77 Matching Results

Search Results

Advanced search parameters have been applied.

Brazed thermocouple pass-through for sodium service in a liquid-metal- cooled fast breeder reactor

Description: Sensors installed in special fuel elements for the EBR-II reactor had 30- ft-long leads that would pass from the sodium environment through a sealed bulkhead. A hydrogen-atmosphere, induction-heated brazing furnace was constructed to simultaneously braze 20-26 separate sensor leads at one time. The brazed seals were leak-tight, and the sheath wall has less than 10 percent interaction with the braze alloy. (auth)
Date: October 1, 1975
Creator: Walker, D.E.
Partner: UNT Libraries Government Documents Department

Workshops and incentive loans program for construction of solar greenhouses, grain dryers, window boxes and food dryers. Final performance report

Description: A Solar Loan Fund was established to provide low-interest incentive loans to families desiring to construct their own solar devices, the only stipulations being allowance of reasonable public visitation and monitoring and employment of parish-trained construction teams if labor is to be hired. About 30 vocational agriculture students built window box collector units as part of their classroom experience, trying several designs. Later, 12 to 15 families built window box collectors for their use. A week long Energy Responsibility: Today and Tomorrow workshop was held involving construction projects and mini-seminars. Another workshop was held to construct bread box type solar hot water heaters, and yet another to build solar food dryers. (LEW)
Date: February 1, 1982
Creator: Walker, D.H.
Partner: UNT Libraries Government Documents Department

Investigation of Energy-Efficient Supermarket Display Cases

Description: Supermarkets represent one of the largest energy-intensive building groups in the commercial sector, consuming 2 to 3 million kWh/yr per store (ES-1). Over half of this energy use is for the refrigeration of food display cases and storage coolers. Display cases are used throughout a supermarket for the merchandising of perishable food products. The cases are maintained at air temperatures ranging from -10 to 35 F, depending upon the type of product stored. The operating characteristics and energy requirements of the refrigeration system are directly related to the refrigeration load. The sources of the display case refrigeration load consist of: (1) Moist and warm air infiltration through the open front of the case--air curtains are employed to inhibit this infiltration, but some ambient air is entrained, which adds a substantial portion to the refrigeration load. (2) Heat conduction through case panels and walls. (3) Thermal radiation from the ambient to the product and display case interior. (4) Internal thermal loads--the use of lights, evaporator fans, periodic defrosts, and antisweat heaters adds to the refrigeration load of the display case as well as directly consuming electric energy. The impact of each of these elements on the refrigeration load is very dependent upon case type (Figure ES-1). For example, air infiltration is the most significant portion of the refrigeration load for open, multi-deck cases, while radiation is the largest part of the load for tub-type cases. The door anti-sweat heaters represent a major share of the refrigeration load for frozen food door reach-in cases. Figure ES-2 shows the distribution of display cases in a typical supermarket (ES-2). Open, multi-deck, medium temperature display cases typically comprise about half of the refrigerated fixtures in a store (ES-3). In addition, medium temperature fixtures and storage coolers account for roughly 70 to 75 percent of the ...
Date: January 21, 2005
Creator: Walker, D.H.
Partner: UNT Libraries Government Documents Department

Cesium Concentration in MCU Solvent

Description: During Modular Caustic-Side Solvent Extraction (CSSX) Unit (MCU) operations, Cs-137 concentrations in product streams will vary depending on the location in the process and on the recent process conditions. Calculations of cesium concentrations under a variety of operating conditions reveal the following: (1) Under nominal operations with salt solution feed containing 1.1 Ci Cs-137 per gallon, the maximum Cs-137 concentration in the process will occur in the strip effluent (SE) and equal 15-16.5 Ci/gal. (2) Under these conditions, the majority of the solvent will contain 0.005 to 0.01 Ci/gal, with a limited portion of the solvent in the contactor stages containing {approx}4 Ci/gal. (3) When operating conditions yield product near 0.1 Ci Cs-137/gal in the decontaminated salt solution (DSS), the SE cesium concentration will be the same or lower than in nominal operations, but majority of the stripped solvent will increase to {approx}2-3 Ci/gal. (4) Deviations in strip and waste stream flow rates cause the largest variations in cesium content: (a) If strip flow rates deviate by -30% of nominal, the SE will contain {approx}23 Ci/gal, although the cesium content of the solvent will increase to only 0.03 Ci/gal; (b) If strip flow rate deviates by -77% (i.e., 23% of nominal), the SE will contain 54 Ci/gal and solvent will contain 1.65 Ci/gal. At this point, the product DSS will just reach the limit of 0.1 Ci/gal, causing the DSS gamma monitors to alarm; and (c) Moderate (+10 to +30%) deviations in waste flow rate cause approximately proportional increases in the SE and solvent cesium concentrations. Recovery from a process failure due to poor cesium stripping can achieve any low cesium concentration required. Passing the solvent back through the contactors while recycling DSS product will produce a {approx}70% reduction during one pass through the contactors (assuming the stripping D value ...
Date: January 18, 2006
Creator: Walker, D
Partner: UNT Libraries Government Documents Department

THE FABRICATION OF FUEL SUBASSEMBLIES FOR THE BORAX-III REACTOR

Description: Each Borax-lIl fuel subassembly consists of a group of aluminum-clad aluminum-uranium alloy fuel plates arranged in an MTR-type array. The fuel plates are electric-resistance spot-welded to two aluminum sideplates and an aluminum central-support plate. An anuminum-0.6 wt.% boron, burnable poison strip is attached to each fuel subassembly. The poison strips are made by hot extruding a mixture of aluminum and elemental boron powders in the desired proportions. (auth)
Date: January 1, 1958
Creator: Walker, D.E. & Noland, R.A.
Partner: UNT Libraries Government Documents Department

Mechanized welding in a glove box

Description: An orbital-tungsten-arc welding gun was installed in a helium glove box to automatically weld final end closures to capsules that were to contain an atmosphere of required composition and quality. A fixture, tooling, and procedures were developed to automatically position the tungsten electrode repetitively with respect to the end of the tube to be welded closed. (auth)
Date: October 1975
Creator: Pugacz, M. A. & Walker, D. E.
Partner: UNT Libraries Government Documents Department

A Fortran 90 code for magnetohydrodynamics

Description: This report describes progress in developing a Fortran 90 version of the KITE code for studying plasma instabilities in Tokamaks. In particular, the evaluation of convolution terms appearing in the numerical solution is discussed, and timing results are presented for runs performed on an 8k processor Connection Machine (CM-2). Estimates of the performance on a full-size 64k CM-2 are given, and range between 100 and 200 Mflops. The advantages of having a Fortran 90 version of the KITE code are stressed, and the future use of such a code on the newly announced CM5 and Paragon computers, from Thinking Machines Corporation and Intel, is considered.
Date: March 1, 1992
Creator: Walker, D.W.
Partner: UNT Libraries Government Documents Department

Solvent Extraction Batch Distribution Coefficients with Savannah River Site Dissolved Salt Cake

Description: Researchers characterized high-level waste derived from dissolved salt cake from the Savannah River Site (SRS) tank farm and measured the cesium distribution coefficients (DCs) for extraction, scrub, and stripping steps of the caustic-side solvent extraction (CSSX) flowsheet. The measurements used two SRS high-level waste samples derived entirely or in part from salt cake. The chemical compositions of both samples are reported. Dissolved salt cake waste contained less Cs-137 and more dianions than is typical of supernate samples. Extraction, scrub, and strip DCs values for both samples exceeded process requirements and agreed well with model predictions. The results indicate no significant problems processing dissolved salt cake compared to supernate. During the course of testing, researchers observed sorption of cesium on glass sample vials containing strip solutions. The problem was detected in the material balance calculated for each organic/aqueous contact. Methods and recommendations for avoiding this problem are discussed.
Date: May 22, 2002
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department

Low Temperature Decomposition Rates for Tetraphenylborate Ion

Description: Previous studies indicated that palladium is catalyzes rapid decomposition of alkaline tetraphenylborate slurries. Additional evidence suggest that Pd(II) reduces to Pd(0) during catalyst activation. Further use of tetraphenylborate ion in the decontamination of radioactive waste may require removal of the catalyst or cooling to temperatures at which the decomposition reaction proceeds slowly and does not adversely affect processing. Recent tests showed that tetraphenylborate did not react appreciably at 25 degrees Celsius over six months suggesting the potential to avoid the decomposition at low temperatures. The lack of reaction at low temperature could reflect very slow kinetics at the lower temperature, or may indicate a catalyst ''deactivation'' process. Previous tests in the temperature range 35 to 70 degrees Celsius provided a low precision estimate of the activation energy of the reaction with which to predict the rate of reaction at 25 percent Celsius. To understand the observations at 25 degrees Celsius, experiments must separate the catalyst activation step and the subsequent reaction with TPB. Tests described in this report represent an initial attempt to separate the two steps and determine the rate and activation energy of the reaction between active catalyst and TPB. The results of these tests indicate that the absence of reaction at 25 degrees Celsius was caused by failure to activate the catalyst or the presence of a deactivating mechanism. In the presence of activated catalyst, the decomposition reaction rate is significant.
Date: November 18, 1998
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department

Design of a Carousel Process for Removing Cesium from SRS Waste Using Crystalline Silicotitanate Ion Exchanger

Description: Designs of a three-column carousel process based on crystalline silicotitanate (CST) ion exchanger have been developed for removing radioactive 137Cs+ from Savannah River Site's (SRS) nuclear wastes. A multicomponent ion exchange equilibrium model (Zheng et al., 1997) from Texas A&M University, which is based on batch data obtained from CST powder, is used to generate cesium loading data at different cesium concentrations for various types of SRS wastes. These loading data are fit to the Langmuir equation to obtain effective single-component cesium isotherm parameters. The predictions are in reasonable agreement with batch test data obtained from CST powder, an early CST pellet batch (38B), and a later batch (IE911) using two SRS waste simulants. The ratios between experimental cesium distribution coefficients and predicted values are between 0.56 and 1.0. The variation appears to be due to inadequate equilibration time in some of the batches. Mass transfer parameters are estimated by analyzing column data of a simulated SRS waste and Melton Valley Storage Tank W29 (MVST-W29) waste. The intraparticle diffusivity estimated for the two wastes can be well correlated by means of the Stokes-Einstein equation.Simulations are performed to determine the length of the mass transfer zone for given feed compositions, Cs+ concentrations, and linear velocities. In order to ensure high column utilization during both the transient and cyclic steady state periods, the length of a single segment in the carousel process is chosen to be the mass transfer zone length after the concentration wave achieves a constant pattern. Analysis of the dimensionless groups in the differential mass balance equations reveals that the normalized mass transfer zone length is linearly proportional to the particle Peclet number. The proportionality constant is a function of the waste composition and the Cs+ concentration in the waste. The higher the effective Cs+ capacity and the higher ...
Date: January 15, 1999
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department

Modeling of Crystalline Silicotitanate Ion Exchange Columns Using Experimental Data from SRS Simulated Waste

Description: Non-elutable ion exchange using crystalline silicotitanate is being considered for removing cesium from Savannah River Site radioactive waste. The construction cost of this process depends strongly on the size of the ion exchange column required to meet product specifications.
Date: March 15, 1999
Creator: Walker, D. D.
Partner: UNT Libraries Government Documents Department

Modeling of Crystalline Silicotitanate Ion Exchange Columns

Description: Non-elutable ion exchange is being considered as a potential replacement for the In-Tank Precipitation process for removing cesium from Savannah River Site (SRS) radioactive waste. Crystalline silicotitanate (CST) particles are the reference ion exchange medium for the process. A major factor in the construction cost of this process is the size of the ion exchange column required to meet product specifications for decontaminated waste. To validate SRS column sizing calculations, SRS subcontracted two reknowned experts in this field to perform similar calculations: Professor R. G. Anthony, Department of Chemical Engineering, Texas A&038;M University, and Professor S. W. Wang, Department of Chemical Engineering, Purdue University. The appendices of this document contain reports from the two subcontractors. Definition of the design problem came through several meetings and conference calls between the participants and SRS personnel over the past few months. This document summarizes the problem definition and results from the two reports.
Date: March 9, 1999
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department

Characterization of Reillex{trademark} HPQ Polymer

Description: This work examined the thermal stability of Reillex(tm) HPQ resin as part of a comprehensive plan to qualify that material for use in HB-line. No low temperature exothermic reactions or volatile organic compounds occurred in various lots of as-received, chloride form Reillex(tm) HPQ polymer or the nitrate form polymer. The studies do not suggest any restrictions on purchase criteria for the resin nor any changes in planned use. Previously observed low temperature exotherms resulted from reaction of nitric acid with the aluminum sample holders used in the Differential Scanning Calorimetry analysis.
Date: December 17, 1998
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department

ITP Solids Stability Operating Window Tests

Description: Tetraphenylborate solids provide a potentially large source of benzene in the slurries produced in the In-Tank Precipitation (ITP) process. The stability of the solids is an important consideration in the safety analysis of the process. Recent tests investigated the stability of the potassium tetraphenylborate (KTPB) solids under process conditions, during both precipitation and washing. In addition, the tests measured the relative stabilities of the sodium, potassium and cesium tetraphenylborate (NaTPB, KTPB, and CsTPB, respectively). Additional tests examined the similarity of the catalytic system in the reaction of soluble and insoluble tetraphenylborates.
Date: April 1998
Creator: Walker, D. D.
Partner: UNT Libraries Government Documents Department

Tetraphenylborate Solids Stability Tests

Description: Tetraphenylborate solids are a potentially large source of benzene in the slurries produced in the In-Tank Precipitation (ITP) process. The stability of the solids is an important consideration in the safety analysis of the process and we desire an understanding of the factors that influence the rate of conversion of the solids to benzene. This report discusses current testing of the stability of tetraphenylborate solids.
Date: June 25, 1997
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department

Radioactive Waste Decontamination Using Selentec Mag*SepSM Particles

Description: A sorbent containing crystalline silicotitanate (CST) tested for cesium removal from simulated Savannah River Site (SRS) soluble high activity waste showed rapid kinetics (1 h contact time) and high distribution coefficients (Kd 4000 mL/g of CST). The sorbent was prepared by Selective Environmental Technologies, Inc., (Selentec) as a MAG*SEP particle containing CST obtained from the Molecular Sieve Department of UOP, LLC, Results of preliminary tests suggest potential applications of the Selentec MAG*SEP particles to radioactive waste decontamination at SRS.
Date: June 1, 1998
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department

Effect of Palladium Form on Tetraphenylborate Decomposition Rate

Description: Palladium catalyzes the decomposition of tetraphenylborate in alkaline solutions. Researchers postulate several decomposition mechanisms that differ in the form of the palladium catalyst. Potential forms include solid and soluble, different soluble species (such as aqueous or organic soluble), and different oxidation states (i.e., 0, II, and IV). Initial tests measured the reactivity and distribution of four Pd forms in tetraphenylborate slurries.
Date: April 28, 1998
Creator: Walker, D. D.
Partner: UNT Libraries Government Documents Department

Effects of oxygen and catalyst on tetraphenylborate decomposition rate

Description: Previous studies indicate that palladium catalyzes rapid decomposition of alkaline tetraphenylborate slurries. Oxygen inhibits the reaction at low temperature (25 C), presumably by preventing activation of the catalyst. The present study investigated oxygen's inhibiting effectiveness at higher temperature (45 C) and catalyst concentrations.
Date: December 15, 1999
Creator: Walker, D.D.
Partner: UNT Libraries Government Documents Department