H. Lettner

In-situ gamma-spectrometric measurement of the contamination in some selected settlements of Byelorussia (BSSR), Ukraine (UkrSSR) and the Russian Federation (RSFSR)

Abstract As a part of the International Chernobyl Project in-situ gamma-spectrometric measurements were performed in some contaminated areas of the USSR in the summer of 1990. A new method for the determination of radionuclide distribution in the soil was first applied during the mission. The results of the analyses were found to be in good agreement with data obtained by other investigators as well as with the official contamination data reported by the USSR authorities. 137 Cs, 134 Cs, 144 Ce, 104 Ru, 125 Sb and 60 Co isotopes were detected in the investigated areas, the first two nuclides being predominant from a dosimetric point of view. 137 Cs concentrations ranging 150–1200 kBq/m 2 were found, with a typical depth distribution relaxation length of 2–3 cm and the depletion phenomenon in the top soil layers, predicted by the model calculations, was also empirically confirmed.

Accumulation of anthropogenic radionuclides in cryoconites on Alpine glaciers.

Cryoconites are airborne sediments which accumulate on the surface of glaciers. In samples of cryoconites a temperate Austrian glacier high activity concentrations of anthropogenic radionuclides were found, which stem from global and Chernobyl fallouts. Radionuclides identified were (137)Cs, (134)Cs, (238)Pu, (239+240)Pu, (90)Sr, (241)Am, (60)Co, (154)Eu, (207)Bi, and (125)Sb. Given the approximately known isotopic ratios, Cs and Pu can be separated into the contributions of either source of origin. Published (137)Cs/(134)Cs and (239+240)Pu/(238)Pu ratios were used for the discrimination of the Dachstein-glacier cryoconites according to their origin from global or Chernobyl fallout. Two different groups of cryoconites were identified, an older population dominated by nuclear weapons fallout and a younger one with predominant Chernobyl fallout. With those data a simple model was formulated to demonstrate the transition and mixing of these two populations on the glacier surface.

90Sr and 137Cs in environmental samples from dolon near the semipalatinsk nuclear test site

The (90)Sr and (137)Cs activities of soil, plant, and milk samples from the village of Dolon, located close to the Semipalatinsk Nuclear Test Site in Kazakhstan, were determined. The areal deposition at the nine sampling sites is in the range of <500 to 6,100 Bq m(-2) and 300 to 7,900 Bq m-2 for (90)Sr and (137)Cs, respectively. Similar values have been reported in the literature. At some of the sites both nuclides mainly have remained in the top 6 cm of the soil profiles; at others they were partly transported into deeper soil layers since the deposition. For most of the samples the (90)Sr yield after destruction of the soil matrix is significantly higher than after extracting with 6 M HCl indicating that (90)Sr is partly associated with fused silicates. The low mean (90)Sr activity concentrations of vegetation samples (14 Bq kg(-1) dw) and milk samples (0.05 Bq kg(-1) fw) suggest that this has favorable consequences in terms of limiting its bioavailability.

Occupational exposure to radon in treatment facilities of the radon-spa Badgastein, Austria

In the spa Badgastein, Austria, radon is used for therapeutic purposes for various diseases. Radon inhalation is applied in a thermal gallery with atmospheric radon concentrations up to 100 kBq/m3, elevated temperature up to 41°C, and humidity close to 100%, or in the form of radon baths where Rn is emanated from water with high natural Rn activity. Frequently, a combination of both treatment procedures is applied. The high environmental radon concentration levels in the thermal gallery, and in the various radon baths, can result in elevated radiation exposure levels, subject to significant local and temporal changes. Particularly in Rn-baths, the treatment procedures can result in high Rn levels or peaks during the use and replacement of Rn-water. For the assessment of the occupational exposure, a combination of long- and intermediate-term integrating Rn-measurements and continuous Rn and Rn-progeny measurements was used to investigate six different treatment facilities. Long-term integrating Rn-measurements, over a period of 1–13 months, provide reliable average Rn-concentration. However, these values cannot be used directly for the dose calculation of individuals due to the short-term fluctuation of the radiation exposure. Parallel integrating and continuous Rn-measurements and continuous Rn-daughter measurements were made to calculate personal occupancy weighting factors and Rn-equilibrium factors to determine potential alpha energy concentration exposure of daytime personnel.

In situ gamma-spectrometry intercomparison exercise in Salzburg, Austria

Abstract In situ gamma-spectrometry has become a useful method of assessing the nuclide concentrations of man-made and natural gamma-emitters in the soil. For the quality assurance of the measurements, periodically conducted intercomparison exercises are essential. Therefore exercises were organized in different European countries since 1990, the last one was conducted in Salzburg, Austria in September 1994. The participation of 27 measurement teams from all over Europe emphasizes the importance of the intercomparison. Salzburg was selected because the Province of Salzburg, Austria was among the most heavily contaminated regions outside the former USSR by the Chernobyl fallout. Two different typical sites were selected for the measurements: Site 1 was inside the urban area of Salzburg on intensively used grassland which had not been tilled since the deposition of the fallout. This site is representative for intensively used agricultural regions in the Province of Salzburg. Site 2 was in the mountainous regions of the Hohe Tauern at an elevated altitude of 1600 m, representing the agricultural soil- and contamination conditions of the Alpine regions in the Tauern. The two sites differ significantly in terms of soil characteristics, a crucial parameter for the evaluation of in situ gamma-spectra. The participants used different approaches for the evaluation of the gamma-spectra in terms of considering the depth distribution. In the paper the results from the 24 European teams are presented.

The Austrian Radon Project

Abstract The aim of the Austrian Radon Project (ARP) is to investigate the 222Rn concentration in 0.3-0.5% of all Austrian dwellings to identify areas with elevated radon exposure. The survey is carried out using short-term and long-term integrating radon detectors covering a population of 2 800 000 persons so far. The homes were randomly selected from the telephone directory. The radon concentration distribution showed a log-normal shape. County-means between 60 and 330 Bq/m3 were found. A radon potential was introduced to deduce a geological risk from the data taken under different circumstances in different types of houses. This radon potential was defined as the annual mean radon concentration in a standard dwelling and is computed by normalizing the measured radon data to this standard dwelling.

Biophysical mechanisms and radiation doses in radon therapy

Publisher Summary This chapter explores the different routes of radon and radon progeny transport from radon-rich water and air to sensitive target cells and tissues for the specific exposure conditions, as they exist in the radon spas Bad Gastein and Bad Hofgastein, Austria. While radon progeny adsorption was hardly affected by the degree of blood circulation and greasiness of the skin, a significant dependence on the pH-value could be observed, with a distinct maximum deposition around 6 to 7. The penetration of radon progeny into the skin was measured by removing several cell layers, revealing a roughly exponential activity distribution in the upper layers of the skin. The transport of radon through the skin into the blood was determined via radon concentration measurements in the exhaled air of the patients. Calculations of doses to different target organs suggest that radon progeny attachment on skin surfaces may play a major role in the therapeutic response for both treatment schemes, while bronchial doses lie well within the natural fluctuations of the doses received by the population, thus causing no additional radiation hazard to the patients undergoing such treatments.

Real-time analysis of endogenous protoporphyrin IX fluorescence from δ-aminolevulinic acid and its derivatives reveals distinct time- and dose-dependent characteristics in vitro

Abstract. Photodynamic therapy (PDT) and photodiagnosis based on the intracellular production of the photosensitizer protoporphyrin IX (PPIX) by administration of its metabolic precursor δ-aminolevulinic acid (ALA) achieved their breakthrough upon the clinical approval of MAL (ALA methyl ester) and HAL (ALA hexyl ester). For newly developed ALA derivatives or application in new tumor types, in vitro determination of PPIX formation involves multiparametric experiments covering variable pro-drug concentrations, medium composition, time points of analysis, and cell type(s). This study uses a fluorescence microplate reader with a built-in temperature and atmosphere control to investigate the high-resolution long-term kinetics (72 h) of cellular PPIX fueled by administration of either ALA, MAL, or HAL for each 10 different concentrations. For simultaneous proliferation correction, A431 cells were stably transfected with green fluorescent protein. The results indicate that the peak PPIX level is a function of both, incubation concentration and period: maximal PPIX is generated with 1 to 2-mM ALA/MAL or 0.125-mM HAL; also, the PPIX peak shifts to longer incubation periods with increasing pro-drug concentrations. The results underline the need for detailed temporal analysis of PPIX formation to optimize ALA (derivative)-based PDT or photodiagnosis and highlight the value of environment-controlled microplate readers for automated in vitro analysis.

Quantification of radon-progeny deposition on the skin in underwater radon-therapy

Publisher Summary For the theoretical calculation of the deposition dynamics, reliable and quantifiable results of progeny measurements on the skin are of fundamental importance. Immediately after leaving the bath tub, the skin of the patients was gently dried by dabbing it with towels and alpha detectors were fixed to the skin by elastic bands. For radon decay product (Rnp) measurements, they used surface barrier detectors directly in contact with the skin, only protected by a mylar foil. The activity decay curve and the alpha spectrum were measured for a period of 30 minutes after the exposure phase, starting approximately 3 minutes after leaving the bath tub. Though the detectors are almost in direct contact with the skin, on that the alpha particles are deposited, a strong distortion of the spectra could be observed. This chapter assumes this effect to be a combination of absorption and migration of the progeny into the skin. With model assumptions on the migration behavior and the production of sweat during the measurement, this chapter tried to interpret the shape of the spectra, to obtain quantitative measurements of the radon progeny on, and in, the skin.

Radiometric measurements in selected settlements in Byelorussia and the Ukraine

Abstract During the assessment of the radiological consequences from the Chernobyl accident, radiometric surveys of Bragin (BSSR), Polesskoje and Ovruc (UkrSSR) have been carried out. The gamma exposure pattern was found to be rather uneven with gamma exposure rates ranging from almost background values up to 3 μSv/h and extremely high values found at hot spots at numerous sites. This fluctuation is due to the unhomogeneous initial deposition pattern and to countermeasures, which usually caused a significant reduction of the dose rate. Indoor gamma dose rate values were found not to be significantly elevated, even in urban areas with increased deposition levels like Polesskoje.