 this was tested in the "Castle Bravo" shot (the device was code-named Shrimp), which had a yield of 15 megatons (2.5 times expected) and is the largest U.S. bomb ever tested.
Efforts in the United States soon shifted towards developing miniaturized Teller–Ulam weapons that could fit into intercontinental ballistic missiles and submarine-launched ballistic missiles. By 1960, with the W47 warhead deployed on Polaris ballistic missile submarines, megaton-class warheads were as small as 18 inches (0.5 m) in diameter and 720 pounds (320 kg) in weight. It was later found in live testing that the Polaris warhead did not work reliably and had to be redesigned. Further innovation in miniaturizing warheads was accomplished by the mid-1970s, when versions of the Teller–Ulam design were created that could fit ten or more warheads on the end of a small MIRVed missile (see the section on the W88 below).
The first Soviet fusion design, developed by Andrei Sakharov and Vitaly Ginzburg in 1949 (before the Soviets had a working fission bomb), was dubbed the Sloika, after a Russian layer cake, and was not of the Teller–Ulam configuration. It used alternating layers of fissile material and lithium deuteride fusion fuel spiked with tritium (this was later dubbed Sakharov's "First Idea"). Though nuclear fusion might have been technically achievable, it did not have the scaling property of a "staged" weapon. Thus, such a design could not produce thermonuclear weapons whose explosive yields could be made arbitrarily large (unlike U.S. designs at that time). The fusion layer wrapped around the fission core could only moderately multiply the fission energy (modern Teller–Ulam designs can multiply it 30-fold). Additionally, the whole fusion stage had to be imploded by conventional explosives, along with the fission core, substantially multiplying the amount of chemical explosives needed.
The first Sloika design test, RDS-6s, was detonated in 1953 with a yield equivalent to 400 TNT equivalent (15–20% from fusion). Attempts to use a Sloika design to achieve megaton-range results proved unfeasible. After the United States tested the "Ivy Mike" bomb in November 1952, proving that a multimegaton bomb could be created, the Soviets searched for an additional design. The "Second Idea", as Sakharov referred to it in his memoirs, was a previous proposal by Ginzburg in November 1948 to use lithium deuteride in the bomb, which would, in the course of being bombarded by neutrons, produce tritium and free deuterium.
The Soviets demonstrated the power of the "staging" concept in October 1961, when they detonated the massive and unwieldy Tsar Bomba, a 50 megaton hydrogen bomb that derived almost 97% of its energy from fusion. It was the largest nuclear weapon developed and tested by any country.
In 1954 work began at Aldermaston to develop the British fusion bomb, with Sir William Penney in charge of the project. British knowledge on how to make a thermonuclear fusion bomb was rudimentary, and at the time the United States was not exchanging any nuclear knowledge because of the Atomic Energy Act of 1946. However, the British were allowed to observe the American Operation Castle and used sampling aircraft in the , providing them with clear, direct evidence of the compression produced in the secondary stages by radiation implosion.
Because of these difficulties, in 1955 British prime minister Anthony Eden agreed to a secret plan, whereby if the Aldermaston scientists failed or were greatly delayed in developing the fusion bomb, it would be replaced by an extremely large fission bomb.
In 1957 the Operation Grapple tests were carried out. The first test, Green Granite was a prototype fusion bomb, but failed to produce equivalent yields compared to the Americans and Soviets, achieving only approximately 300 kilotons. The second test Orange Herald was the modified fission bomb and produced 720 kilotons—making it the largest fission explosion ever. At the time almost everyone (including the pilots of the plane that dropped it) thought that this was a fusion bomb. This bomb was put into service in 1958. A second prototype fusion bomb Purple Granite was used in the third test, but only produced approximately 150 kilotons.
A second set of tests was scheduled, with testing recommencing in September 1957. The first test was based on a "… new simpler design. A two stage thermonuclear bomb that had a much more powerful trigger". This test Grapple X Round C was exploded on November 8 and yielded approximately 1.8 megatons. On April 28, 1958 a bomb was dropped that yielded 3 megatons—Britain's most powerful test. Two final air burst tests on September 2 and September 11, 1958, dropped smaller bombs that yielded around 1 megaton each.
American observers had been invited to these kinds of tests. After Britain's successful detonation of a megaton-range device (and thus demonstrating a practical understanding of the Teller–Ulam design "secret"), the United States agreed to exchange some of its nuclear designs with the United Kingdom, leading to the 1958 US–UK Mutual Defence Agreement. Instead of continuing with its own design, the British were given access to the design of the smaller American Mk 28 warhead and were able to manufacture copies.
The United Kingdom had worked closely with the Americans on the Manhattan Project. British access to nuclear weapons information was cut-off by the United States at one point due to concerns about Soviet espionage. Full cooperation was not reestablished until an agreement governing the handling of secret information and other issues was signed.
A story in The New York Times by William Broad reported that in 1995, a supposed Chinese double agent delivered information indicating that China knew secret details of the U.S. W88 warhead, supposedly through espionage., esp. Ch. 2, "PRC Theft of U.S. Thermonuclear Warhead Design Information". (This line of investigation eventually resulted in the abortive trial of Wen Ho Lee.)
In 1945, the French Atomic Energy Commission (Commissariat à l’Énergie Atomique, CEA) was founded under General Charles de Gaulle; the CEA served as the country’s atomic energy authority, overseeing commercial, military, and scientific uses of atomic power. However it was not until 1952 that a tangible goal of building plutonium reactors progressed. Two years later, a reactor was being built and a plutonium separating plant began construction shortly after. In 1954 the question about continuing to explore building an atomic bomb was raised. The French cabinet seemed to be favoring less the building of an atomic bomb. Ultimately, the Prime Minister decided to continue efforts developing an atomic bomb in secret. In late 1956, tasks were delegated between the CEA and Defense Ministry to propel atomic development such as finding a test site, providing the necessary uranium, and physical device assembly.
General Charles de Gaulle was elected the France’s Fifth Republic’s first president in 1958. De Gaulle, an avid supporter of the nuclear weapons program, approved the country’s first nuclear test to take place in one of the early months of 1960. The country’s first nuclear explosion took place on 13 February at Reggane in the Sahara Desert in French Algeria of the time. It was called "Gerboise Bleue", translating to "Blue jerboa". The first explosion was detonated at a tower height of 105 meters. The bomb used a plutonium implosion design with a yield of 70 kilotons. The Reggane test site was used for three more atmospheric tests before testing activity moved to a second site, Ecker, to carry out a total of 13 underground tests into 1967.
The French nuclear testing site was moved to the unpopulated French atolls in the Pacific Ocean. The first test conducted at these new sites was the "Canopus" test in the Fangataufa in French Polynesia on 24 August 1968, the country’s first multistage thermonuclear weapon test. The bomb was detonated from a balloon at a height of 520 meters. The result of this test was significant atmospheric contamination. Very little is known about France's development of the Teller–Ulam design, beyond the fact that France detonated a 2.6 Mt device in the 'Canopus" test. France reportedly had great difficulty with its initial development of the Teller-Ulam design, but it later overcame these, and is believed to have nuclear weapons equal in sophistication to the other major nuclear powers.
France and China did not sign or ratify the Partial Nuclear Test Ban Treaty of 1963, which banned nuclear test explosions in the atmosphere, underwater, or in outer space. Between 1966 and 1996 France carried out more than 190 nuclear tests. France’s final nuclear test took place on January 27, 1996, and then the country dismantled its Polynesian test sites. France signed the Comprehensive Nuclear-Test-Ban Treaty that same year, and then ratified the Treaty within two years.
France confirmed that its nuclear arsenal contains about 300 warheads, carried by submarine-launched ballistic missiles (SLBMs) and fighter-bombers in 2015. France has four Triomphant-class ballistic missile submarines. One ballistic missile submarine is deployed in the deep ocean, but a total of three must be in operational use at all times. The three older submarines are armed with 16 M45 missiles. The newest submarine, "Le Terrible", was commissioned in 2010, and it has M51 missiles capable of carrying TN 75 thermonuclear warheads. The air fleet is four squadrons at four different bases. In total, there are 23 Mirage 2000N aircraft and 20 Dassault Rafale capable of carrying nuclear warheads. The M51.1 missiles are intended to be replaced with the new M51.2 warhead beginning in 2016, which has a 3,000 km greater range than the M51.1.
President François Hollande announced 180 billion euros would be used from the annual defense budget to improve the country’s nuclear deterrence. France contains 13 International Monitoring System facilities that monitor for nuclear explosive activity on Earth through the use of seismic, infrasound, and hydroacoustic monitors.
France also has about 60 air-launched missiles tipped with TN 80/TN 81 warheads with a yield of about 300 kilotons each. France's nuclear program has been carefully designed to ensure that these weapons remain usable decades into the future. Currently, France is no longer deliberately producing critical mass materials such as plutonium and enriched uranium, but it still relies on nuclear energy for electricity, with Pu-239 as a byproduct.
In an interview in August 2009, the director for the 1998 test site preparations, Dr. K. Santhanam claimed that the yield of the thermonuclear explosion was lower than expected and that India should therefore not rush into signing the CTBT. Other Indian scientists involved in the test have disputed Dr. K. Santhanam's claim. International sources, using local data and citing a United States Geological Survey report compiling seismic data from 125 IRIS Consortium stations across the world, argue that the magnitudes suggested a combined yield of up to 60 kilotonnes, consistent with the Indian announced total yield of 56 kilotonnes.
It is well established that Edward Teller advised and guided the Israeli establishment on general nuclear matters for some twenty years.
On 3 September 2017, the country's state media reported that a hydrogen bomb test was conducted which resulted in "perfect success". According to the U.S. Geological Survey (USGS), the blast resulted in an earthquake with a magnitude of 6.3, 10 times more powerful than previous nuclear tests conducted by North Korea. U.S. Intelligence released an early assessment that the yield estimate was 140 kilotons, with an uncertainty range of 70 to 280 kilotons.
On 12 September, /ref>http://www.38north.org/2017/09/punggye091217/
On 13 September, an analysis of before and after synthetic-aperture radar satellite imagery of the test site was published suggesting the test occurred under of rock and the yield "could have been in excess of 300 kilotons".http://www.armscontrolwonk.com/archive/1203852/sar-image-of-punggye-ri/
Whether these statements vindicate some or all of the models presented above is up for interpretation, and official U.S. government releases about the technical details of nuclear weapons have been purposely equivocating in the past (see, e.g., Smyth Report). Other information, such as the types of fuel used in some of the early weapons, has been declassified, though precise technical information has not been.
Morland eventually concluded that the "secret" was that the primary and secondary were kept separate and that radiation pressure from the primary compressed the secondary before igniting it. When an early draft of the article, to be published in The Progressive magazine, was sent to the DOE after falling into the hands of a professor who was opposed to Morland's goal, the DOE requested that the article not be published, and pressed for a temporary injunction. The DOE argued that Morland's information was (1) likely derived from classified sources, (2) if not derived from classified sources, itself counted as "secret" information under the "born secret" clause of the 1954 Atomic Energy Act, and (3) was dangerous and would encourage nuclear proliferation.
Morland and his lawyers disagreed on all points, but the injunction was granted, as the judge in the case felt that it was safer to grant the injunction and allow Morland, et al., to appeal, which they did in United States v. The Progressive (1979).
Through a variety of more complicated circumstances, the DOE case began to wane as it became clear that some of the data they were attempting to claim as "secret" had been published in a students' encyclopedia a few years earlier. After another H-bomb speculator, Chuck Hansen, had his own ideas about the "secret" (quite different from Morland's) published in a Wisconsin newspaper, the DOE claimed that The Progressive case was moot, dropped its suit, and allowed the magazine to publish its article, which it did in November 1979. Morland had by then, however, changed his opinion of how the bomb worked, suggesting that a foam medium (the polystyrene) rather than radiation pressure was used to compress the secondary, and that in the secondary there was a spark plug of fissile material as well. He published these changes, based in part on the proceedings of the appeals trial, as a short erratum in The Progressive a month later. In 1981, Morland published a book about his experience, describing in detail the train of thought that led him to his conclusions about the "secret".
Morland's work is interpreted as being at least partially correct because the DOE had sought to censor it, one of the few times they violated their usual approach of not acknowledging "secret" material that had been released; however, to what degree it lacks information, or has incorrect information, is not known with any confidence. The difficulty that a number of nations had in developing the Teller–Ulam design (even when they apparently understood the design, such as with the United Kingdom), makes it somewhat unlikely that this simple information alone is what provides the ability to manufacture thermonuclear weapons. Nevertheless, the ideas put forward by Morland in 1979 have been the basis for all the current speculation on the Teller–Ulam design.
The reentry nose cone for the W88 and W87 are the same size, 1.75 meters (69 in) long, with a maximum diameter of 55 cm. (22 in). The higher yield of the W88 implies a larger secondary, which produces most of the yield. Putting the secondary, which is heavier than the primary, in the wider part of the cone allows it to be larger, but it also moves the center of mass aft, potentially causing aerodynamic stability problems during reentry. Dead-weight ballast must be added to the nose to move the center of mass forward.
To make the primary small enough to fit into the narrow part of the cone, its bulky insensitive high explosive charges must be replaced with more compact "non-insensitive" that are more hazardous to handle. The higher yield of the W88, which is the last new warhead produced by the United States, thus comes at a price of higher warhead weight and higher workplace hazard. The W88 also contains tritium, which has a half life of only 12.32 years and must be repeatedly replaced. If these stories are true, it would explain the reported higher yield of the W88, 475 kilotons, compared with only 300 kilotons for the earlier W87 warhead.