Thesis (M.S.)--Ohio State University, 2009. / Title from first page of PDF file. Includes vita. Includes bibliographical references (p. 133-134).

A two-phase experimental loop was designed and built to simulate the operating conditions of the SLOWPOKE reactor. Void growth was measured for both upflow and downflow for velocities between 0.07 to 0.46 m/s and at a pressure of 155 kPa. The buoyancy effect causes the Onset of Significant Void, OSV, to occur at higher subcooling for downflow than for upflow. This effect is maximum close to the bubble rise velocity (0.23 m/s) and decreases at higher velocities. The results indicate that bubble detachment is not the only critical parameter affecting OSV. The OSV correlations from the literature did not predict the experimental results well. Investigation of the heat transfer mechanisms indicates that fully developed sub cooled boiling occurs prior to OSV. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Thesis. 1976. M.S. cn--Massachusetts Institute of Technology. Dept. of Nuclear Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / M.S.cn

Thesis. 1977. M.S.--Massachusetts Institute of Technology. Dept. of Nuclear Engineering. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Includes bibliographical references. / by Cpt. William W. Saylor. / M.S.

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The object of this work was to develop a linear two-point reactor model from an existing nonlinear model and determine optimum parameters for both models in comparison to actual plant data. The importance of keeping the nonlinearity to accurately describe the xenon oscillation problem was also examined. The best chi-square fit to the actual test data was established as the guiding criterion. The nonlinear model initially produced an excellent chi-square fit of 0.708 against plant data. This value could only be reduced through parameter variation to 0.695, approximately 2%. The linear model resulted in a diverging oscillation at the initial one group estimates. Linearizing the oscillatory behavior of the xenon burnup coefficient was attributed to the decrease in the stability of the model. The major flaw of the linear model was the dependence of the nonlinear model for initial conditions. / M. S.

An improved method for evaluating the moderator temperature coefficient (MTC) of reactivity in pressurized water reactors based on a newly established technique is described. Previous work has correlated stochastic fluctuations in the reactor core-exit temperature with similar fluctuations in the in-core neutron flux. The frequency response function between these two stochastic signals has been shown to be proportional to the moderator temperature coefficient. Though this method has been shown to agree well with reactor core design and measured values of the MTC, the method requires over three hours of data processed via the fast Fourier transform, and has certain limitations which suggest that the data analysis be done another way. In the present work, the multivariate autoregressive analysis method is utilized to process under ten minutes of the plant data used previously. Nearly identical results were obtained using only 5 % of the data used in the prior analysis. / Master of Science

A cadmium-aluminum shield for the V.P.I. subcritical reactor was designed and constructed. Aluminum provides structural strength. Suitable access to fuel and experimental facilities was provided. Experimentally it was determined that the shield is opaque to an influx of thermal neutrons. This is manifested by a depression in neutron density near the boundaries of the pile when the shielded and unshielded region counting rates are compared. The natural-uranium slugs and the highly radioactive source are padlocked within the shield. The assembly is also protected from contamination. Practically no additional biological protection is afforded by the shield due to the neutron-gamma reaction in cadmium. / Master of Science