539 Matching Results

Search Results

Advanced search parameters have been applied.

Preliminary investigation of several target-type thrust-reversal devices

Description: Report presenting thrust-reversal performance of several basic target-type jet reflectors of various sizes and with various modifications obtained with unheated air over a range of exhaust-nozzle pressure ratios. Maximum, or near maximum, reversal for any deflector occurred at a spacing which was mechanically feasible and did not affect nozzle air flow.
Date: March 12, 1954
Creator: Steffen, Fred W.; Krull, H. George & Ciepluch, Carl C.
Partner: UNT Libraries Government Documents Department

Solar reflector soiling pattern distributions and reflectance measurement requirements

Description: Short-term specular reflectance losses from optical surfaces used in the collection or concentration of solar energy results in significant reduction of these systems' output. Losses range from 0.1% to 1.0% per day, approaching asymptotes of 25% to 60% for periods greater than one year, depending onsite and season. To appropriately assess the value of a particular location for the production of power, consideration of the rates of soiling and strategies to minimize losses resulting from soiling must be considered. Strategies for measuring the optical performance of reflector materials to a specified degree of accuracy have been developed, according to the types of soiling patterns observed. It was found most soiling occurs with the accumulation of particulates in spots of different sizes, and the spot sizes follow a lognormal distribution. For most practical situations, it was determined that 10 measurements with a 1-cm-diameter beam are enough to place the average value within 3% of the true value, with a confidence level of 95%.
Date: October 1, 1990
Creator: Kidney, K. (Colorado Univ., Denver, CO (USA))
Partner: UNT Libraries Government Documents Department

The formation of optical membrane reflector surfaces using uniform pressure loading

Description: Potentially high quality optical reflector surfaces are attainable with the use of pressure formed membranes. Such reflector surfaces offer the prospect of very low weight and low cost. The formation of such surfaces, using initially flat circular membranes with uniform pressure loading, is studied in this paper. Finite axisymmetric deformations, along with both linear and nonlinear material response is considered. A wide range of focal-length-to-diameter ratios (above 0.6) are addressed and the structural/optical response mechanisms that lead to optical distortions relative to ideal parabolic reflector shapes are also considered. Results show that elastic material response can often lead to a significantly larger deviation from the ideal shape than will inelastic material response. This results primarily from the ability to limit stress nonuniformities when inelastic material response is operative. Furthermore, when under pressure loading the membrane focal length decreases monotonically with increasing radius for both linear and nonlinear material response. Further, the predicted focal length variation is increasingly nonlinear near the membrane support.
Date: August 1, 1987
Creator: Murphy, L.M. & Tuan, C.
Partner: UNT Libraries Government Documents Department

GRAPHITE-MODERATED, GRAPHITE-REFLECTED CRITICAL ASSEMBLIES

Description: Graphite-moderated, graphite reflected critical assemblies have been set up in the LASL Honeycomb remotely controlled machine. lnformation has been obtained on the critical masses of systems having C/Oy ratios of 6650 and 4093. A third system at a smaller ratio is planned. The reactivity contribution of channels through the core and reflector was determined. (auth)
Date: January 1, 1957
Creator: Byers, C.C.
Partner: UNT Libraries Government Documents Department

STEADY-STATE PRESSURE AND THERMAL STRESSES IN THE HRT PRESSURE VESSEL

Description: The methods used to calculate the steady-state pressure and thermal stresses in the spherical portion or the HRT pressure vessel are presented, The stresses reported here were calculated using the methods considered most applicable st the present time. These methods yield stresses significantly greater than originally reported for the HRT because the calculated total heat generation rate in the vessel wall is greater, and its distribution is different. A comparison of tworegion (DP reflector) and single-region operation is made, showing very little difference between them insofar ss stresses are concerned. A limited amount of experimental heat balance data for the HRT vessel wall has been compared to the calculated values. Primarily on the bases of this comparison recommendations are made concerning further procurement of experimental data. (auth)
Date: July 15, 1958
Creator: Cheverton, R.D. & Volk, E.R.
Partner: UNT Libraries Government Documents Department

Neutron Kinetics for Reflected Compact Reactors on Short Periods

Description: The common seventh group approximation for treating the effect of neutron delay due to reflector slowing down and thermalization is presented. Modifications appropriate when reactivity changes are produced by reflector movements are introduced. An improved formulation, allowing distinctions between several different groups of slowing down and thermalizing neutrons, is presented. This formulation is shown to reduce to the seventh group approximation for the case of one atypical neutron group, providing the population and reaction rate of the group are small in comparison to the total neutron population and reaction rate. (auth)
Date: June 1, 1963
Creator: Miller, J.
Partner: UNT Libraries Government Documents Department

PLUTONIUM PLEXIGLAS ASSEMBLIES. PART II

Description: Neutron multiplication measurements were made on tamped and untamped cylindrical assemblies. The assemblies consisted of plutonium metal sheet mcderated with Plexiglas. Experiments were performed to evaluate the effects of inhomogeneity. This work is a continuation of RFP-178. (auth)
Date: April 1, 1960
Creator: Bidinger, G.H.; Schuske, C.L. & Smith, D.F.
Partner: UNT Libraries Government Documents Department

PHASE III-FOREIGN REACTOR-FUEL SAMPLE IRRADIATION OF U$sub 3$O$sub 8$-Al DISPERSIONS. IRRADIATION REQUEST ORNL-MTR-35

Description: The integrity and suitability of 35 vol.% U/sub 3/ O/sub 8/ dispersion in Al as a fuel for foreign reactors were determined. The fuel was exposed in the beryllium reflector of the MTR. Sample fabrication and conditions of exposurne are described, and the results are tabulated. (J.R.D.)
Date: October 18, 1958
Creator: Leitten, C.F. & Kucera, W.J.
Partner: UNT Libraries Government Documents Department

PHASE I--FOREIGN REACTOR FUEL SAMPLE IRRADIATION OF U-S$sub 1$-Al ALLOY. IRRADIATION REQUEST ORNL-MTR-35

Description: The following data summarize the results of calculations presented in this report to determine the irradiation testing for Phase I of Irradiation Request ORNLMTR-35. This phase of the program entails exposure of a 48 wt.% U-3 wt.% Si-49 wt.% Al alloys inthe beryllium reflector of the MTR. (auth)
Date: October 13, 1958
Creator: Leitten, C.F. & Thurber, W.C.
Partner: UNT Libraries Government Documents Department

A THEOREM AND ITS APPLICATION TO FINITE TAMPERS

Description: A theorem is derived which is useful in the analysis of neutron problems in which all neutrons have the same velocity. It is applied to determine extrapolated end-points, the asymptotic amplitude from a point source, and the neutron density at the surface of a medium. Formulas for the effect of finite tampers are derived by its aid, and their accuracy is discussed.
Date: August 15, 1946
Creator: Feynman, R.P.
Partner: UNT Libraries Government Documents Department

A PRELIMINARY REPORT OF BERYLLIUM DAMAGE OBSERVED IN THE MTR REFLECTOR

Description: Evidence of bowing was observed in an MTR beryllium shim rod section during the Cycle 184 shutdown. Inspection and measurements of this and other selected beryllium lattice pieces confirmed this observation. Preliminary measurements were made along a vertical transverse between the north and south reflector walls with some bowing again noted. An inspection of the north wall revealed cracking and spalling of the beryllium sections, primarily in the vicinity of the HB-2 thimble. (auth)
Date: June 20, 1963
Creator: Dykes, J.W. & Ford, J.D.
Partner: UNT Libraries Government Documents Department

Dish/Stirling for Department of Defense applications final report

Description: This report describes a Strategic Environmental Research and Development Program (SERDP) project to field a dish/Stirling system at a southwestern US military facility. This project entitled ``Dish/Stirling for DoD Applications`` was started in August 1993 and was completed in September 1996. The project`s objective was to assist military facilities to field and evaluate emerging environmentally sound and potentially economical dish/Stirling technology. Dish/Stirling technology has the potential to produce electricity at competitive costs while at the same time providing a secure and environmentally benign source of power. In accordance with the SERDP charter, this project leveraged a US Department of Energy (DOE) cost-shared project between Sandia National Laboratories and Cummins Power Generation, Inc. (CPG). CPG is a wholly owned subsidiary of Cummins Engine Company, a leading manufacturer of diesel engines. To accomplish this objective, the project called for the installation of a dish/Stirling system at a military facility to establish first-hand experience in the operation of a dish/Stirling system. To scope the potential DoD market for dish/Stirling technology and to identify the site for the demonstration, a survey of southwestern US military facilities was also conducted. This report describes the project history, the Cummins dish/Stirling system, results from the military market survey, and the field test results.
Date: March 1, 1997
Creator: Diver, R.B. & Menicucci, D.F.
Partner: UNT Libraries Government Documents Department