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Manganese bath systematic effects in measurements of nu-bar and eta

Description: Measurements using the manganese bath technique are central to the discrepancy that has existed between measured values of $nu$-bar for $sup 252$Cf. Manganese bath measurements of $nu$-bar belong to the lower group of values, while the eta measurements are consistent with the higher $nu$-bar values. A three-part study was performed to see if the discrepancy could be explained by differences in manganese bath techniques: (1) A $sup 252$Cf source previously calibrated by De Volpi was calibrated in the MTR manganese bath; (2) The recommendations made by De Volpi for altering the MTR eta values were carefully considered; and (3) The results of the Monte Carlo calculation of the MTR experiments, carried out at Bettis Atomic Power Laboratory, were examined in detail. The study produced insignificant changes in the eta values. (6 tables) (auth)
Date: January 1, 1975
Creator: Smith, J.R.
Partner: UNT Libraries Government Documents Department

/sup 235/Cf anti. nu. discrepancy and the sulfur discrepancy

Description: The cantankerous discrepancy among measured values of anti ..nu.. for /sup 235/Cf appears at last to be nearing a final resolution. A recent review has summarized the progress that has been achieved through revaluation upward by 0.5% of two manganese bath values anti ..nu.. and the performance of a new liquid scintillator measurement. A new manganese bath measurement at INEL is in reasonably good agreement with previous manganese bath values of /sup 235/Cf anti ..nu... It now appears that the manganese bath values could still be systematically low by as much as 0.4% because the BNL-325 thermal absorption cross section for sulfur may be as much as 10% low. There is a bona fide discrepancy between measurements of the sulfur cross section by pile oscillators and the values derived from transmission measurements. The resolution of this discrepancy is a prerequisite to the final resolution of the /sup 235/Cf anti ..nu.. discrepancy. 22 references.
Date: January 1, 1979
Creator: Smith, J.R.
Partner: UNT Libraries Government Documents Department

Rayleigh temperature profiles in a hydrogen diffusion flame

Description: Rayleigh scattering from a hydrogen-air laminar jet diffusion flame in combination with a numerical model of the flame has been used to determine temperature profiles. The model predictions of species concentration are used to calculate a mean Rayleigh cross-section which is used to relate the Rayleigh scattered intensity to temperature. Using an argon ion laser producing 7.5 watts at 488 nm and an optical multichannel analyzer (OMA), the scattered light was imaged into a spectrometer. The OMA was rotated 90 degrees to its normal orientation, allowing scans to be taken along the spectrometer exit slit. This resulted in a spatially resolved Rayleigh signal along the laser beam through the entire flame. Spatial resolution of 0.18 mm on each of the 500 detector elements with good signal-to-noise ratios was achieved even with integration times of only 0.03 second. Since the entire profile is made simultaneously, particulate perturbed profiles are easily recognized and discarded. Transverse profiles are presented to show flame structure. Axial profiles are compared to radiation corrected thermocouple measurements.
Date: September 1, 1978
Creator: Smith, J.R.
Partner: UNT Libraries Government Documents Department

Matrix effects of TRU (transuranic) assays using the SWEPP PAN assay system

Description: The Drum Assay System (DAS) at the Stored Waste Experimental Pilot Plant (SWEPP) is a second-generation active-passive neutron assay system. It has been used to assay over 5000 208-liter drums of transuranic waste from the Rocky Flats Plant (RFP). Data from these assays have been examined and compared with the assays performed at Rocky Flats, mainly utilize counting of {sup 239}Pu gamma rays. For the most part the passive assays are in very good agreement with the Rocky Flats assays. The active assays are strongly correlated with the results of the other two methods, but require matrix-dependent correction factors beyond those provided by the system itself. A set of matrix-dependent correction factors has been developed from the study of the assay results. 3 refs., 4 figs., 3 tabs.
Date: August 1, 1990
Creator: Smith, J.R.
Partner: UNT Libraries Government Documents Department

A MECHANICAL NEUTRON FILTER FOR A CRYSTAL SPECTROMETER

Description: A velocity selector of the Dash-Sommers type with straight slits was constructed for use with the MTR crystal spectrometer. The rotor, designed to remove undesirable higher order contaninants from the Bragg beam, is built of magnesium and fiberglas-epoxy laminate to minimize weight and is driven directly by a 1/8-hp synchronous motor. Vanes of fiberglas laminate are set into 235 slots milled around the periphery of a 4'' diameter magnesium core. High strength is attained by winding the assembled rotor with glass filaments impregnated with epoxy resin. Effective helical pitch is obtained by setting the rotor axis at an angle to the Bragg beam. Delow 0.25 ev, the rotor gave good suppression, but the transmission was low. (auth)
Date: June 14, 1963
Creator: Smith, J.R. & Miller, H.G.
Partner: UNT Libraries Government Documents Department

Acid-permanganate oxidation of potassium tetraphenylboron

Description: Scoping experiments have been performed which show that potassium tetraphenylboron (KTPB) is rapidly oxidized by permanganate in acidic solutions at room temperature. The main Products are CO[sub 2], highly oxidized organic compounds related to tartaric and tartronic acids, boric acid, and potassium phosphate (when phosphoric acid is used as the source of acid). One liter of 0.6M NaMnO[sub 4]/2.5M H[sub 3]PO[sub 4] solution will destroy up to 8 grams of KTPB. The residual benzene concentration has been measured to be less than the RCRA limit of 0.5 ppm. Approximately 30% of the organic material is released as CO[sub 2] (trace CO) and 0.16% as benzene vapor. The reaction is well behaved, no foaming or spattering. Tests were performed from .15M to near 1M permanganate. The phosphoric acid concentration was maintained at a concentration at least three times that of the permanganate since an excess of acid was desired and this is the ratio that these two reagents are consumed in the oxidation.
Date: February 1, 1993
Creator: Smith, J.R.
Partner: UNT Libraries Government Documents Department

Acid-permanganate oxidation of potassium tetraphenylboron

Description: Scoping experiments have been performed which show that potassium tetraphenylboron (KTPB) is rapidly oxidized by permanganate in acidic solutions at room temperature. The main Products are CO{sub 2}, highly oxidized organic compounds related to tartaric and tartronic acids, boric acid, and potassium phosphate (when phosphoric acid is used as the source of acid). One liter of 0.6M NaMnO{sub 4}/2.5M H{sub 3}PO{sub 4} solution will destroy up to 8 grams of KTPB. The residual benzene concentration has been measured to be less than the RCRA limit of 0.5 ppm. Approximately 30% of the organic material is released as CO{sub 2} (trace CO) and 0.16% as benzene vapor. The reaction is well behaved, no foaming or spattering. Tests were performed from .15M to near 1M permanganate. The phosphoric acid concentration was maintained at a concentration at least three times that of the permanganate since an excess of acid was desired and this is the ratio that these two reagents are consumed in the oxidation.
Date: February 1, 1993
Creator: Smith, J. R.
Partner: UNT Libraries Government Documents Department

The hydrogen hybrid option

Description: The energy efficiency of various piston engine options for series hybrid automobiles are compared with conventional, battery powered electric, and proton exchange membrane (PEM) fuel cell hybrid automobiles. Gasoline, compressed natural gas (CNG), and hydrogen are considered for these hybrids. The engine and fuel comparisons are done on a basis of equal vehicle weight, drag, and rolling resistance. The relative emissions of these various fueled vehicle options are also presented. It is concluded that a highly optimized, hydrogen fueled, piston engine, series electric hybrid automobile will have efficiency comparable to a similar fuel cell hybrid automobile and will have fewer total emissions than the battery powered vehicle, even without a catalyst.
Date: October 15, 1993
Creator: Smith, J. R.
Partner: UNT Libraries Government Documents Department

Radiolysis gases from nitric acid solutions containing HSA and HAN

Description: The concentration of hydrogen (H{sub 2}) in the radiolytically produced off-gas from 2.76-4.25M HNO{sub 3}/PU solutions has been found to be greatly reduced in the presence of sulfamic acid (HSA) and hydroxylamine nitrate (HAN). The H{sub 2} concentration ([H{sub 2}]) is reduced from 35 percent to about 4 percent by dilution caused from an increase in the production rates of nitrogen (N{sub 2}), nitrous oxide (N{sub 2}O), and oxygen (O{sub 2}) gases. The generation rate of H{sub 2} was not affected by HSA or HAN giving a measured radiolytic yield, G(H{sub 2}), value of 0.201 molecules/100 eV for 2.765M NO{sub 3}{sup -} solution (a value of 0.213 is predicted from previous data). The G(H{sub 2}) values are dependent on the solution nitrate concentration ([NO{sub 3}{sup -}]). The generation rates of N{sub 2}, N{sub 2}O, and O{sub 2} are not dependent on the [NO{sub 3}{sup -}] in this narrow range, but are dependent on the presence of HSA and the concentration of HAN. The percentage [H{sub 2}] for the 2.5 to 3.0M NO{sub 3}{sup -} range expected in the off- from the FB-Line Pu{sup +3} Hold Tanks is conservatively estimated to be about 3.5 to 4.5 % for Pu + 3 solutions initially containing 0.023M HAN/0.165M HSA. The upper limit [H{sub 2}] may actually be about 4.1 % (4.3 % at 90 % confidence limits) but more {open_quotes}initial{close_quotes} off-gas rate data is needed at about 2.9M [NO{sub 3}{sup -}] in Pu{sup +3} solution for verification. Addition of ascorbic acid had no effect on the off-gas rate of Pu{sup +3} solutions containing HSA and NO{sub 3}{sup -} concentrations higher than those expected in the hold tanks. The maximum {open_quotes}hold time{close_quotes} for 50 grams/liter Pu{sup +3}/0.165M HSA/0.023M HAN/2.5-3.0M HNO{sub 3} solution is 20.3{+-}2.1 days. After this time the HSA initially present will become ...
Date: October 28, 1994
Creator: Smith, J. R.
Partner: UNT Libraries Government Documents Department

Problems and progress regarding resonance parameterization of /sup 235/U and /sup 239/Pu for ENDF/B

Description: The procedures used to obtain the resolved and unresolved resonance parameterization of /sup 235/U and /sup 239/Pu contained in the US Evaluated Nuclear Data File ENDF/B-V are reviewed. For /sup 235/U, recommendations are made to improve the representation by including information on resonance spins and fission-channel vector orientations, and some preliminary results are presented. Evidence is reviewed that it is the fission channels rather than the spins of the resonances that lead to differences in fission mass distributions, the number of neutrons emitted per fission, and fission kinetic energies. The improved parameterization may thus have physics content that will prove of interest in future applications.
Date: January 1, 1981
Creator: Moore, M.S.; de Saussure, G. & Smith, J.R.
Partner: UNT Libraries Government Documents Department

A desiccant dehumidifier for electric vehicle heating

Description: Vehicle heating requires a substantial amount of energy. Engines in conventional cars produce enough waste heat to provide comfort heating and defogging/defrosting, even under very extreme conditions. Electric vehicles (EVs), however, generate little waste heat. Using battery energy for heating may consume a substantial fraction of the energy storage capacity, reducing the vehicle range, which is one of the most important parameters in determining EV acceptability. Water vapor generated by the vehicle passengers is in large part responsible for the high heating loads existing in vehicles. In cold climates, the generation of water vapor inside the car may result in water condensation on the windows, diminishing visibility. Two strategies are commonly used to avoid condensation on windows: windows are kept warm, and a large amount of ambient air is introduced in the vehicle. Either strategy results in a substantial heating load. These strategies are often used in combination, and a trade-off exists between them. If window temperature is decreased, ventilation rate has to be increased. Reducing the ventilation rate requires an increase of the temperature of the windows to prevent condensation. An alternative solution is a desiccant dehumidifier, which adsorbs water vapor generated by the passengers. Window temperatures and ventilation rates can then be reduced, resulting in a substantially lower heating load. This paper explores the dehumidifier heating concept. The first part shows the energy savings that could be obtained by using this technology. The second part specifies the required characteristics and dimensions of the system. The results indicate that the desiccant system can reduce the steady-state heating load by 60% or more under typical conditions. The reduction in heating load is such that waste heat may be enough to provide the required heating under most ambient conditions. Desiccant system dimensions and weight appear reasonable for packaging in an EV.
Date: September 1996
Creator: Aceves, S. M. & Smith, J. R.
Partner: UNT Libraries Government Documents Department

Survey of DOE NDA practices for CH-Tru waste certification--illustrated with a greater than 10,000 drum NDA data base

Description: We have compiled a greater than 10,000 CH-TRU waste drum data base from seven DOE sites which have utilized such multiple NDA measurements within the past few years. Most of these nondestructive assay (NDA) technique assay result comparisons have been performed on well-characterized, segregated waste categories such as cemented sludges, combustibles, metals, graphite residues, glasses, etc., with well-known plutonium isotopic compositions. Waste segregation and categorization practices vary from one DOE site to another. Perhaps the most systematic approach has been in use for several years at the Rocky Flats Plant (RFP), operated by Rockwell International, and located near Golden, Colorado. Most of the drum assays in our data base result from assays of RFP wastes, with comparisons available between the original RFP assays and PAN assays performed independently at the Idaho National Engineering Laboratory (INEL) Solid Waste Examination Pilot Plant (SWEPP) facility. Most of the RFP assays were performed with hyperpure germanium (HPGe)-based SGS assay units. However, at least one very important waste category, processed first-stage sludges, is assayed at RFP using a sludge batch-sampling procedure, prior to filling of the waste drums. 5 refs., 5 figs.
Date: January 1, 1988
Creator: Schultz, F.J.; Caldwell, J.T. & Smith, J.R.
Partner: UNT Libraries Government Documents Department

CDF tau triggers, analysis and other developments

Description: This note is a write-up of contribution made by the author to the HCP2002 conference. It has two principal subjects. The first subject concerns the CDF {tau} triggers, {tau}-cone algorithms and {tau} physics analysis. {tau} physics is going to be very important in Run II because {tau}'s can extend SUSY searches at large tan {beta} in particular, {tau}'s will help in the searches for {tilde {chi}}{sub 1}{sup {+-}}{tilde {chi}}{sub 2}{sup 0}, MSSM Higgs and other non Standard Model (SM) processes. Also, {tau} events are important for various Standard Model processes including Precision Electroweak, t{bar t}, and SM Higgs searches. {tau} triggers are installed and operating at CDF. The second subject of this contribution to the HCP2002 conference concerns the algorithms of backwards differentiation abstracted from their usual setting inside of Automatic Differentiation software packages. Backwards differentiation (reverse-mode differentiation) provides a useful means for optimizing many kinds of problems.
Date: January 15, 2003
Creator: Smith, J. R.
Partner: UNT Libraries Government Documents Department

A hybrid vehicle evaluation code and its application to vehicle design. Revision 1

Description: This paper describes a hybrid vehicle simulation model which can be applied to many of the vehicles currently being considered for low pollution and high fuel economy. The code operates in batch mode with all the vehicle information stored in data files. The code calculates fuel economy for three driving schedules, time for 0--96 km/h at maximum acceleration, hill climbing performance, power train dimensions, and pollution generation rates. This paper also documents the application of the code to a hybrid vehicle that utilizes a hydrogen internal combustion engine. The simulation model is used for parametric studies of the vehicle. The results show the fuel economy of the vehicle as a function of vehicle mass, aerodynamic drag, engine efficiency, accessory load, and flywheel efficiency. The code also calculates the minimum flywheel energy and power to obtain a desired performance. The hydrogen hybrid vehicle analyzed in the paper has a predicted range of 480 km (300 miles), with a gasoline equivalent fuel efficiency of 34.2 km/liter (80.9 mpg).
Date: September 15, 1994
Creator: Aceves, S.M. & Smith, J.R.
Partner: UNT Libraries Government Documents Department

Lean-burn hydrogen spark-ignited engines: the mechanical equivalent to the fuel cell

Description: Fuel cells are considered as the ideal power source for future vehicles, due to their high efficiency and low emissions. However, extensive use of fuel cells in light-duty vehicles is likely to be years away, due to their high manufacturing cost. Hydrogen-fueled, spark-ignited, homogeneous-charge engines offer a near-term alternative to fuel cells. Hydrogen in a spark-ignited engine can be burned at very low equivalence ratios, so that NO[sub x] emissions can be reduced to less than 10 ppm without catalyst. HC and CO emissions may result from oxidation of engine oil, but by proper design are negligible (a few ppm). Lean operation also results in increased indicated efficiency due to the thermodynamic properties of the gaseous mixture contained in the cylinder. The high effective octane number of hydrogen allows the use of a high compression ratio, further increasing engine efficiency. In this paper, a simplified engine model is used for predicting hydrogen engine efficiency and emissions. The model uses basic thermodynamic equations for the compression and expansion processes, along with an empirical correlation for heat transfer, to predict engine indicated efficiency. A friction correlation and a supercharger/turbocharger model are then used to calculate brake thermal efficiency. The model is validated with many 1345 experimental points obtained in a recent evaluation of a hydrogen research engine. The experimental data are used to adjust the empirical constants in the heat release rate and heat transfer correlation. The adjusted engine model predicts pressure traces, indicated efficiency and NO,, emissions with good accuracy over the range of speed, equivalence ratio and manifold pressure experimentally covered.
Date: October 1, 1996
Creator: Aceves, S.M. & Smith, J.R.
Partner: UNT Libraries Government Documents Department

Hybrid and conventional hydrogen engine vehicles that meet EZEV emissions

Description: In this paper, a time-dependent engine model is used for predicting hydrogen engine efficiency and emissions. The model uses basic thermodynamic equations for the compression and expansion processes, along with an empirical correlation for heat transfer, to predict engine indicated efficiency. A friction correlation and a supercharger/turbocharger model are then used to calculate brake thermal efficiency. The model is validated with many experimental points obtained in a recent evaluation of a hydrogen research engine. A The validated engine model is then used to calculate fuel economy and emissions for three hydrogen-fueled vehicles: a conventional, a parallel hybrid, and a series hybrid. All vehicles use liquid hydrogen as a fuel. The hybrid vehicles use a flywheel for energy storage. Comparable ultra capacitor or battery energy storage performance would give similar results. This paper analyzes the engine and flywheel sizing requirements for obtaining a desired level of performance. The results indicate that hydrogen lean-burn spark-ignited engines can provide a high fuel economy and Equivalent Zero Emission Vehicle (EZEV) levels in the three vehicle configurations being analyzed.
Date: December 10, 1996
Creator: Aceves, S.M. & Smith, J.R.
Partner: UNT Libraries Government Documents Department

A hybrid vehicle evaluation code and its application to vehicle design. Revision 2

Description: This paper describes a hybrid vehicle simulation model which can be applied to many of the vehicles currently being considered for low pollution and high fuel economy. The code operates in batch mode with all the vehicle information stored in data files. The code calculates power train dimensions, fuel economy for three driving schedules, time for 0-96 km/h at maximum acceleration, hill climbing performance, and pollution generation rates. This paper also documents the application of the code to a hybrid vehicle that utilizes a hydrogen internal combustion engine. The simulation model is used for parametric studies of the vehicle. The results show the fuel economy of the vehicle as a function of vehicle mass, aerodynamic drag, engine efficiency, accessory load, and flywheel efficiency. The code also calculates the minimum flywheel energy and power to obtain a desired performance. The hydrogen hybrid vehicle analyzed in the paper has a range of 480 km (300 miles), with a predicted gasoline equivalent fuel efficiency of 33.7 km/liter (79.3 mpg).
Date: December 13, 1994
Creator: Aceves, S.M. & Smith, J.R.
Partner: UNT Libraries Government Documents Department

Nitric-phosphoric acid oxidation of organic waste materials

Description: A wet chemical oxidation technology has been developed to address issues facing defense-related facilities, private industry, and small-volume generators such as university and medical laboratories. Initially tested to destroy and decontaminate a heterogenous mixture of radioactive-contaminated solid waste, the technology can also remediate other hazardous waste forms. The process, unique to Savannah River, offers a valuable alternative to incineration and other high-temperature or high-pressure oxidation processes. The process uses nitric acid in phosphoric acid; phosphoric acid allows nitric acid to be retained in solution well above its normal boiling point. The reaction converts organics to carbon dioxide and water, and generates NO{sub x} vapors which can be recycled using air and water. Oxidation is complete in one to three hours. In previous studies, many organic compounds were completely oxidized, within experimental error, at atmospheric pressure below 180{degrees}C; more stable compounds were decomposed at 200{degrees}C and 170 kPa. Recent studies have evaluated processing parameters and potential throughputs for three primary compounds: EDTA, polyethylene, and cellulose. The study of polyvinylchloride oxidation is incomplete at this time.
Date: November 1, 1995
Creator: Pierce, R.A. & Smith, J.R.
Partner: UNT Libraries Government Documents Department

Isothermal heat measurements of TBP-nitric acid solutions

Description: Net heats of reaction were measured in an isothermal calorimeter for both single phase (organic) and two phase (organic and aqueous) TBP/HNO{sub 3} reacting solutions at temperatures above 100 C. The oxidation rate constant was determined to be 5.4E-4 min{sup {minus}1} at 110 C for an open ``vented`` system as compared to 1.33 E-3 min{sup {minus}1} in the closed system. The heat released per unit material oxidized was also reduced. The oxidation in both phases was found to be first order in nitric acid and pseudo-zero order in butylnitrate and water. The hydrolysis (esterification) rate constant determined by Nichols` (1.33E-3 min{sup {minus}1}) fit the experimental data from this work well. Forced evaporation of the volatile components by the product gases from oxidation resulted in a cooling mechanism which more than balanced the heat from the oxidation reaction in the two-phased systems. Rate expressions were derived and rate constants determined for both the single and two phase systems. An approximating mathematical model was developed to fit the experimental data and to extrapolate beyond the experimental conditions. This model shows that one foot of ``reacting`` 14.3M HNO{sub 3} aqueous phase solution at 121 C will transport sufficient water to the organic phase to replace evaporative losses, maintaining endothermicity, for organic layers up to 12.2 + 6.0 feet deep. If the pressure in a reacting system is allowed to increase due to insufficient venting the temperature of the organic phase would increase in temperature to reach a new equilibrium. The rate of oxidation would increase not only due to the increase in temperature but also from the increased concentration of dissolved HNO{sub 3} reduction products. Another important factor is that the cooling system described in this work becomes less effective as the total pressure increases. These factors probably contributed to the explosion at ...
Date: December 16, 1994
Creator: Smith, J.R. & Cavin, W.S.
Partner: UNT Libraries Government Documents Department

Hybrid vehicle system studies and optimized hydrogen engine design

Description: We have done system studies of series hydrogen hybrid automobiles that approach the PNGV design goal of 34 km/liter (80 mpg), for 384 km (240 mi) and 608 km (380 mi) ranges. Our results indicate that such a vehicle appears feasible using an optimized hydrogen engine. We have evaluated the impact of various on-board storage options on fuel economy. Experiments in an available engine at the Sandia CRF demonstrated NO{sub x} emissions of 10 to 20 ppM at an equivalence ratio of 0.4, rising to about 500 ppm at 0.5 equivalence ratio using neat hydrogen. Hybrid simulation studies indicate that exhaust NO{sub x} concentrations must be less than 180 ppM to meet the 0.2 g/mile ULEV or Federal Tier II emissions regulations. LLNL has designed and fabricated a first generation optimized hydrogen engine head for use on an existing Onan engine. This head features 15:1 compression ratio, dual ignition, water cooling, two valves and open quiescent combustion chamber to minimize heat transfer losses. Initial testing shows promise of achieving an indicated efficiency of nearly 50% and emissions of less than 100 ppM NO{sub x}. Hydrocarbons and CO are to be measured, but are expected to be very low since their only source is engine lubricating oil. A successful friction reduction program on the Onan engine should result in a brake thermal efficiency of about 42% compared to today`s gasoline engines of 32%. Based on system studies requirements, the next generation engine will be about 2 liter displacement and is projected to achieve 46% brake thermal efficiency with outputs of 15 kW for cruise and 40 kW for hill climb.
Date: April 26, 1995
Creator: Smith, J.R. & Aceves, S.
Partner: UNT Libraries Government Documents Department

Absolute measurement of anti. nu. for /sup 252/Cf

Description: Neutron yields were determined by measuring the activities produced in the INEL manganese bath. Of the three fission methods used, the neutron-fission coincidence method was found to be the most consistent and reliable. The value of /sup 252/Cf anti ..nu.. obtained by these measurements was 3.764. (RWR)
Date: January 1, 1980
Creator: Smith, J.R.; Reeder, S.D. & Gehrke, R.J.
Partner: UNT Libraries Government Documents Department

The INEL beryllium multiplication experiment

Description: The experiment to measure the multiplication of 14-MeV neutrons in bulk beryllium has been completed. The experiment consists of determining the ratio of {sup 56}Mn activities induced in a large manganese bath by a central 14-MeV neutron source, with and without a beryllium sample surrounding the source. In the manganese bath method a neutron source is placed at the center of a totally-absorbing aqueous solution of MnSo{sub 4}. The capture of neutrons by Mn produces a {sup 56}Mn activity proportional to the emission rate of the source. As applied to the measurement of the multiplication of 14- MeV neutrons in bulk beryllium, the neutron source is a tritium target placed at the end of the drift tube of a small deuteron accelerator. Surrounding the source is a sample chamber. When the sample chamber is empty, the neutrons go directly to the surrounding MnSO{sub 4} solution, and produce a {sup 56}Mn activity proportional to the neutron emission rate. When the chamber contains a beryllium sample, the neutrons first enter the beryllium and multiply through the (n,2n) process. Neutrons escaping from the beryllium enter the bath and produce a {sup 56}Mn activity proportional to the neutron emission rate multiplied by the effective value of the multiplication in bulk beryllium. The ratio of the activities with and without the sample present is proportional to the multiplication value. Detailed calculations of the multiplication and all the systematic effects were made with the Monte Carlo program MCNP, utilizing both the Young and Stewart and the ENDF/B-VI evaluations for beryllium. Both data sets produce multiplication values that are in excellent agreement with the measurements for both raw and corrected values of the multiplication. We conclude that there is not real discrepancy between experimental and calculated values for the multiplication of neutrons in bulk beryllium. 12 figs., ...
Date: March 1, 1991
Creator: Smith, J.R. & King, J.J.
Partner: UNT Libraries Government Documents Department