In 2008, the Oregon State TRIGA® Reactor (OSTR) was converted from highly-enriched uranium (HEU) fuel lifetime improvement plan (FLIP) fuel to low-enriched uranium (LEU) fuel. This effort was driven and supported by the Department of Energy's (DoE's) Reduced Enrichment for Research and Test Reactors (RERTR) program. The basis behind the RERTR program's ongoing conversion effort is to reduce the nuclear proliferation risk of civilian research and test reactors. The original intent of the HEU FLIP fuel was to provide fuel to research reactors that could be utilized for many years before a necessary refueling cycle.
As a research reactor, the OSTR provides irradiation facilities for a variety of applications, such as: activation analysis, fission-track dating, commercial isotope production, neutron radiography, prompt gamma characterization, and many others. In order to accurately perform these research functions, several studies have been conducted on the HEU FLIP fuel core to characterize the neutron spectra in various experimental facilities of the OSTR. As useful as these analyses were, they are no longer valid due to the change in fuel composition and the resulting alteration of core performance characteristics. The purpose of this study is to characterize the neutron spectra in various experimental facilities within the new LEU core so as to provide data that is representative of the OSTR's current state.