Unarmed thermonuclear bombs dropped in Nevada tests

Government scientists have successfully completed two drop tests of an aging and unarmed nuclear bomb at the Tonopah Test Range, National Nuclear Security Administration officials said Thursday.

The helicopter drop tests of inert types of the B61 thermonuclear bomb that can be delivered by Air Force bombers were completed Aug. 14 and Aug. 15 by engineers from Sandia National Laboratories, according to a statement from the NNSA, a branch of the Department of Energy.

The ongoing testing effort at the test range, about 130 miles northwest of Las Vegas, is aimed at refurbishing “the aging B61 nuclear bomb without resorting to underground nuclear testing,” the statement says.

Full-scale, below-ground U.S. nuclear weapons tests were curtailed in 1992 at the Nevada Test Site, now the Nevada National Security Site, after a moratorium that has been extended indefinitely. Scientists have since relied on subcritical experiments involving bits of plutonium to check the aging warheads coupled with supercomputer modeling techniques and other physics tools for ensuring the nuclear stockpile is safe and reliable. Subcritical experiments are designed not to erupt into sustained nuclear chain reactions.

“The B61 contains the oldest components in the U.S. arsenal. As long as the United States continues to have nuclear weapons, we must ensure that they remain safe, secure and effective without the use of underground testing,” Don Cook, NNSA’s deputy administrator for Defense Programs, said in the prepared statement.

He said the B61 bomb, which is roughly 12-feet-long and weighs 700 pounds, “has been in service a decade longer than planned, and our refurbishment program is a scientific and engineering challenge.”

Existing B61 bombs in the U.S. arsenal rely on decades-old vacuum tubes as part of their radar system. The new radar system, which previously had only been tested in a laboratory setting, was installed in a gravity-bomb configuration “and successfully functioned as it was dropped from a helicopter” in the mid-August tests, according to the NNSA statement.

Cook said a new tail kit for the B61 will enable this version, the B61-12, to replace several other air-drop nuclear bombs.

More tests involving arming, fuzing and firing components are planned to meet milestones this year.

Contact reporter Keith Rogers at krogers@reviewjournal.com or 702-383-0308.