István Futó

Diffusion of 3H, 99Tc, 125I, 36Cl and 85Sr in granite, concrete and bentonite

Understanding the characteristics of diffusion is essential in the assessment of radionuclide release through the backfill of waste repository. The diffusion behavior of 3H, 99Tc, 125I, 36Cl and 85Sr in granite, concrete and bentonite was studied in a specially designed diffusion cell. Diffusion coefficients (D, Da) and time-lag (ta) were measured, break-trough curves were plotted and experimental data were interpreted to predict diffusion rates. The results showed that tritium, iodine and chlorine could be considered as non-sorbing tracers, while technetium was weakly and strontium was strongly sorbed (no break-through was observed during the period of the experiments).

Concentration of radiocarbon and its chemical forms in gaseous effluents, environmental air, nuclear waste and primary water of a pressurized water reactor power plant in Hungary

We measured airborne releases of 14C from the Paks Pressurized Water Reactor (PWR) Nuclear Power Plant (NPP).Ttvo continuous stack samplers collect 14C in 14C02 and 14CnHm chemical forms. 14C activities were measured using two techniques; environmental air samples of lower activities were analyzed by proportional counting, stack samples were measured by liquid scintillation counting. 14C concentration of air in the stack varies between 80 and 200 Bqm-3. The average normalized yearly discharge rates for 1988-1993 were 0.74 TBqGW11yy-11 for hydrocarbons and 0.06 TBqGW11yy-11 for CO2. The discharge rate from Paks Nuclear Power Plant is about four times higher than the mean discharge value of a typical Western European PWR NPP. The higher 14C production may be apportioned to the higher level of nitrogen impurities in the primary coolant. Monitoring the long-term average excess from the NPP gave D14C = 3.5%o for CO2 and D14C = 20%o for hydrocarbons. We determined 14C activity concentration in the primary coolant to be ca. 4 kBq liter-1. The 14C activity concentrations of spent mixed bed ion exchange resins vary between 1.2 and 5.3 MBgkg-1 dry weight.

Monitoring of atmospheric excess 14C around Paks nuclear power plant, Hungary

The activity of radiocarbon in 14CO2 and 14CnHm chemical forms is measured in the vicinity of Paks nuclear power plant (NPP), Hungary, by sampling environmental air. Four differential sampling units at different sites collected samples less than 2 km away from the 100-m-high stacks of Paks NPP, and for reference a sampler was operated at a station ~30 km away from Paks NPP. We present the results of continuous observations at the 5 stations covering the time span from 2000 to 2005. The samples have been analyzed by a proportional counting technique. During a cleaning tank incident at unit 2 of Paks NPP in April 2003, a significant release of radioactive isotopes took place from the damaged fuel assemblies, and gaseous products escaped through the chimney. We evaluate the possible short- and long-term impact of this incident on the 14C content of the atmosphere in the surroundings of Paks NPP. Comparing our 14CO2 measurements with data sets from Jungfraujoch and Schauinsland, as well as from Koetice (Czech Republic), we demonstrate that the incident had no definite influence on the 14C content of the atmosphere.

Re-Evaluation of the Neolithic in Eastern Hungary Based on Calibrated Radiocarbon Dates

The chief objective of this paper is to improve our understanding of the Neolithic in Eastern Hungary using absolute chronological data. To accomplish this we calibrated new measurements as well as previously published dates. The up-to-date, standardized evaluation of 261 calibrated measurements showed temporal overlaps between archaeological cultures defined on the basis of ceramic styles. The increasing number of dates suggest that the Neolithic period began at the turn of the 6th and 7th millennia BC and lasted for ca. 1500 yr in the present area of the Great Hungarian Plain (Alfold). Further research should be aimed at complementing the current data set with dates from western Hungary and establishing additional correlations among stratigraphic, typological and radiocarbon dates.

Effect of sample pressure on membrane inlet mass spectrometry

Abstract The effect of sample pressures up to 6 bar on the signal of a membrane inlet mass spectrometer was studied with supported and unsupported membranes of silicone rubber. In both cases we found undesirable pressure effects. With a supported membrane increasing sample pressure causes a reduction of the signal. This is because lateral diffusion of analyte in the interstitial space between the membrane and the membrane support contributes to the transport of analyte to the mass spectrometer, and the space available for this diffusion is increasingly compressed by increasing sample pressure. With an unsupported membrane increasing sample pressure causes an increasing signal, which is caused by the fact that an unsupported membrane bulges increasingly with increasing sample pressure. The consequently increased area and decreased thickness of the membrane results in increased flux of analyte. Bulging depends strongly on the diameter of the unsupported membrane area and on the thickness of the membrane. With a 0.185 mm thick membrane spanning a circular hole of 1 mm diameter the bulging is minimal and there is no significant aberration due to sample pressure up to 2 bar. With a larger diameter, a larger pressure or a thinner membrane, significant aberrations occur including change of relative selectivity to polar and unpolar analytes and hysteresis when the pressure is changed up and down. These effects are due to non-linear elastic deformation of the membrane. The effects described should be taken into account in the design of membrane probes for systems where pressure changes may occur.

Duration of tell settlements at four prehistoric sites in Hungary

The chief objective of this paper is to improve our understanding of the Neolithic in eastern Hungary using absolute chronological data. To accomplish this we calibrated new measurements as well as previously published dates. The up-to-date, standardized evaluation of 147 calibrated measurements showed temporal overlaps between archaeological cultures defined on the basis of ceramic styles. The average timespan of tell settlements of 285 yr was obtained using radiocarbon dates from four major settlements in eastern Hungary: Berettyoujfalu-Herpaly, Hodmezovasahely-Gorzsa-Cukortanya, Ocsod-Kovashalom and Polgar-Csoszhalom.

Performance test of a new graphite target production facility in ATOMKI

We present our new graphite target production system, developed in the Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), for accelerator mass spectrometry (AMS) radiocarbon dating measurements. The system consists of a gas handling line and a graphite target production system. Results of AMS measurements, stable isotope mass spectrometry measurements, and gravimetric/pressure yield determinations have been used to find the proper conditions for the graphitization process. We have also investigated the C-14 contamination and the memory effect of the system during the graphitization processes. This paper covers the details of these experiments and a discussion of the results.

Dating of total soil organic matter used in kurgan studies

We investigated Csipo-halom, one of the kurgans that served as a burial place in the Hortobagy area of the Hungarian Great Plain. For pedological description and other studies of the protected mound and its surroundings, only a few monitoring drillings were permitted to get soil samples. On the basis of morphological and visual studies, the structure and layers of the mound were reconstructed. The Laboratory of Environmental Studies of the Institute of Nuclear Research at the Hungarian Academy of Sciences (INR/HAS) performed radiocarbon measurements of soil samples, applying a bulk combustion pretreatment method. The measured (super 14) C ages of soil samples from reference points, such as the top layer of the mound, the center of mound body, the base layer of the mound, the near surroundings, and the distant surroundings, are in good agreement with the preliminary archaeological concept for this field and give substantial information about the rate of soil generation processes in this area.

Metal container instead of glass bulb in tritium measurement by helium-3 ingrowth method

ABSTRACT The performance of a mass spectrometric system for measurement of tritium by 3He ingrowth method is described. Preparation and measurement includes three steps. The first step is to pump the dissolved gas from the environmental water samples stored in special glass bulb. The second step is the storage of the degassed water for a few months. In the final step the helium-3 formed from tritium is measured by mass spectrometer. In the course of tritium measurement there were some difficulties with the glass bulbs, such as pre-treatment of the glass, storage of the samples in deep freezer, long storage time, O-ring sealing. To solve these problems metal bulbs were built and applied with volume of six litres. The metal bulb was equipped with a metal valve. Three litres of water can be filled into the metal bulb. The large volume of the bulb causes an increase of degassing time, and a decrease of the storage time. The degassing of three litres of water needs twice one and a half hours in two days. The storage time is only two months in contrast to the half-year storage time of glass bulb. The background, the helium penetration from the air is less than using glass bulbs, because the metal bulb can be fitted to the inlet system via copper gasket instead of elastic O-ring.

Application of a noble gas mass spectrometric system in environmental studies

Abstract In environmental research, the measurements and evaluation of the isotope ratios represent an important step in explanation of many processes. There are nuclear processes in the environment where stable noble gas isotopes as well as alpha- and beta-decay or spontaneous fission are generated. Therefore, the isotope ratio and concentration can change to such a pitch that notable explanation about these processes can be given in the course of the evaluation of isotope ratio values. The most often used measurement is the tritium–helium method to determine the tritium concentration of water by 3 He ingrowth. The noble gas isotope ratios can be measured from dissolved gas of groundwater or headspace gases. The measurement is done by a VG5400 noble gas mass spectrometer.