| Themes > Science > Chemistry > Nuclear Chemistry > Nuclear Weapons > The First Nuclear Chain Reaction > The First Nuclear Weapons > TRINITY - The Gadget Test |
The test of the first atomic explosion in history was conducted at the Jornada del Muerto trail (Journey of Death) at the Alamagordo Bombing Range in New Mexico at 33 deg. 40' 31" North latitude, 106 deg. 28' 29" West longitude (33.675 deg. N, 106.475 deg W). The device was called Gadget, the whole test operation was code-named TRINITY. Gadget was a 150 cm sphere consisting of the basic explosive assembly described above with its dural shell, the firing electronics and equipment were mounted externally on the test platform which was atop a 100 foot steel tower, giving Gadget an elevation of 4624 ft above sea level. The assembly of Gadget took five days and began on July 11, 1945. By July 13, the assembly of Gadget's explosive lens, uranium reflector, and plutonium core were completed at Ground Zero. On July 14, Gadget was hoisted to the top of the 100 foot test tower, and the detonators were connected, after which final test preparations began. On July 16, 1945, 5:29:45 a.m. (Mountain War Time) Gadget was detonated. The explosive yield was 20-22 kt (by latest estimates), vaporizing the steel tower. Since the bomb was exploded above the ground it produced only a very shallow crater (mainly created by compression of the soil) - 2 meters deep with an 80 m radius. The crater was surrounded by fused (melted) sand dubbed "trinitite" (or "atomsite"). The exact yield was originally placed at 18.6 kt on the basis of radiochemical tests. Since the projected yield was only 5-10 kt, many of the experiments were damaged or destroyed by the test and failed to yield useful (or any) data. Gadget was exploded close enough to the ground that considerable local fallout was generated (along with significant induced radioactivity at ground zero from the emitted neutrons). The most intense induced radiation was in an irregular circle, about 10 m in radius around ground zero. The cloud rose to 11,000 m. The wind was blowing to the northeast, but significant fallout did not descend for about 20 km downwind. The heaviest fallout was detected about 20 miles northeast of ground zero. In this area radiation levels recorded along U.S. Highway 380 for a distance of ten miles reached "approximately 50 R total." Also in this area was a site dubbed "Hot Canyon". The canyon was 5 miles east of the town of Bingham, 1.1 miles east of a road junction. This is a summary of radiation levels: 15.0 R/hr at 0300 hours after zero 14.0 R/hr at 0330 hours 6.0 R/hr at 0830 hours 0.6 R/hr at 3600 hours The total exposure as this site was 212-230 R. Some evacuations were conducted the path of
the fallout plume out to 30 km. At Bingham, New Mexico gamma intensities
of 1.5 R/hr were recorded between 2 and 4 hours after the test. South of
Bingham readings reached 15 R/hr, but declined to 3.8 R/hr 5 hours after
the detonation, and had decreased to less than 0.032 R/hr one month later. |
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