Master of Science in Mechanical Engineering (MSME)
First Committee Member
Number of Pages
During reprocessing, the spent fuel rod can be divided up into its component parts for separation into different waste streams. These radioactive streams are then directed appropriately toward low-level waste (LLW) storage, high-level waste (HLW) storage, or reuse into a recycled fuel pin. ; The issue that requires evaluation is the nuclear reaction of the higher actinides in reprocessing in an aqueous solution with regard to small temperature changes. This will need an analysis of neutron cross section, which is the measure of the probability that a nuclear reaction will occur; The isotopes' cross sections need to be temperature corrected. This will have a direct effect on the reactivity per gram for an isotope being reprocessed.  These specific cross sections were computed using NJOY version 99.259 with ENDF/B-VII data and applying it toward the criticality code MCNP5; The process entailed research into the structure of the ENDF file format, established criticality benchmarks, and formulated hard spectrum cross sections from the ENDF data with NJOY It also required analyzing the reactivity changes to each actinide, (Np-237, Pu-239, Pu-240, Pu-241, Am-241, Am-242m, Am-243, and Cm-244), as well as formulating soft spectrum cross sections. The contribution of each actinide on the total reactivity difference of the solution needs to be carefully calculated with regard to small changes in density and temperature. ; The study showed that the small change in temperature from 273.15 K to 313.15 K did not have an impact on the reactivity per gram. This was analyzed for all eight of the isotopes in the fast spectrum; This methodology will establish a process for UNLV to commence work into cross-section analysis and reactivity sensitivity studies. It will also produce the research into the formulation of the fast and thermal cross sections for the higher actinides and the calculations for changes in reactivity of the hard spectrum with small changes in temperature.
Actinides; Criticality; Cross; Higher; Neutron; Reprocessing; Safety; Section; Sensitivity; Studies
Nuclear engineering; Nuclear physics; Nuclear physics
University of Nevada, Las Vegas
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Lakeotes, Lawrence J, "Neutron cross-section sensitivity studies in higher actinides for criticality safety in reprocessing" (2008). UNLV Retrospective Theses & Dissertations. 2300.