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Project 58
Coulomb-C detonation
Country United States
Test site Nevada National Security Site
Period 1957–1958
Number of tests 4
Test type Underground / Surface
Max. yield 500 tons of TNT (2,100 GJ)
Previous test Operation Plumbbob
Next test Operation Hardtack I

Project 58 and 58A was a series of four nuclear tests conducted by the United States in Area 3 and Area 12 of the Nevada National Security Site in 1957/1958.[1]

All tests were one-point safety tests.[2] They were intended to freeze device designs prior to full-scale tests at Operation Hardtack I. No significant yield was expected from either, but the second, Coulomb-C, a surface test conducted on December 9, produced an unanticipated yield of 500 tons. Shortly after detonation, fallout readings of fifty roentgens per hour were recorded on the Mercury Highway, and, as the cloud moved toward the southwest, personnel at Jackass Flats involved in construction for future nuclear rocket testing were forced to take cover. Eventually, the cloud reached the Los Angeles area where very low readings briefly caused some public concern.[3]


Project 58 Tests
Name Date, Time (UT[4]) Location Elevation + Height Delivery Purpose Device Yield Notes
Pascal-C December 6, 1957 20:15:00.0 NTS Area 3 37°03′00″N 116°01′54″W / 37.04992°N 116.03159°W / 37.04992; -116.03159 1,202 metres (3,944 ft) - 80 metres (260 ft) unstemmed shaft one-point safety test XW-42 10 tons Unsuccessful; radioactivity not detected off site.
Coulomb-C December 9, 1957 20:00 NTS Area 3 37°02′39″N 116°01′50″W / 37.0443°N 116.0305°W / 37.0443; -116.0305 1,225 metres (4,019 ft) + 0 surface one-point safety test   500 tons unsuccessful; radioactivity not detected off site.
Venus February 22, 1958 1:00:00 NTS Area 12d 37°11′41″N 116°12′02″W / 37.19475°N 116.20068°W / 37.19475; -116.20068 2,104 metres (6,903 ft) - 30 metres (98 ft) tunnel one-point safety test XW-47 0.5 ton unsuccessful; no radioactive release detected.
Uranus March 14, 1958 22:00:00 NTS Area 12c 37°11′36″N 116°12′01″W / 37.193397°N 116.20014°W / 37.193397; -116.20014 2,068 metres (6,785 ft) - 35 metres (115 ft) tunnel one-point safety test XW-47 0.5 ton unsuccessful; no radioactive release detected.


  1. "United States Nuclear Tests: July 1945 through September 1992 (Revision 15)". Department of Energy, Nevada Operations Office. December 2000. Retrieved 2013-10-26. 
  2. "Projects 57, 58, and 58A". The Nuclear Weapon Archive. 
  3. U.S. Department of Energy, Battlefield of the Cold War, The Nevada Test Site, Volume 1, Atmospheric Nuclear Weapons Testing, 1951-1963, DOE/MA-0003
  4. Local time (PST) is 8 hours less than UT (7 for PDT); local date is the day before UT if UT time is before 08:00 (07:00 PDT).

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