A dual method using SMELS for neutron flux self-monitoring and quality control in k0-NAA

Abstract

This study presents a dual method for neutron flux self-monitoring and quality control in the k₀-based neutron activation analysis (k₀-NAA) using the Synthetic Multi-Element Standards (SMELS). SMELS comprise three distinct types, designated as Type I for short-lived, Type II for medium-lived, and Type III for long-lived radionuclides, all of which are employed for validating the k₀-NAA. Each SMELS type incorporates assigned amounts of gold (Au) and can serve as a neutron flux monitor. The Au concentration was automatically integrated into k0-DALAT—a home made software to calculate the gold specific activity (A_sp,Au), thereby derivating of mass fractions of elements of interest in the k₀-NAA. Additionally, the assigned concentrations of other elements within SMELS were used for k₀-NAA quality control purpose. Replicate analyses of NIST-SRM-1633b (Coal Fly Ash) and NIST-SRM-679 (Brick Clay) by k₀-NAA showed determination up to 29 and 25 elements, respectively with deviations within 7%, of which u-scores were almost less than ∣2.58∣, except only for Na and Fe of all 2.99. It revealed that the dual method using SMELS for both neutron flux self-monitoring and quality control considered convenient and consistent in comparison with the results obtained by the conventional independent comparator method biased within 1%.