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Icecap tower, built for a 1992 below-ground nuclear test, stands on Yucca Flat at the Nevada Test Site while a December storm looms in the distance. The test was never conducted because of a moratorium that continues today.
Photo by John Gurzinski.
On a December visit to the Icecap tower, Nick Aquilina discusses the end of the Cold War and the challenges that scientists faced during his tenure as Nevada Test Site manager from 1987 to 1994.
Photo by John Gurzinski.
Click on the image for an enlargement (93k).
Graphic by Mike Johnson.
| Monday, December 18, 2000
Copyright © Las Vegas Review-Journal A New Direction A 1992 moratorium ushered in an era of 'subcritical' nuclear tests By KEITH ROGERS
REVIEW-JOURNAL A steadfast sentry, the Icecap tower stands tall and lonely on Yucca Flat near the heart of the Nevada Test Site. Today, the 157-foot-high steel tower guards craters that riddle the desert where many of the nation's 828 below-ground nuclear blasts in Nevada were conducted. It was built to lower a small nuclear bomb attached to a huge canister and hundreds of data-transmission cables down a 7-foot-wide shaft. The bomb was supposed to explode one day in 1992 at the bottom of the 1,600-foot shaft, but the $70 million test involving hundreds of scientists -- the 25th conducted jointly between the United States and the United Kingdom -- would never detonate. President Bush had put the nation's testing program on hold. Although the bombing that had kept the test site a pivotal player in the arms race for more than four decades had stopped, the work would continue. It would just take a new direction. The president's decision propelled the nation into the modern era of nuclear weapons experiments aimed at ensuring that existing weapons would work, if deployed. Today marks the 50th anniversary of President Truman's designation of Nevada as home of the nation's continental site for testing nuclear weapons. The experiments now being conducted are called "subcriticals" -- high technology detonations that fall short of the chain-reactions that define nuclear weapons. When the first subcritical experiment went off in 1997, there was no fireball, no mushroom cloud, and the ground didn't collapse. The explosion was about one-tenth of 1 percent the size of a full-scale nuclear test. At the time of the 1992 moratorium, not only was Icecap halted but so were 14 other tests that had been planned for the next three years. The Russians had abrogated a previous moratorium, but this time they remained faithful. The Icecap tower is especially symbolic to Nick Aquilina, who managed the Rhode Island-size test site 65 miles northwest of Las Vegas through the metamorphosis of world politics and helped bridge the next generation of nuclear experiments in Nevada, those that use high-explosives to shock small amounts of plutonium. "When you've been part of the history that had the excitement to us of underground nuclear testing, and then to stop, there was that initial letdown," Aquilina said this month, standing where Icecap's unused cables still cross the desert floor. "However, once we saw the extensive technical data that the labs were able to get out of the subcriticals, the excitement kind of bounced back." The end of full-scale testing meant new challenges to the test site's staff and government scientists at the national weapons laboratories in California and New Mexico. "Subcriticals turned out to be truly an underground laboratory," Aquilina said. "It's exciting in its own way, certainly not as exciting as the test days, but also important." The moratorium was extended indefinitely in 1995 by President Clinton, and set the United States on a course to maintain the safety and reliability of the stockpile in the absence of powerful, atomic explosions. The task is being accomplished through the Science-Based Stockpile Stewardship Program. It relies on a combination of subcritical experiments, high-speed computers, and physics tools at the national labs such as enormous lasers and machines that fire intense bursts of electrons at metals to simulate temperatures and pressures of a nuclear detonation. At the center of the test site's effort is the U1a facility, a below-ground complex where subcritical experiments are designed to assess how plutonium ages in the stockpile. The tests are conducted in alcoves, 960 feet beneath the surface. Despite criticism from anti-nuclear activists who claim the experiments could be used to develop new weapons of mass destruction, Department of Energy officials deny that possibility, saying the experiments are necessary to ensure existing weapons would work if needed to counter a nuclear attack. With nothing more than a loud bang, the test site's first subcritical experiment, Rebound, was detonated on July 2, 1997. It shocked three 1-pound plates of plutonium -- each the diameter of a 50-cent piece -- with the force of 160 pounds of chemical explosives. Anti-nuclear activists protested at the site that the moratorium provisions were being violated, but Department of Energy officials insisted that the Rebound experiment didn't skirt provisions of the Comprehensive Test Ban Treaty, signed by Clinton and nearly 200 nations. A second subcritical experiment, Holog, went off on Sept. 18, 1997. With cameras taking three-dimensional, high-speed photographs, scientists captured the detonation on film. Images of burning plutonium fragments could be seen, as well, on a video monitor where the detonation looked like a snowball being blown apart by a firecracker. Since the program was launched, the United States has conducted 13 subcritical experiments, the last one, Oboe 6, on Thursday. The test site's current manager, Kathy Carlson, said when she took over the reins in 1999, "it wasn't clear the subcritical experiments would be a long-term mission." "But, in fact, the three labs have said there are so many things they need to learn that it's at least a 10-year program."
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