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  Partner: UNT Libraries Government Documents Department
 Decade: 1980-1989
 Collection: Technical Report Archive and Image Library
Slow Neutron Leakage Spectra from Spallation Neutron Sources

Slow Neutron Leakage Spectra from Spallation Neutron Sources

Date: February 1980
Creator: Das, Shashikala G.; Carpenter, J. M. & Prael, R. E.
Description: An efficient technique is described for Monte Carlo simulation of neutron beam spectra from target-moderator-reflector assemblies typical of pulsed spallation neutron sources. The technique involves the scoring of the transport-theoretical probability that a neutron will emerge from the moderator surface in the direction of interest, at each collision. An angle-biasing probability is also introduced which further enhances efficiency in simple problems.
Contributing Partner: UNT Libraries Government Documents Department
Branching Fraction in the Radioactive Decay of ⁸⁵mKr

Branching Fraction in the Radioactive Decay of ⁸⁵mKr

Date: February 1980
Creator: Jaffey, A. H.; Steinberg, E. P.; Gindler, J. E.; Gray, J.; Horwitz, E. P.; Hughes, J. P. et al.
Description: The branching fraction in the decay of the fission product ⁸⁵m-krypton⁸⁵m to the ground state ⁸⁵krypton (10.75 y) was measured relative to the total decay to both ⁸⁵krypton and ⁸⁵Rb. Samples of uranium-235 were highly irradiated in a high-flux reactor and dissolved. ⁸⁵Rb was measured by isotope-dilution mass spectrometry, and the ⁸⁵krypton was counted in GM tubes the counting efficiencies of which were calibrated with a standardized ⁸⁵krypton gas of known disintegration rate. The branching fraction measured with both a low-burnup sample and a high-burnup sample was 0.2160 +/- 0.0019, the largest error arising from the uncertainty in the caibration of the standardized gas.
Contributing Partner: UNT Libraries Government Documents Department
Application of International Safeguards to Fast Critical Assembly Facilities. FY 1980 Summary Report

Application of International Safeguards to Fast Critical Assembly Facilities. FY 1980 Summary Report

Date: December 1980
Creator: Argonne National Laboratory
Description: Nuclear materials inventory-verification techniques for large split-table fast critical assemblies are being studied in this program. Emphasis has been given to techniques that minimize fuel handling in order to reduce facility downtime and radiation exposure to the inventory team. The techniques studied include drawer seals, autoradiography, and spectral index measurements. Two-drawer sealing techniques have been studied, and the relative strengths and weaknesses are pointed out. The rod-type locking mechanism would not disrupt the reactor cooling air flow or interfere with autoradiography but is more expensive to implement. Passive autoradiography was used in a ZPPR inventory to verify to a 93% confidence level that less than 8-kg plutonium was missing. The inventory was completed in four days by a five-member team with radiation exposures well within acceptable limits. Two autoradiographic film packages were developed to distinguish HEU from a DU matrix. The 30-mil pack requires an exposure between 4 and 16 hours and fits into most of the drawers. The 40-mil pack requires only a two-hour exposure but fits into less than half the drawers.
Contributing Partner: UNT Libraries Government Documents Department
Corrosion and Mechanical Behavior of Materials for Coal Gasification Applications

Corrosion and Mechanical Behavior of Materials for Coal Gasification Applications

Date: May 1980
Creator: Natesan, K.
Description: A state-of-the-art review is presented on the corrosion and mechanical behavior of materials at elevated temperatures in coal-gasification environments. The gas atmosphere in coal-conversion processes are, in general, complex mixtures which contain sulfur-bearing components (hydrogen sulfide, SO2, and COS) as well as oxidants (carbon dioxide/carbon monoxide and water/hydrogen). The information developed over the last five years clearly shows sulfidation to be the major mode of material degradation in these environments. The corrosion behavior of structural materials in complex gas environments is examined to evaluate the interrelationships between gas chemistry, alloy chemistry, temperature, and pressure. Thermodynamic aspects of high-temperature corrosion processes that pertain to coal conversion are discussed, and kinetic data are used to compare the behavior of different commercial materials of interest. The influence of complex gas environments on the mechanical properties such as tensile, stress-rupture, and impact on selected alloys is presented. The data have been analyzed, wherever possible, to examine the role of environment on the property variation. The results from ongoing programs on char effects on corrosion and on alloy protection via coatings, cladding, and weld overlay are presented. Areas of additional research with particular emphasis on the development of a better understanding of corrosion processes in ...
Contributing Partner: UNT Libraries Government Documents Department
Workshop on Artificial Superlattices. October 30-31, 1980 at University of Illinois, Urbana-Champaign, Illinois, USA

Workshop on Artificial Superlattices. October 30-31, 1980 at University of Illinois, Urbana-Champaign, Illinois, USA

Date: October 1980
Creator: Argonne National Laboratory
Description: The program and 24 abstracts are given. The abstracts are divided into the following categories: structure and elastic properties, transport and electronic properties, magnetism and superconductivity, and phonons. The engineering of novel materials using sophisticated preparation techniques has received considerable attention in recent years. This interest has been mainly stimulated by recent developments in preparation techniques such as Molecular Beam Epitaxy, Thermal Vapor Deposition and Sputtering. These advances in deposition technology allow for the first time the preparation of layered materials with well defined layer thicknesses approaching interatomic spacing and opens up new avenues for the production and stabilization of materials that do not occur in nature. In addition to the extensive experimental work on artificial semiconductor superlattices there has been a parallel, almost independent, development relating to artificial metallic superlattices. Although the experimental sophistication of the field is considerable the development of major related theoretical ideas has not kept pace. In view of the large body of experimental work, a pressing need exists for the development of conceptual ideas relating to the novel physics that is created by artificially adding a new periodicity to the lattice. Because of this the Office of Naval Research is sponsoring the first "Workshop ...
Contributing Partner: UNT Libraries Government Documents Department
Fast Breeder Reactor Studies

Fast Breeder Reactor Studies

Date: July 1980
Creator: Till, C. E.; Chang, Y. I.; Kittel, J. H.; Fauske, H. K.; Lineberry, M. J.; Stevenson, M. G. et al.
Description: This report is a compilation of Fast Breeder Reactor (FBR) resource documents prepared to provide the technical basis for the US contribution to the International Nuclear Fuel Cycle Evaluation. The eight separate parts deal with the alternative fast breeder reactor fuel cycles in terms of energy demand, resource base, technical potential and current status, safety, proliferation resistance, deployment, and nuclear safeguards. An Annex compares the cost of decommissioning light-water and fast breeder reactors. Separate abstracts are included for each of the parts.
Contributing Partner: UNT Libraries Government Documents Department
Improving the Accuracy of Computed Matrix Eigenvalues

Improving the Accuracy of Computed Matrix Eigenvalues

Date: August 1980
Creator: Dongarra, J. J.
Description: A computational method is described for improving the accuracy of a given eigenvalue and its associated eigenvector, arrived at through a computation in a lower precision. The method to be described will increase the accuracy of the pair and do so at a relatively low cost. The technique used is similar to iterative refinement for the solution of a linear system; that is, through the factorization from the low-precision computation, an iterative algorithm is applied to increase the accuracy of the eigenpair. Extended precision arithmetic is used at critical points in the algorithm. The iterative algorithm requires O(n²) operations for each iteration.
Contributing Partner: UNT Libraries Government Documents Department
Solution of the General Nonlinear Programming Problem with Subroutine VMCOM

Solution of the General Nonlinear Programming Problem with Subroutine VMCOM

Date: July 1980
Creator: Crane, Roger L.; Hillstrom, Kenneth E. & Minkoff, Michael
Description: The solution of the general nonlinear programming problem by means of a subroutine called VMCON is described. VMCON uses an algorithm that solves a sequence of positive-definite quadratic programming sub-problems. Each solution determines a direction in which a one-dimensional minimization is performed. In developing this code, changes in the original implementation were made to make the program easier to use and maintain and to incorporate some recently developed LINPACK subprograms. The current implementation contains extensive in-line documentation; an interface subroutine, VMCON1, with a simplified calling sequence; and print options to aid the user in interpreting results.
Contributing Partner: UNT Libraries Government Documents Department
The Delayed-Neutron Fraction in a Pulsed Spallation Neutron Source

The Delayed-Neutron Fraction in a Pulsed Spallation Neutron Source

Date: February 1980
Creator: Carpenter, J. M.
Description: The fraction of delayed neutrons beta in slow-neutron beams from a uranium-238 pulsed spallation neutron source is 0.0053 for 300 MeV protons. This measurement appears to be the first one of this quantity. The result indicates that, for most classes of measurements, the delayed-neutron background in time-of-flight instruments will be unimportant, and places constraints on the physics description of spallation targets. The measurement was performed at the prototype pulsed spallation neutron source, ZING-P', at Argonne National laboratory.
Contributing Partner: UNT Libraries Government Documents Department
ICECO-CEL: A Coupled Eulerian-Lagrangian Code for Analyzing Primary System Response in Fast Reactors

ICECO-CEL: A Coupled Eulerian-Lagrangian Code for Analyzing Primary System Response in Fast Reactors

Date: February 1981
Creator: Wang, C. Y.
Description: This report describes a coupled Eulerian-Lagrangian code, ICECO-CEL, for analyzing the response of the primary system during hypothetical core disruptive accidents. The implicit Eulerian method is used to calculate the fluid motion so that large fluid distortion, two-dimensional sliding interface, flow around corners, flow through coolant passageways, and out-flow boundary conditions can be treated. The explicit Lagrangian formulation is employed to compute the response of the containment vessel and other elastic-plastic solids inside the reactor containment. Large displacements, as well as geometrical and material nonlinearities are considered in the analysis. Marker particles are utilized to define the free surface or the material interface and to visualize the fluid motion. The basic equations and numerical techniques used in the Eulerian hydrodynamics and Lagrangian structural dynamics are described. Treatment of the above-core hydrodynamics, sodium spillage, fluid cavitation, free-surface boundary conditions and heat transfer are also presented. Examples are given to illustrate the capabilities of the computer code. Comparisons of the code predictions with available experimental data are also made.
Contributing Partner: UNT Libraries Government Documents Department