Measurements of reactor parameters in subcritical and critical assemblies : a review

"NYO 10, 207."Includes bibliographical references (pages 50-58)AT(30-1)234

Measurements of neutron capture in U²³⁸ in lattices of uranium rods in heavy water

"NYO-9659."Also issued as a Ph. D. thesis in the Dept. of Nuclear Engineering, 1962Includes bibliographical references (pages 119-145)Contract AT(30-1)-234

Heavy Water Lattice Project final report

MIT-2344-12AEC Research and Development ReportBibliography: leaves 181-192U.S. Atomic Energy Commission contract AT(30-1)234

Pulsed neutron source

Also issued as an Sc. D. thesis, Massachusetts Institute of Technology. Dept. of Nuclear Engineering, 1967"MIT-2344-7."U.S. Atomic Energy Commission contract AT (30-1)234

Measurements of the material bucklings of lattices of natural uranium rods in D₂O

"NYO-9660.""AEC Research and development report UC-34 physics (TID-4500, 16th edition)."Originally issued as the first author's Ph. D. thesis, Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1962U.S. Atomic Energy Commission AT(30-1)234

The measurement of reactor parameters in slightly enriched uranium, heavy water moderated miniature lattices

"MIT-2344-8."U.S. Atomic Energy Commission AT(30-1)234

A study of the fast fission effect in lattices of uranium rods in heavy water

NYO-9661Includes bibliographical references (p. 168-171)AT (30-1) 234

Theory and use of small subcritical assemblies for the measurement of reactor parameters

"NYO-10204 .""TID-4500, 17 ed. UC-34 Physics."Includes bibliographical references (pages 124-126)Contract AT(30-1)234

Analytical and experimental investigations of the behavior of thermal neutrons in lattices of uranium metal rods in heavy water

Statement of responsibility on title-page reads: R. Simms, I. Kaplan, T. J. Thompson, D. D. Lanning"October 11, 1963.""NYO-10211."Also issued by the first author as a Ph. D. thesis, Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1964Includes bibliographical references (leaves 193-199)Measurements of the intracellular distribution of the activation of foils by neutrons were made in lattices of 1/4-inch diameter, 1.03% U-235, uranium rods moderated by heavy water, with bare and cadmium-covered foils of gold, depleted uranium, lutetium, europium and copper. The measurements were made in the M.I.T. Heavy Water Lattice Facility with source neutrons from the M.I.T. Reactor. Two lattices were studied in detail in this work. The more closely packed lattice had a triangular spacing of 1.25 inches, and the less closely packed lattice had a triangular spacing of 2.5 inches. The results of the experiments were compared to one-dimensional, 30-energy group, THERMOS calculations based on the available energy exchange kernels. The comparison indicated that the approximation that the hexagonal cell may be replaced by an equivalent circular cell (the Wigner-Seitz approximation) can lead to serious discrepancies in closely packed lattices moderated b! y heavy water.A modified one-dimensional, and a two-dimensional, calculation were shown to predict the intracellular activation distribution in the closely packed lattice. An analytical treatment of the problem of the flux perturbation in a foil was developed and compared to the experimental results obtained by using gold foils of four different thicknesses in the lattice cell; the method was shown to be adequate. An analytical method to treat the effect of leakage from an exponential assembly was formulated; the results indicated that only in small exponential assemblies would leakage be a significant problem in intracellular flux measurements. A method was developed to predict the cadmium ratio of the foils used in the lattice cell; comparison with available measurements with gold foils indicated good agreement between theory and experiment, except for a lattice having very large ratios of moderator volume, to fuel volume, e.g., 100:1.Calculations of the fuel disadvantage factor by the method of successive generations for gold, lutetium and europium detector foils were compared to the results of THERMOS calculations, because THERMOS was shown to predict the experimental distributions. The comparison indicated that the method of successive generations is a good alternative to the THERMOS calculation, if all that is required is 17 and the thermal utilization.U.S. Atomic Energy Commission contract AT(30-1)234

Use of a moments method for the analysis of flux distributions in subcritical assemblies

Statement of responsibility on title-page reads: H.S. Cheng, I. Kaplan, T.J. Thompson, M.J. Driscoll"MIT-2344 -11."Includes bibliographical references (pages 347-352)A moments method has been developed for the analysis of flux distributions in subcritical neutron-multiplying assemblies. The method determines values of the asymptotic axial and radial buckling, and of the extrapolated height and radius, from foil activation data, in terms of flux moments defined in the usual sense. Analytic expressions are derived for the axial and radial buckling and extrapolated dimensions in terms of the flux moments. These expressions have clear physical meaning and are suitable for the interpretation of conventional buckling measurements. The method treats the moment index as a variable parameter and allows freedom in the choice of the locations of the first and last data points used in the analysis. These degrees of freedom make it possible to reduce the effects of source neutrons, flux transients, and higher harmonics. As a result, the moments method can be applied successfully to very small lattices ("miniature lattices") as well as to large exponential assemblies. The moments method has been tested, in comparison with the conventional least-squares curve-fitting method, by applying the two methods to the analysis of measurements made in several uranium heavy water, and uranium oxide-heavy water lattices investigated at the M. I. T. Lattice Project. In the case of large exponential assemblies, the moments method yielded more consistent results than the curve-fitting method. In the case of miniature lattices, the moments method made it possible for the first time to determine values of axial and radial buckling and extrapolated dimensions.U.S. Atomic Energy Commission contract AT(30-1) 234