Nine alternative LWR fuel cycles are analyzed in terms of the isotopic content of the fuel material, the relative amounts of primary and recycled material, the uranium and thorium requirements, the fuel cycle costs and the fraction of energy which must be generated at secured sites. The fuel materials include low-enriched uranium (LEU), plutonium-uranium (MOX), highlyenriched uranium-thorium (HEU-Th), denatured uranium-thorium (DU-Th) and plutonium-thorium (Pu-Th). The analysis is based on tracing the material requirements of a generic pressurized water reactor (PWR) for a 30-year period at constant annual energy output. During this time period all the created fissile material is recycled unless its reactivity worth is less than 0.2% uranium enri~hment plant tails. i i ; Among the authors, R. L. Aaberg performed the analysis of Cycles A and B as well as programming the routine which computes the separative work, and migration of the minor isotopes in the enrichment cascade. A. J. Boegel performed the analysis of Cycle C, and wrote the fuel cycles description section of the report. He also contributed to the original plan of analysis. C. M. Heeb guided the revisions to the LEOPARD code, and was responsible for the overall analysis effort. U. P. Jenquin studied the effect of resonance interference and evaluated the 232 Th resonance integral measurements and calculations. D. A. Kottwitz created the new 240 pu resonance treatment in LEOPARD. M. A. Lewallen selected the unit cost assumptions and wrote the section on uranium and thorium requirements. E. T. Merrill wrote the original flow diagrams which form the basis of the analysis, did the cash flow analysis for the power costs, and wrote the economics sections of this report. A. M. Nolan performed the analysis of Cycles D, E, G and H, wrote the fissile loading search subroutines in LEOPARD, wrote the introduction, and the section on non-proliferation and diversion resistance.
A method of producing extremely parallel (and monochromatic) beams of neutrons or X-rays by multiple Bragg reflection in perfect crystals is proposed. The scheme is based on the simulation of a forbidden reflection by the COOl~erative action of three other reflections. The conditions necessary for obtaining the desired effect are discussed, and a short list of several reflections satisfying some of the conditions is given.The purpose of this note is to point out the possibility of producing extremely parallel (and monochromatic) beams of neutrons or X-rays by multiple Bragg reflection in a perfect crystal. The proposed scheme is an extension of a previously described methgd in which a partially parallel beam is produced (Kottwitz, 1968). As in the earlier work the method is based on the simulation of a forbidden reflection by the cooperative action of other allowed reflections. However, instead of two cooperative reflections, there now must be three (or more). For simplicity we assume that there are only three.A discussion of the necessary conditions is most readily carried out in terms of the kinematical (geometrical) theory and the reciprocal lattice (James, 1963). Let us consider four noncoplanar reciprocal-lattice points, the first of which is taken as origin (see Fig. 1). The four points are designated by their corresponding lattice vectors h, (n = 1, 2, 3, 4). We note that the noncoplanarity condition may be expressed as h2.h3 X h4 :riO.(1) hi (-O) Ki It is known from geometry that there is a unique point E (generally not a reciprocal-lattice point) equidistant from the four lattice points. We now construct an Ewald sphere with center E and passing through all four lattice points. We assume that no other reciprocal-lattice points lie on the sphere. The four radius vectors K, (n= 1, 2, 3, 4) represent the wave vectors of four plane waves that mutually diffract, one into another. We consider that K1 represents the incident beam and K4 the desired final diffracted beam.It is clear from Fig. 1 that the incident K1 may be connected to the final K4 by a sequence of three reflections: h2, (h3-h2), and (h4-h3). Furthermore K~ and K4 are the only pair of wave vectors connected by this sequence. In general there are three other diffraction 'short cuts' from KI to K4. These are the single direct reflection h4 and two sequences of two reflections: h2 and (h4-h2) , as well as h3 and (h4-h3). However, if these three shortcuts are strictly forbidden by space-group symmetry, then the triple sequence of Bragg reflections stands alone and produces a final beam having a high degree of parallelism and monochromaticity (excluding multiple orders). Denoting the structure amplitude of a reflection by F(h), we may write the necessary conditions asIn Fig. 1 the reciprocal-lattice vectors corresponding to the allowed reflections and forbidden reflections are shown by heavy solid and dashed lines, respectively.In addition to equations (1) and (2) there are other conditions which must be satisfied in order that a triple Bragg reflect...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.