Characteristics of radionuclide contamination of different zones of Semipalatinsk Nuclear Test Site “Opytnoe pole”

Data on the spatial distribution of radionuclides (²⁴¹Am, ²³⁹Pu, ¹³⁷Cs and ¹⁵²Eu) formed during nuclear explosions of different types near P2 SNTS test site are presented. Radionuclide contamination induced by the explosions varies in the concentrations of individual radionuclides, their proportions and species. Examination of the variations is a crucial task to plan remediation activities as well as those aimed at decrease of radiation risk for population and prevention of repeated contamination. Concentrations of ²⁴¹Am and ^239+240Pu that are the most toxic radionuclides in the area lie in hundred thousands of Bqkg^?1. The most contaminated areas are classified by the radionuclide concentration, ratio and form present in soil.     

Study of removal processes of <Superscript>7</Superscript>Be and <Superscript>137</Superscript>Cs from the atmosphere

In order to understand better the way in which radioactive contamination may be transferred from the atmosphere to other ecological compartments it is necessary to obtain information of the deposition mechanisms of radionuclides. Concentration and speciation of ¹³⁷Cs and ⁷Be in the atmospheric aerosol and deposition were studied. The mixed deposition velocities of water-soluble and insoluble ¹³⁷Cs and ⁷Be were determined. The relation between activity concentrations of insoluble ⁷Be in the atmosphere and its amount in deposition was observed. It is supposed that in the deposition process of radiocesium the precipitation plays an important role in scavenging of water-soluble radiocesium by falling raindrops, in contrast to insoluble ¹³⁷Cs where the dry deposition becomes predominant.     

Present status and trends of radioecological research

Radioecology can be defined as the science concerned with the interactions between radionuclides and the environment and with the effects of radionuclides on man and biotic communities. Ecology advanced from radioecological studies because tracer radionuclides were instrumental in understanding many ecological processes. During the period of fallout from nuclear weapons testing the behaviour of the most important radionuclides (typically:⁹⁰Sr,¹³¹I,¹³⁷Cs,^239,240Pu) in the most critical pathways was studied. After the Chernobyl accident studies were extended to natural and semi-natural ecosystems and to other less common radionuclides. In principle the implementation of radiation protection criteria for man, which are based on the protection of a single individual, assures the protection of organisms other than man. In case of serious contamination scenarios there is a need for realistic evaluations of the effectiveness of the countermeasures that could be undertaken. In particular, studies on biogeochemical transfer mechanisms which control the cycling of radionuclides should be developed. With reference to future developments of the nuclear industry, some attention should be paid to the operation and the releases from, e.g., intrinsically safe reactors and fusion plants. Besides such potential new-type sources, the decontamination and possible site restoration of military installations has to be considered.     

Speciation of radionuclides of the Chernobyl origin in aerosol and soil samples

Speciation of^134,137Cs,⁹⁰Sr,²³⁴U,²³⁸U,²³⁸Pu,^239,240Pu and²⁴¹Am was investigated in aerosol samples collected after the Chernobyl accident and in the Chernobyl soil. Sequential extraction experiments have shown a wide range of association of radionuclides, depending on sources, transformation perculiarities and radionuclide nature. Changes in speciation of¹³⁷Cs and⁹⁰Sr at various temperatures in the Chernobyl soil were analyzed. It was found that at 200°C–700°C a transformation of speciation of¹³⁷Cs took place and more available physico-chemical forms of Cs were formed. After heating at 900°C, up to 94% of¹³⁷Cs was found in the residual form and was not extractable even with 7 M HNO₃. Heating of the soil to 450°C and 900° C resulted in the formation of less available forms of⁹⁰Sr.     

Measurement of 137Cs in cultivated soils from two loess areas in Poland

In this paper, a vertical distribution of ¹³⁷Cs in agricultural soil was investigated. ¹³⁷Cs is an anthropogenic radioisotope which is strongly adsorbed in soil and can be used to study soil erosion. This paper presents some preliminary results of measurements of activity of ¹³⁷Cs in soil in Bia?a and Odonów areas. In both areas, the upper part of the soil profile was cultivated. The experimental results show that the vertical distribution of ¹³⁷Cs in agricultural soil is different from the vertical distribution of ¹³⁷Cs in undisturbed soil. The ¹³⁷Cs is more uniformly distributed in the cultivated soil layer than in an undisturbed site. Migration of ¹³⁷Cs below plough depth is limited. These data show that the depth distribution of ¹³⁷Cs in soil profiles for cultivated fields should be considered for precise determination of soil erosion.     

Soil depth profile of 137Cs, 210Pb and 40K in Algeria

ABSTRACT

Three soil depth profiles of ²¹⁰Pb, ¹³⁷Cs and ⁴⁰K at different areas of Algeria were studied. The soil sampling areas are near the location where the French nuclear tests took place at 1960–1966. The two depth soil profiles were collected at Ghardaia region and the third one at Reggane region. The vertical distributions of radionuclides at the two soil depth profiles from Ghardaia region are different, probably due to the different soil composition. The soil depth profile from sandy soil show uniformity in the distribution of radionuclides without a clear maximum (peak). The soil depth profile that characterised by silty sand show a clear peak at 20–50?cm depth for all studied radioactive nuclides, while the observed activities are two times higher than the corresponding values in sandy soil samples. More specifically in Ghardaia region the ²¹⁰Pb, ¹³⁷Cs, ⁴⁰K activity concentrations ranged between 27 and 50?Bq?kg^?1, 0.2 and 3?Bq?kg^?1 and 75 and 90?Bq?kg^?1 respectively in sandy soil type and between 37 and 75?Bq?kg^?1, 4 and 6?Bq?kg^?1 and 140 and 180?Bq?kg^?1 respectively in silty sand soil type. Finally, the third depth soil profile collected from Reggane site presents a completely different distribution of the studied radionuclides. The activity concentrations of ²¹⁰Pb, ¹³⁷Cs, ⁴⁰K ranged between 37 and 51?Bq?kg^?1, 0.16 and 0.39?Bq?kg^?1 and 120 and 309?Bq?kg^?1 respectively. Three peaks in the ¹³⁷Cs distribution revealed, were most probably, Chernobyl related ¹³⁷Cs accounts for the surface peak, while the deeper peaks are connected to the weapons fallout.     

Radioactive contamination of the atmosphere of Cairo,Egypt, from the Fukushima Dai-ichi nuclear plant accident

Radioactive contamination in air dust particles of Cairo atmosphere from the Fukushima accident was detected by the gamma-ray spectroscopy technique. Analysis of the spectra obtained by using an High-Purity Germanium detector showed that there were some traces of ¹³¹I and ^{134, 137}Cs. Estimate and study of concentration of those radionuclides were done over a period of about 5 months after the accident. Comparison with corresponding results in different countries all over the world has been performed.     

Cross-calibration between beta and gamma sources using quartz OSL: Consequences of the use of the SAR protocol in optical dating

The radiation dose delivered by the ⁹⁰Sr beta source of a TL-OSL reader and the one delivered by a ¹³⁷Cs gamma source were compared using OSL dating techniques and tools. Three sets of quartz of different origins (rock, sediment and loess) were studied and measured by the SAR protocol (Single aliquot regenerative dose protocol) after irradiations carried out either by the ⁹⁰Sr source or by a ¹³⁷Cs source. Measurements show that the values obtained by the SAR protocol must be corrected in order to provide an acceptable cross-calibration of the beta and gamma source. Once applied, measurement sets become self-consistent and compatible with expected values. The consequences of the above mentioned observations on the methodology of OSL dating are discussed and suggest that a mixed protocol be used including both the SAR protocol and an added dose techniques close to the SARA protocol (Single aliquot regenerative and added dose protocol).     

Decontamination Effectiveness of Ferrocyanides in Irradiated Rats Contaminated Internally with Radiocesium

The experiment was performed on 192 Wistar rats irradiated with 154.5 mC kg^?1. Therefore, the animals were divided into 5 groups and were treated as follows: group I, controls, with Cs-137; groups II and III with Cs-137 followed by 2-fold administration of ferric ferrocyanide (FF) and ammonium ferric-cyanoferrate (AFCF), respectively; groups IV and V with Cs-137 followed by 6-fold and 10-fold administration of FF and AFCF, respectively. Organ and muscle (16 samples) concentrations of Cs-137 in groups I–III were measured on days 1, 3, 5 and 7, and those of groups IV – V on day 7 after the contamination. The results indicated that in rats contaminated internally with Cs-137 one day post irradiation 2-fold treatment with FF and AFCF in the day resulted in a similar and significant decrease of Cs-137, whereas manyfold treatment (6× or 10×) with these agents did not increase their decontamination effectiveness.     

Hyperfine density shifts of137Ba+ ions in noble gas buffers

Fractional hyperfine density shifts (fds) for¹³⁷Ba⁺ (I=3/2) ions are measured by means of direct optical pumping in noble gas buffers. The results for the fds (¹³⁷Ba⁺, 6s ² S _1/2) in units of 10^?9/Torr (0 ?C) (measured at temperatures between 375 and 395 K) are: + 7(7) (He), ?74(8) (Ne), ?825(80) (Ar), ?1 500(200) (Kr), and < ?1600 (Xe). These shifts for the¹³⁷Ba⁺ ion are considerably more negative than those for the isoelectronic¹³⁷Cs atom. It is shown that this difference can be explained by taking into account the additional charge induced interaction. The hyperfine splitting frequency of the unperturbed¹³⁷Ba⁺ 6s ² S _1/2 state is extrapolated tov ₀=8037741.6(6)kHz.     

Multiple scattering of gamma rays in water,concrete and sand

The transmitted photon spectra of¹³³Ba,²²Na,¹³⁷Cs,⁵⁴Mn and⁶⁰Co point sources are measured through different thicknesses of water, concrete and sand. The multiple-scatter peaks observed in these materials at 60, 90 and 100 keV energies respectively are found to be independent of incident photon energy and thickness of the medium.     

Study of evaporating the irradiated graphite in equilibrium low-temperature plasma

The paper describes a problem of accumulation of irradiated graphite due to operation of uranium-graphite nuclear reactors. The main noncarbon contaminants that contribute to the overall activity of graphite elements are iso-topes ¹³⁷Cs, ⁶⁰Co, ⁹⁰Sr, ³⁶Cl, and ³H. A method was developed for processing of irradiated graphite ensuring the volu-metric decontamination of samples. The calculation results are presented for equilibrium composition of plasma-chemical reactions in systems “irradiated graphite?argon” and “irradiated graphite?helium” for a wide range of tem-peratures. The paper describes a developed mathematical model for the process of purification of a porous graphite surface treated by equilibrium low-temperature plasma. The simulation results are presented for the rate of sublimation of radioactive contaminants as a function of plasma temperature and plasma flow velocity when different plasma-forming gases are used. The extraction coefficient for the contaminant ¹³⁷Cs from the outer side of graphite pores was calculated. The calculations demonstrated the advantages of using a lighter plasma forming gas, i.e., helium.     

Neue Referenzpräparate für die quantitative Autoradiographie und andere kernmeßtechnische Prüfverfahren

Radioactive surface reference sources are represented. The radionuclides in these sources are embeded into epoxy resins. Two new types of sources were developed for the calibration and standardization ofautoradiograms: The Tc-99 step wedge references source and the beta calibration set. Further on radioactive labelled surface sources for different nuclear measuring methods using as reference sources are described. These sources are labelled with Co-57, Co-60, Ni-63, Sr-90/Y-90, Tc-99, Ba-133, Cs-137, Pm-147, Eu-152, Tl-204, Am-241. The lowest density per unit area is 5 mg · cm^?2, the maximum area of a source is 300 cm². Commonly the radioactivity concentration amounts from 5 Bq · cm^?2 to 50 kBq · cm^?2, higher concentration is possible.     

Inflammation-induced synergetic enhancement of nanoparticle treatments with DOXIL<Superscript>®</Superscript> and <Superscript>90</Superscript>Y-Lactosome for orthotopic mammary tumor

Polymeric micelles (Lactosome) in the size of 20–30 nm were labeled with radionuclides of ¹¹¹In (¹¹¹In-DOTA-Lactosome) for SPECT imaging and ⁹⁰Y (⁹⁰Y-DOTA-Lactosome) for β-ray irradiation for mammary tumor in mice. The tumor site at the femoral right leg grafted with 4T1 cells was clearly imaged at 24 h after the intravenous injection. Biodistribution revealed that the half-life time of ¹¹¹In-DOTA-Lactosome was 11 h, which enabled the nanoparticle selectively accumulated in tumor site due to the enhanced permeability and retention (EPR) effect. The anti-tumor therapeutic effect of ⁹⁰Y-DOTA-Lactosome was observed depending on the dose frequency and amount. Under the condition of the percutaneous ethanol injection treatment, the therapeutic effect of ⁹⁰Y-DOTA-Lactosome was enhanced due to the super EPR effect. Owing to the super EPR effect, co-administration of ⁹⁰Y-DOTA-Lactosome and DOXIL^® inhibited the tumor growth during 15 days with their administrations.     

Monte Carlo modelling of human body for dose conversion coefficients of 137Cs in soil of the Eastern Black Sea region of Turkey

Absorbed dose conversion coefficients for a human body standing on the soil surface were calculated for ¹³⁷Cs in the soil of Eastern Black Sea region of Turkey using the Monte Carlo simulation method. The results were given in nGy h^?1 per Bq cm^?2 as a function of depth. Simple numerical integration of this function multiplied with the known specific activity as a function of depth gives the absorbed dose conversion coefficients for any distribution of ¹³⁷Cs in soil. Gaussian distribution of ¹³⁷Cs in the soil was considered for calculations.     

In vitro Studies on the Ability of Natural Zeolites to sorb some Radionuclides

The aim of our work was to study sorption and sorption kinetics of ⁸⁵Sr, ¹³⁷Cs and ¹³¹I from rumen liquid after application of zeolite (clinoptilolite) under laboratory conditions. Zeolite dump corresponded with usual (3%) and high (9%) dose of zeolite in feed. We have ascertained that zeolite is characterized with a high sorption ability for ⁸⁵Sr and ¹³⁷Cs from rumen liquid. 84% of ⁸⁵Sr and 98% of ¹³⁷Cs was bound after 24 hours.     

Determination of the soil-to-grass transfer of 137Cs and its relation to several soil properties at various locations in Serbia

Transfer coefficients of ¹³⁷Cs from soil to grass were determined for the terrain around the city of Kragujevac in central Serbia. Mass activity concentrations of ¹³⁷Cs in soil and grass samples were determined with a high-purity Ge-detector (HPGe). The activity concentration at the depth of 20 cm was found to be in the range of 14.92–124.05 Bq kg^?1, whereas the activity in grass for the same location was in the range of 4.60–84.95 Bq kg^?1. Transfer factors (TFs) were in the range of 0.07 up to 1.94.

Dependences of TFs on different soil characteristics were presented graphically. Weak dependences were determined between them. Absalom's model was used to predict TFs based on soil characteristics: pH value, contents of clay, exchangeable potassium and humus.

A comparison of measured and predicted values from Absalom's model is shown graphically. It has been found that Absalom's model might be carefully used for the prediction of ¹³⁷Cs in grass for specific regions.     

Evaluation of Transmutation of ^137Cs（γ, n） 136Cs Using Ultra-Intense Lasers in Solid Targets

Relativistic electrons produced in ultra-intense laser-solid interaction generate highly collimated γ-ray beams through Bremsstrahlung that can be used to induce photonuclear reactions. Photonuclear transmutation （of （% n） type） of ^137 Cs, one of the hazardous nuclear wastes with half-life of 30.17 years which cannot be transmuted practically with neutron bombardment due to its very low neutron capture cross section, has been considered. Nuclear activity of produced 136Cs with half-life of 13.16 days has been evaluated analytically using available experimental data. With irradiating a ^137Cs sample by p-polarized laser light of 10^20 Wcm^-2 and the repetition rate of 10Hz for 30min, the activity of 0.24 Bq is obtained. It is found that intensity has a large effect in yield around 10^21 Wcm^-2. For similar laser with intensity of 5 ×10^21 Wcm^-2, the activity increases with a factor of 10^5.     

Artificial radionuclides in oils from the underground nuclear test site (Perm region,Russia)

The results of radionuclide determination in oil samples from the Gezh oil deposit (Perm region, Russia) where five underground nuclear explosions took place are presented. High³H and¹⁴C concentrations were found in oil from the wells were the explosions were made as well as from distant wells. This contradicts the assumption that the holes after the explosion are hermetic and the radionuclide leakage is negligible.     

Characteristic X-ray detector: In-situ imaging of radioactive contaminant distributions

The characteristic X-ray detector (CXRD), a CsI(Tl) scintillator with a 50-mm diameter, is a directional X-ray sensor that measures characteristic X-rays from radioactive material, such as ¹³⁷Cs, and identifies the direction of radioactive contamination. We evaluated a CXRD and visualized the distribution of radioactivity in the contaminated area near the Fukushima Dai-ichi nuclear power station, where the ambient dose equivalent rate was 2.1 μSv/h at 1 m above ground level. We found a good correlation between the characteristic X-ray fluxes and the distribution of radioactive contaminants with a 0.823 Pearson product–moment correlation coefficient.