Research Agenda for Test Methods and Models to Simulate the Accelerated Aging of Infrastructure Materials Report of a Workshop (1999) / Chapter Skim
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2 Background Presentations
2 Background Presentations
Pages 12-24
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From page 12... ...
Jantzen of the Savannah River Technology Center discussed vitreous materials for the long-term storage of hazardous and radioactive waste. The final presentation of the morning session, given by John Stringer of the Electric Power Research institute, focused on lifecycle performance in the electric utility industry.
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From page 13... ...
The widespread use of timber treated with fire retardent in roofs has required major repairs because of unanticipated fractures after the materials had been in · ~ service tor many years. Stucco applied over insulation on thousands of homes and buildings has had to be removed and replaced because the wood framing underneath has rotted; thousands of other buildings will probably have to be repaired for the same reason.
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From page 14... ...
Of course, advancements have been, and continue to be, made, but accurate tests for assessing the effects of environmental conditions on their lifetimes will require a much better fundamental understanding of the damage process before they can test results could be used for making life predictions. The adoption of these materials will also depend on their economic advantage in a highly competitive market.
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Richard Wachnik, IBM Microelectronics Division Integrated circuits are critical parts of the data and telecommunications of effort has been exceeded in trying to infrastructure. Although a good deal , , ~ understand the detailed phenomena underlying the degradation of integrated circuits, determining their stability or reliability is often largely empirical.
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From page 16... ...
Dielectric degradation includes polarization, which affects performance, and leakage, which affects dynamic circuits and potentially affects static circuits. Radiation effects include single-event upsets as well as radiation damage.
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Extreme caution must be used to maintain the dissolution mechanism being modeled, to verify the long-term durability using natural analogs, and to perform service-life tests in actual disposal environments. The mechanisms modeled for glass durability are
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From page 18... ...
More recent models mathematically describe the glass dissolution mechanisms in the form of time-dependent master equations rather than as simple diffusion processes. Although the kinetic models describe the leaching behavior of a given glass, they cannot predict which of a given group of glasses will be most durable or whether a waste glass of composition A will be as durable as a given natural analog of composition B
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From page 19... ...
The generation component involves: coal-fired thermal systems, which are responsible for approximately 55 percent of the electricity generated in the United States; natural-gas-fired systems, which include Rankine and Brayton-cycle based systems; oil-fired systems; nuclear-power thermal generators, which currently represent about 20 percent of generating capacity; hydroelectric generators; and a very small percentage of other sources, including biomass-fired systems, wind turbines, and solar photovoltaic systems. The major lifetime issues are related to the significant fraction of thermal generating plants that are more than 25 years old, which was their notional lifetime.
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From page 20... ...
He then described the four elements of life prediction: the need to describe the physical behavior, i.e., damage and failure modes modeling the behavior, including discrete events and multiple processes identifying measurable independent observables as inputs to the models actual life predictions, which are extensions, generalizations, and accelerations of laboratory experience Professor Reifsnider explained durability and the damage-tolerance approach to life prediction, described relevant environmental factors, and described the specific mechanism of polymer degradation. He then presented data on a number of physical processes affecting service life and showed how these relationships could be incorporated into models of physical processes, and, ultimately, into more complex, predictive models.
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From page 21... ...
He noted the need for analysis and experiments on changes in material states; a materials science base for dependence relationships with time, temperature, and environments; and data with which to populate models. Accelerated-Testing Approaches for Infrastructure Applications Jonathan W
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From page 23... ...
Appendixes
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