Radioactive dust cloud over the Nevada Test Site (NTS). The cloud of radioactive dust was accidentally vented into the atmosphere after an underground nuclear weapon test. The device, codename Baneberry, had been buried 280 metres under the surface of Yucca Flat, near the northern boundary of the NTS area. The dust cloud rose 3,000 metres into the air, some of the dust then drifted off the site. Radiation levels off site remained within safety levels. 86 workers at NTS were exposed to radiation from Baneberry, but this too was within the limits set for NTS workers. The weapon was detonated on 18 December 1970.