Authors:R. Jaćimović, V. Stibilj, L. Benedik, and B. Smodiš
The neutron distribution in a defined volume (gradient) for different matrices (air, water, cellulose, biological material and silicon dioxide) in two typical irradiation channels (pneumatic tube (PT) and IC40-channel in the carousel facility) in the TRIGA Mark II reactor at the Joef Stefan Institute (IJS) was studied. Our experiment was based on inserting Fe wires (flux monitors) into the chosen matrices. The wires were cut into small pieces after irradiation and the induced activities of 59Fe measured. The results showed that for the studied geometry the average spatial thermal neutron flux inhomogeneities (for five studied matrices) are about 2.3% in the PT-channel and about 2.9% in the IC40-channel.
Authors:R. Jaćimović, B. Smodiš, T. Bučar, and P. Stegnar
A suite of natural matrix reference materials (RMs) were used to assess the quality of analytical results obtained by k0-instrumental neutron activation analysis (k0-INAA) at the Joef Stefan Institute (IJS). Five certified reference materials (CRMs) from the Institute for Reference Materials and Measurements (IRMM), two standard reference materials (SRMs) from the National Institute of Standards and Technology (NIST), three RMs from the International Atomic Energy Agency (IAEA) and one RM from IJS were analyzed. Altogether, results for twenty-four elements in inorganic matrices and twenty-nine elements in organic matrices, obtained by k0-INAA, were compared to certified values. Results obtained show good agreement with certified or assigned values except for Fe, La, Nd, Sm and U in inorganic matrices, and Ag, Al and Cr in organic matrices.
Authors:Z. Jeran, R. Jaćimović, U. Sansone, and M. Bell
Adsorption of fine suspended material on the surface of aquatic plants may lead to great problems in the interpretation of results for their trace element composition, since it is quite impossible to clean the inorganic material from the biota completely. A carefully designed field experiment was performed in the River Stella in North-Eastern Italy aimed at studying the adsorption of fine suspended material on benthic algae-periphyton. More than 20 elements, were determined in water, suspended material and biota using k0-INAA, and enrichment factors were calculated for selected elements using Sc as a normalizing element.
Authors:B. Smodiš, R. Jaćimović, G. Medin, and S. Jovanović
The k0-standardization method of INAA (instrumental neutron activation analysis) was applied to three reference materials: NIST (National Institute for Standards and Technology, Washington, D.C., USA) SRM (Standard Reference Material) 1646 Estuarine Sediment, NIST SRM 2704 Buffalo River Sediment and IAEA (International Atomic Energy Agency) CRM (Certified Reference Material) SL-1 Lake Sediment. Among the 50 elements sought yielding long-lived radioisotopes after (n, ) activation, for 32 elements numerical values were obtained, and for the remaining 18, only detection limits were estimated. When comparing the results obtained in this work to certified, recommended or other literature values, good agreement was found, proving that the same analytical procedure can be applied with confidence for analysis of environmental sediment samples.
Authors:S. Jovanović, B. Smodiš, R. Jaćimović, P. Vukotić, and P. Stegnar
Neutron-flux behaviour during irradiation should be known when applying the ko-method of neutron activation analysis /NAA/. During two 100-hour operating periods of the TRIGA MARK II reactor, Ljubljana, the flux was measured by means of a197Au/n,/198Au monitor /E=411.8 keV/. Cadmium-covered irradiations were also performed to obtain the epithermal flux and thermal-to-epithermal flux ratio variations. Consistency was found between these results and the reactor operators' logbook record.
Authors:B. Smodiš, R. Jačimović, P. Stegnar, and S. Jovanović
The k0-standardization method of neutron activation analysis was applied for the multielement analysis of the NIST (National Institute of Standards and Technology) proposed Standard Reference Material (SRM) No. 1547 Peach Leaves. At the moment, 50 elements can be determined from a one day irradiation, using the TRIGA Mark II reactor of the Joef Stefan Institute, Ljubljana. Among them, 28 elements were determined quantitatively, and for the remaining 22 elements, less than values were obtained.
Authors:M. Svetina, B. Smodiš, Z. Jeran, and R. Jaćimović
Three watersheds were studied by sampling bulk precipitation deposition, seepage water at 50 cm soil depth and spring water. As the main analytical method for determination of trace elements and heavy metals in water samples, thek0-based method of INAA was used. The results showed an increased content and concentration range of trace elements in precipitation, soil water and spring water in the vicinity of the otanj Thermal Power Plant. We demonstrated that thek0-based method of INAA as a multielement nondestructive technique is a highly suitable approach to determining some toxic trace elements in environmental studies of the water cycle.
Authors:Katalin Mészáros Szécsényi, V. Leovac, R. Petković, Ž. Jaćimović, and G. Pokol
The deaquation of two isostructural compounds of general formula [M(HL)2(H2O)2](NO3)2 (M=Co, Ni, HL=3,5-dimethyl-1H-pyrazole-1-carboxamidine) is discussed in the view of their crystal and molecular structure. The compounds contain the same
number and type of hydrogen bonds of the adjacent nitrate ions, only in the opposite orientation. On the basis of their deaquation
pattern such a small difference may be detected, i.e., methods of thermal analysis are sensitive enough to show very small
Authors:S. Jovanović, P. Vukotić, B. Smodiš, R. Jaćimović, N. Mihaljević, and P. Stegnar
The nonideality of the epithermal neutron flux distribution at a reactor site can be described by a 1/E1+ spectrum representation, with parameter being a measure of the nonideality. -values were determined in 3 typical irradiation positions of the TRIGA MARK II reactor of the Jozef Stefan Institute, Ljubljana, Yugoslavia, using the Cd-ratio for multi-monitor method. The simpler Cd-ratio for dual monitor method (monitors:197Au–94Zr) also yielded reliable results. This characterisation is of use in the k0-method of NAA, which is recently introduced at the Institute.
Authors:M. Bounakhla, L. Mrabet, R. Jacimovic, K. Embarch, H. Bounouira, A. Benchrif, and B. Attrassi
The aim of this study is to evaluate the sensitivity of Ko-method of Instrumental Neutron Activation Analysis for minor, trace
and toxic elements in the most consumed foodstuff purchased from large commercial markets in Kenitra’s city (Morocco) which
has been chosen for a pilot project on food monitoring in the west of Morocco. Samples have been analyzed by Ko-INAA method
using TRIGA Mark II reactor at Josef Stefan Institute in Slovenia. The quality control of results was assessed using the Standard
Reference Material SRM 1547 (Peach leaves). Results show an adequate sensitivity for the most studied elements in foodstuffs
except for beef, onion and whole wheat which show a high sensitivity factor for Cd and As. INAA seems to be an adequate choice
for element analysis in foodstuffs.