The distribution of photons detected in a spectrometer as a function of their path length in the sample can be approximated by a one-parametric family of functions. The members of the family, having different average path lengths, describe the transport of photons in samples of different shapes. The value of the parameter corresponding to the actual counting geometry is obtained from the measured average path of photons in the sample. The self-attenuation factor as a function of the attenuation coefficient is calculated as the Laplace transform of the member of the family, defined by the extracted value of the parameter.
A new method for determination of efficiency calibration curves in -spectrometry is described. From the calibration curves for a bulky sample and a point source, the curves for sources with the same geometrical parameters as the bulky sample but different attenuation coefficients may be calculated. The method was tested at an energy of 88 keV on a set of samples with attenuation coefficients between 0.2 and 2 cm2 g–1. The conditions where the new method is useful are discussed.
The radioactivities of90Sr,137Cs and134Cs have been measured in soil, fodder and milk from the south-western region of Slovenia, Yugoslavia after the Chernobyl accident. Maximal concentrations of Sr-isotopes in samples and the rate of their decrease in a period up to two years after the accident are given. The transfer of radionuclides from soil to grass and from fodder to milk is discussed.
Authors:D. Glavič-Cindro, M. Korun, and B. Vodenik
The environmental monitoring system in the counting room of Gamma-Ray Spectrometry Group at the Joǽef Stefan Institute was designed in such a way that it fulfills the requirements of the ISO 17025 standard without causing any additional burden to the staff. In addition to the environmental parameters (temperature, humidity and oxygen concentration in air) the voltage and frequency of the electric power supply and the pressure of the compressed air are monitored. The monitoring system is connected to the main computer and the software automatically checks the recorded data on a daily basis and issues automatic warnings if the recorded values are outside the prescribed limits of acceptance. In this paper, monitoring and control of the environmental and other parameters of the facilities in our laboratory that can affect the measurement result are presented, as well as their time dependencies, correlations among them and correlations between the temperature and the background peak count rates of the spectrometers.
Authors:D. Glavič-Cindro, M. Korun, and B. Vodenik
Peak search and analysis of the programs often associate peaks found in gamma-ray spectra of the radionuclides that are not
present in the sample. Such radionuclides have to be excluded from the reported results. The dilemmas connected with reporting
of the results near the detection limit are usually avoided by introducing a reporting limit exceeding considerably the detection
limit. This approach has the drawback that small concentrations of emitters may not be reported, even though enough evidence
for their presence in the sample is available. In this paper the statistical analysis of causes, which lead to manual elimination
of radionuclides from the results of automatic analysis is presented for a set of measurements in our laboratory, covering
a period of more than two years. Possibilities to improve the software to automatically detect and eliminate such results
are presented as well. From the conclusions additional instructions to the operators on how to evaluate such peaks can be
Authors:T. Petrovič, M. Lipoglavšek, B. Zorko, M. Nečemer, and M. Korun
Activity concentrations of 40K and 3H in drinking water from four sources in the vicinity of NPP Krško and their correlation with geological data are presented.
The data extends from the year 1996 until present. In addition, activity concentrations of 40K in drinking water at randomly selected sources in Slovenia are presented on a map. These activity concentrations vary by
more than an order of magnitude with the largest values in northeastern part of the country.
Authors:P. Povinec, M. Pham, J. Sanchez-Cabeza, G. Barci-Funel, R. Bojanowski, T. Boshkova, W. Burnett, F. Carvalho, B. Chapeyron, I. Cunha, H. Dahlgaard, N. Galabov, L. Fifield, J. Gastaud, J. Geering, I. Gomez, N. Green, T. Hamilton, F. Ibanez, M. Ibn Majah, M. John, G. Kanisch, T. Kenna, M. Kloster, M. Korun, L. Liong Wee Kwong, J. La Rosa, S. Lee, I. Levy-Palomo, M. Malatova, Y. Maruo, P. Mitchell, I. Murciano, R. Nelson, A. Nouredine, J. Oh, B. Oregioni, G. Le Petit, H. Pettersson, A. Reineking, P. Smedley, A. Suckow, T. van der Struijs, P. Voors, K. Yoshimizu, and E. Wyse
A reference material designed for the determination of anthropogenic and natural radionuclides in sediment, IAEA-384 (Fangataufa
Lagoon sediment), is described and the results of certification are presented. The material has been certified for 8 radionuclides
(40K, 60Co, 155Eu, 230Th, 238U, 238Pu, 239+240Pu and 241Am). Information values are given for 12 radionuclides (90Sr, 137Cs, 210Pb (210Po), 226Ra, 228Ra, 232Th, 234U, 235U, 239Pu, 240Pu and 241Pu). Less reported radionuclides include 228Th, 236U, 239Np and 242Pu. The reference material may be used for quality management of radioanalytical laboratories engaged in the analysis of radionuclides
in the environment, as well as for the development and validation of analytical methods and for training purposes. The material
is available from IAEA in 100 g units.