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Power deposition measurements at the LAMPF Neutron Radiation Effects Facility

Description: A calorimeter has been used in the LAMPF A-6 neutron radiation effects area to measure the power deposition about 20 cm from the isotope production targets. The measured value is about 2 w/cm/sup 3//mA, in reasonable agreement with previously calculated values. 3 refs., 3 figs.
Date: June 1, 1985
Creator: Brown, R.D.
Partner: UNT Libraries Government Documents Department

Radionuclides in US coals

Description: The current state of knowledge with respect to radionuclide concentrations in US coals is discussed. Emphasis is placed on the levels of uranium in coal (and lignite) which are considered to represent a concern resulting from coal combustion; areas of the US where such levels have been found; and possible origins of high radionuclide levels in coal. The report reviews relevant studies and presents new data derived from a computerized search of radionuclide content in about 4000 coal samples collected throughout the coterminous US. 103 references, 5 figures, 5 tables.
Date: March 1, 1984
Creator: Bisselle, C. A. & Brown, R. D.
Partner: UNT Libraries Government Documents Department

Radiation-induced changes in magnetic properties of Nd-Fe-B permanent magnets

Description: The high remanence and intrinsic coercivity of Nd-Fe-B magnets make them desirable for use in the accelerators. Use in the radiation environment of an accelerator requires that the sensitivity of these magnets to radiation be determined and the mechanisms responsible be understood. We present results comparing the relative radiation sensitivity of a number of commercially available Nd-Fe-B magnets. Small samples of these magnets were irradiated at the Omega West Reactor in a neutron flux of 2 x 10/sup 13/ n/cm/sup 2/s at a temperature of 350/sup 0/K (77/sup 0/C). At various time intervals during the irradiation, samples were removed from the reactor and the open-circuit remanence measured. We also measured the second quadrant demagnetization curve of samples before and after neutron irradiation to monitor changes in remanence and intrinsic coercivity. Our results show that the sensitivity to radiation varies widely among magnets from different vendors. In general, these samples showed a decrease in the remanence and an increase in the intrinsic coercivity. We present results showing that the rate of remanence decay decreases monotonically with increasing length-to-diameter (L/D) ratio for samples of the same material. Thus, it is important to compare decay rates corrected to some constant L/D ratio. 7 refs., 3 figs., 2 tabs.
Date: January 1, 1987
Creator: Brown, R.D. & Cost, J.R.
Partner: UNT Libraries Government Documents Department

Mechanical properties of 800-MeV proton-irradiated metals

Description: Accelerator beam line components and spallation neutron targets operate in an irradiation environment where changes in mechanical properties can adversely affect component integrity. The present work presents a preliminary study of the effects of low fluences (10/sup 19/ to 10/sup 20/ p/cm/sup 2/) of 800-MeV protons on the yield strength, tensile strength, and ductility of samples of 304 stainless steel, Alloy 718, molybdenum, and tantalum. Tensile samples (0.75 or 1.6 mm thick) were directly water cooled during irradiation and were tested at room temperature. For the 304 stainless steel and annealed Alloy 718, the yield strengths increased by about a factor of 3 and 1.6, respectively, while the ductility decreased approx. 30 and 40 percent. In the bcc metals (tantalum and molybdenum) the yield strengths increased by at least a factor of 2. Tantalum samples retained significant ductility at room temperature, while several molybdenum specimens broke at less than 0.2 percent strain. These irradiation-induced changes at low proton fluences should not impair the usefulness of these materials (other than molybdenum) in accelerator environments.
Date: January 1, 1982
Creator: Brown, R.D. & Cost, J.R.
Partner: UNT Libraries Government Documents Department

Graphite targets at LAMPF

Description: Rotating polycrystalline and stationary pyrolytic graphite target designs for the LAMPF experimental area are described. Examples of finite element calculations of temperatures and stresses are presented. Some results of a metallographic investigation of irradiated pyrolytic graphite target plates are included, together with a brief description of high temperature bearings for the rotating targets.
Date: January 1, 1983
Creator: Brown, R.D. & Grisham, D.L.
Partner: UNT Libraries Government Documents Department

Health and environmental effects of oil and gas technologies: research needs

Description: This report discusses health and environmental issues associated with oil and gas technologies as they are currently perceived - both those that exist and those that are expected to emerge over the next two decades. The various sections of this report contain discussions of specific problem areas and relevant new research activities which should be pursued. This is not an exhaustive investigation of all problem areas, but the report explores a wide range of issues to provide a comprehensive picture of existing uncertainties, trends, and other factors that should serve as the focus of future research. The problem areas of major concern include: effects of drilling fluids, offshore accidents, refineries and worker health, and biota and petroleum spills, indoor air pollution, information transfer, and unconventional resources. These are highlighted in the Executive Summary because they pose serious threats to human health and the environment, and because of the sparcity of accumulated knowledge related to their definition. Separate abstracts have been prepared for selected sections of this report for inclusion in the Energy Data Base. (DMC)
Date: July 1, 1981
Creator: Brown, R. D.
Partner: UNT Libraries Government Documents Department

LANSCE target calculations

Description: The LANSCE target operates at a beam current of 30 microamps. We present here the results of the finite-element calculations for the temperatures and stresses in the present target operated at 100 microamps. The calculations were run using the ABAQUS finite-element code. All finite-element codes require as input both the boundary conditions for the material being heated, and such material properties as the thermal conductivity, specific heat, and the elastic modulus. For the LANSCE target, the boundary conditions involve knowing the power deposition from the beam, and the heat transfer coefficients between the tungsten-alloy cylinder and the cooling water. We believe that these numbers are quite well established. 5 refs., 6 figs.
Date: January 1, 1989
Creator: Grisham, D.L. & Brown, R.D.
Partner: UNT Libraries Government Documents Department

Water-cooled pyrolytic graphite targets at LAMPF: design and operation

Description: Design considerations and actual operating experience are reported for water-cooled pyrolytic graphite targets at the Clinton P. Anderson Meson Physics Facility (LAMPF). Emphasis is placed on the use of finite element computer calculations to determine target temperatures and stresses, which can then be evaluated to judge the usefulness of a particular design. Consideration is also given to the swelling of the target following irradiation, and to the measures taken to prolong target lifetime.
Date: January 1, 1981
Creator: Brown, R.D. & Grisham, D.L.
Partner: UNT Libraries Government Documents Department

Radiation effects on samarium-cobalt permanent magnets

Description: With the recent advances in rare-earth-cobalt (REC) permanent magnet technology, new applications are being implemented that were previously not feasible. One such application is the use of permanent magnetic lenses for accelerator and beam transport systems. In many of these areas the magnetic transport systems are subjected to high radiation levels. Consequently, there is considerable interest in the United States and abroad in the possible changes in the magnetic field when subjected to radiation. This is a description of our approach in performing the field measurements before and after irradiating samples of samarium-cobalt permanent magnets.
Date: July 1, 1982
Creator: Brown, R.D.; Bush, E.D. Jr. & Hunter, W.T.
Partner: UNT Libraries Government Documents Department

Beam line windows at LAMPF

Description: The A-6 main beam-line window at LAMPF separates the vacuum of the main beam line from the isotope production station, proton irradiation ports, and the beam stop, which operate in air. This window must withstand the design beam current of 1 mA at 800 MeV for periods of at least 3000 hours without failure. The window is water cooled and must be strong enough to withstand the 2.1 MPa (300 psig) cooling water pressure, as well as beam-induced thermal stresses. Two designs have been used to meet these goals, a stepped-plate window and a hemispherical window, both made from a precipitation-hardened nickel base alloy, Alloy 718. Calculations of the temperatures and stresses in each of these windows are presented.
Date: January 1, 1985
Creator: Brown, R.D.; Grisham, D.L. & Lambert, J.E.
Partner: UNT Libraries Government Documents Department

Mechanical properties testing of several 800 MeV proton irradiated BCC metals and alloys. [Candidate window materials for SIN beam stop]

Description: A spallation neutron source for the 600-MeV proton accelerator facility at the Swiss Institute for Nuclear Research (SIN) consists of a vertical cylinder filled with molten Pb-Bi. The proton beam enters the cylinder, passing upward through a window in contact with the Pb-Bi eutectic liquid. Investigations are underway at the 800-MeV proton accelerator at LAMPF to test the performance of candidate SIN window materials. Based on considerations of chemical compatibility with molten Pb-Bi, as well as radiation damage mechanisms, Fe, Ta, Fe-2.25Cr-1Mo, and Fe-12Cr-1Mo (Ht-9) were chosen as candidate materials. Sheet tensile samples were sealed inside capsules containing Pb-Bi and were proton-irradiated at LAMPF to two fluences, 4.8 and 54 x 10/sup 23/ p/m/sup 2/. The beam current was approximately equal to the 1 mA anticipated for the upgraded SIN accelerator. Yield and ultimate strengths increased upon irradiation in all materials, while the ductility decreased. The pure metals, Ta and Fe, exhibited the greatest radiation hardening and embrittlement. The HT-9 alloy showed the smallest changes in strength and ductility.
Date: January 1, 1986
Creator: Brown, R.D.; Wechsler, M.S. & Tschalaer, C.
Partner: UNT Libraries Government Documents Department

Irradiation damage in metals produced by 800-MeV protons

Description: Theoretical calculations of damage energies in metals from 800-MeV proton irradiation motivated an experimental transmission electron microscopy study of the damage produced. Damage produced by 800-MeV protons is accompanied by a higher level of helium production than for reactor neutron irradiation. To allow irradiation of samples on a routine basis, a proton irradiation port (PIP) was constructed in beam line A at LAMPF. This port allowed a high damage-rate irradiation of metal foils several mils thick. Irradiations were completed on foils of aluminum, niobium, molybdenum, and vanadium to damage levels between 0.05 dpa and several dpa, the damage occurring at homologous temperatures above 0.5 T/sub m/. Disks were punched from the irradiated foils and thinned for TEM examination. No voids were observed in irradiated aluminum samples. Molybdenum samples showed a low density of cavities which were believed to be gas filled at these high temperatures. Vanadium samples showed a high density of irradiation-produced defects resulting from irradiation-injected impurities. Such defects have been reported previously in ion-irradiated vanadium. The nature of the damage produced is compared to that found at lower temperatures following neutron or ion bombardment.
Date: July 1, 1979
Creator: Brown, R.D.; Sommer, W.F. & Green, W.V.
Partner: UNT Libraries Government Documents Department

Remote recovery of irradiated tensile samples incapsulated in Pb-Bi

Description: The Swiss Institute for Nuclear Research (SIN) is upgrading their proton accelerator to 1 to 2 mA Beam current at 600 MeV. Molten Pb-Bi is being considered as a beam stop. The materials in the beam stop must be chemically compatible with molten Pb-Bi, retain ductility and strength, and have a lifetime of at least six months. In a joint venture between the United States and SIN, four capsules were designed and loaded with eight tensile samples. The tensile samples were Ta, Cr (Fe-2 1/4% Cr-1% Mo), Fe, and HT (Fe-12%, Cr-1% Mo). The cavity of the capsule was then filled with a molten Pb-Bi alloy so it would surround the tensile samples. The capsule lids were then welded in place. The capsules were irradiated in the proton beam at the Los Alamos Meson Physics Facility (LAMPF). The LAMPF facility was used because of its similarity to the proposed SIN upgrade. The LAMPF 800 MeV proton beam passing through the capsules subjects the Pb-Bi and tensile samples to temperatures between 350 to 400/sup 0/ centigrade. These temperatures were verified with melt wires placed in previous irradiation experiments. The Pb-Bi is molten at operating temperatures and tests the compatibility of the tensile samples with molten Pb-bi. Through transmutation by irradiation, Po-210 and Hg were produced. The containment of these toxic isotopes was a major concern during the planning for the disassembly of this experiment.
Date: January 1, 1985
Creator: Nicol, A.G.; Brown, R.D. & Cook, J.H.
Partner: UNT Libraries Government Documents Department

Progress report on the accelerator production of tritium materials irradiation program

Description: The Accelerator Production of Tritium (APT) project is developing an accelerator and a spoliation neutron source capable of producing tritium through neutron capture on He-3. A high atomic weight target is used to produce neutrons that are then multiplied and moderated in a blanket prior to capture. Materials used in the target and blanket region of an APT facility will be subjected to several different and mixed particle radiation environments; high energy protons (1-2 GeV), protons in the 20 MeV range, high energy neutrons, and low energy neutrons, depending on position in the target and blanket. Flux levels exceed 10{sup 14}/cm{sup 2}s in some areas. The APT project is sponsoring an irradiation damage effects program that will generate the first data-base for materials exposed to high energy particles typical of spallation neutron sources. The program includes a number of candidate materials in small specimen and model component form and uses the Los Alamos Spallation Radiation Effects Facility (LASREF) at the 800 MeV, Los Alamos Neutron Science Center (LANSCE) accelerator.
Date: May 1997
Creator: Maloy, S. A.; Sommer, W. F.; Brown, R. D. & Roberts, J. E.
Partner: UNT Libraries Government Documents Department

Data qualification for the Waste Isolation Pilot Plant

Description: The Waste Isolation Pilot Plant (WIPP) site near Carlsbad, New Mexico, has been the subject of scientific and engineering investigations for more than twenty years. Data from these investigations are now being used as part of the process to certify compliance of the WIPP with the governing regulations. Some of these data were collected prior to the development and implementation of the quality assurance (QA) standards that are now being applied in the WIPP compliance certification process, and are considered ``existing data`` within the current QA program. This paper discusses the process for qualification of existing data (QED) defined for the WIPP project, the implementation of that process, and some of the results. This process incorporates many lessons learned, and should be useful to others in the radioactive waste management system who are dealing with ``existing data.``
Date: March 1, 1996
Creator: Brown, R.D. & Harper-Slaboszewicz, V.J.
Partner: UNT Libraries Government Documents Department

Neutron irradiation study of Nd-Fe-B permanent magnets made from melt-spun ribbons

Description: Radiation-induced changes in the magnetization of sintered Nd-Fe-B permanent magnets are known to vary widely among specimens produced by different manufacturers. Samples of Nd-Fe-B MAGNEQUENCH magnets, which are made from melt-spun ribbons, have now been studied and show a much reduced sensitivity to neutron irradiation than do sintered Nd-Fe-B magnets. All melt-spun ribbon-based MAGNEQUENCH magnets, i.e., epoxy-bonded, hot-pressed, and die-upset magnets, show essentially the same slow decrease in magnetic remanence with neutron dose. Measurements of the open-circuit remanence B/sub r//B/sub ro/ at various times during the irradiation show a decay of only 1.5% of the preirradiated value for the MAGNEQUENCH magnets after 1 hour of irradiation, or a dose of 1.4 /times/ 10/sup 16/ neutrons/cm/sup 2/, compared to a 4.6% drop in remanence for the best sintered Nd-Fe-B magnet (Sumitomo 3OH) with the same irradiation dose. Moreover, after 5.3 hours of irradiation, the remanence drops by only 3% for the MAGNEQUENCH magnets. Magnets made from melt-spun ribbons are thus the least sensitive to neutron irradiation so far measured for Nd-Fe-B permanent magnets, but are somewhat more sensitive than samarium-cobalt magnets. 12 refs., 1 fig.
Date: January 1, 1988
Creator: Brown, R.D.; Cost, J.R.; Meisner, G.P. & Brewer, E.G.
Partner: UNT Libraries Government Documents Department

Rabbit system for foil activation irradiations at the Los Alamos Spallation Radiation Effects Facility at LAMPF

Description: A ''rabbit'' system has been installed in an insert at the Los Alamos Spallation Radiation Effects Facility (LASREF). Spallation neutrons at LASREF are produced by the passage of the LAMPF 800-MeV proton beam through the Isotope Production (IP) targets and into the beam stop. This dosimetry insert allows measurement of the spallation neutron and secondary proton fluxes and energy spectra in any of the 12 neutron irradiation locations. Four ''rabbit'' tubes allow radial measurements at 0.12, 0.18, 0.27, and 0.38 meters off beam centerline. Aluminum capsules (''rabbits'') are used to hold the activation foils. As many as five capsules can be stacked on top of one another in each tube to allow measurements below, on, and above beam centerline. Thirteen multiple-foil activation experiments were done at these two locations. Neutron spectra were similar with the exception of the reduction of the high-energy tail outside the beam stop. The spectra outside the beam stop for eight and zero IP targets were similar in spectral shape but reduced in magnitude by a factor of two when eight IP targets were inserted into the proton beam. Measurements showed no difference in the flux below, on, or above beam centerline. With respect to the radial variation in the flux, measurements showed similar spectral shapes between the first three tubes. The fourth tube showed an enhancement in the 24-keV region due to the transmission window in the iron cross section. The ''rabbit'' system is available for use by experimenters at LASREF.
Date: January 1, 1986
Creator: Davidson, D.R.; Brown, R.D.; Taylor, I.K.; Sommer, W.F. & Martinez, L.
Partner: UNT Libraries Government Documents Department

Radiation damage in YBa/sub 2/Cu/sub 3/O/sub 7/ by fast neutrons

Description: The superconducting transition temperature of sintered YBa/sub 2/Cu/sub 3/O/sub 7/ decreases at a rate of 2.7 K/10/sup 18/ n/cm/sup 2/ (E > 0.1 MeV) for fast neutron irradiation. The critical current density J/sub c/ increases a factor of three at zero field and more than three at nonzero fields for fluences up to 2 x 10/sup 18/ n/cm/sup 2/. At both 7 and 75 K, J/sub c/ is decreasing with fluence near 3 x 10/sup 18/ n/cm/sup 2/.
Date: January 1, 1987
Creator: Willis, J.O.; Cost, J.R.; Brown, R.D.; Thompson, J.D. & Peterson, D.E.
Partner: UNT Libraries Government Documents Department

Defect formation in 800-MeV proton-irradiated aluminum

Description: Transmission electron microscopy was used to investigate the formation of irradiation-induced defects in proton-irradiated high-purity aluminum. The specimens were irradiated by 800-MeV protons to about 0.25 displacements per atom (dpa) in the Los Alamos Meson Physics Facility (LAMPF), producing about 20 atomic ppM helium, 130 atomic ppM hydrogen, and approximately 70 atomic ppM of spallation products. The as-irradiated microstructure mainly consisted of cavities with a mean size of 88 A, number density of 1 x 10/sup 15/ cavities/cm/sup 3/, and volume fraction of about 0.05%. The swelling was comparable to that of high-purity aluminum samples neutron-irradiated to the same displacement level. However, the high production rate of gas atoms during the proton irradiation increased the cavity number density by an order of magnitude relative to neutron irradiation, and reduced the cavity size by a factor of about 3. A postirradiation annealing treatment at 250/sup 0/C resulted in complete disappearance of the small cavities and formaion of gas bubbles on grain boundaries.
Date: November 1, 1979
Creator: Jang, H.; Moteff, J.; Levinson, L.; Brown, R.D. & Green, W.V.
Partner: UNT Libraries Government Documents Department

The development of small-scale quadrupoles to operate at 20 to 50K

Description: The development of cryogenically cooled, high-frequency linacs at Los Alamos necessitates that small quadrupoles be developed to operate inside the drift tubes at temperatures as low as 20 K. A program has been undertaken to procure some of these quads, designed to critical specifications, and to test them for field-gradient and harmonic- distortion changes when taken down to the 20- to 50-K operating range and cycled many times back to room temperature. In this application SmCo/sub 5/ and Sm/sub 2/Co/sub 17/ will be used. Both low-temperature operation and resistance to radiation damage are required of these critical components; therefore, the test program also involves exposure to high radiation fluxes in the Omega West reactor at Los Alamos, coupled with post-irradiation field tests. 2 refs., 3 figs., 1 tab.
Date: January 1, 1988
Creator: Liska, D.J.; Kraus, R.H.; Brown, R.D. & Cost, J.R.
Partner: UNT Libraries Government Documents Department

Radiation effects in rare-earth permanent magnets. [Nd-Fe-B; Sm-Co]

Description: Nd-Fe-B and Sm-Co permanent magnets have been irradiated with fission neutrons and gamma rays. Irradiated samples were periodically removed for room temperature measurements of the open-circuit remanence. Hysteresis loops were measured before and after irradiation. For neutron irradiation, two magnets showed a rapid loss of remanence, while a third decayed more slowly. Irradiation in the Omega West Reactor at Los Alamos with fast neutrons caused the fast-decay samples to have an initial loss of remanence of 1% for irradiation at 350 K to a fluence of 10/sup 15/ n/cm/sup 2/. Both SmCo/sub 5/ and Sm/sub 2/Co/sub 17/ magnets showed excellent resistance to radiation-induced loss of remanence for neutron irradiation to a fluence of 2.6 x 10/sup 18/ n/cm/sup 2/. Results for gamma irradiation are presented and discussed in terms of possible mechanisms for radiation-induced loss of magnetic properties.
Date: January 1, 1987
Creator: Cost, J.R.; Brown, R.D.; Giorgi, A.L. & Stanley, J.T.
Partner: UNT Libraries Government Documents Department

Rat mammary carcinogenesis following neutron- or x-radiation

Description: From effects of neutron irradiation upon cell function; Neuherberg, F. R. Germany (20 Oct 1973). Sprague-Dawley female rats, 61 to 63 days of age, were given a single dose of either 0.10, 0.40, 1.6, or 6.4 rads of 0.43-MeV neutrons, or 28, 56, or 85 rads of 250-kVp x rays, or no radiation in a single experiment. The interim results, either in terms of percent of rats with mammary neoplasia or mean number of mammary neoplasms per rat, at the end of 14 months after irradiation, indicate that 0.10 to 0.40 neutron rads was followed by a mammary neoplastic response much like that following 28 xray rads. The mammary neoplastic response to either 6.4 neutron rads or 56 to 85 x-ray rads was similar. Thus the RBE for neutrons for the induction of mammary neoplasia in the SpragueDawley rat is much larger at low neutron doses than at high doses. (auth)
Date: January 1, 1973
Creator: Shellabarger, C.J.; Kellerer, A.M.; Rossi, H.H.; Goodman, L.J.; Brown, R.D.; Mills, R.E. et al.
Partner: UNT Libraries Government Documents Department