János Somlai

Dependence of radon emanation of red mud bauxite processing wastes on heat treatment.

Natural radioactivity content, radon emanation and some other physical characteristics of red mud were investigated, so that to identify the possibilities of the safe utilization of such material as a building material additive. Based on the radionuclide concentration, red mud is not permitted to be used directly as a building material, however, mixing of a maximum 20% red mud and 80% clay meets the requirements. The main aim of this work was to determine the dependence of the emanation factor of red mud firing temperature and some other parameters. The relevant experimental procedure was carried out in two different ways: without any additional material, and by adding a known amount of sawdust (5-35 wt%) then firing the sample at a given temperature (100-1000 degrees C). The average emanation factor of the untreated dry red mud was estimated to 20%, which decreased to about 5% at a certain heat treatment. Even lower values were found using semi-reductive atmosphere. It has been concluded that all emanation measurements results correlate well to the firing temperature, the specific surface and the pore volume.

Concentration of 226Ra in Hungarian bottled mineral water.

Concentration of the radionuclide 226Ra was determined in almost every type of bottled mineral water commercially available in Hungary. Determination of the radon coming from the radium dissolved in the water was used for activity measurement. As the results show, the 226Ra concentrations exceed the level of 100 mBq l(-1) in six cases out of the 28 types of mineral water investigated. In one case 3 Bq l(-1) was measured, which provides 0.3 mSv year(-1) committed effective dose for adults in the case of a consumption rate of 1 l day(-1). In soft drinks produced from mineral water a concentration of 2.6 Bq l(-1) was determined, which means 1.4 mSv year(-1) effective dose in the age group 12-17 years in the case of permanent daily drinking of 1 l of these beverages.

Radiation Hazard of Coal-Slags as Building Material in Tatabanya Town (Hungary)

High concentrations of 226Ra (865-2,383 Bq kg(1)) were measured in the coal-slags, originated from the region of the settlement Tatabánya, Transdanubian Middle Mountains, Hungary. These slags are commonly used as building materials in this district. The external gamma dose rate was measured in 188 rooms at different heights above the floor. In 124 rooms with slags used for construction, the average absorbed dose rate was 296 nGy h(-1). In 10 apartments the average radon concentration was 502 Bq m(-3). In that case the estimated effective dose due to inhaled radon and its progeny and gamma radiation was 10.3 mSv y(-1).

226Ra and 222Rn concentrations of spring waters in Balaton Upland of Hungary and the assessment of resulting doses

Abstract222Rn and 226Ra concentration of 18 frequently visited and regularly used, consumed spring waters on the Balaton Uplands have been measured by radon emanation method and alpha-spectrometry. 222Rn concentration varied between 1.5-55 Bq/l while 226Ra concentration between -601 mBq/l. The expected dose, between 14.1-119 mSv/y, has been assessed from the value of concentration supposing a daily consumption of 1 liter.

Preliminary results from an indoor radon thoron survey in Hungary

More than half of the radiation dose of natural origin comes from radon. However, according to some surveys in certain cases, the radiation dose originating from thoron may be considerable. Among the factors disturbing the measurement of radon, the presence of thoron may also influence the measured radon value, making the estimated radiation exposure imprecise. Thoron has previously been surveyed, mainly in Asia; however, recent surveys for some European locations have found that significant thoron concentrations also need to be considered. In this survey, several types of commercially available SSNTDs (solid-state nuclear track detectors) capable of measuring both radon and thoron were placed at the same time in 73 houses and 7 workplaces in Hungary with 3-month exposition periods. In order to measure thoron, the distance of the detector sets was fixed as 15-20 cm from the walls. The radon concentration was measured with five types of SSNTDs: NRPB, NRPB SSI, Raduet, DTPS and DRPS. The first four types had relatively good accordance (within ± 10 %), but the results of the DRPS detectors were considerably lower when compared with other detectors for radon concentrations over 100 Bq m(-3). The thoron averages were provided by two different types of detectors: Raduet and DTPS. The difference between their average results was more than 30 % and was six times the maximum values. Therefore, the thoron measurement results were judged to be erroneous, and their measurement protocol should be clearly established for future work.

Radiation dose contribution from coal-slags used as structural building material

A significant dose contribution on the population could be derived from coal slags used as isolation material. Extremely high natural activities are measured in the coal slag, derived from the region of the settlement Ajka, Hungary. In some buildings monitored, the elevated γ-doses were nearly 5–10 times higher than the world average ones. The annual average indoor radon concentrations from the slag exceeded 400 Bq/m3 and in some cases up to 1200 Bq/m3. Due to the elevated exposure and the radon concentrations in the dwellings the annual dose was estimated to 8–24 mSv/y more than 5–10 times of the world average one.

A sedimentation study of St. Ana Lake (Romania) applying the 210Pb and 137Cs dating methods

The biggest problem with most lakes that have no contact with other water sources and are being charged by precipitation is the massive eutrophication. The aim of this work was to determine the sedimentation rate in order to evaluate the progress of eutrophication for St. Ana Lake (Ciomad Mountain near the Băile Tuşnad in Harghita County (Romania)). The concentration of 210Pb was determined by means of high resolution gamma spectrometry as well as derived from 210Po activity which was measured through alpha spectrometry; values obtained are in good agreement. For the excess 210Pb activity values between 4.0±0.5 Bq/kg and 218±20 Bq/kg have been found. As an alternative method, the 137Cs dating method was applied as well. Calculated mass sedimentation rates are in the range of 0.06±0.01 to 0.32±0.05 g/cm2 year with a mean of value of 0.15±0.02 g/cm2 year. Linear sedimentation rates yielded much higher sedimentation values (between 0.5±0.1 and 7.9±0.7 cm/year with a mean of 2.4±0.6 cm/year), due to the predominant organic matter composition and the long suspension time of the sediment. This is an indication for the process of eutrophication which will probably lead to the transformation of the lake into a peat bog.

Study on endocronological effects of radon speleotherapy on respiratory diseases

Background: Radon, as a radioactive noble gas of natural origin, is generally present in the atmosphere of caves during the speleotherapeutic treatment of different diseases. However, the role of radon in the therapeutic effect is not fully clarified yet. Endocrine parameter levels may be influenced by radon-like endocrine levels in balneotherapeutic treatments (bath treatment). For this reason changes of these parameters were examined in this study. Patients and method: A total of 81 speleotherapy patients were involved in the survey. They spent four hours daily in Tapolca Cave, five days a week, for two weeks. In this study, the thyreoiedea stimulating hormone, free triiodine-tironin, free thyroxine, prolactine, cortisol, dehydroepiandrosterone sulphate, adrenocorticotropic hormone, and beta endorphine levels of the body were examined before and after the treatment. Results: After statistical analysis of the data a significant decrease of cortisol levels of patients was found, which was not directly correlated with radon concentration. In the case of thyroid hormones, there were no significantly detectable changes of the hormone levels except for low radon concentration levels a significant decrease in the free thyroxine and the thyreoiedea stimulating hormone level of male patients was observed. Conclusion: Speleotherapy has an effect on the level of endocrine hormones; however, no direct correlation with differences in radon level was found. For patients whose endocrine levels fell outside the normal endocrine parameter values, more striking changes in endocrine hormone levels were seen, but changes of these parameters could not be statistically analyzed due to the small number of cases.

Hydrodynamics of the effectiveness of the AP-CITROX decontamination technology

During the optimization of the AP-CITROX decontamination technology the effect of the different flow rates of the decontamination solutions on the radioactive contamination and corrosion state of stainless steel tube samples originating from steam generators of Paks NPP were studied by a pilot-plant circulation system. The results have proved that a significant increase (up to 2.89 m/s) in the flow rate of the decontamination solution in the 1-5 steps is highly recommended and in order to improve the passivity of the surfaces it should be kept as low as possible (0.5 m/s) during the passivation.

DOSE CONTRIBUTION FROM SCHOOL BUILDINGS CONTAINING COAL SLAG INSULATION WITH ELEVATED CONCENTRATIONS OF NATURAL RADIONUCLIDES

Coals mined in some regions of the Transdanubian Middle Mountains in Hungary have elevated concentrations of natural radionuclides as238U,226Ra, etc. Therefore, coal slags and ashes used for insulation of the school buildings may lead to high dose contributions on the students. In the city of Tatabánya one school was found where the external dose rates in the classrooms were of 500–900 nGy/h. In spite of the high external dose rates, the radon concentrations measured were small usually less than 100 Bq/m3.