RADIOACTIVITY RELEASED BY UNDERGROUND EXPERIMENT NEAR CARLSBAD, NEW MEXICO The first nuclear detonation in the Commission's Plowshare program to develop peaceful uses for nuclear explosives was Project Gnome, a multipurpose experiment in a salt bed 25 miles southeast of Carlsbad, New Mexico. The nuclear device, with a yield of about three kilotons, was detonated at 12:00 noon, MST, on December 10, 1961,.1,200 feet underground. The detonation raised a small cloud of dust from the surface. Shortly, thereafter, a white vapor was seen issuing from the mouth of the 1,200 foot vertical shaft. This vapor, holding close to the ground, was blown north-northwest, to the east of the city of Carlsbad. There was no evidence of venting in the vicinity of surface ground zero. Monitoring results demonstrated that the cloud was largely gaseous in nature. Although every effort had been made to mini- mize the deposition of radioactivity in any inhabited off-site area, small amounts of short-lived radioactivity were deposited in the path of the cloud for the first ten miles or so. The following is a summary of the data obtained by the U. S. Public Health Service Off-Site Radiological Safety Organization of the Office of Field Operations, now the Nevada Operations Office, AEC, in the vicinity of the test site. DOE ARCHIVES

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