Project 58

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.

All tests were one-point safety tests. 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.

Tests
