High-Temperature Gas-Cooled Reactor in-Containment Sensing and Control Systems .

This paper reviews the status of underground pumped hydro storage (UPHS) for electric utility peaking and energy-storage applications. The salient features of major recent studies are reviewed. Turbomachinery options and advances in high-head pump/turbines are discussed. The effect of head, capacity, turbomachinery unit size and type, and other performance variables on the cost of a UPHS plant are presented. Market potential, siting criteria, lower reservoir construction, and geologically-related issues are addressed. The environmental impact of a UPHS plant is deduced from comparable facilities, and these issues and other safety concerns are presented. UPHS is an economically viable scheme for energy-storage and peaking applications in which considerable savings in premium fuels can be achieved through the replacement of combustion gas turbines. The technology for UPHS is available, but additional research and development are required for high-head turbomachinery, motor/generators, cavern geology, and system optimization. IntroductionThe Need for Energy Storage Electric utilities face large variations in daily electric-power demand. During periods of relatively steady demand, power is generally provided by nuclear or coal-fired baseload plants that are economical to operate. For peak-load periods, gas turbine-driven

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Dissociative hydrogen chemisorption on the Li20 surfaces of the (1 00), (1 lo), and (1 1 1) planes has been investigated with ab initio Hartree-Fock calculations. Calculations for welaxed crystal Li20 structures indicated that except for the (100) surface, the (1 10) and (1 1 1) surfaces are stable. Results on the heterolytic sites of n-layer (1 10) (where n L 2) slabs and three-layer (1 11) slabs suggest that dissociative hydrogen chemisorption is endothermic. For a one-layer (1 10) slab at 100% surface coverage, the dissociative hydrogen chemisorption is exothermic, forming OHT and Li%i+. The results al So indicate that the low coordination environment in Surface step structures, such as kinks and ledges, may play an important role in the hydrogen chemisorption process. On the homolytic sites of the (1 10) and (1 1 1) surfaces, there is no hydrogen chemisorption.

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