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Analysis of in-situ tritium recovery from solid fusion-reactor blankets

Description: The proposed concept for in-situ tritium recovery from the STARFIRE blanket involves circulation of a low pressure (approx. 0.05 MPa) helium through formed channels in the highly porous solid breeding material. Tritium generated within the grains must diffuse to the grain boundaries, migrate through the grain boundaries to the particle surface and then percolate through the packed bed to the helium purge channel. Highly porous ..cap alpha..-LiAlO/sub 2/ with a bimodal pore distribution is proposed for the breeding material to facilitate the tritium release.
Date: January 1, 1980
Creator: Smith, D.L.; Clemmer, R.G.; Jankus, V.Z. & Rest, J.
Partner: UNT Libraries Government Documents Department

Analysis of the October 5, 1979 lithium spill and fire in the Lithium Processing Test Loop

Description: On October 5, 1979, the Lithium Processing Test Loop (LPTL) developed a lithium leak in the electromagnetic (EM) pump channel, which damaged the pump, its surrounding support structure, and the underlying floor pan. A thorough analysis of the causes and consequences of the pump failure was conducted by personnel from CEN and several other ANL divisions. Metallurgical analyses of the elliptical pump channel and adjacent piping revealed that there was a significant buildup of iron-rich crystallites and other solid material in the region of the current-carrying bus bars (region of high magnetic field), which may have resulted in a flow restriction that contributed to the deterioration of the channel walls. The location of the failure was in a region of high residual stress (due to cold work produced during channel fabrication); this failure is typical of other cold work/stress-related failures encountered in components operated in forced-circulation lithium loops. Another important result was the isolation of crystals of a compound characterized as Li/sub x/CrN/sub y/. Compounds of this type are believed to be responsible for much of the Fe, Cr, and Ni mass transfer encountered in lithium loops constructed of stainless steel. The importance of nitrogen in the mass-transfer mechanism has long been suspected, but the existence of stable ternary Li-M-N compounds (M = Fe, Cr, Ni) had not previously been verified.
Date: December 1, 1981
Creator: Maroni, V.A.; Beatty, R.A.; Brown, H.L.; Coleman, L.F.; Foose, R.M.; McPheeters, C.C. et al.
Partner: UNT Libraries Government Documents Department

Analysis of the sensitivity of spectrum-average cross sections to individual characteristics of differential excitation functions

Description: A simple procedure for analyzing the sensitivity of computed spectrum-average cross sections to detailed properties of excitation functions for threshold nuclear reactions commonly used in reactor dosimetry is described. This procedure is shown to be useful in identifying specific needs for improved differential data and as a tool to be employed in performing evaluations. Several examples are presented to illustrate the subject matter.
Date: March 1, 1977
Creator: Smith, D. L.
Partner: UNT Libraries Government Documents Department

Analysis of the tritium-water (T-H{sub 2}O) system for a fusion material test facility

Description: The need for a high flux, high energy neutron test facility to evaluate performance of fusion reactor materials is urgent. An accelerator based D-Li source is generally accepted as the most reasonable approach to a high flux neutron source in the near future. The idea is to bombard a high energy (35 MeV) deuteron beam into a lithium target to produce high energy neutrons to simulate the fusion environment. More recently it was proposed to use a 21 MeV triton beam incident on a water jet target to produce the required neutron source for testing and simulating fusion material environments. The advantages of such a system are discussed. Major concerns regarding the feasibility of this system are also highlighted.
Date: April 1, 1992
Creator: Hassanein, A.; Smith, D. L.; Sze, D. K. & Reed, C. B.
Partner: UNT Libraries Government Documents Department

Analysis of the tritium-water (T-H sub 2 O) system for a fusion material test facility

Description: The need for a high flux, high energy neutron test facility to evaluate performance of fusion reactor materials is urgent. An accelerator based D-Li source is generally accepted as the most reasonable approach to a high flux neutron source in the near future. The idea is to bombard a high energy (35 MeV) deuteron beam into a lithium target to produce high energy neutrons to simulate the fusion environment. More recently it was proposed to use a 21 MeV triton beam incident on a water jet target to produce the required neutron source for testing and simulating fusion material environments. The advantages of such a system are discussed. Major concerns regarding the feasibility of this system are also highlighted.
Date: April 1, 1992
Creator: Hassanein, A.; Smith, D.L.; Sze, D.K. & Reed, C.B.
Partner: UNT Libraries Government Documents Department

Application of high temperature ceramic superconductors (CSC) to commercial tokamak reactors

Description: Ceramic superconductors operating near liquid nitrogen temperature may experience higher heating rates without losing stability, compared to conventional superconductors. This will permit cable design with less stabilizer, reducing fabrication costs for large fusion magnets. Magnet performance is studied for different operating current densities in the superconductor, and cost benefits to commercial tokamak reactors are estimated. It appears that 10 kA . cm/sup -2/ (at 77 K and approx.10 T) is a target current density which must be achieved in order for the ceramic superconductors to compete with conventional materials. At current densities around 50 kA . cm/sup -2/ most potential benefits have already been gained, as magnet structural steel begins to dominate the cost at this point. For a steady state reactor reductions of approx.7% are forecast for the overall capital cost of the power plant in the best case. An additional approx.3% cost saving is possible for pulsed tokamaks. 9 refs., 4 figs., 8 tabs.
Date: October 1, 1987
Creator: Ehst, D.A.; Kim, S.; Gohar, Y.; Turner, L.; Smith, D.L. & Mattas, R.
Partner: UNT Libraries Government Documents Department

Application of high temperature ceramic superconductors (CSC) to commercial tokamak reactors

Description: Ceramic superconductors operating near liquid nitrogen temperature may experience higher heating rates without losing stability, compared conventional superconductors. This will permit cable design with less stabilizer, reducing fabrication costs for large fusion magnets. Magnet performance is studied for different operating current densities in the superconductor, and cost benefits to commercial tokamak reactors are estimated. It appears that 10 kA /center dot/ cm/sup /minus/2/ (at 77 K and /approximately/10 T) is a target current density which must be achieved in order for the ceramic superconductors to compete with conventional materials. At current densities around 50 kA /center dot/ cm/sup /minus/2/ most potential benefits have already been gained, as magnet structural steel begins to dominate the cost at this point. For a steady state reactor reductions of /approximately/7% are forecast for the overall capital cost of the power plant in the best case. An additional /approximately/3% cost saving is possible for pulsed tokamaks. 9 refs., 4 figs., 8 tabs.
Date: August 1, 1988
Creator: Ehst, D.A.; Kim, S.; Gohar, Y.; Turner, L.; Smith, D.L. & Mattas, R.
Partner: UNT Libraries Government Documents Department

Applied uses of level density models

Description: This paper addresses issues associated with the use of nuclear level density models in calculations made for data applications. The two most commonly used models, the Gilbert Cameron and the Back-Shifted Fermi Gas, are briefly summarized and examples are provided of recent efforts to improve their parameterization. Calculated particle emission spectra are compared with recent experimental data in order to assess performance and sensitivity to these models. Extrapolation of nuclear level densities for calculations involving nuclei away from stability poses special problems and examples of recent efforts to improve such extrapolations are cited. The sensitivity of current schemes in the modeling of fission transition state densities are explored through calculated (n,f) cross sections. Two newer phenomenological models, those of Ignatyuk and Schmidt, provide a more physically realistic description of level densities. Calculations concerning {sup 207}Pb(n,xn) cross sections compare results using the Ignatyuk formalism with the Gilbert Cameron results. 31 refs., 10 figs.
Date: January 1, 1989
Creator: Arthur, E.D.; Guenther, P.T.; Smith, A.B.; Smith, D.L. (Los Alamos National Lab., NM (USA) & Argonne National Lab., IL (USA))
Partner: UNT Libraries Government Documents Department

An approach for dealing with large errors.

Description: Numerical functions or equivalent algorithms are commonly used to derive estimates for physical quantities that can be expressed in terms of more fundamental physical parameters. It is shown that in situations where large uncertainties (errors) are involved in these parameters, or where error amplification occurs through severe non-linearity of the functions, conventional deterministic techniques for calculating the derived quantities and estimating their errors can lead to erroneous results. Instead, it is necessary to resort to a probabilistic approach and thereby obtain estimates for mean values and variances of the derived quantities through Monte Carlo simulation in order to preserve the essential information without distortion. The correct choice for a probability distribution is suggested by the inherent nature of the random variable in question. Examples are given from the analysis of radioactivity decay, the shielding of penetrating radiation, and the derivation of nuclear reaction rates that are used in astrophysical calculations to model nucleosynthesis of the elements in stellar explosions. Subsequent analyses that use these derived quantities must also be carried out in a probabilistic manner to insure that the obtained results will reflect the underlying information properly.
Date: October 17, 2001
Creator: Smith, D. L.; Naberejnev, D. G. & Van Wormer, L. A.
Partner: UNT Libraries Government Documents Department

Assessment of solid breeding blanket options for commercial tokamak reactors

Description: This study examines the materials and design implications regarding the use of solid breeding materials with respect to compatibility with structure and coolant, tritium processing, chemical and radiation stability and thermal-hydraulics. Four solid breeding materials considered, viz., Li/sub 7/Pb/sub 2/, Li/sub 2/O, Li/sub 2/SiO/sub 3/ and LiAlO/sub 2/, are representative of the metallic and ceramic compounds available. The major design problems regarding the use of solid breeding materials relate to the limited range of operating temperatures acceptable for tritium release and chemical stability or compatibility. The allowable ranges of breeder temperatures for which in-situ tritium recovery is potentially viable are evaluated for the candidate breeding materials.
Date: January 1, 1979
Creator: Smith, D.L.; Clemmer, R.G. & Davis, J.W.
Partner: UNT Libraries Government Documents Department

Basic concepts underlying fast-neutron-based contraband interrogation technology

Description: All accelerator-based fast-neutron contraband interrogation systems have many closely interrelated subsystems, whose performance parameters will be critically interdependent. For optimal overall performance, a systems analysis design approach is required. This paper provides a general overview of the interrelationships and the tradeoffs to be considered for optimization of nonaccelerator subsystems.
Date: January 1, 1992
Creator: Fink, C. L.; Guenther, P. T. & Smith, D. L.
Partner: UNT Libraries Government Documents Department

Basic concepts underlying fast-neutron-based contraband interrogation technology. A systems viewpoint

Description: All accelerator-based fast-neutron contraband interrogation systems have many closely interrelated subsystems, whose performance parameters will be critically interdependent. For optimal overall performance, a systems analysis design approach is required. This paper provides a general overview of the interrelationships and the tradeoffs to be considered for optimization of nonaccelerator subsystems.
Date: December 1, 1992
Creator: Fink, C. L.; Guenther, P. T. & Smith, D. L.
Partner: UNT Libraries Government Documents Department

Basic Research Needs for Solid-State Lighting. Report of the Basic Energy Sciences Workshop on Solid-State Lighting, May 22-24, 2006

Description: The workshop participants enthusiastically concluded that the time is ripe for new fundamental science to beget a revolution in lighting technology. SSL sources based on organic and inorganic materials have reached a level of efficiency where it is possible to envision their use for general illumination. The research areas articulated in this report are targeted to enable disruptive advances in SSL performance and realization of this dream. Broad penetration of SSL technology into the mass lighting market, accompanied by vast savings in energy usage, requires nothing less. These new ?good ideas? will be represented not by light bulbs, but by an entirely new lighting technology for the 21st century and a bright, energy-efficient future indeed.
Date: May 24, 2006
Creator: Phillips, J. M.; Burrows, P. E.; Davis, R. F.; Simmons, J. A.; Malliaras, G. G.; So, F. et al.
Partner: UNT Libraries Government Documents Department

Be(d,n) source at a modest facility

Description: Source characterization for deuteron energies less than 8 MeV is discussed including: intensity, spectrum and angular distributions. Pulsed and steady-state applications of the source to the acquisition of fast-neutron data are illustrated by energy-averaged neutron total cross-section and spectrum-averaged activation cross-section measurements. Source utilization, measurement techniques, and experimental results are described with attention to self-shielding effects, background suppression and specification of uncertainties. These illustrations are extrapolated to broader-scope studies, taking advantage of the high fact-neutron intensities. The present and future potential is determined more by detection capability than by source properties. 19 refs., 9 figs.
Date: January 1, 1986
Creator: Smith, A.B.; Smith, D.L. & Whalen, J.F.
Partner: UNT Libraries Government Documents Department

Blanket materials for DT fusion reactors

Description: This paper presents an overview of the critical materials issues that must be considered in the development of a tritium breeding blanket for a tokamak fusion reactor that operates on the D-T-Li fuel cycle. The primary requirements of the blanket system are identified and the important criteria that must be considered in the development of blanket technology are summarized. The candidate materials are listed for the different blanket components, e.g., breeder, coolant, structure and neutron multiplier. Three blanket concepts that appear to offer the most potential are: (1) liquid-metal breeder/coolant, (2) liquid-metal breeder/separate coolant, and (3) solid breeder/separate coolant. The major uncertainties associated with each of the design concepts are discussed and the key materials R and D requirements for each concept are identified.
Date: January 1, 1981
Creator: Smith, D.L.
Partner: UNT Libraries Government Documents Department

Calculations on the compatibility of refractory metals in a tritium environment and cold trapping method for tritium removal from a lithium blanket

Description: From joint meeting of the American Nuclear Society and the Atomic Industrial Forum and Nuclear Energy Exhibition; San Francisco, California, USA (11 Nov 1973). Thermodynamic calculations were made on the distribution of hydrogen and tritium between various refractory metals and liquid lithium as a function of temperature. The limiting tritium pressures that can be attained by cold trapping of secondary liquid metals such as Na, K, and NaK were calculated. In the absence of tritium breeding, these pressures are 2.5 x 10/sup -5/, 2 x 10/ sup -7/ and 1.2 x 10/sup -10/o torr for Na, K, and NaK, respectively, and these correspond to tritium concentrations in lithium of 45, 4, and <1 ppM, respectively, at 700 deg C. For a thermonuclear reactor of 1000 MW(t) thermal power with a tritium breeding rate of 150 g/day, a tritium recovery system that incorporates a separate lithium purification loop with niobium as the permeable membrane, NaK as the secondary heat transport fluid and with tungsten cladding on the IHX tubes seems to yield tritium pressures of ~10/sup -9/ torr or less in the secondary system. This leads to tritium release rate of ~10/sup -6/g/ hr to the steam system for a steam generator clad with tungsten and operating at ~600 deg C. This corresponds to activity release rate of~300 Ci/yr. (17 figures, 61 references) (auth)
Date: January 1, 1973
Creator: Natesan, K. & Smith, D.L.
Partner: UNT Libraries Government Documents Department

Characteristics of the neutron flux from a D-Li neutron source

Description: A D-Li neutron source produces a high flux of neutrons which can be used for testing fusion materials. The characteristics exhibited by the neutron flux inside the test assembly volume of a D-Li neutron source irradiation facility is a function of several design options, such as deuteron energy, beam current, beam cross sectional area, and lithium target configuration, among others. The influence of each of these parameters on the overall performance of the machine, in terms of best results for irradiation of materials for fusion applications, can be inferred by scoping their impact on the uncollided neutron flux magnitude and distribution. The first part of this paper describes an analysis performed on the uncollided neutron flux (without material inside the test assembly region) for different beam-target configurations for determining the effect of varying the elements of the configuration on the uncollided neutron flux gradient. The second section deals with the neutron energy spectrum from the D-Li reaction and a brief discussion on {open_quotes}fusion reactor spectrum{close_quotes} is also presented. In the third section results from calculations of the volume with uncollided neutron above a threshold value are presented.
Date: July 1, 1994
Creator: Gomes, I. & Smith, D. L.
Partner: UNT Libraries Government Documents Department

Characterization of an accelerator neutron source based on the Be(d,n) reaction

Description: Small accelerator neutron sources offer considerable potential for applied neutron radiography applications. Among the desirable features are relatively low costs, limited operating hazards, opportunities for tailoring primary neutron spectra, compactness and portability, and modest licensing requirements (compared to fission reactors). However, exploitation of this potential has been somewhat limited, in part, by incomplete knowledge of the primary-neutron yields and energy spectra from the favorable source reactions. This work describes an extensive experimental determination of zero-degree neutron yields and energy spectra from the {sup 9}Be(d,n) {sup 10}B source reaction, for incident deuterons of 2.6 to 7.0 MeV on a thick beryllium metal target. This information was acquired by means of time-of-flight measurements that were conducted with a calibrated uranium fission detector. Tables and plots of neutron-producing reaction data are presented. This information provides input which will be essential for applications involving the primary spectrum as well as for the design of neutron moderators and for calculation of thermal-neutron yield factors. Such analyses will be prerequisites in assessing the suitability of this source for various possible neutron radiography applications and, also, for assisting in the design of appropriate detectors to be used in neutron imaging devices.
Date: July 1, 1992
Creator: Meadows, J. W. & Smith, D. L.
Partner: UNT Libraries Government Documents Department

Characterization of an accelerator neutron source based on the Be(d,n) reaction

Description: Small accelerator neutron sources offer considerable potential for applied neutron radiography applications. Among the desirable features are relatively low costs, limited operating hazards, opportunities for tailoring primary neutron spectra, compactness and portability, and modest licensing requirements (compared to fission reactors). However, exploitation of this potential has been somewhat limited, in part, by incomplete knowledge of the primary-neutron yields and energy spectra from the favorable source reactions. This work describes an extensive experimental determination of zero-degree neutron yields and energy spectra from the {sup 9}Be(d,n) {sup 10}B source reaction, for incident deuterons of 2.6 to 7.0 MeV on a thick beryllium metal target. This information was acquired by means of time-of-flight measurements that were conducted with a calibrated uranium fission detector. Tables and plots of neutron-producing reaction data are presented. This information provides input which will be essential for applications involving the primary spectrum as well as for the design of neutron moderators and for calculation of thermal-neutron yield factors. Such analyses will be prerequisites in assessing the suitability of this source for various possible neutron radiography applications and, also, for assisting in the design of appropriate detectors to be used in neutron imaging devices.
Date: January 1, 1992
Creator: Meadows, J.W. & Smith, D.L.
Partner: UNT Libraries Government Documents Department

Characterization of nuclear transmutations in materials irradiated test facilities

Description: This study presents a comparison of nuclear transmutation rates for candidate fusion first wall/blanket structural materials in available, fission test reactors with those produced in a typical fusion spectrum. The materials analyzed in this study include a vanadium alloy (V-4Cr-4Ti), a reduced activation martensitic steel (Fe-9Cr-2WVTa), a high conductivity copper alloy (Cu-Cr-Zr), and the SiC compound. The fission irradiation facilities considered include the EBR-II fast reactor, and two high flux mixed spectrum reactors, HFIR (High Flux Irradiation Reactor) and SM-3 (Russian reactor). The transmutation and dpa rates that occur in these test reactors are compared with the calculated transmutation and dpa rates characteristic of a D-T fusion first wall spectrum. In general, past work has shown that the displacement damage produced in these fission reactors can be correlated to displacement damage in a fusion spectrum; however, the generation of helium and hydrogen through threshold reactions [(n,x,{alpha}) and (n,xp)] are much higher in a fusion spectrum. As shown in this study, the compositional changes for several candidate structural materials exposed to a fast fission reactor spectrum are very low, similar to those for a characteristic fusion spectrum. However, the relatively high thermalized spectrum of a mixed spectrum reactor produces transmutation rates quite different from the ones predicted for a fusion reactor, resulting in substantial differences in the final composition of several candidate alloys after relatively short irradiation time.
Date: May 1, 1994
Creator: Gomes, I. C. & Smith, D. L.
Partner: UNT Libraries Government Documents Department

The COBRA accelerator pulsed-power driver for Cornell/Sandia ICF research

Description: This paper introduces and describes the new Cornell Beam Research Accelerator, COBRA, the result of a three and one-half year collaboration. The flexible 4 to 5-MV, 100 to 250-kA, 46-ns pulse width accelerator is based on a four-cavity Inductive Voltage Adder (IVA) design. In addition to being a mix of new and existing components, COBRA is unique in the sense that each cavity is driven by a single pulse forming line, and the IVA output polarity may be reversed by rotating the cavities 1800 about their vertical axis. Our tests with negative high voltage on the inner MITL stalk indicate that the vacuum power flow has established reasonable azimuthal symmetry within about 2 ns (or 0.6 m) after the cavity output cap. Preliminary results with the accelerator, single cavity, and MITL are presented alone, with the design details and circuit model predictions.
Date: July 1, 1995
Creator: Smith, D.L.; Ingwersen, P.; Bennett, L.F.; Boyes, J.D.; Anderson, D.E.; Greenly, J.B. et al.
Partner: UNT Libraries Government Documents Department