History of nuclear weapons

[1] In August 1945, the atomic bombings of Hiroshima and Nagasaki were conducted by the United States, with British consent, against Japan at the close of that war, standing to date as the only use of nuclear weapons in hostilities.

[3] In a 1924 article, Winston Churchill speculated about the possible military implications: "Might not a bomb no bigger than an orange be found to possess a secret power to destroy a whole block of buildings—nay to concentrate the force of a thousand tons of cordite and blast a township at a stroke?

After Fermi achieved the world's first sustained and controlled nuclear chain reaction with the creation of the first atomic pile, massive reactors were secretly constructed at what is now known as the Hanford Site to transform uranium-238 into plutonium for a bomb.

In April 1944 it was found by Emilio Segrè that the plutonium-239 produced by the Hanford reactors had too high a level of background neutron radiation, and underwent spontaneous fission to a very small extent, due to the unexpected presence of plutonium-240 impurities.

If such plutonium were used in a gun-type design, the chain reaction would start in the split second before the critical mass was fully assembled, blowing the weapon apart with a much lower yield than expected, in what is known as a fizzle.

The difficulties with implosion centered on the problem of making the chemical explosives deliver a perfectly uniform shock wave upon the plutonium sphere— if it were even slightly asymmetric, the weapon would fizzle.

[21] After D-Day, General Groves ordered a team of scientists to follow eastward-moving victorious Allied troops into Europe to assess the status of the German nuclear program (and to prevent the westward-moving Soviets from gaining any materials or scientific manpower).

The Japanese navy lost interest when a committee led by Yoshio Nishina concluded in 1943 that "it would probably be difficult even for the United States to realize the application of atomic power during the war".

Under the clause of the 1943 Quebec Agreement that specified that nuclear weapons would not be used against another country without mutual consent, the atomic bombing of Japan was recorded as a decision of the Anglo-American Combined Policy Committee.

Truman and his Secretary of State James F. Byrnes were also intent on ending the Pacific war before the Soviets could enter it,[28] given that Roosevelt had promised Stalin control of Manchuria if he joined the invasion.

The Soviet program, under the suspicious watch of former NKVD chief Lavrenty Beria (a participant and victor in Stalin's Great Purge of the 1930s), would use the Report as a blueprint, seeking to duplicate as much as possible the American effort.

[48] Indeed, within the U.S. government, including the Departments of State and Defense, there was considerable confusion over who actually knew the size of the stockpile, and some people chose not to know for fear they might disclose the number accidentally.

[47] The notion of using a fission weapon to ignite a process of nuclear fusion can be dated back to September 1941, when it was first proposed by Enrico Fermi to his colleague Edward Teller during a discussion at Columbia University.

The Joe-1 atomic bomb test by the Soviet Union that took place in August 1949 came earlier than expected by Americans, and over the next several months there was an intense debate within the U.S. government, military, and scientific communities regarding whether to proceed with development of the far more powerful Super.

The reasons were in part because the success of the technology seemed limited at the time (and not worth the investment of resources to confirm whether this was so), and because Oppenheimer believed that the atomic forces of the United States would be more effective if they consisted of many large fission weapons (of which multiple bombs could be dropped on the same targets) rather than the large and unwieldy super bombs, for which there was a relatively limited number of targets of sufficient size to warrant such a development.

On March 1, 1954, the U.S. detonated its first practical thermonuclear weapon (which used isotopes of lithium as its fusion fuel), known as the "Shrimp" device of the Castle Bravo test, at Bikini Atoll, Marshall Islands.

While technically true, this hid a more gruesome point: the last stage of a multi-staged hydrogen bomb often used the neutrons produced by the fusion reactions to induce fissioning in a jacket of natural uranium and provided around half of the yield of the device itself.

Early nuclear armed rockets—such as the MGR-1 Honest John, first deployed by the U.S. in 1953—were surface-to-surface missiles with relatively short ranges (around 15 mi/25 km maximum) and yields around twice the size of the first fission weapons.

This apparent paradox of nuclear war was summed up by British Prime Minister Winston Churchill as "the worse things get, the better they are"—the greater the threat of mutual destruction, the safer the world would be.

Also involved in the debate about nuclear weapons policy was the scientific community, through professional associations such as the Federation of Atomic Scientists and the Pugwash Conference on Science and World Affairs.

The "Baby Tooth Survey," headed by Dr Louise Reiss, demonstrated conclusively in 1961 that above-ground nuclear testing posed significant public health risks in the form of radioactive fallout spread primarily via milk from cows that had ingested contaminated grass.

The international politics of brinkmanship led leaders to exclaim their willingness to participate in a nuclear war rather than concede any advantage to their opponents, feeding public fears that their generation may be the last.

Civil defense programs undertaken by both superpowers, exemplified by the construction of fallout shelters and urging civilians about the survivability of nuclear war, did little to ease public concerns.

The missiles had 2,400 mile (4,000 km) range and would allow the Soviet Union to quickly destroy many major American cities on the Eastern Seaboard if a nuclear war began.

Fears of communication difficulties led to the installment of the first hotline, a direct link between the superpowers that allowed them to more easily discuss future military activities and political maneuverings.

An improved version of 'Fat Man' was developed, and on 26 February 1952, Prime Minister Winston Churchill announced that the United Kingdom had an atomic bomb and a successful test took place on 3 October 1952.

This doctrine resulted in a large increase in the number of nuclear weapons, as each side sought to ensure it possessed the firepower to destroy the opposition in all possible scenarios.

These systems were used to launch satellites, such as Sputnik, and to propel the Space Race, but they were primarily developed to create Intercontinental Ballistic Missiles (ICBMs) that could deliver nuclear weapons anywhere on the globe.

In a major move of symbolic de-escalation, Boris Yeltsin, on January 26, 1992, announced that Russia planned to stop targeting United States cities with nuclear weapons.

"[88] Known as the Vela incident, it was speculated to have been a South African or possibly Israeli nuclear weapons test, though some feel that it may have been caused by natural events or a detector malfunction.

Trinity- Gadget , an implosion-type plutonium device tested on July 16, 1945, by the United States was the first successful nuclear weapon ever created. It yielded approximately 25 kilotons of TNT.
In nuclear fission , the nucleus of a fissile atom (in this case, enriched uranium ) absorbs a thermal neutron, becomes unstable and splits into two new atoms, releasing some energy and between one and three new neutrons, which can perpetuate the process.
Leo Szilard , pictured in about 1960, invented the electron microscope, linear accelerator, cyclotron, nuclear chain reaction and patented the nuclear reactor
The final iteration of the Gadget nuclear device prior to its successful test on July 16, 1945, the culmination of the United States' 3-year Manhattan Project 's research and development of nuclear weapons
Physicist J. Robert Oppenheimer led the Allied scientific effort at Los Alamos .
Proportions of uranium-238 (blue) and uranium-235 (red) found naturally versus grades that are enriched by separating the two isotopes atom-by-atom using various methods that all require a massive investment in time and money.
Electromagnetic U 235 separation plant at Oak Ridge, Tenn. Massive new physics machines were assembled at secret installations around the United States for the production of enriched uranium and plutonium .
The two fission bomb assembly methods.
The atomic bombings of Hiroshima and Nagasaki killed tens of thousand Japanese combatants and non-combatants and destroyed dozens of military bases and supply depots as well as hundreds (or thousands) of factories . They were the first-ever deployment of nuclear weapons in an active war-scenario.
The Bockscar B-29 that was used to deliver the Fat Man bomb and a post war Mk III nuclear weapon painted to resemble the Fat Man, at the National Museum of the United States Air Force
Hiroshima: burns from the intense thermal effect of the atomic bomb.
Hungarian physicist Edward Teller toiled for years trying to discover a way to make a fusion bomb.
A view of the Ivy- Mike "Sausage" device casing, with its instrumentation and cryogenic equipment attached. The long pipes connected to the device to the left were for measuring purposes; the first thermonuclear weapon test-design required cryogenic-fuel lowered to a temperature of near-absolute-zero; a design initially considered far too cumbersome as a deliverable weapon.
Ivy Mike , the first full test of the Teller–Ulam design (a staged fusion bomb), with a yield of 10.4 megatons (November 1, 1952)
The SHRIMP device, utilized in the Bravo test of Operation Castle , was the first ever solid-fueled thermonuclear weapon design ever tested by the United States, light and compact enough to be theoretically deliverable by its existing bomber-aircraft fleet.
Castle- Bravo , 15 megatons. The most powerful nuclear-weapons test ever conducted by the United States. Its unexpectedly higher yield and destructive power resulted in an international incident from the significant amount of nuclear fallout it generated.
November 1951 nuclear test at the Nevada Test Site , from Operation Buster , with a yield of 21 kilotons. It was the first U.S. nuclear field exercise conducted on land; troops shown are 6 mi (9.7 km) from the blast.
Despite having an almost-exact explosive-yield and assembly method as Little Boy , the first nuclear weapon ever deployed in combat, the W9 nuclear artillery-shell test-fired during Operation Upshot-Knothole series of tests was far smaller and lighter than its predecessors; a result of the evolving efficiencies of new nuclear-weapon designs.
Test-deployment of the 3.88-megaton Teak via the PGM-11 Redstone rocket during the Hardtack series of nuclear-weapons tests were made possible from the culmination of many aeronautical-engineering research and developments gathered from a post-war Germany.
The introduction of nuclear armed rockets, like the MGR-1 Honest John , reflected a change in both nuclear technology and strategy.
Long-range bomber aircraft, such as the B-52 Stratofortress , allowed deployment of a wide range of strategic nuclear weapons .
A SSM-N-8 Regulus is launched from USS Halibut ; prior to the development of the SLBM , the United States employed submarines with Regulus cruise missiles in the submarine-based strategic deterrent role.
With early warning systems, it was thought that the strikes of nuclear war would come from dark rooms filled with computers , not the battlefield of the wars of old.
Women Strike for Peace during the Cuban Missile Crisis
U-2 photographs revealed that the Soviet Union was stationing nuclear missiles on the island of Cuba in 1962, beginning the Cuban Missile Crisis .
Newer, and more varied deployment weapon options, such as via Submarine-launched ballistic missiles , made defending against nuclear attack increasingly impractical.
ICBMs , like the American Minuteman missile , allowed nations to deliver nuclear weapons thousands of miles away with relative ease.
On 12 December 1982, 30,000 women held hands around the 6 miles (9.7 km) perimeter of the RAF Greenham Common base, in protest against the decision to site American cruise missiles there.
Large stockpile with global range (dark blue), smaller stockpile with global range (medium blue), small stockpile with regional range (light blue).