Environmental monitoring for safeguards using k0-standardised Neutron Activation Analysis

Multi-elemental analysis of samples containing uranium by Instrumental Neutron Activation Analysis (INAA) has been generally known as a problematic task due to the numerous radioisotopes produced from the uranium fission when the sample is irradiated with thermal neutrons. In k
₀
-standardised NAA (k
₀
-NAA)it is possible to correct for this effect through the introduction of k
₀
-fission factors. In this work the aim was to determine the feasibility of k
₀
-NAA as a screening technique for accurate U and n(
²³⁵
U)/n(
²³⁸
U) isotopic ratio determination (we further refer to the technique as k
₀
-UNAA) and where k
₀
-UNAA could be positioned versus the other screening techniques. In k
₀
-UNAA we use an adapted k
₀
formalism to determine the n(
²³⁵
U)/n(
²³⁸
U)-ratio. Several swipe samples spiked with different isotopic ratio's U were analysed and demonstrate the feasibility of k
₀
-UNAA as a accurate and reliable screening method for the quantification of environmental samples up to several tens of ng. At these levels the uranium concentration can be quantified with a reasonable uncertainty and reliable n(
²³⁵
U)/n(
²³⁸
U) isotopic ratio analysis could also be performed.