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Cermets and method for making same

Description: The present invention is directed to a method for making a wide variety of general-purpose cermets and for radioactive waste disposal from ceramic powders prepared from urea-dispersed solutions containing various metal values. The powders are formed into a compact and subjected to a rapid temperature increase in a reducing atmosphere. During this reduction, one or more of the more readily reducible oxides in the compact is reduced to a selected substoichiometric state at a temperature below the eutectic phase for that particular oxide or oxides and then raised to a temperature greater than the eutectic temperature to provide a liquid phase in the compact prior to the reduction of the liquid phase forming oxide to solid metal. This liquid phase forms at a temperature below the melting temperature of the metal and bonds together the remaining particulates in the cermet to form a solid polycrystalline cermet.
Date: April 1, 1981
Creator: Aaron, W.S.; Kinser, D.L. & Quinby, T.C.
Partner: UNT Libraries Government Documents Department

Bibliography for the Satellite Power System (SPS) Concept Development and Evaluation Program

Description: This bibliography encompasses systems definition and engineering aspects; environmental assessment of microwave health and ecology, risks to space workers and atmospheric effects; a societal assessment covering resource requirements (land and materials) international and institutional issues; and a comparative assessment of the SPS Reference System relative to other advanced energy technologies, such as fusion. (MHR)
Date: April 1, 1981
Creator: Abromavage, M.; Calzadilla, R. & Murray, M.
Partner: UNT Libraries Government Documents Department

Approach to ecological assessment of power-plant-intake (316b) related issues: the Prairie Island case

Description: Assessment approaches and strategies useful in addressing important issues in section 316(b) of the 1972 Federal Water Pollution Control Act are illustrated in this report through the analysis and evaluation of the Prairie Island Nuclear Station 316(b) data base. The main issues in 316(b) demonstrations, cooling water intake operation and location, involve determining the impacts of entrainment and impingement. Entrainment impacts were addressed by applying the equivalent adult approach and correcting for inherent biases and by determining the through-plant survival of zooplankton. An assessment of impingement impacts was made by comparing for each of various species the number of fish impinged to estimates of population size. Densities of plankton and fish were compared between the intake area and an alternate area to determine if the location of the present intake minimizes impacts. No definitive conclusion relative to the best location of the intake could be made because of high year to year variability in the data and the differential dominance of trophic groups between areas.
Date: April 1, 1981
Creator: Adams, S.M.; Vaughan, D.S.; Hildebrand, S.G. & Kumar, K.D.
Partner: UNT Libraries Government Documents Department

Solar coal-gasification reactor with pyrolysis-gas recycle. [Patent application]

Description: Coal (or other carbonaceous matter, such as biomass) is converted into a product gas that is substantially free from hydrocarbons. The coal is fed into a solar reactor, and solar energy is directed into the reactor onto coal char, creating a gasification front and a pyrolysis front. A gasification zone is produced well above the coal level within the reactor. A pyrolysis zone is produced immediately above the coal level. Steam, injected into the reactor adjacent to the gasification zone, reacts with char to generate product gases. Solar energy supplies the energy for the endothermic steam-char reaction. The hot product gases flow from the gasification zone to the pyrolysis zone to generate hot char. Gases are withdrawn from the pyrolysis zone and reinjected into the region of the reactor adjacent the gasification zone. This eliminates hydrocarbons in the gas by steam reformation on the hot char. The product gas is withdrawn from a region of the reactor between the gasification zone and the pyrolysis zone. The product gas will be free of tar and other hydrocarbons, and thus be suitable for use in many processes.
Date: April 6, 1981
Creator: Aiman, W.R. & Gregg, D.W.
Partner: UNT Libraries Government Documents Department

Age and location of volcanic centers less than or equal to 3. 0 Myr old in Arizona, New Mexico and the Trans-Pecos Area of West Texas

Description: This map is one of a series of maps designed for hot dry rock geothermal assessment in Arizona, New Mexico, and the Trans-Pecos area of west Texas. The 3.0 m.y. cutoff age was selected because original heat has probably largely dissipated in older rocks. The location of volcanic centers is more important to geothermal resource assessment than the location of their associated volcanic rocks; however, ages have been determined for numerous flows far from their source. Therefore, the distribution of all volcanic rocks less than or equal to 3.0 m.y. old, for which there is at least one determined age, are shown. Location of the volcanic vents and rocks were taken from Luedke and Smith (1978).
Date: April 1, 1981
Creator: Aldrich, M.J. & Laughlin, A.W.
Partner: UNT Libraries Government Documents Department

Location, age, and rock type of volcanic rocks younger than 5 million years in Arizona and New Mexico

Description: As part of the assessment of the Hot Dry Rock geothermal energy potential of Arizona and New Mexico, a compilation of the locations and ages of volcanic rocks less than 5 Myr was made. The locations of those rocks less than 3 Myr are shown on a map of the region. Because the compiled information has many uses in addition to geothermal exploration, the entire compilation is presented as a tabulation. The table is organized first by state and secondly by latitude and longitude within each state. Rock type, age and error, method of dating, and original reference are also given. The K-Ar dates have not been recalculated using the most recent decay constants for /sup 40/K. A few references gave only verbal descriptions of sample location; these locations were converted to approximate latitude and longitude.
Date: April 1, 1981
Creator: Aldrich, M.J. Jr. & Laughlin, A.W.
Partner: UNT Libraries Government Documents Department

Geothermal resource base of the world: a revision of the Electric Power Research Institute's estimate

Description: Review of the Electric Power Research Institute's (EPRI) method for calculating the geothermal resource base of a country shows that modifications are needed for several of the assumptions used in the calculation. These modifications include: (1) separating geothermal belts into volcanic types with a geothermal gradient of 50{sup 0}C/km and complex types in which 80% of the area has a temperature gradient of 30{sup 0}C/km and 20% has a gradient of 45{sup 0}C/km, (2) using the actual mean annual temperature of a country rather than an assumed 15{sup 0}C average ambient temperature, and (3) making separate calculations for the resource stored in water/brine and that stored in rock. Comparison of this method (Revised EPRI) for calculating a geothermal resource base with other resource base estimates made from a heat flow map of Europe indicates that the technique yields reasonable values. The calculated geothermal resource bases, stored in water and rock to a depth of 5 km, for each country in the world are given. Approximately five times as much energy is stored in rock as is stored in water.
Date: April 1, 1981
Creator: Aldrich, M.J.; Laughlin, A.W. & Gambill, D.T.
Partner: UNT Libraries Government Documents Department

Power-cable-carrier control (PC/sup 3/) system

Description: A control system has been developed that uses a carrier signal imposed on an existing ac power circuit to transmit commands. This system was specifically developed to control an entire solar collector field by sending sun-tracking information to the trough collectors or by commanding them to assume safe positions (STOW) if out-of-limit conditions were encountered. Objectives were to develop a control system that operates reliably and has enough functions to control an entire collector field, yet do it at less cost than for conventional approaches. Development, design, operating characteristics, and field testing and results of the new system, the Power Cable Carrier Control (PC/sup 3/) System are described.
Date: April 1, 1981
Creator: Alvis, R.L.; Wally, K. & Rosborough, J.R.
Partner: UNT Libraries Government Documents Department

Power Cable Carrier Control (PC3) System

Description: A control system has been developed that uses a carrier signal imposed on an existing ac power circuit to transmit commands. This system was specifically developed to control an entire solar collector field by sending sun-tracking information to the trough collectors or by commanding them to assume safe positions (STOW) if out-of-limit conditions were encountered. Objectives were to develop a control system that operates reliably and has enough functions to control an entire collector field, yet do it at less cost than for conventional approaches. Development, design, operating characteristics, and field testing and results of the new system, the Power Cable Carrier Control (PC³) System are described.
Date: April 1981
Creator: Alvis, Robert L.; Wally, Karl & Rosborough, John R.
Partner: UNT Libraries Government Documents Department

High-temperature-staged fluidized-bed combustion (HITS), bench scale experimental test program conducted during 1980. Final report

Description: An experimental program was conducted to evaluate the process feasibility of the first stage of the HITS two-stage coal combustion system. Tests were run in a small (12-in. ID) fluidized bed facility at the Energy Engineering Laboratory, Aerojet Energy Conversion Company, Sacramento, California. The first stage reactor was run with low (0.70%) and high (4.06%) sulfur coals with ash fusion temperatures of 2450/sup 0/ and 2220/sup 0/F, respectively. Limestone was used to scavenge the sulfur. The produced low-Btu gas was burned in a combustor. Bed temperature and inlet gas percent oxygen were varied in the course of testing. Key results are summarized as follows: the process was stable and readily controllable, and generated a free-flowing char product using coals with low (2220/sup 0/F) and high (2450/sup 0/F) ash fusion temperatures at bed temperatures of at least 1700/sup 0/ and 1800/sup 0/F, respectively; the gaseous product was found to have a total heating value of about 120 Btu/SCF at 1350/sup 0/F, and the practicality of cleaning the hot product gas and delivering it to the combustor was demonstrated; sulfur capture efficiencies above 80% were demonstrated for both low and high sulfur coals with a calcium/sulfur mole ratio of approximately two; gasification rates of about 5,000 SCF/ft/sup 2/-hr were obtained for coal input rates ranging from 40 to 135 lbm/hr, as required to maintain the desired bed temperatures; and the gaseous product yielded combustion temperatures in excess of 3000/sup 0/F when burned with preheated (900/sup 0/F) air. The above test results support the promise of the HITS system to provide a practical means of converting high sulfur coal to a clean gas for industrial applications. Sulfur capture, gas heating value, and gas production rate are all in the range required for an effective system. Planning is underway for additional testing of the ...
Date: April 1, 1981
Creator: Anderson, R. E.; Jassowski, D. M.; Newton, R. A. & Rudnicki, M. L.
Partner: UNT Libraries Government Documents Department

Evaluation of alternate extractants to tributyl phosphate. Phase I

Description: Preliminary evaluations have indicated that tri(n-hexyl) phosphate (THP) and tri(2-ethylhexyl) phosphate (TEHP) have some significant advantages over tri(n-butyl) phosphate (TBP) for fuel reprocessing although they also have some disadvantages. The longer alkyl chains in these new extractants decrease their aqueous phase solubility and increase the organic phase solubility of their metal complexes and the metal complexes of their degradation products. Both THP and TEHP extract uranium and plutonium more strongly than TBP; thorium extraction is in the order THP > TBP > TEHP. Tritium extraction is highest with TBP because of slightly higher water extraction. In extractions of thorium, a third liquid phase was formed using TBP at a solvent loading of about 40 g/L of thorium and above. Third-phase formation did not occur with THP or TEHP. The dialkyl phosphoric acid degradation products of THP and TEHP showed a markedly lower tendency to precipitate with thorium than did dibutyl phosphoric acid (HDBP). Chemical stability studies showed TEHP to have much greater stability to acid hydrolysis than TBP and THP, which were about equivalent. No differences were detected in the radiation stability of the three extractants. The phase separation properties of THP and TEHP are inferior to those of TBP in both the nitric acid and sodium carbonate (solvent wash) systems. Phase separation was improved appreciably by using a lower extractant concentration than 1.09 M (equivalent to 30 vol % TBP). Difficulties were encountered with TEHP, however, owing to rapid degradation of its phase separation properties with time of contact with HNO{sub 3}; this problem requires additional study.
Date: April 1, 1981
Creator: Arnold, W.D. & Crouse, D.J.
Partner: UNT Libraries Government Documents Department

Preliminary assessment of Fort Hood solar cogeneration plant performance

Description: An analysis has been performed to enable a preliminary assessment of the performance that can be expected of a solar thermal cogeneration system designed to serve a selected group of buildings at Fort Hood, Texas. A central receiver system utilizing a molten salts mixture as the receiver coolant, heat transfer fluid, and storage medium is assumed. The system is to supply a large share of the space heating, air conditioning, domestic hot water, and electricity needs of a 20-building Troop Housing Complex. Principal energy loads are graphed and tabulated, and the principal electric parasitic loads are tabulated and the methodology by which they are estimated is reviewed. The plant model and the performance calculations are discussed. Annual energy displacement results are given. (LEW)
Date: April 1, 1981
Creator: Ator, J.
Partner: UNT Libraries Government Documents Department

Moving energy-conserving design into the mainstream of the US buildings industry

Description: Two programs discussed that are greatly accelerating the rate at which the US buildings industry is moving towards mass production of energy conserving solar buildings are: the Passive Solar Manufactured Buildings Program and the Solar Home Builders Program in the Denver metropolitan area. These programs provide a useful model for other efforts in accelerating private industry's rate of change. The concepts discussed on which this model is based include: industry participation in planning; incremental change; builders and architects; technical assistance (not money); large volume builders; competitive selection; simplified contractual procedures; public exposure; sensitive, concerned management. Progress of the programs are discussed. (MCW)
Date: April 1981
Creator: Baccei, B. C.
Partner: UNT Libraries Government Documents Department

Model testing of a 1-kg high-explosive-cell maze

Description: The basement of the proposed High Explosives Applications Facility (Building 353) at the Lawrence Livermore National Laboratory includes several explosive test cells for the assembly and/or storage of up to 10 kg of high explosive (HE). This document reports 1/8-scale and 1/4-scale model tests conducted to confirm maze design criteria, to determine the cell explosive weight limit based on an allowable 10 psi reflected shock pressure at the hallway-maze doorway, and to specify permissible areas for handling HE within the cell. The integrity of cube-root scaling of the explosive charges detonated in the 1/8-scale model was verified by explosive testing in a comparable 1/4-scale model. Reflected shock pressures in the hallway adjacent to the maze and the effect of HE charge orientation were investigated and are also reported.
Date: April 1, 1981
Creator: Bacigalupi, C.M. & Burton, W.A.
Partner: UNT Libraries Government Documents Department

Study of the production of ethanol from sugar beets for use as a motor fuel. Final report, February 1, 1980-April 30, 1981

Description: This study was performed to assess the feasibility of producing fuel ethanol from sugar beets. Sugar beets are a major agricultural crop in the area and the beet sugar industry is a major employer. There have been some indications that increasing competition from imported sugar and fructose sugar produced from corn may lead to lower average sugar prices than have prevailed in the past. Fuel ethanol might provide an attractive alternative market for beets and ethanol production would continue to provide an industrial base for labor. Ethanol production from beets would utilize much of the same field and plant equipment as is now used for sugar. It is logical to examine the modification of an existing sugar plant from producing sugar to ethanol. The decision was made to use Great Western Sugar Company's plant at Mitchell as the example plant. This plant was selected primarily on the basis of its independence from other plants and the availability of relatively nearby beet acreage. The potential feedstocks assessed included sugar beets, corn, hybrid beets, and potatoes. Markets were assessed for ethanol and fermentation by-products saleability. Investment and operating costs were determined for each prospective plant. Plants were evaluated using a discounted cash flow technique to obtain data on full production costs. Environmental, health, safety, and socio-economic aspects of potential facilities were examined. Three consulting engineering firms and 3 engineering-construction firms are considered capable of providing the desired turn-key engineering design and construction services. It was concluded that the project is technically feasible. (DMC)
Date: April 27, 1981
Creator: Baird, H W
Partner: UNT Libraries Government Documents Department

Conversion of solvent refined lignite into premium liquid fuels. Annual report, January-December, 1980

Description: Comparison of three preasphaltene samples separated from three lignite derived samples obtained from GFETC prepared at 404, 460 and 480/sup 0/C shows that increased temperature tends to produce higher molecular weight preasphaltene fractions containing more aromatic carbons with fewer acid (phenolic) sites per molecule. Ether cleavage studies of the model compounds; diphenyl ether, bibenzothiophene, dibenzofuran and anisole, show that partial or complete ether cleavage was obtained with sodium in hexamethyl phosphoramide solvent. Thus a careful consideration of acidity before and after cleavage can now give a measure of the diaryl ether content of a mixture. This reaction may be useful in coal liquid analysis. Denitrification of N,N-Dimethylamine without aromatic ring reduction occurs with CO-H/sub 2/O and H/sub 2/ at 425/sup 0/C in about 13% conversion. The optimum of 21 conditions gave a 19% conversion which occurs at 150 psi H/sub 2/S and 750 psi H/sub 2/. Thus, H/sub 2/S enhances nitrogen removal from this model compound. Using ESR dispersion techniques we have shown the presence of a second CO radical species on MgO, probably CO-.. observed by ESR, treatment of carbon monoxide radical species on both CO and MgO with CO/sub 2/ or H/sub 2/O causes a destruction of one of the radical species at a rate greater than that of the other.
Date: April 1, 1981
Creator: Baltisberger, R.J.; Stenberg, V.I.; Klabunde, K.J. & Woolsey, N.F.
Partner: UNT Libraries Government Documents Department

Paleoecology of the Devonian-Mississippian black-shale sequence in eastern Kentucky with an atlas of some common fossils

Description: The Devonian-Mississippian black-shale sequence of eastern North America is a distinctive stratigraphic interval generally characterized by low clastic influx, high organic production in the water column, anaerobic bottom conditions, and the relative absence of fossil evidence for biologic activity. The laminated black shales which constitute most of the black-shale sequence are broken by two major sequences of interbedded greenish-gray, clayey shales which contain bioturbation and pyritized micromorph invertebrates. The black shales contain abundant evidence of life from upper parts of the water column such as fish fossils, conodonts, algae and other phytoplankton; however, there is a lack of evidence of benthic life. The rare brachiopods, crinoids, and molluscs that occur in the black shales were probably epiplanktic. A significant physical distinction between the environment in which the black sediments were deposited and that in which the greenish-gray sediments were deposited was the level of dissolved oxygen. The laminated black shales point to anaerobic conditions and the bioturbated greenish-gray shales suggest dysaerobic to marginally aerobic-dysaerobic conditions. A paleoenvironmental model in which quasi-estuarine circulation compliments and enhances the effect of a stratified water column can account for both depletion of dissolved oxygen in the bottom environments and the absence of oxygen replenishment during black-shale deposition. Periods of abundant clastic influx from fluvial environments to the east probably account for the abundance of clays in the greenish-gray shale as well as the small amounts of oxygen necessary to support the depauparate, opportunistic, benthic faunas found there. These pulses of greenish-gray clastics were short-lived and eventually were replaced by anaerobic conditions and low rates of clastic sedimentation which characterized most of black-shale deposition.
Date: April 1, 1981
Creator: Barron, L.S. & Ettensohn, F.R.
Partner: UNT Libraries Government Documents Department

Reliability and maintainability seminar: summary of proceedings

Description: The following are described briefly: Overview of the Federal Reliability and Maintainability Program Plan, Summary of Proceedngs, Overview of Southern Solar Energy Center Programs, and Solar Domestic Hot Water Design Guidelines Handbook. Also included are the Seminar Agenda and the list of Seminar Attendees. (MHR)
Date: April 1, 1981
Creator: Beek, C.R.
Partner: UNT Libraries Government Documents Department

Systems analysis of hydrogen/natural gas supplementation and separation

Description: The methodology for the study involved first selecting a specific site for the study, since using national estimates tends to obscure specific regional issues and problems which are critical to the evaluation of such concepts. After the selection of the site, the evaluation focuses upon specific potential markets for hydrogen, and then examines the mix of customers comprising these markets. This establishes the incentives and barriers in the market sphere. Finally, the pipeline infrastructure, its capability for use to store and transmit hydrogen, and the incentives and drawbacks in this area are studied. Preliminary specific conclusions that can be made are as follows: the regulatory problems are certainly not insoluble. If hydrogen, for fuel or non-fuel use or both, is eventually shown to be competitive or desirable by using the natural gas system, as opposed to a separate system, the incentives will lead to regulatory changes. There is sufficient use of both hydrogen and natural gas in potential hydrogen-consuming industries to overcome the problem of reinjection of natural gas into the pipeline after separation. Certainly, this is a non-problem if fuel cells penetrate the electrical utility market in situations where the utility provides both electric and gas service. However, this problem requires further study. The pipeline flexibility problem must be studied for each region of interest to determine the optimality for combined use. This will then lead to rate structure determinations. The economics of using natural gas pipelines with separation must be examined against those of dedicated new hydrogen lines, as well as other terminal onsite hydrogen production options. The overall system economics can be performed parametrically, regardless of the hydrogen sources.
Date: April 1, 1981
Creator: Beller, M; D'Acierno, J & Hermelee, A
Partner: UNT Libraries Government Documents Department

H/sup -/ and D/sup -/ production by backscattering from surfaces

Description: Three experiments are described in which H/sup -/ or D/sup -/ ions have been produced by backscattering from surfaces coated with alkali metals: (1) Backscattering of H/sup -/ and D/sup -/ produced by 0.15- to 4-keV/nucleus H/sub 2//sup +/, H/sub 3//sup +/, D/sub 2//sup +/, and D/sub 3//sup +/ bombarding clean targets of Cs, Rb, K, Na, and Li. For each target, the H/sup -/ and D/sup -/ yields were maximized at incident energies between 300 and 1200 eV/nucleus and always at a lower incident energy for H than for D on a given target. At any given incident energy, both the H/sup -/ and D/sup -/ yields decreased in going from Cs to Li in the order given above. (2) A Mo surface was bombarded by a low-energy flux of H atoms produced in a tungsten furnace. As the surface work function was reduced by evaporating Cs onto the target, a small fraction (10/sup -9/) of the incident hydrogen atoms was observed as backscattered H/sup -/ ions. (3) Surfaces of Mo, W, Pt, Ni, Cu, Re, Ta, and Pd were bombarded by hydrogen ions produced in a discharge. Two classes of H/sup -/ ions were observed when Cs was added to the discharge - H/sup -/ ions leaving the surface with approximately < 10 eV and H/sup -/ ions leaving the surface with approximately 50 to 100 eV.
Date: April 1, 1981
Creator: Berkner, K.H.; Ehlers, K.W.; Graham, W.G.; Leung, K.N.; Pyle, R.V.; Schneider, P.J. et al.
Partner: UNT Libraries Government Documents Department

Conversion of atactic polypropylene waste to fuel oil. Final report

Description: A stable, convenient thermal pyrolysis process was demonstrated on a large scale pilot plant. The process successfully converted high viscosity copolymer atactic polypropylene to predominantly liquid fuels which could be burned in commercial burners. Energy yield of the process was very high - in excess of 93% including gas phase heating value. Design and operating data were obtained to permit design of a commercial size atactic conversion plant. Atactic polypropylene can be cracked at temperatures around 850/sup 0/F and residence time of 5 minutes. The viscosity of the cracked product increases with decrease in time/temperature. A majority of the pyrolysis was carried out at a pressure of 50 psig. Thermal cracking of atactic polypropylene is seen to result in sigificant coke formation (0.4% to 0.8% on a weight of feed basis) although the coke levels were of an order of magnitude lower than those obtained during catalytic cracking. The discrepancy between batch and continuous test data can be atrributed to lowered heat transfer and diffusion rates. Oxidative pyrolysis is not seen as a viable commercial alternative due to a significant amount of water formation. However, introduction of controlled quantities of oxygen at lower temperatures to affect change in feedstock viscosity could be considered. It is essential to have a complete characterization of the polymer composition and structure in order to obtain useful and duplicable data because the pyrolysis products and probably the pyrolysis kinetics are affected by introduction of abnormalities into the polymer structure during polymerization. The polymer products from continuous testing contained an olefinic content of 80% or higher. This suggests that the pyrolysis products be investigated for use as olefinic raw materials. Catalytic cracking does not seem to result in any advantage over the Thermal Cracking process in terms of reaction rates or temperature of operation.
Date: April 1, 1981
Creator: Bhatia, J.
Partner: UNT Libraries Government Documents Department

Moving baseline for evaluation of advanced coal-extraction systems

Description: This document reports results from the initial effort to establish baseline economic performance comparators for a program whose intent is to define, develop, and demonstrate advanced systems suitable for coal resource extraction beyond the year 2000. Systems used in this study were selected from contemporary coal mining technology and from conservative conjectures of year 2000 technology. The analysis was also based on a seam thickness of 6 ft. Therefore, the results are specific to the study systems and the selected seam thickness. To be more beneficial to the program, the effort should be extended to other seam thicknesses. This document is one of a series which describe systems level requirements for advanced underground coal mining equipment. Five areas of performance are discussed: production cost, miner safety, miner health, environmental impact, and recovery efficiency. The projections for cost and production capability comprise a so-called moving baseline which will be used to assess compliance with the systems requirement for production cost. Separate projections were prepared for room and pillar, longwall, and shortwall technology all operating under comparable sets of mining conditions. This work is part of an effort to define and develop innovative coal extraction systems suitable for the significant resources remaining in the year 2000.
Date: April 15, 1981
Creator: Bickerton, C.R. & Westerfield, M.D.
Partner: UNT Libraries Government Documents Department

Criticality Experiments with Subcritical Clusters of 2.35 Wt% and 4.31 Wt% {sup 235}U Enriched UO{sub 2} Rods in Water with Steel Reflecting Walls

Description: A series of criticality experiments with 2.35 wt% and 4.31 wt% {sup 235}U enriched UO{sub 2} rods in water were performed to provide well defined benchmark type data on the effects of thick steel reflecting walls. For each fuel enrichment. the critical separation between three subcritical fuel clusters was observed to increase as 178.5 mm thick reflecting walls of reactor grade steel was moved towards the fuel. This increase was observed for fuel clusters having an undermoderated water-to-fuel volume ratio of 1.6 and for fuel clusters having near optimum neutron moderation (2.92 for the 2.35 wt% {sup 235}U enriched fuel and 3,88 for the 4.31 wt% {sup 235}U enriched fuel). In all cases the critical separation between fuel clusters increased to a maximum as the steel walls were moved towards the fuel clusters. This maximum effect was observed with about 10 mm of water between the fuel clusters and the steel reflecting walls. As this water gap was decreased, the critical separation between the fuel clusters also decreased slightly. Measurement data were also obtained for each enrichment with neutron absorber plates between the fuel clusters having the l .6 water-to-fuel volume ratio. During these measurements, the steel reflecting walls were at the near optimum distance from the fuel clusters. The fixed neutron absorbers for which data were obtained include 304-L steel, borated 304-L steel, copper, copper containing 1 wt% cadmium, cadmium, and two trade name materials containing boron (Boral and Boroflex), A comparison between these data and data from previous experiments indicates a slight reduction in the effectiveness of the absorber plates when the steel reflecting walls are present.
Date: April 1, 1981
Creator: Bierman, S. R. & Clayton, E. D.
Partner: UNT Libraries Government Documents Department