Implementation of the k0-standardization Method at the Penn State Breazeale Reactor

open_access
Open Access
Author:
Kelly, Kassia Brynne
Graduate Program:
Nuclear Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
Kenan Unlu, Thesis Advisor/Co-Advisor
Keywords:
k0-method
NAA
Neutron Activation Analysis
Breazeale
Penn State
Abstract:
Neutron activation analysis (NAA) is an analytical technique used to determine the elemental concentrations of samples activated by the (n,γ) reaction. The Penn State Breazeale Reactor (PSBR), located at the Radiation Science and Engineering Center (RSEC), is utilized to irradiate samples for NAA applications. The current work presents the implementation of the k0-standardization method of NAA at the PSBR. For the application of the k0-method, the neutron flux characterization parameters of the irradiation facility must be accurately measured. The neutron flux characterization parameters for the irradiation positions in the PSBR core, namely the dry irradiation tubes 1 and 2 (DT-1 and DT-2), were measured by irradiating the bare gold-aluminum wires (0.112% Au), lutetium-aluminum wires (0.1% Lu), and high purity zirconium foils provided in the k0-IAEA Software Package. The thermal to epithermal neutron flux ratio (f), epithermal flux shape factor (α), the average neutron temperature (Tn), and the spectral index (r√(Tn/T0 )) parameters were measured as follows: 23.1 ± 1.8, -0.067 ± 0.02, 308 ± 19 K, and 0.051 ± 0.004 for DT-1 and 24.3 ± 1.9, -0.077 ± 0.03, 314 ± 20 K, and 0.051 ± 0.004 for DT-2, respectively. Samples from five certified standard reference materials were analyzed, including NBS-1575 Pine Needles, NBS-1573 Tomato Leaves, NIST-2704 Buffalo River Sediment, NBS-1633a Trace Elements in Coal Fly Ash, and NBS-98b Plastic Clay. The samples were irradiated in each dry tube for 10 minutes at 800 kWt power. Gamma ray spectroscopy was performed on the activated samples and their constituent concentrations were calculated using the standard INAA method and the established k0-method. The measured elemental concentrations were then compared with respective certified and/or information elemental concentration values for each standard reference material. In total, 20 elements were identified using the implemented analytical methods. Elemental concentrations measured for Na, Sc, Ca, Zn, Ba, Hf, Ce, Se, K, Cr, Ga, As, Br, Sb, La, Sm, Eu, Fe, Mn, and Rb were all in reasonable agreement with the certified/information concentrations for most of the samples. The majority of the z-scores for the k0-method were less than those of the INAA method for all of the analyzed standard reference materials. The percent error of the measured elemental concentrations was greatly reduced when using the k0-method rather than the INAA method, therefore validating the accuracy of the k0-method also established for the PSBR.