Estimation of intakes of 131I, 137Cs and 134Cs after the Chernobyl accident

Activities of (131)I and (137)Cs excreted in urine from two healthy males during May 1986, when contaminated air masses from Chernobyl arrived on the territory of the Czech Republic, were determined by bioassay. The data were used to estimate the intakes and committed effective doses from these radionuclides. The results for inhalation intakes are of particular interest, in the absence of sufficient contemporary data for airborne activity. They are found to be higher than initial estimates based on air sampling.     

Accuracy of field spectrometry in estimating 137Cs contamination in high altitude alpine soils

In situ gamma ray spectrometry is an attractive method for providing information on the concentrations of radionuclides in the soil. This method requires separate knowledge of the soil density and of the radioactivity distribution relative to soil depth. In-field gamma spectrometry measurements were performed together with sampling of the soil at the same site for subsequent gamma spectrometry analysis in the laboratory. Results of 137Cs concentration were compared in order to: (i) verify the effectiveness of in situ gamma spectrometry in averaging local inhomogeneties in the soil; and (ii) quantify the sensitivity of the gamma ray spectrometry soil radioactivity evaluation with respect to the variability of the depth profiles obtained from a single site sampling. The site of study is a high altitude pasture, in the Alpine environment.     

Decontamination of sandy soils from 137Cs by reagent treatment with agitation leaching

The simplest and the most efficient method for decontamination of sandy soils is separation of the finely dispersed fraction (<0.1 mm), with which ∼90% of the contaminating radionuclides are associated, by gravity sedimentation in water. However, for sandy soils from the Russian Research Centre Kurchatov Institute, the decontamination factor in this case is as low as 4–5. The decontamination factor can be further increased by using reagent treatment. The main parameters of the process are reagent composition and concentration, temperature, and liquid to solid ratio. The decontamination factor of 10–14 can be attained by reagent treatment with 2 M H₂SO₄ + 1 M H₃PO₄ or 3–4 M H₂SO₄ solutions for 7 h at 80°C, at the liquid to solid ratio of no less than 2 : 1. Two times higher decontamination factor can be attained by treatment with a 2 M H₂SO₄ + 0.6 M NH₄F solution, but high toxicity of fluorides restricts the possibility of using this reagent.     

Vertical distributions and gamma dose rates of 40K, 232Th, 238U and 137Cs in the selected forest soils in Izmir, Turkey

This paper presents the results obtained from a radioecological study carried out in the selected forest sites of Izmir, Turkey. The levels of gamma-emitting radionuclides, 40K, 232Th, 238U and 137Cs, in soils were determined using gamma spectroscopy. The activity profile for 40K, 232Th and 238U exhibits a uniform distribution with respect to depth. The depth distribution of 137Cs activity was established by fitting the experimental points to an exponential or a Gaussian function. About 42-97% of the 137Cs deposition was found in the first 10 cm of soil even after 18 y from Chernobyl accident. The dose-rate and annual-effective dose received from external irradiation were quantified. It is indicated that 137Cs from the fallout plays a less role in external radiation exposures in forest sites of Izmir than in potential exposures from naturally occurring radionuclides accounted for by soil.     

Cesium-137 contamination of soils in settlements of Leningrad oblast and assessment of data accumulated after the Chernobyl accident

The results of works performed in 2007 and 2008 to determine the contamination density (CD) of soil with ¹³⁷Cs and its depth distribution in 45 settlements of the Volosovo and Kingisepp raions of Leningrad oblast, affected by the Chernobyl accident, are reported. With the lognormal distribution of CD values assumed, the confidence ranges for the CD values averaged for specific settlements were estimated on the basis of the results of the above-mentioned works and of the whole set of data accumulated by now. The shortcomings of the Methodical Recommendations of 1990 as applied to the contamination conditions characteristic of Leningrad oblast are noted. In 35 of the 45 settlements surveyed, the volume of data accumulated by now is insufficient for making substantiated management and legal decisions. One of possible ways to make the studies less labor-consuming within the framework of the statistical model used is discussed.     

Determination of 137Cs in seawater under the field conditions

To monitor ¹³⁷Cs in seawater, Mikoton-Cs used for Cs sorption from highly saline liquid radioactive wastes was proposed. Sorption of ¹³⁷Cs on Mikoton-Cs was studied in relation to the S: L ratio, sorption time, and the temperature. The sorbent amount required to obtain a representative sample was determined. Two analytical procedures suitable for cesium determination under the field conditions were proposed.     

Aluminosilicophosphate geoceramics as matrices for the immobilization of partitioned 90Sr and 137Cs wastes

Immobilization of ⁹⁰Sr and ¹³⁷Cs in geoceramic matrices synthesized on the basis of phosphatized calcinate of simulated radioactive wastes and apatite ore dressing tailings is studied. The samples were sintered at 950–1150°C for 1 h. Leaching tests were carried out at 90°C with double-distilled water in the quasiflow and accumulative modes. The leaching was monitored by the conductivity of the liquid phase. To estimate the leaching rates R, the Na, Cs, and Sr concentrations were measured by flame photometry. The best samples of geoceramics are characterized by R of (5–15) × 10^?6 and <0.3 × 10^?6 g cm^?2 day^?1 with respect to Cs and Sr, respectively. Aluminosilicophosphate geoceramics show promise as materials for immobilization of partitioned ⁹⁰Sr and ¹³⁷Cs radioactive wastes.     

Reconstruction of Global 137Cs Concentration in Lake Onega

The dynamics of global ¹³⁷Cs content in Lake Onega in the past 25 years was reconstructed. Based on a sorption-diffusion model of ¹³⁷Cs behavior in the lake water-bottom sediment system, the decontamination of the lake water from ¹³⁷Cs as influenced by natural factors was analyzed.     

Global <Superscript>137</Superscript>Cs as a sediment marker in deep lakes

Global ¹³⁷Cs is used as a marker for identification of a bottom sediment layer whose age corresponds to the maximal contamination of the hydrosphere with radiocesium in 1964. This method allowed determination of the current sediment accumulation rate in deep lakes. For an Arctic lake with the maximal depth of 110 m (Central Taimyr), the sediment accumulation rate is estimated to be 0.8–3.0 mm/year. The relatively long lifetime of ¹³⁷Cs (30 years) is sufficient to provide long-time monitoring of the sedimentation of nonradioactive materials in deep lakes.     

Formation and dynamics of propagation of radioactive contamination in rivers of belarus after the chernobyl nuclear accident

The formation of radioactive contamination in rivers in Belarus caused by the Chernobyl nuclear accident is analyzed, the peculiarities of monitoring in the experimental Iput catchment are described, a conceptual model of radionuclide migration in the river system is suggested, calculations are carried out, and experimental data and calculation results on transfer of radioactive contamination of terrestrial surface water are analyzed. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 1, pp. 73–80, January–February, 1997.     

Intensity of transmitted photon spectra as a function of transverse and longitudinal dimensions of soil medium using 137Cs

Transmitted photon spectra (pulse-height distribution) of (137)Cs gamma rays are measured through longitudinal and transverse dimensions of the soil medium. The intensity (photon fluence rate) of the multiple-scattered peak, appearing in the lower energy part of the spectrum, has been studied as a function of longitudinal as well as transverse thickness of the soil medium. The intensity of multiple-scatter peak decreases exponentially with the increase in longitudinal thickness of the soil medium, whereas a reverse trend of multiple-scatter peak intensity with transverse thickness occurs as the longitudinal dimension increases. The soil medium as a whole takes part in multiple scattering affecting the intensities of transmitted photons.     

Levels of 90Sr and 137Cs in the urine of Finnish people

The aim of this study was to estimate the current concentrations of 90Sr and 137Cs in the urine of Finnish people and to estimate the doses. Two to three daily urine samples were collected from 18 adult Finnish volunteers in connection with studies of 137Cs body burdens in 1999-2001. The 90Sr activities in urine varied between 1.4 and 11 mBq l(-1). The 137Cs activity in urine varied between 0.36 and 56 Bq l(-1). The daily urinary excretion was found to be 4.8-17 mBq for 90Sr and 0.81-68 Bq for 137Cs. Assuming that the daily 90Sr intake was constant and that 18% of the ingested activity was excreted in urine, the mean intake in the investigated group would vary between 27 and 96 mBq d(-1). Based on these estimated intake values, the respective annual effective internal doses from 90Sr and 90Y varied from 0.3 to 1.0 microSv and from 137Cs from 4 to 350 microSv during the sampling period.     

Measurement of the whole-body 137Cs in residents around the Chernobyl nuclear power plant

To understand the current situation of internal radiation exposure in the population around the Chernobyl Nuclear Power Plant (CNPP), we examined the 137Cs body burden in six residents of Belarus, Ukraine and Russia in 2002 and 2004 using the whole-body counter (WBC) at Nagasaki University (Japan). The data were compared with those of our previous study performed in 1993-1994 using the same method. In 2002 and 2004, peaks of 137Cs were detected in two residents from Gomel, which was heavily contaminated by the CNPP accident, one from Minsk (Belarus) and one from Kiev (Ukraine), but another resident from Minsk showed no 137Cs peaks. The results of the present study suggests that residents around the CNPP are still exposed to chronic 137Cs internal irradiation, probably due to the daily consumption of contaminated domestic foods, but the risk of any disease by the irradiation is quite low. Long-term follow-up of WBC around the CNPP is useful and may contribute to radiation safety regulation together with a reduction of unnecessary radiophobia for the residents.