Ivy King
Encyclopedia
Ivy King was the largest pure fission
nuclear bomb
ever tested by the United States. The bomb was tested during the Truman
administration as part of Operation Ivy
. This series of tests involved the development of very powerful nuclear weapons in response to the nuclear weapons program of the Soviet Union
.
The production of Ivy King was hurried so it would be ready if its sister project, Ivy Mike
, failed in its attempt to achieve a thermonuclear reaction
. The Ivy King test actually took place two weeks after Mike. Unlike the Mike bomb, the Ivy King device could theoretically have been added to United States' nuclear arsenal because it was designed to be air-deliverable.
On November 16, 1952 at 11:30 local time (23:30 GMT) a B-36H bomber
dropped the bomb over a point 2,000 feet (610 m) north of Runit Island in the Enewetak
atoll, resulting in a 500 kiloton
explosion at 1,480 feet (450 m).
The Ivy King bomb, designated as a Mk-18 bomb
and named the "Super Oralloy Bomb", was a modified version of the Mk-6D bomb
. Instead of using an implosion system similar to the Mk-6D, it used a 92 point implosion system initially developed for the Mk-13. Its uranium
-plutonium
core was replaced by 60kg of highly enriched uranium (HEU)
fashioned into a thin-walled sphere equivalent to approximately four critical masses. The thin-walled sphere was a commonly used design which ensured that the fissile material remained sub-critical until imploded. The HEU sphere was then enclosed in a natural uranium tamper
. To physically prevent the HEU sphere collapsing into a critical condition if the surrounding explosives were detonated, or if the sphere was crushed following an aircraft accident, the hollow centre was filled with a chain made from aluminium
and boron
which was pulled out to arm the bomb. The boron coated chain also absorbed the neutron
s needed to drive the nuclear reaction.
The primary designer of the Super Oralloy Bomb, physicist Ted Taylor, later became a vocal proponent of nuclear disarmament
.
Nuclear fission
In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts , often producing free neutrons and photons , and releasing a tremendous amount of energy...
nuclear bomb
Nuclear weapon
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission or a combination of fission and fusion. Both reactions release vast quantities of energy from relatively small amounts of matter. The first fission bomb test released the same amount...
ever tested by the United States. The bomb was tested during the Truman
Harry S. Truman
Harry S. Truman was the 33rd President of the United States . As President Franklin D. Roosevelt's third vice president and the 34th Vice President of the United States , he succeeded to the presidency on April 12, 1945, when President Roosevelt died less than three months after beginning his...
administration as part of Operation Ivy
Operation Ivy
Operation Ivy was the eighth series of American nuclear tests, coming after Tumbler-Snapper and before Upshot-Knothole. Its purpose was to help upgrade the U.S. arsenal of nuclear weapons in response to the Soviet nuclear weapons program...
. This series of tests involved the development of very powerful nuclear weapons in response to the nuclear weapons program of the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
.
The production of Ivy King was hurried so it would be ready if its sister project, Ivy Mike
Ivy Mike
Ivy Mike was the codename given to the first United States test of a thermonuclear weapon, in which a major part of the explosive yield came from nuclear fusion. It was detonated on November 1, 1952 by the United States at on Enewetak, an atoll in the Pacific Ocean, as part of Operation Ivy...
, failed in its attempt to achieve a thermonuclear reaction
Nuclear fusion
Nuclear fusion is the process by which two or more atomic nuclei join together, or "fuse", to form a single heavier nucleus. This is usually accompanied by the release or absorption of large quantities of energy...
. The Ivy King test actually took place two weeks after Mike. Unlike the Mike bomb, the Ivy King device could theoretically have been added to United States' nuclear arsenal because it was designed to be air-deliverable.
On November 16, 1952 at 11:30 local time (23:30 GMT) a B-36H bomber
Convair B-36
The Convair B-36 "Peacemaker" was a strategic bomber built by Convair and operated solely by the United States Air Force from 1949 to 1959. The B-36 was the largest mass-produced piston engine aircraft ever made. It had the longest wingspan of any combat aircraft ever built , although there have...
dropped the bomb over a point 2,000 feet (610 m) north of Runit Island in the Enewetak
Enewetak
Enewetak Atoll is a large coral atoll of 40 islands in the Pacific Ocean, and forms a legislative district of the Ralik Chain of the Marshall Islands. Its land area totals less than , surrounding a deep central lagoon, in circumference...
atoll, resulting in a 500 kiloton
TNT equivalent
TNT equivalent is a method of quantifying the energy released in explosions. The ton of TNT is a unit of energy equal to 4.184 gigajoules, which is approximately the amount of energy released in the detonation of one ton of TNT...
explosion at 1,480 feet (450 m).
The Ivy King bomb, designated as a Mk-18 bomb
Mark 18 nuclear bomb
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...
and named the "Super Oralloy Bomb", was a modified version of the Mk-6D bomb
Mark 6 nuclear bomb
The Mark 6 nuclear bomb was an American nuclear bomb based on the earlier Mark 4 nuclear bomb and its predecessor, the Mark 3 Fat Man nuclear bomb design.The Mark 6 was produced from 1951-1955 and saw service until 1962...
. Instead of using an implosion system similar to the Mk-6D, it used a 92 point implosion system initially developed for the Mk-13. Its uranium
Uranium
Uranium is a silvery-white metallic chemical element in the actinide series of the periodic table, with atomic number 92. It is assigned the chemical symbol U. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons...
-plutonium
Plutonium
Plutonium is a transuranic radioactive chemical element with the chemical symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, forming a dull coating when oxidized. The element normally exhibits six allotropes and four oxidation...
core was replaced by 60kg of highly enriched uranium (HEU)
Enriched uranium
Enriched uranium is a kind of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% 238U isotope, with 235U only constituting about 0.711% of its weight...
fashioned into a thin-walled sphere equivalent to approximately four critical masses. The thin-walled sphere was a commonly used design which ensured that the fissile material remained sub-critical until imploded. The HEU sphere was then enclosed in a natural uranium tamper
Tamper
Tamper can mean:*Tamp, a device used to compact or flatten an aggregate or other powdered or granular material, like ground coffee or gravel*A tool used to pack tobacco into a smoking pipe, as well as to flatten or scoop the ash; usually nail-shaped and sometimes combined into a pipe tool*Ballast...
. To physically prevent the HEU sphere collapsing into a critical condition if the surrounding explosives were detonated, or if the sphere was crushed following an aircraft accident, the hollow centre was filled with a chain made from aluminium
Aluminium
Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances....
and boron
Boron
Boron is the chemical element with atomic number 5 and the chemical symbol B. Boron is a metalloid. Because boron is not produced by stellar nucleosynthesis, it is a low-abundance element in both the solar system and the Earth's crust. However, boron is concentrated on Earth by the...
which was pulled out to arm the bomb. The boron coated chain also absorbed the neutron
Neutron
The neutron is a subatomic hadron particle which has the symbol or , no net electric charge and a mass slightly larger than that of a proton. With the exception of hydrogen, nuclei of atoms consist of protons and neutrons, which are therefore collectively referred to as nucleons. The number of...
s needed to drive the nuclear reaction.
The primary designer of the Super Oralloy Bomb, physicist Ted Taylor, later became a vocal proponent of nuclear disarmament
Nuclear disarmament
Nuclear disarmament refers to both the act of reducing or eliminating nuclear weapons and to the end state of a nuclear-free world, in which nuclear weapons are completely eliminated....
.
External links
- Operation Ivy
- Video of the Ivy King Nuclear Test