TRAMP is used to calculate the transport of metallic fission products along multiple parallel paths; the primary application is transport in and release from nuclear-grade graphite. The transport mechanisms are concentration-driven diffusion, thermal diffusion, and convection.
The one-dimensional computer program PADLOC is designed to analyze steady-state and time-dependent plateout of fission products in an arbitrary network of pipes. The problem solved is one of mass transport of impurities in a fluid, including the effects of sources in the fluid and in the plateout surfaces, convection along the flow paths, decay, adsorption on surfaces (plateout), and desorption from surfaces. These phenomena are governed by a system of coupled, nonlinear partial differential equations. The solution is achieved by (a) linearizing the equations about an approximate solution, employing a Newton Raphson iteration technique, (b) employing a finite difference solution method with an implicit time integration, and (c) employing a substructuring technique to logically organize the systems of equations for an arbitrary flow network.
PADLOC performs one-dimensional calculation of plateout in an arbitrary pipe network, e.g. an HTGR primary coolant circuit, a test loop, etc. The problem solved is one of mass transport of fission products in a fluid, including the effects pf sources in the fluid and in the plateout surfaces, convection along the flow paths, decay, adsorption on surfaces (plateout), and desorption from surfaces. These phenomena are governed by a system of coupled, nonlinear partial differential equations.
The performance of TRISO-coated carbide fissile particles, of the type to be used in the large HTGR, correlates well with statistically based calculations of stresses in the SiC coating. Three coated particle batches, containing a total of nearly 104 individual coated particles, showed insignificant coating failure (≤0.2%) after exposure to essentially the most severe combined conditions of fast neutron exposure, burnup, and temperature to be experienced by fuel in a large HTGR. This high reliability derives from the fact that less than 1% of the particles in each batch had SiC tensile stresses greater than 30 000 psi, while the SiC layer in about 80% of the coated particles in each batch remained in compression throughout life. Two additional experimental batches of TRISO-coated carbide fissile particles had thinner coatings that resulted in higher mean SiC stresses in each batch and in probabilities of SiC coating stresses greater than 30 000 psi of 3.5 and 8.5%. This compares with the observed incidence of coating failure during irradiation to full design exposures of about 4% in both cases. These results provide further confirmation of the value of analytical stress models in interpreting the results of coated particle irradiation experiments, and emphasize the importance of a statistical approach to coated particle design.
Self-powered neutron detectors are suitable for continuous flux measurements and were used to monitor some of Gulf General Atomic’s irradiation experiments in the Engineering Test Reactor in connection with the development of fuel for high temperature gas-cooled reactors. For the purpose of detector current data reduction, the special case of a rhodium detector is analyzed and explicit solutions for the neutron flux and neutron fluence are developed. The solutions describe the time-dependence of flux and fluence for detector irradiation times ≳1 h. Independent variables are the detector current and its time derivative, both of which are functions of time. Constants appearing in the equations are the neutron flux, the corresponding electrical current and its time derivative at the time of calibration, the decay constant of 104Rh (4.36 min), and the effective cross section for 103Rh(n,γ)104Rh reactions.
Click to increase image sizeClick to decrease image size Additional informationNotes on contributorsM. J. BellM. J. Bell (PhD, ChE, Princeton University, 1968), a development engineer in the Chemical Technology Division of Oak Ridge National Laboratory, is responsible for specifying the radiation and shielding requirements for fuel cycle facilities. His present interests involve the estimation of quantities of radioactive effluents from nuclear facilities.Mojtaba TaherzadehMojtaba Taherzadeh (PhD, physics, University of California, Los Angeles, 1964), associated with Jet Propulsion Laboratory/Cal Tech since 1969, is a project leader and a member of the technical staff in charge of analytical research in determination of radiation characteristics of nuclear power sources. He is also responsible for radiation interference studies with regard to the scientific instruments aboard spacecraft. Prior to 1969, Taherzadeh was a scientific specialist with Edgerton, Germeshausen & Grier. In this capacity he was responsible for nuclear radiation hardening and higher power electron beam design for the simulation of electromagnetic pulses.W. W. HudritschW. W. Hudritsch (Diplom Ingenieur, physics, Vienna University of Technology, 1964) has been active for four years in all phases of fuel irradiation programs and analytical design studies at Siemens AG, Erlangen, West Germany, and Gulf General Atomic, San Diego, California. He also worked in heat transfer for two years and taught two years at an engineering college in Austria. His current work includes irradiation damage studies and statistical approaches to high temperature gas reactor fuel characterization.Brian F. IvesBrian F. Ives (PhD, chemical engineering, State University of New York at Buffalo, 1972) recently accepted a position in the Component Engineering and Technology Department of Atomics International. This paper results from his PhD research; the experimental portion was carried out at the Western New York Nuclear Research Center.Harry T. CullinanHarry T. Cullinan Jr. (center) (PhD, chemical engineering, Carnegie Institute of Technology, 1965) is professor and chairman of the Department of Chemical Engineering at the State University of New York at Buffalo. During 1972-73 he is on leave as a visiting professor of chemical engineering at the University of Manchester Institute of Science and Technology.John Y. YangJohn Y. Yang (bottom) (PhD, chemistry, University of Kansas, 1957) is currently a principal chemist at the Environmental Systems Department of the Cornell Aeronautical Laboratory. He is interested in radiation-induced chemical processes and their applications to air and water pollution studies.T. F. CraftT. F. Craft (PhD, Georgia Institute of Technology, 1969) is a senior research scientist in the Nuclear and Biological Sciences Division of the Engineering Experiment Station, Georgia Institute of Technology. Since 1962 he has been engaged in research worK concerning environmental pollution, primarily water pollution. His current interests include methods of improving water and wastewater treatment, the application of radiotracers to environmental problems, and the beneficial uses of ionizing radiation.G. G. EichholzG. G. Eichholz (PhD, University of Leeds, England, 1947) has been professor of nuclear engineering at Georgia Institute of Technology since 1963. His current interests include industrial applications of radiation technology, radiotracer applications, and environmental aspects of nuclear technology.S. J. AltschulerS. J. Altschuler (left) (BChE, The Cooper Union for the Advancement of Science and Art, 1957) is a research physicist at Dow Chemical USA's Rocky Flats Plant working on computer calculations for nuclear criticality safety purposes.C. L. SchuskeC. L. Schuske (MS, physics, University of Southern California) is the director of nuclear safety at Dow Chemical USA's Rocky Flats Plant. An ANS and APS member, he is primarily interested in critical mass physics and process plant nuclear criticality safety.J. M. DonhoweJ. M. Donhowe (top left) (PhD, University of Wisconsin, 1966) is an associate professor of nuclear engineering at the University of Wisconsin-Madison. He is presently studying radiation damage in metals due to charged-particle bombardment using heavy ions, light ions, and electron beams.D. L. KlarstromD. L. Klarstrom (top right) (PhD, University of Wisconsin, 1970) is an assistant professor in the Materials Department at the University of Wisconsin-Milwaukee. His research interests include the use of transmission and scanning electron microscopy to study x-ray diffraction, braze joining of metals, and mechanical deformation of crystalline solids.M. L. SundquistM. L. Sundquist (bottom left) (BS, Antioch College, 1967; MS, University of Wisconsin, 1969) is presently finishing his PhD on void formation in aluminum under ion bombardment in the Nuclear Engineering Department of the University of Wisconsin-Madison.W. J. WeberW. J. Weber (bottom right) (BS, University of Wisconsin-Oshkosh, 1971) is now working on his Master&s degree in the Nuclear Engineering Department at the University of Wisconsin-Madison.D. C. CutforthD. C. Cutforth (PhD, mechanical engineering, Utah State University, 1969) joined Argonne National Laboratory in 1963. He has been associated with BORAX V, EBR-II, and the Hot Fuels Examination Facility. His current interests include neutron radiographic inspections of fast reactor fuels and materials specimens.
The behavior of some of the prominent fission products along their convection pathways is dominated by the interaction of other species with them. This gave rise to the development of a plateout code capable of analyzing coupled species effects. The single species plateout computer program PADLOC is described in Part I of this report. The present Part II is concerned with the extension of PADLOC to MULTI*PADLOK, a multiple species version of PADLOC. MULTI*PADLOC is designed to analyze the time and one-dimensional spatial dependence of the concentrations of interacting (fission product) species in the carrier gas and on the surrounding wall surfaces on an arbitrary network of flow channels. The problem solved is one of mass transport of several impurity spceis in a gas, including the effects of sources in the gas and on the surface, convection along the flow paths, decay interaction, sorption interaction on the wall surfaces, and chemical reaction interactions in the gas and on the surfaces. These phenomena are governed by a system of coupled, nonlinear partial differential equations. The solution is achieved by: (a) linearizing the equations about an approximate solution and employing a Newton-Raphson iteration technique, (b) employing a finite difference solution method with an implicit time integration, and (c) employing a substructuring technique to logically organize the systems of equations for an abitrary flow network.
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