Reevaluation of Neutron Flux Characterization Parameters for NIST RT-2 Facility

Published

December 31, 2014

Author(s)

Dagistan Sahin, Vladimir Radulovic, Richard M. Lindstrom, Andrej Trkov

Abstract

It has been difficult to characterize the thermal to epithermal neutron flux ratio (f) and the measure of the nonideal epithermal neutron flux distribution (α) for the RT-2 pneumatic rabbit facility at the NIST National Bureau of Standards Reactor (NBSR). In a previous paper, only cadmium-covered irradiations yielded physically reasonable parameters. New measurements were performed using chromium, manganese, cobalt, zinc, zirconium, molybdenum, antimony, gadolinium, lutetium, and gold. The neutron temperature (T_n) in RT-2 measured using bare lutetium and gold foils gave unphysical values. The bare foil methods for measuring f and α gave inconsistent results. The underlying reasons are demonstrated via MCNP simulation results for cumulative reaction rates of selected isotopes. To determine expected intervals for f, α and T, parametric methods were explored. Measured reaction rate probability per target atom (R_p) values for the listed elements were fitted to a modified Westcott curve using an iterative least-squares method to verify consistency of measurements and nuclear data. An advanced parametric approach using a detailed MCNP model of the NBSR was used to calculate neutron flux characterization parameters.

Citation

Journal of Radioanalytical Chemistry

Volume

300

Pub Type

Journals

Download Paper

DOI Link

Keywords

Neutron Activation Analysis (NAA), k0 method, neutron flux characterization, neutron temperature, Westcott formalism

Citation

Sahin, D. , , V. , Lindstrom, R. and Trkov, A. (2014), Reevaluation of Neutron Flux Characterization Parameters for NIST RT-2 Facility, Journal of Radioanalytical Chemistry, [online], https://doi.org/10.1007/s10967-014-3076-3 (Accessed October 8, 2024)