Nuclear Engineering Commons^™

A Monte Carlo Calculation Of Neutron Reflection From Various Curved Surfaces, Charles Jack Kalter

Doctoral Dissertations

"Plane parallel neutron beams normally incident upon the curved surface of a solid reflector are studied with the Monte Carlo method. The geometries studied are cylindrical, parabolic, and hemispherical. It is shown that when the curved surface is cylindrical, a small "focusing effect" occurs in the reflected neutron beam. Parabolic and hemispherical surfaces do not show "focusing". A study of the factors which determine the spatial dependence of the reflected flux shows that the probability of emergence of a neutron, traveling a fixed distance from a point inside the reflector, depends upon the curvature of the surface. It is only …

Low-Energy Electron Transport By The Method Of Discrete Ordinates, David E. Bartine

Doctoral Dissertations

"The one-dimensional discrete ordinates code ANISN has been adapted to simulate the transport of low-energy (on the order of a few MeV) electrons. Two different calculational techniques have been utilized for the treatment of electron-electron collisions that result in a small energy transfer. One method treats such collisions by a continuous slowing-down approximation, while the other method treats these collisions by the use of a very approximate cross section. Calculated results obtained with ANISN are compared with experimental data for the transmitted energy and angular distributions for 1-, 2.5-, 4-, and 8- MeV electrons normally incident on aluminum slabs of …

Higher Space Mode Analysis Of A Large Cylindrical Pulsed H₂O System, Harold David Hollis

Doctoral Dissertations

"By utilizing a geometrically centered pulsed source internal to a large (B²_g) ≈ 0.002) cylindrical H₂O system, the neutron flux was measured as a function of position and time. A least square fit of the data yielded the fundamental and five higher decay constants and amplitudes of the thermal neutron flux. Symmetrical and enhanced neutron densities were obtained as a result of the internal source. Long waiting times were unnecessary and data acquisition was accelerated.

The decay constants were found to be independent of position, pulse width, counting time and rates, method of normalization, or waiting time. …

Investigation By Neutron Diffraction Utilizing White Neutron Radiation, Arlen Ray Schade

Doctoral Dissertations

"The most probable reactor core neutron velocity was determined by analysis of data obtained from single crystals of copper and lithium fluoride. Derivation of the relationship between the maximum in experimental count rate and the most probable velocity, an error analysis of the method, and the computer routine are given for the method used to obtain the most probable velocity. The most probable velocity was used to index the maxwellian distributions from polycrystalline materials. Investigations were done with white neutron radiation of various silicon steel samples of different preferred orientation. A method is described by which the preferred orientation of …

A Study Of The Supercooling Behavior Of High Purity Liquid Bismuth, B. L. Bramfitt

Doctoral Dissertations

"This investigation involves a study of the supercooling behavior of pure bismuth as affected by the melting atmosphere, the amount of superheat, and the intentional addition of metallic and non-metallic foreign materials to the melt. It was found that the amount of oxide on the melt surface is a controlling factor in the degree of supercooling obtainable in bismuth. In the presence of a thick bismuth oxide surface layer the amount of superheat below a 15°C drastically decreases the amount of supercooling due to the retention of nuclei in the surface film that promote nucleation upon cooling of the melt. …