Interfacial effects in fast reactors
Author(s)Saidi, Mohammad Said; Driscoll, Michael J.
Massachusetts Institute of Technology. Department of Nuclear Engineering
United States. Department of Energy
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The problem of increased resonance capture rates near zone interfaces in fast reactor media has been examined both theoretically and experimentally. An interface traversing assembly was designed, constructed and employed to measure U-238 capture rates near the blanket-reflector interface in the MIT Blanket Test Facility. Prior MIT experiments on a thorium-uranium interface in a blanket assembly were also reanalyzed. Extremely localized fertile capture rate increases of on the order of 50% were measured immediately at the interfaces relative to extrapolation of asymptotic interior traverses, and relative to state-of-the-art (LIB-IV, SPHINX, ANISN/2DB) calculations which employ infinite-medium self-shileding throughout a given zone. A method was developed to compute a spatially varying background scattering cross section per absorber nucleus, a , which takes into account both homogeneous and heterogeneous effec~s on the interface flux transient. This permitted use of the standard self-shielding factor method (Bondarenko f-factors) to generate modified cross sections for thin layers near the interfaces. Calculations of the MIT experiments using this approach yielded good agreement with the measured data.
"May 1979."Also written as a Ph. D. thesis by the first author and supervised by the second author, MIT Dept. of Nuclear Engineering, 1979Includes bibliographical references (pages 191-193)
Cambridge, Mass. : Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 
MITNE ; no. 226COO (Series) ; 2250-37