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Feasibility of Zircaloy as a fuel clad and structural material in an LAFR-LWR

Description: A preliminary analysis of the radiation environment in a Linear Accelerator Fuel Regenerator (LAFR) has been made. The response of Zircaloy to this environment in combination with that in a Light Water Reactor (LWR) has been projected. It is concluded that the response to irradiation of Zircaloy in a combined LAFR-LWR cycle will lead to a more deleterious change of properties than for an equivalent LWR exposure.
Date: January 1, 1979
Creator: Parkin, D.M.
Partner: UNT Libraries Government Documents Department

Analysis of radiation damage in fusion-simulation neutron spectra

Description: Various parameters which are relevant to an understanding of radiation effects in metals have been evaluated utilizing available neutron spectrum information for several existing sources, e.g., EBRII, HFIR, and LAMPF, as well as the hypothetical spectrum at a fusion reactor first wall, and measured Li(d,n) spectra. Recoil energy distributions were calculated for several metals including Al, Cu, and Nb. The recoil energy range was divided into groups, and the fraction of recoils occurring in each energy group was compared with the fraction of the damage energy contributed by that group. From this comparison it was possible to conclude that the significant recoil range differs by about an order of magnitude between fission and fusion sources. The analysis further confirms that basic defect production characteristics depend upon the neutron spectrum, and that integral calculations of radiation-effect parameters do not provide a complete description of the dependence. This is equally true for comparisons between fusion-related spectra or fission-reactor spectra independently. Four recoil-dependent parameter functions which describe different aspects of radiation damage were used in the calculations. The relative effectiveness of neutron sources was found to depend upon the choice of parameter function. Fission-reactor spectra comparisons are relatively insensitive to the parameter functions used whereas spectra with an appreciable component of high-energy neutrons are much more sensitive. (auth)
Date: January 1, 1975
Creator: Parkin, D.M. & Goland, A.N.
Partner: UNT Libraries Government Documents Department

Radiation induced amorphization in YBa2Cu3O7 and GdBa2Cu3O7 superconductors

Description: The response of YBa2Cu3O7 and GdBa2Cu3O7 high temperature superconductors to particle irradiation is examined. Both ion and electron irradiations have been shown to first produce an orthorhombic-to-tetragonal transformation at doses roughly a factor of 10 higher. Analysis of the displacement stoichiometry that results from 120, 300, and 1000 keV electron irradiations, 400 and 500 keV O irradiations, and 300 keV helium irradiations indicate that the orthorhombic-to-tetragonal transformation is driven by O atoms displacements either alone or in the presence of metal atom displacements and that the transformation to the amorphous phase is driven by displacements on the Y, Gd, or other rare earth atom site. 10 refs., 3 figs., 1 tab.
Date: January 1, 1988
Creator: Parkin, D.M. & Nastasi, M.
Partner: UNT Libraries Government Documents Department

Displacement cascades in diatomic materials

Description: A new function, the specified-projectile displacement function p/sub ijk/ (E), is introduced to describe displacement cascades in polyatomic materials. This function describes the specific collision events that produce displacements and hence adds new information not previously available. Calculations of p/sub ijk/ (E) for MgO, Al/sub 2/O/sub 3/ and TaO are presented and discussed. Results show that the parameters that have the largest effect on displacement collision events are the PKA energy and the mass ratio of the atom types in the material. It is further shown that the microscopic nature of the displacement events changes over the entire recoil energy range relevant to fusion neutron spectra and that these changes are different in materials whose mass ratio is near one than in those where it is far from one.
Date: January 1, 1981
Creator: Parkin, D.M. & Coulter, C.A.
Partner: UNT Libraries Government Documents Department

Damage energy functions for compounds and alloys

Description: The concept of the damage energy of an energetic primary knock-on atom in a material is a central component in the procedure used to calculate dpa for metals exposed to neutron and charged particle radiation. Coefficients for analytic fits to the calculated damage energy functions are given for Al/sub 2/O/sub 3/, Si/sub 3/N/sub 4/, Y/sub 2/O/sub 3/, and NbTi. Damage efficiencies are given for Al/sub 2/O/sub 3/. (MHR)
Date: January 1, 1977
Creator: Parkin, D.M. & Coulter, C.A.
Partner: UNT Libraries Government Documents Department

Inorganic insulator program at LASL

Description: Experiments are conducted to determine electrical and structural changes resulting from neutron and ionizing radiation. Calculations were made of damage effects in compounds and the dependence of this damage on neutron energy was studied. These activities are outlined. (MOW)
Date: January 1, 1980
Creator: Clinard, F.W. Jr. & Parkin, D.M.
Partner: UNT Libraries Government Documents Department

Displacement cascades in polyatomic materials

Description: Using a continuous-slowing-down, random amorphous material model, we have studied displacement cascades in a number of diatomic materials. This paper reviews a number of previous results that elucidate the effects of atomic mass, recoil energy, displacement energy, capture energy and material stoichiometry on the numbers of displacements in a cascade. The displacement cascade reveals a complex structure that is dependent on the type of irradiation and the material properties. Conclusions related to damage analysis for fusion reactors are given.
Date: January 1, 1982
Creator: Parkin, D.M. & Coulter, C.A.
Partner: UNT Libraries Government Documents Department

High-energy-neutron damage in Nb/sub 3/Sn: changes in critical properties, and damage-energy analysis

Description: Filamentary wires of Nb/sub 3/Sn have been irradiated with fission-reactor, 14.8-MeV, and d-Be neutrons and the changes in critical properties measured. The changes observed scale reasonably well with the calculated damage energies for the irradiations. A critical dose for operation of these conductors in fusion-magnet applications is determined to be 0.19 eV/atom damage energy or 0.0019 dpa.
Date: January 1, 1981
Creator: Snead, C.L. Jr.; Parkin, D.M. & Guinan, M.W.
Partner: UNT Libraries Government Documents Department

Differential neutron cross section for free interstitial production in copper

Description: Free interstitials produced by monoenergetic neutrons were monitored by changes in Young's modulus of a vibrating foil specimen. These changes can be related to the number of pinners on dislocations which depends on the number of defects produced. The pinning rate is compared with displacement cross section calculations and agrees with the Norgett--Robinson--Torrens (NRT) model. Electron irradiations on the same sample yield estimates of the free interstitial production cross section to be approx. 1% of the NRT cross section.
Date: January 1, 1979
Creator: Goldstone, J.A.; Parkin, D.M. & Simpson, H.M.
Partner: UNT Libraries Government Documents Department

New facility for ion beam materials characterization and modification at Los Alamos

Description: The Ion Beam Materials Laboratory (IBML) is a new Los Alamos laboratory devoted to the characterization and modification of the near surfaces of materials. The primary instruments of the IBML are a tandem electrostatic accelerator, a National Electrostatics Corp. Model 9SDH, coupled with a Varian CF-3000 ion implanter. The unique organizational structure of the IBML as well as the operational characteristics of the 9SDH (after approximately 3000 h of operation) and the laboratories' research capabilities will be discussed. Examples of current research results will also be presented. 5 refs., 2 figs.
Date: January 1, 1988
Creator: Tesmer, J.R.; Maggiore, C.J. & Parkin, D.M.
Partner: UNT Libraries Government Documents Department

DT fusion neutron radiation strengthening of copper and niobium

Description: The initial results of a comparative study of the radiation strengthening and damage structures produced in Cu and Nb by D-T fusion and fission reactor neutrons are described. The radiation strengthening produced by a given fluence of fusion neutrons above about 10$sup 17$ n/cm$sup 2$ is equal to that produced by a fluence of fission reactor neutrons (E greater than 0.1 MeV) ten times as great. This difference is about twice as large as would be expected if the strengthening scaled with damage energy or dpa. Initial transmission electron microscopy observations of the damage structures in fusion and fission reactor neutron irradiated copper indicate that the same type of primary structural defects, vacancy and interstitial point defect clusters and small dislocation loops with a/3 (111) and a/2 (110) Burgers vectors, are produced in both cases. The difference in the radiation strengthening produced by fusion and fission reactor neutrons in Cu appears to result from a substantially greater rate of accumulation of damage, in the form of point defect clusters, during irradiation with fusion neutrons than during irradiation with fission reactor neutrons plus a significant difference in the size and spatial distributions of the damage clusters. (auth)
Date: September 29, 1975
Creator: Mitchell, J.B.; Van Konynenburg, R.A.; Echer, C.J. & Parkin, D.M.
Partner: UNT Libraries Government Documents Department

DT fusion neutron radiation strengthening of copper and niobium

Description: The initial results of a comparative study of the radiation strengthening and damage structures produced in Cu and Nb by D-T fusion and fission reactor neutrons are described. The radiation strengthening produced by a given fluence of fusion neutrons above about 10$sup 17$n/cm$sup 2$ is equal to that produced by a fluence of fission reactor neutrons (E greater than 0.1 MeV) ten times as great. This difference is about twice as large as would be expected if the strengthening scaled with damage energy or dpa. Initial transmission electron microscopy observations of the damage structures in fusion and fission reactor neutron irradiated copper indicate that the same type of primary structural defects, vacancy and interstitial point defect clusters and small dislocation loops with a/3 (111) and a/2 (110) Burgers vectors, are produced in both cases. The difference in the radiation strengthening produced by fusion and fission reactor neutrons in Cu appears to result from a substantially greater rate of accumulation of damage, in the form of point defect clusters, during irradiation with fusion neutrons than during irradiation with fission reactor neutrons plus a significant difference in the size and spatial distributions of the damage clusters. (auth)
Date: October 30, 1975
Creator: Mitchell, J.B.; Van Konynenburg, R.A.; Echer, C.J. & Parkin, D.M.
Partner: UNT Libraries Government Documents Department

Preliminary neutron foil dosimetry characterization of the BLIP neutron facility

Description: The Brookhaven Linac Isotope Producer (BLIP) produces neutrons from 200 MeV proton bombardment of a transparent (relative to 200 MeV protons) Be target. Threshold foil dosimetry techniques were utilized to characterize the BLIP neutron spectra which includes neutrons with energies greater than 15 MeV. Some operational characteristics of spallation neutron sources were also determined. The derived BLIP neutron spectrum has a hard component (neutrons between 6 to q2 MeV which peaks at 8 to 9 MeV) and a soft component characteristic of neutron scattering. Between 10 and 30% of the neutrons have energies below 0.25 MeV and less than 0.1% of the neutrons have energy in excess of 15 MeV. The derived neutron flux is 8.0 plus or minus 3 x 10/sup 9/ n/cm/sup 2/ mu C. (auth)
Date: August 29, 1973
Creator: Parkin, D.M.; Dudey, N.D.; Heinrich, R.R. & Fluss, M.J.
Partner: UNT Libraries Government Documents Department

Initial increase, ''peaking effect'', in the internal friction of copper following pulsed neutron and electron irradiation

Description: Under certain experimental conditions the internal friction in metals can first increase and following prolonged irradiation decrease. Many models have been proposed to account for this ''peaking effect''; however, in many of the cases, no effort is made to distinguish between the influence of interstitials and/or vacancies. To determine the nature of the point defect responsible for the peaking effect in high purity copper, we have performed a series of pulsed irradiations using neutrons and electrons. In all of the experiments an initial very rapid rise in the internal friction and Young's modulus was observed. These data show that a fast diffusing defect is responsible for the peaking effect: i.e. the interstitial.
Date: January 1, 1985
Creator: Simpson, H.M.; Parkin, D.M.; Goldstone, J.A. & Hemsky, J.W.
Partner: UNT Libraries Government Documents Department

Kinetics analysis of diffusion of point defects to dislocations following pulsed neutron and electron irradiations

Description: The kinetics of point defect-dislocation interactions following pulsed neutron and electron irradiations has been studied in high purity copper. In all experiments, data showed a very rapid increase in the modulus defect followed by a more gradual change. The magnitude of the rapid change in the modulus defect was proportional to the fluence. The initial rapid rise was too fast to allow for kinetics analysis; however, the slower continuous process was analyzed. Results are interpreted in terms of a model wherein interstitials are rapidly depleted and responsible for the initial rapid increase; the slower process is due to vacancy diffusion and arrival at dislocations.
Date: January 1, 1985
Creator: Parkin, D.M.; Goldstone, J.A.; Simpson, H.M. & Hemsky, J.W.
Partner: UNT Libraries Government Documents Department

MATERIALS WITH COMPLEX ELECTRONIC/ATOMIC STRUCTURES

Description: We explored both experimentally and theoretically the behavior of materials at stresses close to their theoretical strength. This involves the preparation of ultra fine scale structures by a variety of fabrication methods. In the past year work has concentrated on wire drawing of in situ composites such as Cu-Ag and Cu-Nb. Materials were also fabricated by melting alloys in glass and drawing them into filaments at high temperatures by a method known as Taylor wire technique. Cu-Ag microwires have been drawn by this technique to produce wires 10 {micro}m in diameter that consist of nanoscale grains of supersaturated solid solution. Organogels formed from novel organic gelators containing cholesterol tethered to squaraine dyes or trans-stilbene derivatives have been studied from several different perspectives. The two types of molecules are active toward several organic liquids, gelling in some cases at w/w percentages as low as 0.1. While relatively robust, acroscopically dry gels are formed in several cases, studies with a variety of probes indicate that much of the solvent may exist in domains that are essentially liquid-like in terms of their microenvironment. The gels have been imaged by atomic force microscopy and conventional and fluorescence microscopy, monitoring both the gelator fluorescence in the case of the stilbene-cholesterol gels and, the fluorescence of solutes dissolved in the solvent. Remarkably, our findings show that several of the gels are composed of similarly appearing fibrous structures visible at the nano-, micro-, and macroscale.
Date: September 1, 2000
Creator: PARKIN, D. M.; CHEN, L. & AL, ET
Partner: UNT Libraries Government Documents Department

Center for Materials Science, Los Alamos National Laboratory. Status report, October 1, 1990--September 30, 1991

Description: This report summarizes the progress of the Center for Materials Science (CMS) from October 1, 1990 to September 30, 1991, and is the nineth such annual report. It has been a year of remarkable progress in building the programs of the Center. The extent of this progress is described in detail. The CMS was established to enhance the contribution of materials science and technology to the Laboratory`s defense, energy and scientific missions, and the Laboratory. In carrying out these responsibilities it has accepted four demanding missions: (1) Build a core group of highly rated, established materials scientists and solid state physicists. (2) Promote and support top quality, interdisciplinary materials research programs at Los Alamos. (3) Strengthen the interactions of materials science and Los Alamos with the external materials science community. and (4) Establish and maintain modern materials research facilities in a readily accessible, central location.
Date: October 1, 1991
Creator: Parkin, D. M. & Boring, A. M.
Partner: UNT Libraries Government Documents Department

New developments in pulsed fields at the US National High Magnetic Field Laboratory

Description: Los Alamos National Laboratory is a member of a consortium (with Florida State University and the University of Florida) to operate the National High Magnetic Field Laboratory (NHMFL), with funding from the National Science Foundation and the State of Florida. Los Alamos provides unique resources for its component of NHMFL in the form of a 1.4 GW inertial storage motor-generator for high field pulsed magnets and infrastructure for fields generated by flux compression. The NHMFL provides a user facility open to all qualified users, develops magnet technology in association with the private sector, and advances science and technology opportunities. The magnets in service at Los Alamos are of three types. Starting with the pre-existing explosive flux compression capability in 1991, NHMFL added capacitor-driven magnets in December, 1992, and a 20 tesla superconducting magnet in January, 1993. The capacitor-driven magnets continue to grow in diversity and accessibility, with four magnet stations now available for several different magnet types. Two magnets of unprecedented size and strength are nearing completion of assembly and design, respectively. Under final assembly is a quasi-continuous magnet that contains 90 MJ of magnetic energy at full field, and being designed is a non-destructive 100 T magnet containing 140 MJ.
Date: December 1, 1996
Creator: Campbell, L.J.; Parkin, D.M.; Rickel, D.G. & Pernambuco-Wise, P.
Partner: UNT Libraries Government Documents Department

Design status of the US 100 tesla non-destructive magnet system

Description: A collaborative effort is now underway in the US between the Department of Energy and the National Science Foundation to design, build, and use a 100 T non-destructive magnet for studying the properties of materials at high fields. The National High Magnetic Field Laboratory (NHMFL) at Tallahassee, Florida, and Los Alamos, New Mexico, where the magnet will be sited, is carrying out this task. This magnet will join other pulsed magnets at NHMFL, to provide magnetic fields at strengths, time durations, and volumes that are longer (in combination) than any now available. In particular, the goal for the 100 T magnet is a time duration above 80 T of about 15 ms in a cold bore of 24 mm. The present status of the design effort and various design issues are presented here.
Date: September 1996
Creator: Schneider-Muntau, H.; Eyssa, Y.; Pernambuco-Wise, P.; Boenig, H.; Campbell, L. J.; Eberl, K. R. et al.
Partner: UNT Libraries Government Documents Department

Megagauss Fields During Milliseconds

Description: A non-destructive, one megagauss magnet is now being designed in cooperation between Los Alamos and the National High Magnetic Field Laboratory (NHMFL) through joint funding by the US Department of Energy and the US NSF. The design combines two types of pulsed magnet now in use at the NHMFL: a capacitor-driven 'insert' magnet with a total pulse width of order 10 ms and a much larger 'outsert' magnet with a total pulse width of order 2 seconds that is driven by a controlled power source. The insert and outsert produce approximately 1/2 megagauss each. Although the design uses CuAg as the principal conductor further design efforts and materials development are exploring CuNb and stainless steel-clad copper as possible future alternatives. A crucial innovation was to employ wound steel strip (sheet) as a reinforcement in both insert and outsert coils. This gives extra strength due to the higher degree of cold-work possible in strip materials. For this leading edge magnet a key role is played by materials development. A major component, the 7 module 560 MVA controlled dc power supply required for the outsert, has been installed and commissioned.
Date: October 18, 1998
Creator: Campbell, L.J.; Embury, D.; Han, K.; Parkin, D.M.; Baca, A.; Kihara, K.H. et al.
Partner: UNT Libraries Government Documents Department