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Neutron and gamma transport effects by heterogeneous core designs. [LMFBR]

Description: The use of diffusion theory for the prediction of power production near a reactor core-blanket interface and the assumption that gammas are absorbed in situ can lead to substantial errors. This is primarily due to the breakdown of Fick's law for neutron diffusion near the core-blanket boundary, and the gamma leakage from the core into the blanket. These considerations are more pronounced in a situation where a large number of internal blanket assemblies are present, such as in the large heterogeneous core designs. The power distribution is studied for both fission and gamma heating in a large heterogeneous LMFBR with 3 core zones separated by 2 internal blanket zones. Comparisons are made between diffusion and transport theory for neutronics calculations, and between in-situ absorption and rigorous transport theory calculation for gamma heating.
Date: January 1, 1977
Creator: Lam, S.K.
Partner: UNT Libraries Government Documents Department

Theories on plasma arc-drop in thermionic energy converters. Final report on thermionics energy conversion research analysis

Description: A summary of the theoretical developments of the problem of plasma arc-drop in thermionic energy converters carried out during 1976 to 1982 at Princeton University is presented. It reviews the basic formulation of the isothermal model which delineates the physical origin of the arc-drop, its order of magnitude and the possibilities of arc-drop reduction under one-dimensional, steady-state, ignited-mode operation, and also the generalization of the isothermal model to the non-isothermal model. The possibility of a heat-to-laser energy recombination laser using a thermionic diode operating in the unsteady mode is discussed. An analysis of the low-current regime with attentions focussed on the effects of ion reflections and trapped-ions effects in the emitter sheath is presented.
Date: March 1, 1983
Creator: Lam, S.H.
Partner: UNT Libraries Government Documents Department

Plasmadynamics and ionization kinetics of thermionic energy conversion

Description: To reduce the plasma arc-drop, thermionic energy conversion is studied with both analytical and numerical tools. Simplifications are made in both the plasmadynamic and ionization-recombination theories. These are applied to a scheme proposed presently using laser irradiation to enhance the ionization kinetics of the thermionic plasma and thereby reduce the arc-drop. It is also predicted that it is possible to generate the required laser light from a thermionic-type cesium plasma. The analysis takes advantage of theoretical simplifications derived for the ionization-recombination kinetics. It is shown that large laser ionization enhancements can occur and that collisional cesium recombination lasing is expected. To complement the kinetic theory, a numerical method is developed to solve the thermionic plasma dynamics. To combine the analysis of ionization-recombination kinetics with the plasma dynamics of thermionic conversion, a finite difference computer program is constructed. It is capable of solving for both unsteady and steady thermionic converter behavior including possible laser ionization enhancement or atomic recombination lasing. A proposal to improve thermionic converter performance using laser radiation is considered. In this proposed scheme, laser radiation impinging on a thermionic plasma enhances the ionization process thereby raising the plasma density and reducing the plasma arc-drop. A source for such radiation may possibly be a cesium recombination laser operating in a different thermionic converter. The possibility of this being an energy efficient process is discussed. (WHK)
Date: February 1, 1982
Creator: Lawless, J.L. Jr. & Lam, S.H.
Partner: UNT Libraries Government Documents Department

Theory of thermionic energy converter with variable plasma electron temperature

Description: A computational procedure for calculating the C-V characteristic, the plasma arc-drop and other important parameters for a cesium vapor thermionic energy converter has been developed. The original theory dealing with the constant electron temperature has been extended to treat the problem for the variable electron temperature. Comparison between the two cases shows that the C-V characteristic moves generally toward the left as the electron thermal conductivity decreases, but the magnitude of ths degradation appears small.
Date: September 1, 1978
Creator: Yen, A.T. & Lam, S.H.
Partner: UNT Libraries Government Documents Department

Heat Sweep Analysis of Thermal Breakthrough at Los Humeros and La Primavera Fields, Mexico

Description: Early evaluation of the potential for geothermal breakthrough of reinjected fluids in newly developed geothermal fields can be obtained with the SGP one-dimensional heat sweep model. The model was used to estimate fluid cooldown from wells selected for the first wellhead generating units to be installed at the Los Humeros and La Primavera geothermal fields in Mexico, based on staff-compiled geometric and geologic data, thermal properties of the reservoir rock, and expected production conditions. Geometric considerations were evaluated with respect to known and postulated fault zones and return flow angle of the reinjected fluid. The results show the range of parameter values that affect the rate of thermal breakthrough to an abandonment temperature of 170 ÂșC corresponding to the minimum inlet pressure to the CFE 5-MW wellhead generator units. 9 figs., 4 tabs., 11 refs.
Date: January 20, 1987
Creator: Kruger, P.; Lam, S.; Molinar, R. & Aragon, A.
Partner: UNT Libraries Government Documents Department


Description: Extensive study of the Cerro Prieto geothermal field has provided much geologic and thermodynamic data of its structurally-complex, liquid-dominated reservoir. Several of the studies investigated the resource characteristics of fluid and energy flow. An early report by Mercado (1975) showed that the heat source for the part of the reservoir under development, now called Cerro Prieto I (CPI), originated in the eastern part of the field. Subsequent studies confirmed the flow of hot water from the east. A summary of several experimental and numerical studies of fluid and energy transport in the field was given by Lippmann and Bodvarsson (1983). The hydrogeologic model of Halfman et al. (1982) shows hot-water flow from the east divided into a shallow (alpha) aquifer at about 120Om and a deeper (beta) aquifer at about 170Om depth. A cross section along an east-west direction shows a central upflow to the two aquifers and uncertain geology beyond the western border of the field near well M-9. It also shows a fault dividing the line of border wells at M-29 from the inner wells at M-25 to the east. The hydrogeology of the field was described by Sanchez and de la Pena (1981) as an alluvial unit from the surface to about 700 m over the production zone and a shale-sandstone unit comprising an upper, shallow (alpha) aquifer bounded below by a basement horst overlying a deeper (beta) aquifer. To date, much of the cumulative production at Cerro Prieto I has been from the alpha aquifer. Piezometric level measurements over the first 5 years of operation showed a decline in the western zone beyond the production wells. Over the 10-year period of continuous production, a significant temperature decline has been observed along the westernmost line of wells. Several investigations of the recharge characteristics of the field have ...
Date: January 22, 1985
Creator: Kruger, P.; Lam, S.; Hunsbedt, A.; Esquer, C.; Marquez, R. & Hernandez, L. Cobo, J.
Partner: UNT Libraries Government Documents Department