U.S. scientists detonated a nuclear weapon buried 1,200 feet beneath the Nevada desert Friday, the second test announced this year.

"It was a complete success. There was no leak of radiation and no earth motion felt outside the boundaries of the test site," said U.S. Department of Energy spokesman Jim Boyer.The test, code named "Kawich", was triggered at 9:15 a.m. 85 miles northwest of Las Vegas.

Boyer said he was at a control point 15 miles south of ground zero and felt no ground motion from the detonation which had a yield of less than 20 kilotons.

Twenty kilotons is equivalent to 20,000 tons of dynamite. The atomic bomb dropped on Hiroshima in World War II was a 13 kiloton weapon.

"Kawich" was the 689th nuclear detonation at the Nevada Test Site since the facility opened in 1951 and was No. 484 since the United States and the Soviet Union agreed to halt atmospheric nuclear weapons testing in 1963.

The first U.S. nuclear experiment in 1989 was announced Feb. 10 with a yield of 20 to 150 kilotons.