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U.S. Plans Subcritical Nuclear Experiment “Armando”
The latest U.S. subcritical nuclear experiment has been designed to help determine whether the United States can manufacture new plutonium pits that function like those of nuclear weapons tested more than a decade ago, according to Aviation Week & Space Technology (see GSN, May 25). Expected to be conducted 1,000 feet underground in coming weeks at the Nevada Test Site, the latest in a series of subcritical tests — code named “Armando” — will be the 21st conducted under the Energy Department’s Stockpile Stewardship Program. When then-President George H.W. Bush suspended U.S. nuclear testing in the early 1990s, the primary means of performance verification was eliminated. As U.S. policies at the time did not allow development of new nuclear weapons, it was understood that the existing stockpile would have to last indefinitely. Previously, any given type of weapon was expected to remain in the inventory for approximately 11 years before it was replaced. The Stockpile Stewardship Program was launched in 1995 to keep the nuclear arsenal safe and functional without testing. Subcritical experiments use small quantities of plutonium but are able to approximate the dynamics of a nuclear explosion. “A ‘subcrit’ is a dynamic experiment in which plutonium does not achieve self-sustaining fission chain reaction,” said Ghazar Papazian, Los Alamos National Laboratory’s project director for Nevada Test Site activities. “Basically, we’re surrounding plutonium with high explosives to dynamically shock (the fissionable material) and better understand plutonium manufacturing and production issues — such as the effects of cleaning agents and welding,” he added. While the primary purpose of subcritical experiments is to provide data for maintenance efforts, they also keep the Nevada Test site infrastructure “warm,” by training a new generation of scientists and experiment personnel, according to Aviation Week. Under a presidential directive, scientists must be ready to resume nuclear weapons testing 24-36 months after an order to resume. “But that’s being moved up to 18 months in about a year,” Papazian said. “If an order comes, we have to be ready to conduct a test in 18 months. It has a cost — about $18-20 million to keep the doors open here — but the byproduct is readiness,” he added (William Scott, Aviation Week, May 31).
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