Time filter

Source Type

Debrecen, Hungary

Papp L.,Hungarian Academy of Sciences | Palcsu L.,Hungarian Academy of Sciences | Major Z.,Hungarian Academy of Sciences | Rinyu L.,Hungarian Academy of Sciences | Toth I.,Isotoptech Ltd.
Isotopes in Environmental and Health Studies

This paper describes the procedure followed for noble gas measurements for litres, millilitres and microlitres of water samples in our laboratory, including sample preparation, mass spectrometric measurement procedure, and the complete calibrations. The preparation line extracts dissolved gases from water samples of volumes of 0.2 μ l to 3 l and it separates them as noble and other chemically active gases. Our compact system handles the following measurements: (i) determination of tritium concentration of environmental water samples by the 3He ingrowth method; (ii) noble gas measurements from surface water and groundwater; and (iii) noble gas measurements from fluid inclusions of solid geological archives (e.g. speleothems). As a result, the tritium measurements have a detection limit of 0.012 TU, and the expectation value (between 1 and 20 TU) is within 0.2 % of the real concentrations with a standard deviation of 2.4 %. The reproducibility of noble gas measurements for water samples of 20-40 ml allows us to determine solubility temperatures by an uncertainty better than 0.5 °C. Moreover, noble gas measurements for tiny water amounts (in the microlitre range) show that the results of the performed calibration measurements for most noble gas isotopes occur with a deviation of less than 2 %. Theoretically, these precisions for noble gas concentrations obtained from measurements of waters samples of a few microlitres allow us to determine noble gas temperatures by an uncertainty of less than 1 °C. Here, we present the first noble gas measurements of tiny amounts of artificial water samples prepared under laboratory conditions. © 2012 Copyright Taylor and Francis Group, LLC. Source

Molnar M.,Institute of Nuclear Research of the HAS | Palcsu L.,Institute of Nuclear Research of the HAS | Major Z.,Institute of Nuclear Research of the HAS | Svingor E.,Institute of Nuclear Research of the HAS | And 2 more authors.
Journal of Radioanalytical and Nuclear Chemistry

Investigation of the effect of nuclear fuel rods to the composition of the dissolved gas in the cooling water of the cooling ponds of Paks Nuclear Power Plant is presented. Dissolved gases in coolant were measured for surveying the condition of the nuclear fuel remained in service pool No. 1 of reactor unit No. 2 after its incident in April of 2003. Two different experimental ways were applied in parallel for ensuring the better reliability of the results. © 2010 Akadémiai Kiadó, Budapest, Hungary. Source

Palcsu L.,Hungarian Academy of Sciences | Molnar M.,Hungarian Academy of Sciences | Major Z.,Hungarian Academy of Sciences | Svingor E.,Hungarian Academy of Sciences | And 3 more authors.
Journal of Radioanalytical and Nuclear Chemistry

As decay products, helium isotopes can clearly indicate the presence of tritium and alpha decaying isotopes in a closed system. This study presents the helium and neon measurements and their interpretation of long-term headspace gas investigations in L/ILW waste drums from Paks Nuclear Power Plant and closed vaults of the Radioactive Waste Treatment and Disposal Facility, Püspökszilágy, Hungary. Development of special sampling methods and preparation lines as well as isotope-analytical measurements of the headspace gas samples were done in the Hertelendi Laboratory of Environmental Studies in the ATOMKI. In the gas samples helium isotopes as well as neon isotopes have been determined mass spectrometrically. While neon content can be of atmospheric origin only, helium can be produced either by alpha decay ( 4He) or decay of tritium (3He). 3H/ 4He and He/Ne ratios have been used to determine the different origin of the helium isotopes. Helium isotope ratios always represented 3He enrichment in the headspace gases produced by the decay of the tritium in the waste. Using the recent 3He concentration in headspace gas the total amount of 3H restored in L/ILW vaults was estimated. The investigated seven different vaults were closed between 1979 and 1995 when they had been full with L/ILW. The calculated tritium activities based on the He measurements showed good agreement with the documented isotope inventory of the vaults. Typical tritium activity concentrations were between 0.1 and 10 Bq/L gas in the drums and between 10 and 1000 Bq/L gas in the vaults. Additionally, one drum showed a higher He/Ne ratio compared to air, which clearly indicates 4He excess, thus the presence an alpha source in the waste. © 2010 Akadémiai Kiadó, Budapest, Hungary. Source

Janovics R.,Hungarian Academy of Sciences | Kelemen D.I.,Debrecen University | Kern Z.,Hungarian Academy of Sciences | Kapitany S.,Public Ltd Company for Radiactive Waste Management | And 4 more authors.
Journal of Environmental Radioactivity

Tree ring series were collected from the vicinity of a Hungarian radioactive waste treatment and disposal facility and from a distant control background site, which is not influenced by the radiocarbon discharge of the disposal facility but it represents the natural regional 14C level. The 14C concentration of the cellulose content of tree rings was measured by AMS. Data of the tree ring series from the disposal facility was compared to the control site for each year. The results were also compared to the 14C data of the atmospheric 14C monitoring stations at the disposal facility and to international background measurements. On the basis of the results, the excess radiocarbon of the disposal facility can unambiguously be detected in the tree from the repository site. © 2015. Source

Keri M.,Debrecen University | Palcsu L.,Hungarian Academy of Sciences | Turi M.,Hungarian Academy of Sciences | Heim E.,Isotoptech Ltd. | And 3 more authors.

Alpha-cellulose is a part of the wooden material that preserves isotopic composition during tree-growth, and therefore provides important indirect data for paleoclimatological studies. For this reason, it is exceptionally important to extract the alpha-cellulose component from plants, e.g. from tree rings of wood. Since the cell wall of plant cells consists of multicomponent polysaccharides, the extraction of cellulose from wood is not an obvious task. In this paper, we describe, evaluate and compare nine methods, based on the literature and experimental observations, for obtaining cellulose from tree rings of wood. We show that the distortionless enhancement by polarization transfer (DEPT-135) variant of liquid-state 13C NMR spectroscopy is a powerful analytical method for monitoring the preparation process. Trifluoroacetic acid was applied as solvent for the NMR analysis. We proved that all the preparation methods give pure cellulose samples without hemicellulose and lignin content, and we propose methods resulting in non-fragmented cellulose. 13C and 18O isotope ratio measurements have shown that all the applied extraction methods result in similar isotope ratios, thus they are suitable for paleoclimatological studies. © 2015, Springer Science+Business Media Dordrecht. Source

Discover hidden collaborations