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Direct Fast-Neutron Detection: A Progress Report
It is widely acknowledged that Mure neutron-detection technologies will need to offer increased performance at lower cost. One clear route toward these goals is rapid and direct detection of fast neutrons prior to moderation. This report describes progress to date in an effort to achieve such neutron detection via proton recoil within plastic scintillator. Since recording proton-recoil events is of little practical use without a means to discriminate effectively against gamma-ray interactions, the present effort is concentrated on demonstrating a method that distinguishes between pulse types. The proposed method exploits the substantial difference in the speed of fission neutrons and gamma-ray photons. Should this effort ultimately prove successful, the resulting. technology would make a valuable contribution toward meeting the neutron-detection needs of the next century. This report describes the detailed investigations that have been part of Pacific Northwest National Laborato@s efforts to demonstrate direct fast-neutron detection in the laboratory. Our initial approach used a single, solid piece of scintillator along with the electronics needed for pulse-type differentiation. Work to date has led to the conclusion that faster scintillator and/or faster electronics will be necessary before satisfactory gamma-ray discrimination is achieved with this approach. Acquisition and testing of both faster scintillator …
Date:
October 18, 1998
Creator:
Peurrung, AJ; Stromswold, DC; Reeder, PL & Hansen, RR
Object Type:
Report
System:
The UNT Digital Library
Mechanical properties and microstructural characteristics of laser and electron-beam welds in V-4Cr-4Ti.
Mechanical properties and microstructural characteristics of laser and electron-beam welds of a 500-kg heat of V4Cr4Ti were investigated in as-welded condition and after postwelding heat treatment by impact testing, microhardness measurement, optical microscopy, X-ray diffraction, and transmission electron microscopy (TEM). Ductile-brittle transition temperatures of the laser and electron-beam welds were significantly higher than that of the base metal. However, excellent impact properties could be restored in both types of welds by postwelding annealing at 1000 C for 1 h in vacuum. Analysis by TEM revealed that annealed weld zones were characterized by extensive networks of fine V(C,O,N) precipitates, which clean away O, C, and N interstitial from the grain matrices. This process is accompanied by simultaneous annealing-out of the dense dislocations present in the weld zone. This finding could be useful in identifying an optimal welding procedure by controlling and adjusting the cooling rate of the weld zone by an innovative method to maximize the precipitation of V(C,O,N).
Date:
May 18, 1998
Creator:
Chung, H. M.
Object Type:
Article
System:
The UNT Digital Library
Preparation of a 1 mg/cm{sup 2} {sup 13}C target.
We give a description for the production of {sup 13}C foils and the preparation of an approximately 1 mg/cm{sup 2} thick target. A recent experiment to measure the mass of {sup 36}Ca via the {sup 40}Ca({sup 4}He,{sup 8}He){sup 36}Ca reaction at the S800 magnetic spectrometer at MSU, needed a precise determination of the beam energy and calibration of the focal plane of the magnetic spectrometer in order to achieve the most accurate value for the {sup 36}Ca mass. The 1 mg/cm{sup 2} {sup 13}C target was essential for these purposes. Target performance along with some preliminary results will also be discussed.
Date:
November 18, 1998
Creator:
Greene, J. P.
Object Type:
Article
System:
The UNT Digital Library
Corrosion behavior of environmental assessment glass in product consistency tests of extended duration.
We have conducted static dissolution tests to study the corrosion behavior of the Environmental Assessment (EA) glass, which is the benchmark glass for high-level waste glasses being produced at US Department of Energy facilities. These tests were conducted to evaluate the behavior of the EA glass under the same long-term and accelerated test conditions that are being used to evaluate the corrosion of waste glasses. Tests were conducted at 90 C in a tuff groundwater solution at glass surface area/solution volume (WV) ratios of about 2000 and 20,000 m{sup {minus}1}. The glass dissolved at three distinct dissolution rates in tests conducted at 2000 m{sup {minus}1}. Based on the release of boron, dissolution within the first seven days occurred at a rate of about 0.65 g/(m{sup 2} {center_dot} d). The rate between seven and 70 days decreased to 0.009 g/(m{sup 2} {center_dot} d). An increase in the dissolution rate occurred at longer times after the precipitation of zeolite phases analcime, gmelinite, and an aluminum silicate base. The dissolution rate after phase formation was about 0.18 g/(m{sup 2} {center_dot} d). The formation of the same zeolite alteration phases occurred after about 20 days in tests at 20,000 m{sup {minus}}. The average dissolution …
Date:
November 18, 1998
Creator:
Bates, J.K.; Buck, E.C.; Ebert, W.L.; Luo, J.S. & Tam, S.W.
Object Type:
Report
System:
The UNT Digital Library
Development of niobium spoke cavities for a superconducting light-ion Linac.
This paper reports the development of 350 MHz niobium superconducting cavities for the velocity range 0.2< v/c <0.6. Such cavities could be used to form a linac of exceptional flexibility, capable of efficiently accelerating beams of either protons, deuterons, or any of a wide range of light ions, at intensities sufficient for a production beam for a radioactive beam facility. Results of numerical modeling for several resonator geometries are presented. The design and construction status of prototype niobium cavities is discussed.
Date:
November 18, 1998
Creator:
Shepard, K. W.
Object Type:
Article
System:
The UNT Digital Library
Radiological dose assessment of the disposal of NORM wastes via landspreading.
Petroleum production activities sometimes result in the accumulation of naturally occurring radioactive materials (NORM) at elevated concentrations in by-product waste streams, such as scale and sludge. In the past, the petroleum industry commonly disposed of these wastes via landspreading, a practice consisting of spreading the waste over the soil surface and, sometimes, mixing it into the top layer of soil. Potential radiological doses to workers and the general public from landspreading of NORM waste have been assessed for a variety of scenarios, including the landspreading worker scenario and future residential, industrial, recreational, and agricultural scenarios. The exposure pathways evaluated include external radiation, inhalation of resuspended dust and radon, ingestion of soil and groundwater, and ingestion of contaminated foodstuff grown on the property. In general, potential doses to landspreading workers and members of the general public exposed through future recreational or agricultural use of the property are negligible. Potential doses to future residential or industrial users can vary greatly, depending on such factors as type of building construction, presence or absence of clean cover material, and on-site erosion rates. On the basis of the results presented in this paper, it is recommended that (a) any landspreading activity that would result in …
Date:
December 18, 1998
Creator:
Smith, K. P.
Object Type:
Article
System:
The UNT Digital Library
Advanced Commercial Liquid-Desiccant Technology Development Study
The objective of this report is to provide information to help DOE plan its future activities on liquid-desiccant technologies. The report meets this objective by (1) identifying commercial and residential markets where the liquid-desiccant systems will first be most successful and (2) identifying advances in the individual components of a liquid-desiccant system that will allow it to expand into new markets.
Date:
November 18, 1998
Creator:
Lowenstein, A. (AIL Research, Inc.); Slayzak, S.; Ryan, J. & Pesaran, A. (National Renewable Energy Laboratory)
Object Type:
Report
System:
The UNT Digital Library
Building 594 waste ion exchange facility final survey report.
The Waste Ion Exchange Facility was free released for demolition on July 30, 1998. No surprises or unknowns were noted. The building and associated piping were demolished and removed in September, 1998. The north drain line was removed to three feet outside of the foundation of the building. The east drain line was removed to the foundation of Building 593. The piping located in the north pit drain and east pit drain (which were located under the concrete) were free released. The catch basin, which was located on the south side of the building and also connected to equalization tanks in building 592, was released for unrestricted use and was left intact.
Date:
November 18, 1998
Creator:
Geraghty, D. C.
Object Type:
Report
System:
The UNT Digital Library
YUCCA Mountain Project - Argonne National Laboratory, Annual Progress Report, FY 1997 for activity WP 1221 unsaturated drip condition testing of spent fuel and unsaturated dissolution tests of glass.
This document reports on the work done by the Nuclear Waste Management Section of the Chemical Technology Division of Argonne National Laboratory in the period of October 1996 through September 1997. Studies have been performed to evaluate the behavior of nuclear waste glass and spent fuel samples under the unsaturated conditions (low-volume water contact) that are likely to exist in the Yucca Mountain environment being considered as a potential site for a high-level waste repository. Tests with actinide-doped waste glasses, in progress for over 11 years, indicate that the transuranic element release is dominated by colloids that continuously form and span from the glass surface. The nature of the colloids that form in the glass and spent fuel testing programs is being investigated by dynamic light scattering to determine the size distribution, by autoradiography to determine the chemistry, and by zeta potential to measure the electrical properties of the colloids. Tests with UO{sub 2} have been ongoing for 12 years. They show that the oxidation of UO{sub 2} occurs rapidly, and the resulting paragenetic sequence of secondary phases forming on the sample surface is similar to that observed for uranium found in natural oxidizing environments. The reaction of spent fuel …
Date:
September 18, 1998
Creator:
Bates, J. K.; Buck, E. C.; Emery, J. W.; Finch, R. J.; Finn, P. A.; Fortner, J. et al.
Object Type:
Report
System:
The UNT Digital Library
Small-angle and surface scattering from porous and fractal materials.
We review the basic theoretical methods used to treat small-angle scattering from porous materials, treated as general two-phase systems, and also the basic experimental techniques for carrying out such experiments. We discuss the special forms of the scattering when the materials exhibit mass or surface fractal behavior, and review the results of recent experiments on several types of porous media and also SANS experiments probing the phase behavior of binary fluid mixtures or polymer solutions confined in porous materials. Finally, we discuss the analogous technique of off-specular scattering from surfaces and interfaces which is used to study surface roughness of various kinds.
Date:
September 18, 1998
Creator:
Sinha, S. K.
Object Type:
Article
System:
The UNT Digital Library
Recent developments in theories of pion production in nucleon-nucleon collisions.
Recent developments in theories of pion production in nucleon-nucleon collisions are reviewed.
Date:
November 18, 1998
Creator:
Lee, T. S. H.
Object Type:
Article
System:
The UNT Digital Library
Measurement of oxygen disorder and nano-twin microstructure associated with columnar defects in YBCO.
Studies of defects generated by high energy (>1 GeV) heavy ion irradiation in high-Tc superconductors have been performed by transmission electron microscopy (TEM). Our study shows that high dose irradiation leads to the formation of nano-twins, by which the columnar defects are connected. An analysis of the local Fourier components of the image intensity in [001] lattice images indicates that these new ''twin'' boundaries are much more diffuse than pre-existing twin boundaries in YBCO. The mechanism of the formation of nano-twin boundaries on {l_brace}110{r_brace} planes and their possible relation to superconducting properties are discussed.
Date:
December 18, 1998
Creator:
Yan, Y,
Object Type:
Article
System:
The UNT Digital Library
Tensile impact properties of vanadium-base alloys irradiated at <430{degree}C.
Tensile and impact properties were investigated at <430 C on V-Cr-Ti, V-Ti-Si, and V-Ti alloys after irradiation to {approx}2-46 dpa at 205-430 C in lithium or helium in the Fast Flux Test Facility (FFTF), High Flux Isotope Reactor (HFIR), Experimental Breeder Reactor II (EBR-II), and Advanced Test Reactor (ATR). A 500-kg heat of V-4Cr-4Ti exhibited high ductile-brittle transition temperature and minimal uniform elongation as a result of irradiation-induced loss of work-hardening capability. Work-hardening capabilities of 30- and 100-kg heats of V-4Cr-4Ti varied significantly with irradiation conditions, although the 30-kg heat exhibited excellent impact properties after irradiation at {approx}390-430 C. The origin of the significant variations in the work-hardening capability of V-4Cr-4Ti is not understood, although fabrication variables, annealing history, and contamination from the irradiation environment are believed to play important roles. A 15-kg heat of V-3Ti-1Si exhibited good work-hardening capability and excellent impact properties after irradiation at {approx}390-430 C. Helium atoms, either charged dynamically or produced via transmutation of boron in the alloys, promote work-hardening capability in V-4Cr-4Ti and V-3Ti-1Si.
Date:
May 18, 1998
Creator:
Chung, H. M.
Object Type:
Article
System:
The UNT Digital Library
Vortex melting and the liquid state in YBa{sub 2}Cu{sub 3}O{sub x}.
The experimental vortex phase diagram of YBa{sub 2}Cu{sub 3}O{sub x} is reviewed, with emphasis on first order vortex melting, the upper and lower critical points on the melting line, and the effect of disorder arising from twin boundary and point defect pinning.
Date:
November 18, 1998
Creator:
Crabtree, G. W.
Object Type:
Article
System:
The UNT Digital Library
First tests of a traveling-wave chopper for the ATLAS positive ion linac.
A ten segment traveling-wave chopper has been constructed and successfully tested at 5% of the design 12 MHz repetition rate. The chopper must remove unbunched tails from a partially bunched heavy-ion beam in order to avoid undue emittance growth in the linac and the production of undesirable satellite beam bunches. When poorly bunched beams traverse the traditional sine-wave chopper, it produces unacceptable transverse emittance growth and unnecessary beam loss. These effects are expected to be much reduced in the traveling wave chopper. First tests have confirmed the validity of these claims, clearly showing much reduced transverse emittance growth as compared to the original sine wave chopper and excellent selectivity for the desired beam. Details of these tests will be presented and compared to calculations. Operation of the new chopper at the full 12 MHz rate is the next goal. Development of a driver power supply capable of full CW operation will also be described.
Date:
November 18, 1998
Creator:
Pardo, R. C.
Object Type:
Article
System:
The UNT Digital Library
Dynamic modulus estimation and structural vibration analysis.
Often the dynamic elastic modulus of a material with frequency dependent properties is difficult to estimate. These uncertainties are compounded in any structural vibration analysis using the material properties. Here, different experimental techniques are used to estimate the properties of a particular elastomeric material over a broad frequency range. Once the properties are determined, various structures incorporating the elastomer are analyzed by an interactive finite element method to determine natural frequencies and mode shapes. Then, the finite element results are correlated with results obtained by experimental modal analysis.
Date:
November 18, 1998
Creator:
Gupta, A.
Object Type:
Article
System:
The UNT Digital Library
Vibrational density of states of thin films measured by inelastic scattering of synchrotron radiation.
Vibrational spectra of thin films were measured by inelastic nuclear resonant scattering of synchrotrons radiation in grazing incidence geometry. A strong enhancement of the inelastic signal was obtained by designing the layer system as x-ray waveguide and coupling the incident beam into a guided mode. This effect opens the possibility to study vibrational excitations in thin films that were so far impossible to obtain due to flux limitations.
Date:
September 18, 1998
Creator:
Rohlsberger, R.
Object Type:
Article
System:
The UNT Digital Library
Unsaturated drip tests on sludge based SRL glass : the effects of prior vapor hydration.
The behavior of a sludge-based Savannah River Laboratory (SRL) waste glasses exposed to as much as 7 years of unsaturated test conditions is reported. This test series included both as-cast glass and glass that had been pre-altered by exposure to 200 C water vapor. Actinides (except neptunium) are retained in alteration products and released primarily as solution-borne colloids and particulate when fresh glass is reacted. Pre-altered glass, however, rapidly releases most elements (including actinides) in a nearly congruent manner when first exposed to dripping water. Normalized boron release from the aged glass is more rapid than that of any other element by an order of magnitude. The response of pre-altered glass, as determined by cumulative boron release, follows a power-law behavior with time, corresponding roughly to t{sup 1/4}. This is consistent with a diffusion transport through clay alteration phases on the glass surface.
Date:
December 18, 1998
Creator:
Fortner, J. A.
Object Type:
Article
System:
The UNT Digital Library
A general kinetic-flow coupling model for FCC riser flow simulation.
A computational fluid dynamic (CFD) code has been developed for fluid catalytic cracking (FCC) riser flow simulation. Depending on the application of interest, a specific kinetic model is needed for the FCC flow simulation. This paper describes a method to determine a kinetic model based on limited pilot-scale test data. The kinetic model can then be used with the CFD code as a tool to investigate optimum operating condition ranges for a specific FCC unit.
Date:
May 18, 1998
Creator:
Chang, S. L.
Object Type:
Article
System:
The UNT Digital Library
Evidence for K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}
The first observation of the decay K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} has been reported. The E787 experiment presented evidence for the K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}} decay, based on the observation of a single clean event from data collected during the 1995 run of the AGS (Alternating Gradient Synchrotron at Brookhaven National Laboratory). The branching ratio indicated by this observation, B(K{sup +} {r_arrow} {pi}{sup +} {nu}{bar {nu}}) = 4.2{sub {minus}3.5}{sup +9.7} x 10{sup {minus}10}, is consistent with the Standard Model expectation although the central experimental value is four times larger. The final E787 data sample, from the 1995--98 runs, should reach a sensitivity of about five times that of the 1995 run alone. A new experiment, E949, has been given scientific approval and should start data collection in 2001. It is expected to achieve a sensitivity of more than an order of magnitude below the prediction of the Standard Model.
Date:
December 18, 1998
Creator:
Kettell, S.
Object Type:
Article
System:
The UNT Digital Library
Neutron beam characterization at the Intense Pulsed Neutron Source.
The Intense Pulsed Neutron Source (IPNS) at Argonne National Laboratory is a spallation neutron source dedicated to materials research. Its three cryogenic methane moderators provide twelve neutron beams to fourteen neutron scattering instruments and test facilities. The moderators at IPNS are of cryogenic methane (CH{sub 4}); one of liquid methane at 100 K, and two of solid methane at 30 K. These moderators produce intense beams of both cold and thermal neutrons. The moderators are each of a different physical configuration in order to tailor their performance for the instruments and facilities that operate on the neutron beams. As part of the ongoing operation of IPNS, as well as new enhancements to the target, moderator, and reflector systems, we have performed experiments characterizing the energy and time distribution of neutrons in the various beams. These measurements provide absolutely normalized energy spectra using foil activation techniques joined with time-of-flight measurements, and energy-dependent time distributions using a time-focused crystal analyzer. The IPNS accelerator system delivers 14 {micro}A of 450 MeV protons, in 100 ns pulses at 30 Hz, to a target composed of water-cooled depleted uranium disks. The solid methane ''H'' moderator is 100 by 100 by 45 mm in size, centerline …
Date:
May 18, 1998
Creator:
Iverson, E. B.
Object Type:
Article
System:
The UNT Digital Library
Practical superconductor development for electrical power applications - quarterly report for the period ending March 31, 1998 1997.
This is a multiyear experimental research program focused on improving relevant material properties of high-T{sub c} superconductors and on development of fabrication methods that can be transferred to industry for production of commercial conductors. The development of teaming relationships through agreements with industrial partners is a key element of this program. Recent work on microstructural development and current distribution in Bi-2223 powder-in-tube (PIT) tapes, grain-boundary studies, and a novel application for high-temperature (high-T{sub c}) superconductors are discussed.
Date:
May 18, 1998
Creator:
unknown
Object Type:
Report
System:
The UNT Digital Library
Advanced electrodialysis and pervaporation for fermentation-derived organic acids production.
Lactate esters produced from carbohydrate have potential markets as nontoxic replacements for halogenated and toxic solvents and as feedstocks for large-volume chemicals and polymers. Argonne National Laboratory has developed a novel process for the production of high-purity lactate esters from carbohydrate. The process uses advanced electrodialysis and pervaporation technologies to overcome major technical barriers in product separation; more specifically, the process involves cation elimination without the generation of salt waste and efficient esterification for final purification. This patented process requires little energy input, is highly efficient and selective, eliminates the large volumes of salt waste produced by conventional processes, and significantly reduces manufacturing costs. The enabling membrane separation technologies make it technically and commercially feasible for lactate esters to penetrate the potential markets.
Date:
November 18, 1998
Creator:
Tsai, S. P.
Object Type:
Article
System:
The UNT Digital Library
Metal waste forms from treatment of EBR-II spent fuel.
Demonstration of Argonne National Laboratory's electrometallurgical treatment of spent nuclear fuel is currently being conducted on irradiated, metallic driver fuel and blanket fuel elements from the Experimental Breeder Reactor-II (EBR-II) in Idaho. The residual metallic material from the electrometallurgical treatment process is consolidated into an ingot, the metal waste form (MWF), by employing an induction furnace in a hot cell. Scanning electron microscopy (SEM) and chemical analyses have been performed on irradiated cladding hulls from the driver fuel, and on samples from the alloy ingots. This paper presents the microstructures of the radioactive ingots and compares them with observations on simulated waste forms prepared using non-irradiated material. These simulated waste forms have the baseline composition of stainless steel - 15 wt % zirconium (SS-15Zr). Additions of noble metal elements, which serve as surrogates for fission products, and actinides are made to that baseline composition. The partitioning of noble metal and actinide elements into alloy phases and the role of zirconium for incorporating these elements is discussed in this paper.
Date:
May 18, 1998
Creator:
Abraham, D. P.
Object Type:
Article
System:
The UNT Digital Library