Date

Feb 20, 1947

Description

Joseph Hoffman, who directed the radiation monitoring activities for the area beyond the Trinity site, produced a detailed account of the monitoring immediately at the time of the July 1945 test. According to Hoffman, “one half of all the [radio]activity available was precipitated in the two weeks after the explosion” and 90 percent of it was in New Mexico. As Brodie noted, Hoffman acknowledged “that a localized ‘hot spot’ might have occurred, none was found, and the actual contamination indicated a uniform distribution at a concentration which is considered not to constitute a health hazard.” No monitoring occurred near the Mescalero Apache Reservation or at Ruidoso, the location of a girls camp that “received significant fallout.” With respect to the Apache reservation, Brodie suggests that the test planners chose a day when the “most likely wind direction blew to the north,” thus avoiding the area around that territory.

Almost all of the names of the radiation monitors and other officials mentioned in this report were excised for “privacy reasons.” For example, Arthur Breslow’s name was excised (and Hoffman did not mention his vivid account). Given that the excisions were probably made decades after Hoffman produced this report, they were likely a misuse of the Privacy Act; the individuals mentioned were probably long retired from government service. The National Security Archive has requested an unredacted copy of the report.

Source

DOE Open-Net

Document published in following posting(s):

The First Atomic Explosion, 16 July 1945

Jul 16, 2024

Joseph G. Hoffman, “Nuclear Explosion 16 July 1945: Health Physics Report on Radioactive Contamination Throughout New Mexico Following the Nuclear Explosion,” Official Use Only, Los Alamos Scientific Laboratory, 20 February 1947, Official Use Only, excised copy