Military Wiki
Operation Ivy
Ivy Mike
Country United States
Test site Pacific Proving Grounds
Period November 1952
Number of tests 2
Test type Atmospheric tests
Device type Thermonuclear (Mike)
Fission (King)
Max. yield 10.4 Mt
Previous test Operation Tumbler-Snapper
Next test Operation Upshot-Knothole

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. The two explosions were staged in late 1952 at Eniwetok Atoll in the Pacific Proving Ground in the Marshall Islands.



The first Ivy shot, Mike, was the first successful full-scale test of a multi-megaton thermonuclear weapon ("hydrogen bomb") using the Teller-Ulam design. Unlike later thermonuclear weapons, Mike used deuterium as its fusion fuel, maintained as a liquid by an expensive and cumbersome cryogenic system. It was detonated on Elugelab Island yielding 10.4 megatons, almost 500 times the yield of the bomb dropped on Nagasaki. Eight megatons of the yield was from fast fission of the uranium tamper, creating massive amounts of radioactive fallout. The detonation left an underwater crater 6,240 ft (1.9 km) wide and 164 ft (50 m) deep where Elugelab Island had been. Following this successful test, the Mike design was weaponized as the EC-16, but it was quickly abandoned for solid-fueled designs after the success of the Castle Bravo shot.

Jimmy P. Robinson,[1] a USAF captain, was lost while piloting his F-84G through the mushroom cloud to collect air samples; he ran out of fuel and attempted to land on water but was never found.[2]


The second test, King, fired the largest nuclear weapon to date using only nuclear fission (no fusion nor fusion boosting). This "Super Oralloy Bomb" was intended as a backup if the fusion weapon failed. King yielded 500 kilotons, 25 times more powerful than the Fat Man weapon.

Ivy tests
Name Date, Time (UT[3]) Location Elevation + Height Delivery Purpose Device Yield Notes
Mike October 31, 1952 19:14:59.4 Elugelab ("Flora") Island, Enewetok 11°39′57″N 162°11′21″E / 11.66573°N 162.18928°E / 11.66573; 162.18928 2 metres (6 ft 7 in) + 8 metres (26 ft) surface weapon development TX-16 10.4–12 megatons First Teller-Ulam design hydrogen bomb; cryogenic deuterium fuel; Elugelab completely erased.
King November 15, 1952 23:30:00.0 2,000 feet (610 m) north of Runit ("Yvonne") Island, Enewetok 11°33′32″N 162°20′43″E / 11.55878°N 162.34541°E / 11.55878; 162.34541 0 + 450 metres (1,480 ft) free airdrop weapon development Mark 18f 500 kilotons Largest pure-fission bomb; nicknamed the SOB, for SuperOralloy Bomb.

See also


  1. "Into the Mushroom Cloud | History of Flight | Air & Space Magazine". Retrieved 2012-11-01. 
  2. Michael Robert Patterson. "Jimmy Priestly Robinson, Captain, United States Air Force". Retrieved 2012-11-01. 
  3. Local time (MHT) is 12 hours later than UT; local date is one day after UT if UT time is on or after 12:00.

External links

This page uses Creative Commons Licensed content from Wikipedia (view authors).