Nuclear Warhead Tested in Nevada

The federal government detonated a nuclear warhead deep beneath the desert Thursday in the second weapons test in eight days at the Nevada test site, the Department of Energy said.

The explosion was the 15th set off by the United States since the Soviet Union imposed a unilateral test ban nearly a year ago. It was also the third in less than a month at the nation’s nuclear proving grounds.

The warhead was detonated at 8:05 a.m., 1,300 feet beneath the surface of Yucca Flats, 85 miles northwest of Las Vegas. The test, code-named Cornucopia, had a yield of less than 20,000 kilotons, said Energy spokeswoman Barbara Yoerg.

The blast followed the detonation July 17 of a nuclear weapon that the Department of Energy classified as between 20,000 and 150,000 kilotons, the largest allowable under existing treaties with the Soviet Union. A test was also held on June 25.

Although the Department of Energy does not release exact yields of the warheads, the National Earthquake Information Center in Golden, Colo., said the latest test measured 4.6 on the Richter scale, compared to a 5.6 reading for the July 17 test.

Yoerg said Cornucopia, which was not announced in advance, was sponsored by the Lawrence Livermore National Laboratory and was weapons-related.

The test, the eighth announced this year, brings the total number of atmospheric and underground tests announced at the site to 654 since testing began there in 1951. For security reasons, not all tests are announced.