Sedan (nuclear test)

Sedan (nuclear test)
source
Name	Sedan
Picture description	The Sedan crater, the largest human-made crater in the United States.
Country	United States
Test site	Nevada Test Site (Area 10)
Series	Operation Plowshare
Date	July 6, 1962
Time	10:00:00.0
Time zone	PST
Yield	104 kilotons
Test type	Cratering
Previous test	Small Boy
Next test	Johnie Boy

Sedan (nuclear test). The Sedan test was a high-yield underground nuclear detonation conducted by the United States Atomic Energy Commission as part of Operation Plowshare. Detonated on July 6, 1962, at the Nevada Test Site, its primary purpose was to investigate the potential for using nuclear explosives in large-scale civil engineering and excavation projects. The test created a massive crater, becoming a significant event in both the history of nuclear weapons testing and the study of peaceful nuclear explosions.

Background and purpose

The Sedan test was the centerpiece of Operation Plowshare, a U.S. Atomic Energy Commission program initiated in the late 1950s to explore non-military applications for nuclear explosives. Proposed uses included creating harbors, canals, and open-pit mines, with a particular interest in the Panama Canal and a potential new sea-level canal through Central America. Scientists, including those from the Lawrence Livermore National Laboratory, theorized that a deeply buried device could efficiently displace massive amounts of earth. The test was named after the city of Sedan, continuing the Operation Plowshare tradition of using names associated with excavation or earth-moving.

Test execution

On July 6, 1962, the 104-kiloton thermonuclear device was detonated 635 feet (194 meters) below the surface of Yucca Flat at the Nevada Test Site, specifically in Area 10. The explosion vaporized surrounding rock and soil, creating a cavity that collapsed seconds later. This formed a subsidence crater approximately 1,280 feet (390 meters) in diameter and 320 feet (100 meters) deep. The detonation, one of the largest ever conducted in continental U.S. territory, produced a characteristic "base surge" of radioactive dust. The event was extensively instrumented and filmed, with data collected by personnel from the Lawrence Livermore National Laboratory and the United States Geological Survey.

Effects and aftermath

The immediate effect was the creation of the largest human-made crater in the United States, displacing about 12 million tons of earth. The explosion generated a massive mushroom cloud that rose to 12,000 feet (3,700 meters) and a radioactive plume that drifted northeast across parts of Nevada, Utah, Colorado, South Dakota, Iowa, and Nebraska. Significant nuclear fallout was detected, contributing to public exposure and adding to the cumulative burden from other tests like those in Operation Dominic and Operation Nougat. The crater itself became a permanent feature and a stark visual symbol of the test's power, later designated a National Historic Landmark.

Scientific and engineering data

The test provided vast amounts of data on cratering mechanics, seismology, and the behavior of materials under extreme conditions. Measurements confirmed predictions about the scaling of crater dimensions with yield and burial depth. Seismic signals were recorded globally by organizations like the United States Geological Survey and were equivalent to a magnitude 4.75 earthquake. The extensive radionuclide release offered a case study in atmospheric dispersion, informing later models of fallout transport. However, the data ultimately underscored the severe economic and radiological challenges of using nuclear explosives for civilian projects.

Legacy and cultural impact

Sedan effectively ended serious consideration of large-scale peaceful nuclear explosions for excavation due to the unacceptable levels of radioactive contamination it produced. It remains a key case study in the history of nuclear weapons and Cold War-era technological ambition. The crater is a notable tourist stop on tours of the Nevada National Security Site (formerly the Nevada Test Site). The test is frequently cited in discussions of nuclear fallout and domestic testing, and its imagery is iconic within the documentation of the Atomic Age. It stands as a monument to a controversial chapter in American science and engineering. Category:1962 in the United States Category:Nuclear test sites in the United States Category:Operation Plowshare Category:Nuclear weapons tests of the United States