The Laboratory for Neutron Activation Analysis at CDTN/CNEN, Brazil, acquired the k0_IAEA software package during the Workshop
on Nuclear Data for Activation Analysis, 2005, held at the Abdus Salam International Centre for Theoretical Physics, Italy.
The IAEA distributed the software to several laboratories and has accepted suggestions from the users about the performance
of the program. This paper describes the validation procedure carried out aiming at the validation of the software package.
The procedure was to analyze the SMELS samples and to compare the results obtained by this software to the commercial KayWin
software package, already established at CDTN/CNEN. The results were compared to the values obtained by the Jožef Stefan Institute,
Slovenia. The laboratories applied the same software: k0_IAEA and KayWin. The overall results pointed out that the k0_IAEA
software set up at CDTN/CNEN, Brazil, is working properly. The u-score test showed that all results, except data in SMELS Type III for Se obtained at the JSI, are within 95% confidence interval
once setting up u-score as 1.96 (P = 95% or ±2σ).
The k0-standardization method of neutron activation analysis (NAA) is very sensitive to the irradiation and counting time during measurement of the induced radionuclide by -spectrometry on the HP Ge detector. If the irradiation and counting time of the sample and co-irradiated standard is relatively short or the decay constant small, the application of the standard equation in the software for the specific count rate may become numerically unstable and the program aborts. In this work, attention is focused on the direct influence of saturation and "measurement" factors on the specific count rate for simple decay and for more complex types calculated directly by exponential functions, and by an alternative form using a truncated Taylor's series expression.
The accuracy and precision of the results obtained for total mercury in various environmental and biological samples and certified
reference materials (CRMs) by various analytical methods, including k0-instrumental neutron activation analysis (k0-INAA), radiochemical neutron activation analysis (RNAA) and cold vapour atomic absorption (and atomic fluorescence) spectrometry
(CVAAS/AFS) used in routine analysis in our laboratory, were investigated. Three natural matrix reference materials (RMs)
from the International Atomic Energy Agency (IAEA), five CRMs from the Institute for Reference Materials and Measurements
(IRMM), six CRMs from the National Institute of Standards and Technology (NIST) and one from the Jožef Stefan Institute (IJS)
were analyzed. The results obtained show good agreement between certified or assigned values, and between the methods used,
except for some data obtained by k0-INAA in biological samples. This can be explained by losses during irradiation in semi-open systems (irradiation in plastic
ampoules) and/or spectral interferences.
An experimental verification of Monte Carlo neutron flux calculations in typical irradiation channels in the TRIGA Mark II reactor at the Joef Stefan Institute is presented. It was found that the flux, as well as its spectral characteristics, depends rather strongly on the position of the irradiation channel. Comparison of the results for parameter f (thermal-to-epithermal flux ratio), experimentally obtained by the Cd ratio multi-monitor method and Monte Carlo simulations shows relatively good agreement for most studied configurations except for the channel IC40 in the carousel facility, where differences are relatively large and not understood.
Authors:Lj. Jaćimović, R. Drašković, and B. Ostojić
The contents of Hg, Cr, La, Sc, Co, Fe and Sb in some human concretions have been determined by instrumental radioactivation
analysis. Urinary bladder and kidney concretions surgical removed from the patient have also been analyzed.
Quantitative data on trace elements in two tobacco leaf (candidate) reference materials OTL-1 and VTL-2 prepared by the Polish Academy of Sciences and the Institute of Nuclear Chemistry and Technology, Warsaw, Poland, are presented and compard to recommended values, where available. By instrumental neutron activation analysis (INAA), as well as by radiochemical technique (RNAA) 30 elements were quantitatively determined and fair agreement was found between the results and recommended values for the first material.
Authors:T. Bučar, B. Smodiš, P. Pelicon, J. Simčič, and R. Jaćimović
Cellulose cylinders and circular filter papers spiked with known amounts of standard element solutions were prepared for studying
some aspects of assessing measurement uncertainty of NAA and the elemental distribution measured by micro-PIXE analysis. Results
for the cylinders showed strongly non-homogeneous distribution of the elements, both in radial and vertical directions, dominantly
caused by osmosis driven transport of added liquid solution from the centre to the edges. Results for the thin cellulose filter
paper disks exhibited weaker peaking of the standard element concentrations at the edges in comparison with the thick cylinders.
Authors:R. Jaćimović, P. Makreski, V. Stibilj, and T. Stafilov
Major and trace element contents in iron ore reference materials were investigated using k0-instrumental neutron activation analysis (k0-INAA). To avoid iron interferences, radiochemical separation was developed (k0-RNAA). The determination of the investigated elements in the inorganic phase from hydrochloric acid solution was performed
after radiochemical separation of iron by diisopropyl ether. It was found that after the Fe elimination, the limit of detection
for some elements was much lower that enables their direct determination. The distribution of 39 elements (with intermediate/medium
and long half-life radionuclides) after Fe removal was investigated.