Introduction 

Five of the first six nuclear tests conducted by the United States occurred in the far reaches of the Pacific Ocean. 

Almost immediately, scientists and military planners discovered that logistics, weather, security and safety 

concerns required the need for a continental test site. The effort of transporting, supplying and housing a nuclear 

test task force in the middle of the Pacific was more than originally anticipated. In addition to the communist 

insurgency in Korea, the need for a continental proving ground was evident. The Armed Forces Special Weapons 

Project conducted a top-secret feasibility study, code named 

Nutmeg, to identify the best location for a test site. The study 

concluded that arid southwest of the United States was the ideal 

location. In December, 1950, the Nevada Proving Grounds was 

established. Thirty one days later, the first atmospheric test was 

conducted in Nevada. 

Atmospheric Testing at the Nevada Test Site 

Operation Ranger was the first atmospheric nuclear weapons test 

series conducted by the Atomic Energy Commission at the Nevada 

Test Site. This 1951 series consisted of five nuclear tests, all of 

which were airdrops detonated at heights of about 1,000-1,400 

feet. 

Operation Upshot-Knothole was unique in that the first test, Annie, 

was conducted for the Federal Civil Defense Administration 

(FCDA) in 1953. In preparation for the test, the FCDA constructed 

Climax crates a fireball at the Nevada Test Site in 1953. "a typical American community" complete with houses, utility 

Climax was an airdrop, weapons-related test. stations, automobiles, furniture, appliances, food, and even 

mannequins simulating the people who might live in the town. It 

was witnessed by more than 600 Civil Defense observers and 

media. Grable, also part of the 1953 Upshot-Knothole series, was significant in that it was the only test fired from 

a military cannon. 

Operation Teapot, in early 1955, had two primary objectives: to establish military doctrine and tactics for the use 

of ground forces on a nuclear battlefield; and to improve the nuclear weapons used for strategic bomber delivery 

and missile delivery and those used for tactical battlefield situations. 

Operation Plumbbob in 1957, included five safety experiments, conducted to ensure that no nuclear reaction 

would occur if the high explosive components of the device were accidentally detonated during storage or 

transport. 

Operation Hardtack II, conducted in 1958, was the last nuclear test series before the United States adopted a 

nuclear test moratorium, which had originally been intended to last one year but continued until 1961. The 

nuclear weapons tests were conducted to evaluate the yield and efficiency of newly developed nuclear 

devices.The United States resumed nuclear weapons testing on September 15, 1961. The last atmospheric test 

conducted at the Nevada Test Site was Little Feller I on July 17, 1962. 
A total of 100 atmospheric tests were conducted at the Nevada Test Site. These tests were conducted to provide 

information on weapons effects, effects of the height of burst on overpressure, and information on nuclear 

phenomena to improve the design of nuclear weapons. Atmospheric testing ceased for good in 1963, after which 

nuclear testing moved underground. 

Pacific Testing 

After the atomic bomb attacks on Japan abruptly ended World War II, postwar atmospheric testing took place in 

the southern Pacific Ocean. 

Operations Crossroads and Sandstone were designed to produce information not available from the Trinity test. 

Their primary purposes were scientific data collection and to determine the effects of atomic bombs on naval 

vessels positioned in the Pacific Ocean. 

Pacific testing offered ample protected anchorage for both a target fleet and support ships, but as a test site, it held 

two drawbacks: the distance from the continental United States made extraordinary logistical demands; and the 

humid climate created numerous problems for sophisticated electronic and photographic equipment. 

While the test site was established as the continental site, larger yield atmospheric tests continued to be tested in 

the Pacific.There were a total of 106 atmospheric tests in the Pacific. Notably, Operation Greenhouse was 

significant to the development of nuclear weapons for defense, more specifically, the use of thermonuclear 

weapons. Although Operation Greenhouse did not test thermonuclear devices, two of the tests in the series 

involved thermonuclear experiments. One test, George, was an important step toward thermonuclear development 

by demonstrating the initiation of a sustained thermonuclear reaction by use of a fission reaction. This led directly 

to the first successful thermonuclear test, Mike (Operation Ivy) in the South Pacific 16 months later. In addition, 

Item, the fourth test of the series, involved boosting the efficiency of fission explosions. 

Prior to 1955, most nuclear weapons had been tested in the atmosphere, on the surface of the earth or water, or at 

shallow underwater depths. The Navy expressed interest in investigating deep underwater effects by detonating a 

weapon at sufficient depth to contain all the initial energy of the nuclear explosion in the water. On May 14, 1955 

Wigwam was conducted in the Pacific Ocean approximately 500 miles southwest of San Diego, California. The 

device was detonated at a depth of 2,000 feet in water 16,000 feet deep. Results showed that most of the radioactivity from Wigwam was confined deep under the surface of the water. 

Additional weapons effects tests, named Operation Argus, occurred in the South Atlantic in 1958. 

For more information, contact: 

U.S. Department of Energy 

National Nuclear Security Administration 

Nevada Site Office 

Office of Public Affairs 

P.O. Box 98518 

Las Vegas, NV 89193-8518 

phone: 702-295-3521 

fax: 702-295-0154 

email: nevada@nv.doe.gov 

http://www.nv.doe.gov 

DOE/NV - -716 - REV 1 

March 2005