On September 19, 1957, the United States detonated a 1.7-kiloton
nuclear weapon in an underground tunnel at the Nevada Test Site
(NTS), a 1,375-square-mile research center located 65 miles north
of Las Vegas. The test, known as Rainier, was the first fully contained
underground detonation and produced no radioactive fallout. A
modified W-25 warhead weighing 218 pounds and measuring
25.7 inches in diameter and 17.4 inches in length was used
for the test. Rainier was part of a series of 29 nuclear weapons
and nuclear weapons safety tests known as Operation Plumbob
that were conducted at the NTS between May 28, 1957, and
October 7, 1957.
