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YOU might hear a loud BOOM occasionally, but little else indicates what goes on there. Tucked away in the rugged, grassy hills between Livermore and California's Central Valley is Lawrence Livermore's Experimental Test Site. It has been known as Site 300 since the days when Livermore was part of Berkeley Radiation Laboratory: Berkeley was Site 1, Livermore was Site 2, and the testing range was Site 3. Times and names have changed, but the periodic BOOMS continue.
The explosions, known as shots, result from destructive tests of high explosives (HE) and other nonnuclear weapon components--100 to 200 of them a year in the last 10 years. Powerful x-ray machines, interferometers, high-speed cameras, and other diagnostic equipment record information about the experiment in the first nanoseconds after detonation. Site 300 also conducts nondestructive tests that may, for example, subject a prototype to vibration and extreme heat, conditions comparable to those it might encounter while being transported across a desert. Another big part of Site 300's work is fabricating and machining HE and assembling experiment devices prior to testing. All of these activities are potentially hazardous, yet Site 300 has a stellar safety record. In 44 years, no injuries involving high explosives have occurred.
Much of Site 300's effort supports Lawrence Livermore's main mission today of overseeing the nation's nuclear arsenal through the Department of Energy's science-based Stockpile Stewardship Program. As part of the program, the Accelerated Strategic Computing Initiative (ASCI) is bringing almost unimaginable power to Livermore's modeling capability to simulate weapons performance. And in a few years, the National Ignition Facility will be available for addressing the physics of thermonuclear fusion. Yet, even with these unprecedented capabilities at Livermore, tests at Site 300 are perhaps more important now than ever before.
HE testing, using nonnuclear materials, is almost the only available high-fidelity way of experimentally examining the operation of a nuclear weapon. The U.S. no longer conducts nuclear tests, and only a few subcritical (no nuclear yield) experiments are being conducted at the Nevada Test Site. The high-explosives tests are also important for improving our understanding of the effects that aging has on chemical high explosives in stockpile systems and of compatibility with other materials. Validation of models and simulations through actual experiments are essential for scientists to know whether their design is, figuratively speaking, on target.
Testing More Parameters
According to Randy Simpson, a chemist and HE expert at Livermore, "We understand the stars and supernovae better than we understand high explosives. When high explosives detonate, they can generate up to 500,000 atmospheres of pressure and may move at speeds of up to 10 kilometers per second. Reactions take place in less than a billionth of a second, releasing enormous amounts of energy. Our
Site 300 experiments study how high explosives release their energy-for example, how they accelerate metals or what chemical reactions they cause."
The tests allow us to study the performance of HE materials, their reliability and safety, and ways to optimize the materials and manufacturing methods. Three avenues of testing ensure the HE portion of stockpile performance: core surveillance testing of operational weapon HE function, enhanced surveillance to test the effects of aging on HE, and testing of replacement and specialized HE components.
For as long as the U.S. has had a nuclear stockpile, personnel at Site 300 have been participating in core surveillance of the stockpile. Periodically, weapons have been taken apart and components put through their paces to ensure that everything is still operating as designed. |