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By the year 2010, about 63,000 metric tons of nuclear waste from commercial nuclear power reactors and 8,000 metric tons of solidified nuclear waste from defense programs are slated for permanent disposal in an underground repository. The DOE is investigating the suitability of a potential site for the nation's first high-level nuclear waste repository. For several years, LLNL has been evaluating the waste form, the performance of candidate waste package materials, and the near-field environment in which containers will function. Through a combination of laboratory tests, field tests, and models, we seek to predict the total performance of the emplaced waste and the components of an engineered barrier system surrounded by natural geological barriers, namely zeolitic rock. Federal criteria for containing and then strictly limiting the release of radionuclides from the repository are unprecedented, extending 10,000 years into the future. With further study, including modeling, computer codes, and extensive experiments to be undertaken at LLNL and at the Exploratory Studies Facility at Yucca Mountain, Nevada, we have high confidence that the system we are helping to design will protect future generations from harm for tens of thousands of years.
During the implosion of a nuclear weapon, its materials are driven inward to enormously high pressures and temperatures in order to achieve nuclear fission. The ultrahigh compressions subject the weapon materials to continual change in physical properties-volume, crystal structure, density, and the like-changes that strongly affect the course of the implosion and therefore the final yield. Weapons designers have the utmost interest in knowing exactly what those material properties are if they are to compute the performance of a device reliably. However, the great violence and brevity of a nuclear event combine to prevent the collection of precise data. Until roughly two decades ago, the only alternative to nuclear tests for measuring ultrahigh pressure and temperature properties was shock experiments. These, too, are dynamic. The diamond anvil cell enables us to test theoretical descriptions of materials of interest by exposing them to ultrahigh compressions for durations that allow us to collect complete and accurate data. The diamond anvil cell is an inexpensive way to compress tiny samples of weapons-related materials to ultrahigh pressures comparable to those at the center of the Earth in order to identify changes in their properties that can affect weapon performance.
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