Biggest U.S. Test Underground

Press, Volume CVI, Issue 31248, 21 December 1966, Page 21

Biggest U.S. Test Underground

(N.Z. Press Association—Copyright)

LAS VEGAS, December 20.

United States scientists prepared today to detonate the country’s largest underground thermonuclear device.

The Atomic Energy Commission warned that earth shock waves probably would sway multi-storey casinos in Las Vegas and topple old buildings in a desert town 30 miles from the test site.

Pahute Mesa, a remote region on the Nevada test site 100 miles north-east of Las Vegas, was tightly sealed off for safety and security reasons.

The Atomic Energy Commission spent last week notifying all persons in buildings of more than three storeys that structures might sway. Las Vegas residents were warned to stay off high places and ladders at the time of the blast. The device was scheduled to be tested on November 21, but trouble in the electrical cable system caused a postponement. The cables were repaired a week ago by workers at the test site. Vertical Shaft

According to reports, the device is cradled at the bottom of a vertical shaft 4000 ft deep. The hole cost two million dollars to prepare. Earth and concrete were poured into the shaft, filling it to a level of 1700 feet. Scientists hoped this would prevent radiation from leaking into the atmosphere. The weapons test, possibly designed to refine anti-ballis-tic missile systems or the Pseidon rocket system for underwater launching, was desscribed by the commission as one of “intermediate yield.”

The term means that the thermonuclear device will have a maximum force 50 times larger than that of the atomic bomb dropped on Hiroshima. It will have a force, of one megaton, or the equivalent of a million tons of T.N.T. The blast was scheduled to be triggered at 4.30 a.m. on December 21, New Zealand time.

If there were high winds at this section of the test site at blast time, the test could be delayed as a precautionary measure, as winds could carry any radiation leakage over long distances.

It would be a violation of the 1963 ban on atmospheric testing agreement with Russia for fallout to cross the continental boundaries of the United States. The Soviet Union conducted a test on October 27 on the Arctic island of Novaya Zemlya which was rated by United States experts as the biggest underground nuclear blast ever made. Authorities said the Russian test was 50 times more powerful than the Hiroshima bomb and twice as big as anything set off by the Atomic Energy Commission in Nevada.