Greenhouse Item was an American

nuclear test Nuclear weapons tests are experiments carried out to determine nuclear weapons' effectiveness, Nuclear weapon yield, yield, and explosive capability. Testing nuclear weapons offers practical information about how the weapons function, how detona ...

conducted on May 25, 1951, as part of

Operation Greenhouse 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 (''hydrogen bombs''). Conducted at the new Pacific Proving Gro ...

at the Pacific Proving Ground, specifically on the island of Engebi in the

Eniwetok Atoll Enewetak Atoll (; also spelled Eniwetok Atoll or sometimes Eniewetok; mh, Ānewetak, , or , ; known to the Japanese as Brown Atoll or Brown Island; ja, ブラウン環礁) is a large coral atoll of 40 islands in the Pacific Ocean and with it ...

in the Central Pacific Ocean. This test explosion was the first test of a

boosted fission weapon 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 ...

Description

In this test

deuterium Deuterium (or hydrogen-2, symbol or deuterium, also known as heavy hydrogen) is one of two stable isotopes of hydrogen (the other being protium, or hydrogen-1). The nucleus of a deuterium atom, called a deuteron, contains one proton and one ...

tritium Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of ...

(D-T) gas was injected into the

enriched uranium Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U ...

core of a nuclear fission bomb. The extreme heat of the fissioning bomb produced

thermonuclear fusion Thermonuclear fusion is the process of atomic nuclei combining or “fusing” using high temperatures to drive them close enough together for this to become possible. There are two forms of thermonuclear fusion: ''uncontrolled'', in which the re ...

reactions within the D-T gas, but not enough of them to be considered a full nuclear fusion bomb. This fusion reaction released a large number of free

neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...

s, which greatly increased the efficiency of the nuclear fission reaction. The explosive yield of this bomb was 45.5

kiloton TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...

s, about twice the yield of the unboosted bomb. Greenhouse - Item device 1

This bomb was known as the "Booster" in its development stages, a name for the mechanism coined by

Edward Teller Edward Teller ( hu, Teller Ede; January 15, 1908 – September 9, 2003) was a Hungarian-American theoretical physicist who is known colloquially as "the father of the hydrogen bomb" (see the Teller–Ulam design), although he did not care for ...

in September 1947. Planning for it had begun in the late 1940s. According to the researcher

Chuck Hansen Chuck Hansen (May 13, 1947 - March 26, 2003) was the compiler, over a period of 30 years, of the world's largest private collection of unclassified documents on how America developed atomic and thermonuclear weapons. Research Hansen's documents ...

, it was mentioned in official

U.S. Atomic Energy Commission The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology. President ...

documents as early as 1947. The main problems in development were making modifications to the fission core to accept the gas correctly without reducing its own efficiency. The 1951 test was primarily to test the nuclear principles involved, and to gain research data, and it was not considered a design for a weaponizable device. Even as late as 1954, no boosted weapon had entered into the nuclear-weapons stockpile, and the only use for the Greenhouse Item nuclear test had been for its research results. The "Booster" device was detonated at 6:17 am on May 25, 1951, from a shot tower on the island of Engebi in the Enewetok Atoll, and its fusion fuel was injected by means of a cryogenic pump at the base of the tower.

References

, ''Swords of Armageddon'', 1995, esp. "The Item Shot" in Volume III.

External links

*
Operation Greenhouse
at nuclearweaponarchive.org {{Nuclear weapons tests of the United States Explosions in 1951 Enewetak Atoll nuclear explosive tests 1951 in the Marshall Islands 1951 in the United States 1951 in military history 1951 in science May 1951 events in Oceania