A neutron spectrum-independent compound nuclear constant, Iko, is proposed for fission interference corrections in reactor NAA by parametric method. Ik0 values for eight major fission interference cases, belonging to three different types, have been determined in six irradiation positions (withth/e 13,7–134) of three research reactors in our Institute. The general agreement among experimental Ik0 's from different irradiation positions and between experimental and calculated Ik0 values for the same interference case verifies the validity of the method. Calculated Ik0 values for all the possible fission interferences are tabulated. Interferences from238U(n,) and232Th(n,) reactions and reactor fast neutron induced238U(n, f) and232Th(n, f) reactions are discussed.
A simple two step radiochemical separation scheme has been developed which permits the RNAA determination of As, Cd, Cu and Mo in biological matrices. The RNAA separation is applied following the INAA determination of at least 17 other elements in the same samples. Under our experimental conditions which included a four day decay period for handling and shipping from a remote reactor site, detection limits for As, Cd, Cu and Mo are 0.24, 6.6, 45 and 3.4 ng, respectively, in NBS biological standard reference materials SRM 1571 and 1567. Decontamination factors for the major spectral interferences,82Br,42K,24Na32P and122Sb have been determined and found to be sufficiently high for measurement of the elements of interest in most biological matrices. The overall INNA/RNAA procedure takes full advantage of high resolution Ge(Li) gamma-ray spectroscopy and involves minimal chemical processing.
Various theoretical and practical aspects of epithermal neutron activation analysis (ENAA) and fast-neutron-induced reaction interferences in conventional instrumental thermal neutron activation analysis (TNAA) have been considered. A new generalized advantage factor which reflects a practical improvement of detection limits in ENAA is proposed. In the determination of practical advantage factors, consideration is also given to the different irradiation channels available for the experiment in a given reactor, or even in several accessible reactors. Fast neutron reaction interference factors are tabulated for both ENAA and TNAA and examples are given of specific interferences in TNAA for some biological and geological matrices.
45 elements have been determined by NAA in an IAEA Lake Sediment RM SL-3 Multitechniques were used to fully tap the potential of NAA in terms of the number of the determinable elements and the accuracy of each data.
Authors:Fangli Fan, Huajie Ding, Jing Bai, Xiaolei Wu, Fuan Lei, Wei Tian, Yang Wang, and Zhi Qin
The sorption of uranium(VI) from aqueous solutions was investigated using synthesized magnesium silicate hollow spheres as
a novel adsorbent. Batch experiments were conducted to study the effects of initial pH, amount of adsorbent, contact time
and initial U(VI) concentrations on uranium sorption efficiency. The desorbing of U(VI) and the effect of coexisting ions
were also investigated. Kinetic studies showed that the sorption followed a pseudo-second-order kinetic model. The Langmuir
sorption isotherm model correlates well with the uranium sorption equilibrium data for the concentration range of 25–400 mg/L.
The maximum uranium sorption capacity onto magnesium silicate hollow spheres was estimated to be about 107 mg/g under the
experimental conditions. Desorption of uranium was achieved using inorganic acid as the desorbing agent. The practical utility
of magnesium silicate hollow spheres for U(VI) uptake was investigated with high salt concentration of intercrystalline brine.
This work suggests that magnesium silicate hollow spheres can be used as a highly efficient adsorbent for removal of uranium
from aqueous solutions.
Authors:Hai-Qing Zhang, Bang-Fa Ni, Wei-Zhi Tian, Gui-Ying Zhang, Dong-Hui Huang, Cun-Xiong Liu, Cai-Jin Xiao, Peng Nie, and Hong-Chao Sun
An expression of γ-ray efficiency for large samples is proposed based on numerical integration of efficiencies over compositional
point sources. The widely used expression on radial variation of HPGe efficiency for point source originally proposed by Noguchi
et al. (Int J Appl Radiat Isot 32:17–22, 1980 [<cite>1</cite>]) was amended and a new expression was proposed. A comparison between the two expressions indicates that the newly proposed
expression brings about an obvious improvement, and Self-absorption correction for a voluminous source is also given out by
using the EID principle. The functional relationship between HPGe efficiency for γ-rays from a point source and the spatial
position of the source was established. The results of this study can be applied in order to determine γ attenuation effects
of unknown bulky samples with various shapes and materials.
Twenty different brands of Chinese tea were analyzed for multiple trace elements, including some essential and toxic elements,
by neutron activation analysis (NAA). A comparison among tea brands from China, India, US and other countries was made for
the ranges and averages of concentrations for Na, K, Mn, Cu, and Br. It has been observed that the trace element contents
in tea leaves are largely dependent upon the soil and the environment where the tea grows. Chinese tea is rich in Mn and Cu
comparing with those of other counties surveyed, but is indigent in Na. The transference ratio for each element determined
(i.e., the fraction of an element in tea leave transferred into solution when tea is leached by percolation) is also reported.
Adult daily intakes of some essential and toxic elements from tea drinking were also estimated.