Characterization of the neutron flux energy spectrum at the Missouri University of Science and Technology Research Reactor (MSTR)

• A multi-foil irradiation experiment was performed at MSTR.
• SAND II was used to calculate the neutron energy spectrum.
• The first full- and half-power neutron energy spectrums were calculated for MSTR.
• Estimated effects of uncertainties in the foil activities are also presented.

A newly constructed remotely accessible shielded cell is available at the Missouri University of Science and Technology Research Reactor (MSTR). This heavily shielded cell will be able to receive high activity specimens (up to 0.457 Ci of Cs137 or 102.2 mCi Co60) coming directly from the reactor core. The cell also allows the manipulation and monitoring of specimens both from local as well as remote locations using a Web-based internet interface making it useful to a wide variety of users. In support of the shielded cell the neutron spectrum of MSTR has been fully characterized for the first time using foils as neutron flux monitors. Multiple foils were irradiated in the core of MSTR and iterative runs were completed using the SAND-II program. An MCNP model was used to obtain an approximate neutron flux spectrum to serve as an initial estimate for the SAND-II least squares fitting technique. The results showed good agreement in the thermal neutron energy region, while in the intermediate and fast neutron energy regions the agreement was not as good, probably due to self-shielding in the intermediate region of the spectrum. Thermal, intermediate, and fast neutron full power fluxes for the MSTR were respectively calculated to be 2.94E + 12 ± 1.9E + 10, 1.86E + 12 ± 3.7E + 10, and 2.65E + 12 ± 3.0E + 3 n/cm2s. The total neutron flux was calculated to be 7.55E + 12 ± 5.7E + 10 n/cm2s.