‘Milestone experiment’ measures safety of aging nuclear stockpile

Scientists at the Nevada National Security Site this week fired the 100th shot on their JASPER gas gun to help them assess the safety and reliability of the nation’s aging nuclear weapons stockpile.

National Nuclear Security Administration spokesman Darwin Morgan said a team from Lawrence Livermore National Laboratory in California conducted the milestone experiment Tuesday at the JASPER facility, in the south central part of the former Nevada Test Site, 80 miles northwest of Las Vegas.

The 90-foot-long, two-stage gas gun shoots projectiles at tiny discs of plutonium to show how they blow apart under certain pressures, temperatures and strain rates.

The facility known by its acronym, JASPER, for Joint Actinide Shock Physics Experimental Research, opened for plutonium experiments in 2003, but it has been operational since 2001 for targets made of surrogate materials. Of the 100 shots, 41 have involved the nuclear weapons ingredient, plutonium.

In a statement Wednesday, National Nuclear Security Administration Deputy Administrator for Defense Programs Don Cook applauded the "remarkable milestone" achievement.

"Data gathered from experiments conducted on JASPER and the other tools and facilities throughout the national nuclear security enterprise helps the NNSA meet its mission in ensuring the safety, security and effectiveness of the nuclear deterrent without underground nuclear explosive testing," Cook said.

He noted that the experiments "also help achieve President Obama’s nuclear security objectives."

The experiments are conducted by Lawrence Livermore National Laboratory for the National Nuclear Security Administration, with Joint Laboratory Operations-Nevada, a collaboration of Lawrence Livermore and the Los Alamos, N.M., national laboratories and National Security Technologies, the management and operating contractor for the site.

The JASPER gun fires projectiles into targets within confinement chambers at about the same velocity as a bullet fired from a hunting rifle.

JASPER uses gunpowder and compressed nitrogen gas to fire a small projectile of metal tantalum at nearly 16 times the speed of sound: 11,677 mph. The round projectile, the diameter of a 50-cent piece, impacts a gram-size amount of plutonium bomb material.

The JASPER facility was shut down for two years after scientists discovered that plutonium fragments had escaped a primary containment vessel during an experiment in February 2009.

The National Nuclear Security Administration is a semiautonomous agency within the Department of Energy. The agency spent $18.9 million to replace some equipment and the two containment chambers and returned the gun to full operation for plutonium experiments in September 2011.

From 1951 through 1992, the site’s role focused on full-scale tests of nuclear weapons. During that time, 100 were conducted in the atmosphere until the Limited Test Ban Treaty took effect in 1963.

That was followed by 828 that rumbled through the desert after they were set off below ground in shafts and tunnels.

Sixty-two of those full-scale tests involved simultaneous detonations, bringing the total number of devices set off to 1,021.

The last full-scale test, Divider, was conducted on Sept. 23, 1992. What followed was a moratorium that has been extended indefinitely.

The stockpile stewardship mission now relies in part on studying how plutonium ages in the decades after weapons were produced.

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