Orange Herald was a British nuclear weapon, tested on 31 May 1957. At the time it was reported as an H-bomb, although in fact it was a large boosted fission weapon and remains to date, the largest fission device ever detonated.
Orange Herald was a British nuclear weapon, tested on 31 May 1957. At the time it was reported as an H-bomb, although in fact it was a large boosted fission weapon and remains to date, the largest fission device ever detonated.
Orange Herald was a fusion boosted British fission nuclear weapon (called a core-boosted device by the British), comprising a U-235 core containing a small amount of lithium deuteride (LiD). [1] [2] 'Herald' was suitable for mounting on a missile, utilizing 117 kg of U-235. However, Britain's annual production of U-235 was only 120 kg at this time, which would have made such weapons rare and very expensive. [3]
Two versions were designed - an "Orange Herald Large" with an overall diameter of 39 inches (1.0 m), and an "Orange Herald Small" with overall diameter of 30 inches (0.75 m). [3] The difference between the two was in the size of the high explosives; the fissile cores were similar. Orange Herald Small was intended as a warhead for a ballistic missile. Orange Herald Large was designed as a device which would have the most certainty to give a yield in the megaton range. However, due to its size it was not suited as a warhead for the ballistic missile and was more of an insurance which could be used if other devices failed to achieve the desired yield.
The Orange Herald Small version was tested once, yielding 720 kt of explosive power on 31 May 1957, during the Grapple 2/Orange Herald tests on Malden Island in the Pacific. [4] Orange Herald remains the largest fission device ever tested.
It is thought that the fusion boosting failed to increase the yield. A higher compression but smaller fission pit American weapon, the Mark 18 Super Oralloy Bomb, had a yield of 500 kilotons from a pit with slightly over 60 kilograms of highly enriched uranium, around 8 kilotons per kilogram of uranium, about the practical maximum 50% fission yield efficiency[ citation needed ] for very large or very highly boosted fission weapons. Even with less compression, the larger 117 kg pit of HEU in the Orange Herald Small should have had a roughly similar efficiency, but the observed 720 kiloton yield equals only just over 6 kilotons per kilogram of uranium.
Orange Herald was the first British nuclear device to use an external neutron source. [5]
Britain rushed the development of these predicted-megaton class weapons because in 1955 it seemed that atmospheric testing could soon be outlawed by treaty. As a result, the UK wanted to demonstrate its ability to manufacture megaton class weapons by proof-testing them before any legal prohibitions were in place. According to an article in New Scientist , Prime Minister Harold Macmillan was also hoping to convince the US to change the McMahon Act, which prohibited sharing information even with the British, by demonstrating that the UK had the technology to make a thermonuclear weapon (an H-bomb), and he put William Penney, a British professor who had worked in the Manhattan Project, in charge of developing this bomb. In this the test of the Orange Herald was successful. [6]
It is believed by some that the large requirements of tritium that Orange Herald needed (actually it contained only a small amount of thermonuclear material [2] ) was a major cause of the Windscale fire. It was unpopular with the scientists who worked on the project. One of the workers in the British nuclear program, Dr. Bryan Taylor, is quoted as saying "I thought that Orange Herald was a stupid device. It wasn't elegant, it couldn't be developed any further, it was a dead end design. And it consumed an enormous amount of very expensive fissile material". [7] This is the thesis of a BBC documentary on the topic of the fire, Windscale: Britain’s Biggest Nuclear Disaster. [8]
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion reactions, producing a nuclear explosion. Both bomb types release large quantities of energy from relatively small amounts of matter.
Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types:
Operation Grapple was a set of four series of British nuclear weapons tests of early atomic bombs and hydrogen bombs carried out in 1957 and 1958 at Malden Island and Kiritimati in the Gilbert and Ellice Islands in the Pacific Ocean as part of the British hydrogen bomb programme. Nine nuclear explosions were initiated, culminating in the United Kingdom becoming the third recognised possessor of thermonuclear weapons, and the restoration of the nuclear Special Relationship with the United States in the form of the 1958 US–UK Mutual Defence Agreement.
Operation Greenhouse was the fifth American nuclear test series, the second conducted in 1951 and the first to test principles that would lead to developing thermonuclear weapons. Conducted at the new Pacific Proving Ground, on islands of the Enewetak Atoll, it mounted the devices on large steel towers to simulate air bursts. This series of nuclear weapons tests was preceded by Operation Ranger and succeeded by Operation Buster-Jangle.
Yellow Sun was the first British operational high-yield strategic nuclear weapon warhead. The name refers only to the outer casing; the warhead was known as "Green Grass" in Yellow Sun Mk.1 and "Red Snow" in Yellow Sun Mk.2.
Red Snow was a British thermonuclear weapon, based on the US W28 design used in the B28 thermonuclear bomb and AGM-28 Hound Dog missile. The US W28 had yields of 70, 350, 1,100 and 1,450 kilotonnes of TNT and while Red Snow yields are still classified, declassified British documents indicate the existence of "kiloton Red Snow" and "megaton Red Snow" variants of the weapon, suggesting similar yield options, while other sources have suggested a yield of approximately 1 megatonne of TNT (4.2 PJ).
The Soviet atomic bomb project was the classified research and development program that was authorized by Joseph Stalin in the Soviet Union to develop nuclear weapons during and after World War II.
Joe 4 was an American nickname for the first Soviet test of a thermonuclear weapon on August 12, 1953, that detonated with a force equivalent to 400 kilotons of TNT. The proper Soviet terminology for the warhead was RDS-6s, Reaktivnyi Dvigatel Specialnyi, lit. 'Special Jet Engine'.
A boosted fission weapon usually refers to a type of nuclear bomb that uses a small amount of fusion fuel to increase the rate, and thus yield, of a fission reaction. The neutrons released by the fusion reactions add to the neutrons released due to fission, allowing for more neutron-induced fission reactions to take place. The rate of fission is thereby greatly increased such that much more of the fissile material is able to undergo fission before the core explosively disassembles. The fusion process itself adds only a small amount of energy to the process, perhaps 1%.
A thermonuclear weapon, fusion weapon or hydrogen bomb is a second-generation nuclear weapon design. Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs, a more compact size, a lower mass, or a combination of these benefits. Characteristics of nuclear fusion reactions make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as uranium-235 or plutonium-239. The first full-scale thermonuclear test 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.
The Teller–Ulam design is a technical concept behind modern thermonuclear weapons, also known as hydrogen bombs. The design – the details of which are military secrets and known to only a handful of major nations – is believed to be used in virtually all modern nuclear weapons that make up the arsenals of the major nuclear powers.
The explosive yield of a nuclear weapon is the amount of energy released such as blast, thermal, and nuclear radiation, when that particular nuclear weapon is detonated, usually expressed as a TNT equivalent (the standardized equivalent mass of trinitrotoluene which, if detonated, would produce the same energy discharge), either in kilotonnes (kt—thousands of tonnes of TNT), in megatonnes (Mt—millions of tonnes of TNT), or sometimes in terajoules (TJ). An explosive yield of one terajoule is equal to 0.239 kilotonnes of TNT. Because the accuracy of any measurement of the energy released by TNT has always been problematic, the conventional definition is that one kilotonne of TNT is held simply to be equivalent to 1012 calories.
Gun-type fission weapons are fission-based nuclear weapons whose design assembles their fissile material into a supercritical mass by the use of the "gun" method: shooting one piece of sub-critical material into another. Although this is sometimes pictured as two sub-critical hemispheres driven together to make a supercritical sphere, typically a hollow projectile is shot onto a spike, which fills the hole in its center. Its name is a reference to the fact that it is shooting the material through an artillery barrel as if it were a projectile.
The Mark 18 nuclear bomb, also known as the SOB or Super Oralloy Bomb, was an American nuclear bomb design which was the highest yield fission bomb produced by the US. The Mark 18 had a design yield of 500 kilotons. Nuclear weapon designer Ted Taylor was the lead designer for the Mark 18.
Violet Club was a nuclear weapon deployed by the United Kingdom during the Cold War. It was Britain's first operational "high-yield" weapon and was intended to provide an emergency capability until a thermonuclear weapon could be developed from the 1956–1958 Operation Grapple tests. Violet Club was ultimately replaced in service by the Red Snow warhead, derived from the US W28 warhead.
A fizzle occurs when the detonation of a device for creating a nuclear explosion grossly fails to meet its expected yield. The bombs still detonate, but the detonation is much less than anticipated. The cause(s) for the failure can be linked to improper design, poor construction, or lack of expertise. All countries that have had a nuclear weapons testing program have experienced some fizzles. A fizzle can spread radioactive material throughout the surrounding area, involve a partial fission reaction of the fissile material, or both. For practical purposes, a fizzle can still have considerable explosive yield when compared to conventional weapons.
In nuclear weapon design, the pit is the core of an implosion nuclear weapon, consisting of fissile material and any neutron reflector or tamper bonded to it. Some weapons tested during the 1950s used pits made with uranium-235 alone, or as a composite with plutonium. All-plutonium pits are the smallest in diameter and have been the standard since the early 1960s. The pit is named after the hard core found in stonefruit such as peaches and apricots.
ET.317 was a thermonuclear weapon of the British Royal Navy, developed for the UK version of the UGM-27 Polaris missile.
The British hydrogen bomb programme was the ultimately successful British effort to develop hydrogen bombs between 1952 and 1958. During the early part of the Second World War, Britain had a nuclear weapons project, codenamed Tube Alloys. At the Quebec Conference in August 1943, British prime minister Winston Churchill and United States president Franklin Roosevelt signed the Quebec Agreement, merging Tube Alloys into the American Manhattan Project, in which many of Britain's top scientists participated. The British government trusted that America would share nuclear technology, which it considered to be a joint discovery, but the United States Atomic Energy Act of 1946 ended technical cooperation. Fearing a resurgence of American isolationism, and the loss of Britain's great power status, the British government resumed its own development effort, which was codenamed "High Explosive Research".
Cold War military projects of the United Kingdom | ||
|---|---|---|
| air-to-air missiles |  | |
| air-to-surface missiles | ||
| surface-to-air missiles | ||
| surface-to-surface missiles | ||
| satellite launch vehicles | ||
| nuclear bombs | ||
| nuclear warheads | ||
