Greenhouse-Item was an American

nuclear test Nuclear weapons tests are experiments carried out to determine the performance of nuclear weapons and the effects of their explosion. Nuclear testing is a sensitive political issue. Governments have often performed tests to signal strength. Bec ...

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 Teller-Ullam, thermonuclear weapons (''hydrogen bombs''). Conducted at the new Pacific ...

at the Pacific Proving Ground, specifically on the island of Engebi in the Eniwetok Atoll in the Central Pacific Ocean. This test explosion was the second 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 fast fusion neutrons released by the fusion reactions add to the fast ...

, the second instance of artificial

thermonuclear fusion Nuclear fusion is a reaction in which two or more atomic nuclei combine to form a larger nuclei, nuclei/neutron by-products. The difference in mass between the reactants and products is manifested as either the release or absorption of ener ...

, following the

Greenhouse George 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 Grou ...

test on May 9.

Description

In this test

deuterium Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, H. The deuterium nucleus (deuteron) contains one proton and one neutron, whereas the far more c ...

tritium Tritium () or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.33 years. The tritium nucleus (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the ...

(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 (23 ...

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

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 , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

s, which greatly increased the efficiency of the

nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...

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. A ton of TNT equivalent is a unit of energy defined by convention to be (). It is the approximate energy released in the det ...

s, about twice the yield of the unboosted bomb. The device was code-named "''Booster''" in its development stages, a name for the mechanism coined by

Edward Teller Edward Teller (; January 15, 1908 – September 9, 2003) was a Hungarian and American Theoretical physics, theoretical physicist and chemical engineer who is known colloquially as "the father of the hydrogen bomb" and one of the creators of ...

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

Chuck Hansen Chuck Hansen (May 13, 1947March 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 were ...

, it was mentioned in official U.S. Atomic Energy Commission 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.

Gallery

File:Greenhouse Item 001.jpg, ''Item'' fireball. File:Greenhouse - Item Device 3.png, Device being raised upward towards its shot-tower. File:Greenhouse - Item device 2.jpg, Preparing the "booster" for the test. File:Greenhouse - Item device 1.jpg, The ''Item'' casing.

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 in Oceania