Influence of plant roots upon the mobility of radionuclides in soil, with respect to location of contamination below the surface

The movement of⁸⁵Sr,¹³⁷Cs,⁵⁴Mn and⁶⁰Co in the 50 cm soil profile was studied with and without the presence of plant roots (triticum aestivum) in order to investigate the influence of roots and depth contamination upon the migration of radionuclides. The water table was maintained manually at 3 cm from the bottom. The physiochemical characteristics (E_h Fe^–2, NH ₄ ⁺ , pH and moisture content) as well as the total and extractable radioactivity were investigated. In the discrete contamination, where the location of contamination varied within the soil profile (0–5, 25–30 or 45–50 cm from the top), the influence of location upon the movement of these radionuclides was also studied. It was found that the changes in the soil physicochemical characteristics influenced the mobility of the four radionuclides. The extractability of⁵⁴Mn and⁶⁰Co was significantly increased in the reducing region of the soil, whereas that of⁸⁵Sr,¹³⁷Cs was not. Plant roots excerted significant effects upon the soil characteristics, via, reducing the E_h pH and moisture content of the soil; increasing the extractability of both⁵⁴Mn and⁶⁰Co from the depth of 35 cm downwards. Radionuclide migration occurred via physicochemical and biological transport. The biological transport via plant roots was of particular importance for¹³⁷Cs. Location of contamination had a significant influence upon the mobility of radionuclides. The migration of radionuclides was in the sequence of contamination in middle>bottom>top. The degree of the influence varied with radionuclides concemed. In the top layer contamination, the rank of the migration from the contamination layers, on the other hand⁵⁴Mn,⁶⁰Co and¹³⁷Cs were more mobile and the movement was:⁸⁵Sr⁵⁴Mn⁶⁰Co>¹³⁷Cs. In the middle and bottom contamination layers, on the other hand,⁵⁴Mn and⁶⁰Co and¹³⁷Cs were more mobile and the movement was⁸⁵Sr⁵⁴Mn⁶⁰Co>¹³⁷Cs. The results provide evidence conceming the soil-root interaction influencing the transfer efficiency of radionuclides from below the soil surface into the human food chain.     

Studies on sorption of antimony and europium from liquid organic and aqueous radioactive wastes on different sorbents

Sorption of¹²⁴Sb(III) from benzene, toluene, o-xylene and nitrobenzene on treated fly ash, pyrolysis residue and bentonite clay was studied at room temperature using the batch method. In comparison to a former study for the sorption of¹²⁴Sb(V), the results revealed relatively higher sorption of the trivalent state than the pentavalent one. According to the type of the nonpolar solvent used, the order of uptake of the radioactive isotopes was often o-xylenetoluene>benzene. The sorption tendency of the sorbents used towards the radionuclides was: bentonitepyrolysis residue>treated fly ash. Sorption from an aqueous medium on the same sorbents has also been investigated for¹²⁴Sb(III) compared to¹²⁴Sb(V),¹⁵²Eu(III) and their mixtures. The obtained results showed that the order of uptake of the different radionuclides was: Eu(III)>>Sb(III)>Sb(V)>mixture. The investigation was extended to the desorption studies of these radionuclides in the acidic and the neutral media from the dried radioactivity loaded sorbents.     

A rapid method for the determination of radionuclides in reactor coolant by ion exchange membranes

This paper deals with a rapid method to determine radionuclides in reactor coolant by anion, cation, and anion-cation exchange membranes. A high pressure filtration device was established to simulate the THOR cooling water sampling system by means of several membranes mentioned above. The experimental results indicate that the adsorption efficiency of each membrane for several radionuclides is /1/ >95% with cation exchange membrane for Zn, Co, Na, Mn, Cu, Cs, Ba, La, W etc., /2/ >98% with anion exchange membrane for I, and /3/ <98% with anion-cation exchange membranes for Fe and Cr. The results are obtained using cooling water of Tsing Hua Open-Pool Reactor and the following radionuclides were identified:^99mTc,¹⁴⁰Ba,¹⁴⁰La,⁵¹Cr,¹³¹I,⁵⁸Co,⁶⁰Co,⁵⁴Mn,⁴⁶Sc,⁵⁹Fe,²⁴Na, etc.     

Utilization of low-cost sorbent for removal and separation of 134Cs, 60Co and 152+154Eu radionuclides from aqueous solution

Eggshell material was used as low-cost and eco-friendly biosorbent for removal of ¹³⁴Cs, ⁶⁰Co and ^152+154Eu radionuclides from aqueous solution. The eggshell material was calcined at 500 and 800 °C, and then characterized. Comparative studies on the natural and calcined eggshell for sorption of the three radionuclides were carried out. It was found that, the uptake is in the order: Eu(III) > Co(II) > Cs(I). Further, column chromatography was used in separation of ¹³⁴Cs, ⁶⁰Co and ^152+154Eu using 0.15, 0.2 and 0.5 mol/l nitric acid, respectively. Eggshell material can be considered as a promising material for separation of radionuclides from radioactive waste solution.     

Retention of some radionuclides in furnace lining during incineration of radioactive wastes

The incineration is one of the widely used method for treatment of solid radioactive wastes. The high volume and weight reduction coefficient (100–150 respectively 10–15) are advantages of this method. The greater part of radionuclides from solid radioactive wastes is retained in ash. From point of view of workers external irradiation, the radionuclides accumulation in furnace lining is one of risk factors. The Kalinit O 1200 is furnace lining material on NPPRIs Experimental Incineration facility. In the first step the sorption properties of this material from¹³⁷Cs,⁶⁰Co,⁵⁴Mn,⁶⁵Zn solutions were studied. The best results had⁶⁰Co, its distribution coefficient was 7036 kg · dm^–3. Cesium-137 was not absorbed on this material. The cylinders (height 5 cm, diameter 2 cm) from lining materials were made latest and were applicated inside the furnace and technological tract to study sorption properties from combustion gases. The penetration of radionuclide into lining material was studied too. The results obtained with this experiments are described in this paper.     

Migration of 134Cs in unsaturated soils at a site in Egypt

To demonstrate the safety performance assessment for the disposal of ¹³⁴Cs radionuclide in a geological formation, several investigations were required to calculate the possible release of radionuclides into groundwater. This research examined the sorption behavior of radioactive cesium (¹³⁴Cs) in natural groundwater. Cesium chloride (10^-6 to 10^-2 mol^.l^-1) was used as a carrier, traced with ¹³⁴Cs radionuclide. Distribution coefficients of radiocesium for sorption and desorption were measured on natural soil samples of different grain size fractions (400 to 36 mm). Cesium sorption and desorption were found reversible at cesium chloride concentrations between 10^-6 mol^.l^-1 to less than 10^-3 mol^.l^-1. Sequential extraction procedures showed that the cesium sorption on soils were of various types: those easily desorbed, ion-exchanged, bound to carbonate, iron oxides, and organic matter. To demonstrate the safety performance assessment for the disposal of ¹³⁴Cs radionuclide in a geological formation, several investigations were required to calculate the possible release of radionuclides into groundwater. This research examined the sorption behavior of radioactive cesium (¹³⁴Cs) in natural groundwater. Cesium chloride (10^-6 to 10^-2 mol^.l^-1) was used as a carrier, traced with ¹³⁴Cs radionuclide. Distribution coefficients of radiocesium for sorption and desorption were measured on natural soil samples of different grain size fractions (400 to 36 mm). Cesium sorption and desorption were found reversible at cesium chloride concentrations between 10^-6 mol^.l^-1 to less than 10^-3 mol^.l^-1. Sequential extraction procedures showed that the cesium sorption on soils were of various types: those easily desorbed, ion-exchanged, bound to carbonate, iron oxides, and organic matter.     

Uptake and Distribution of Trace Elements in Growing Cucumber

Multitracer technique was used to study the uptake and distribution of some relatively long half-life radionuclides Be, Na, Mn, Co, Sc to growing cucumber (Cucumis Sativus L.) with two different treatments. In Hoagland solution, only ⁵⁴Mn and ⁶⁰Co accumulated in the every part of plants. ⁵⁴Mn, ⁶⁰Co and other radionuclides were absorbed in distilled water. The results indicate that there were major differences in the accumulation of trace elements between the two different treatments.     

Evaluation of radioactivity induced in the accelerator building and its application to decontamination work

For decommissioning of the cyclotron and electron synchrotron facilities, the residual radioactivity in surface and core samples of concrete, collected from various parts of buildings, was determined by gamma-ray spectrometry. It was found that the concrete samples were activated mainly by neutrons and that the major radioisotopes were ¹⁵²Eu, ⁶⁰Co, ¹³⁴Cs, ²²Na and ⁵⁴Mn. The maximum activity induced by thermal neutron capture was observed at the depth of 10 cm in the concrete wall near the deflector of the cyclotron. Tritium was also produced by the neutron reaction, because its concentration was proportional to the activities of ¹⁵²Eu and ⁶⁰Co. The surface dose rates inside the accelerator room were also monitored to define the decontamination area. The surface dose rate was proportional to the residual radioactivity, such as ⁶⁰Co. A careful evaluation was very useful in order to minimize the radioactive waste during decontamination.     

Monte Carlo and experimental efficiency calibration of gamma-spectrometers for non-destructive analysis of large volume samples of irregular shapes

A comparison of efficiency calibration of a HPGe gamma-ray spectrometer applied for non-destructive analysis of gamma-ray emitters in large volume samples of irregular shape is presented. The detector efficiency calibration was carried out during the analysis of cosmogenic radionuclides (⁶⁰Co, ⁵⁴Mn, ²²Na and ²⁶Al) in fragments of the Ko?ice meteorite. Fourteen meteorite fragments were available for the analysis with masses from 27 to 2,163 g. A reasonable agreement in the estimation of the HPGe detector efficiency was obtained using the Monte Carlo simulation GEANT 3 code, and the experimental calibration using radioactive standards mixed with iron–silica–copper powder housed in mock-ups of similar shapes as the original samples. The differences in the efficiency estimation obtained by both methods were within 10 %. It is recommended that the Monte Carlo simulation of the detector efficiency can be applied in routine analysis of gamma-ray emitters in large volume samples of regular or irregular shapes.     

The use of universal comparator method in large-scale NAA

For simplicity and unification of the comparator methods it is proposed to obtain a calibrating function of changing relative efficiency of registrating -radiation for any geometry of measurement (for any detector) from -spectrum comparator isotopes directly. In determining elements by their short- and medium-lived radionuclides the comparators⁵²V and²⁴Na were used. Biisotope comparator (⁶⁵Zn,¹²²Eu or¹⁸²Ta) was used for long-lived radionuclides. The developed universal comparator method significantly simplifies the procedures for determining relative registration efficiencies of analytical lines of interesting radionuclides, thus reducing the labor and time requirements of analysis; this is very important in the case of a large scale NAA.     

Extraction-chromatographic system TBP-HBr in radiochemical neutron activation analysis of high-purity materials

The extraction and extraction-chromatographic behaviour of a variety of elements in the TBP-HBr system with concentrations from 0.1 to 7M HBr has been studied. The results allowed the development of simple procedures for radiochemical neutron activation determination of 22 impurity elements (Na, K, Sc, Cr, Mn, Fe, Co, Ni, Cu, Ga, As, Se, Rb, Sr, Zn, Mo, Ag, Sb, Te, Ba, La, Hf and W) in high-purity cadmium and indium samples with detection limits from 1 g g^–1 for Fe and Zr to 0.01 ng g^–1 for Na, Sc, Mn with relative standard deviations < 0.15. To increase the selectivity of the extraction-chromatographic separation, use was made of extraction suppression and co-extraction effects. The procedure for the extraction-chromatographic separation of scandium from a number of other elements is described as an example. The procedure can be used for simultaneous quantitative separation of impurity radionuclides from radiation produced long-life scandium radionuclides in the neutron activation analysis of titanium and vanadium.     

Radionuclide contents in environmental samples as related to the Chernobyl accident

Many kinds of environmental samples including total diet samples, were collected in the Chernobyl (Ukraine) vicinity and in Ibaraki prefecture (Japan). Six radionuclides and twelve stable elements were analyzed. After samples were dry-ashed, radioactivities of¹³⁷Cs,¹³⁴Cs,⁴⁰K,⁶⁰Co and⁵⁴Mn were determined by -ray spectroscopy with a germanium detector. Strontium-90 was determined by low-background -spectrometry. Stable elements were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Comparison of the levels of radionuclides between the Ukraine and Ibaraki showed the former were several times to a few tens of thousands of times higher than the latter, depending on the samples.     

Cosmic induced radioactivity in the meteorite Trebbin

7 days after the fall of a stony meteorite its -spectrum has been measured on a Ge/Li/-detector installed in an underground laboratory. The activity of²²Na,²⁶Al,⁴⁰K,⁴⁸V, and⁵⁴Mn has been determined.     

Leaching of uranium,radium and thorium from vertisol soil by ground water

Shallow land burial is routinely used for the disposal of low-level radioactive waste. Natural processes causing leaching of radionuclides can lead to contamination of surrounding ground water and soil by the radionuclides. The comparative leachability of radionuclides U_(nat), ²²⁶Ra, ²²⁸Ra and Th_(nat) from the soil of a radioactive waste disposal site, by ground water was evaluated. The probability of leaching was obtained in the following order Ra (≈77%) > U (≈40%) > Th (≈20%). Observed ratios (OR) were calculated to correlate leachability of radionuclides to that of major cations Ca²⁺ and Mg²⁺. The leaching of the radionuclides was seen to be dependent on Ca²⁺ and SO₄²⁻ leached from the soil. This study provides sitespecific leachability of radionuclides, that can be used as indicator of the tendency for migration or retention in soil. It can play an important role during an unforeseen accident like breach of containment at the waste disposal site leading to contamination of soil and ground water and causing hazard to public via drinking water route.     

Multitracer study on the behavior of various elements in atmosphere plant-systems

The direct absorption of atmospheric elements via soybean leaves has been studied using a radioactive multitra r technique. Soybean was cultivated until it bore seeds in a box under no-rain conditions and with introduction of multitracer-adsorbed cellulose powders. The radioactive nuclides of 40 elements were produced from Au target irradiated with¹⁴N, and the nuclides with relatively long half-life of the elements Sc, Mn, Co, As, Se, Rb, Sr, Y, Eu, Gd, Yb, Re, and Ir were dominantly observed in each part of soybean plant.     

Non-destructive gamma-spectrometry analysis of cosmogenic radionuclides in fragments of the Ko?ice meteorite

Results of analysis of cosmogenic radionuclides (^57,58,60Co, ⁵⁴Mn, ⁴⁶Sc, ²²Na, ⁴⁸V and ²⁶Al) in fragments of the Ko?ice meteorite are presented and discussed. Analyses were carried out using a low-level HPGe-spectrometer placed in a lead-iron-copper shield. Twelve meteorite fragments were available for the analysis with masses from 27 to 2,163?g. The lowest massic activities were observed for ⁴⁶Sc (down to 0.1?mBq/g), and the highest for ²²Na (up to 2?mBq/g). The measured radionuclide activities showed differences between fragments, as indicated mainly by the ⁶⁰Co data, which were caused by different positions of meteorite fragments from the center of the meteorite body.     

Multitracer study on transport and distribution of metal ions in plants

Transport and distribution of metal ions in rice and soybean plants were studied using multitracers produced by irradiating an Au target by 135 MeV/nucleon¹²C,¹⁴N, or¹⁶O ions accelerated by RIKEN Ring Cyclotron. The multitracer consisted of radioisotopes of the following elements: Be, Na, Sc, Mn, Fe, Co, Zn, Se, Rb, Sr, Y, Zr, Nb, Ag, Te, Ba, Ce, Pm, Eu, Gd, Tb, Tm, Yb, Lu, Hf, Ir, and Pt. Rice and soybean plants were grown in a nutrient solution and also on soil containing a multitracer. -ray spectroscopy of different parts of the plants showed that all the elements were more or less taken up by roots, while appreciable transport to leaves and seeds was observed only for Mn, Zn, Se, Rb, Sr, and Ba.     

Gamma-ray induced decomposition of double nitrates of lanthanides with univalent and divalent cations

Double nitrates of Na and K having the composition 2M^INO₃·Ln^III(NO₃)₃·2H₂O(Ln^III=Pr, Nd, Sm, Eu, Gd, Tb and Dy) and of Ni and Cu with the composition 3M^II(NO₃)₂·2Ln^III(NO₃)₃·24H₂O (Ln^III=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb and Dy) have been prepared and their -radiolytic decomposition studied up to 500 kGy. G(NO ₂ ^– ) values of K double nitrates at 230 kGy follow the order Dy³⁺>Pr³⁺=Nd³⁺=Sm³⁺>Tb³⁺>Eu³⁺> Gd³⁺·G(NO ₂ ³⁺ ) for NI double nitrates are higher than those of Cu double nitrates. Variation of G(NO ₂ ^– ) with cationic radii and the number of f electrons in lanthanide ion show a minimum at Eu. Thermal decomposition studies of double nitrates were also carried out.     

Anthropogenic radiotracers assessment as tool to environmental compliance rules and management

A framework, within models and studies can be applied, to develop coherent and logical environmental impact management methodologies for ionizing radiation, is essential. A number of components, which form the basis for such a system, included the dilution factor for radioactive liquid effluent releases. In this study we established a strategic, fast and cheap methodology to estimate the dilution factor for the release of liquid radioactive effluents at IPEN. The radioisotopes ³H, ⁵⁴Mn, ⁶⁰Co, ⁶⁵Zn, and ¹³⁷Cs, generated in the routine operation of the Research Reactor IEA-R1, were used as radiotracers. The generated liquid radioactive effluent was stored in a 300 m³ capacity tank. The initial concentration of its present radioisotopes were determined. A planned release of effluent from the storage tank was carried-out. Simultaneously, the sampling was made upstream of the storage tank discharge point and the concentration ³H, ⁵⁴Mn, ⁶⁰Co, ⁶⁵Zn and ¹³⁷Cs in the mix sewerage system discharge point E1 at IPEN were monitored. The estimated dilution factor of discharge point of the aqueous effluent for ³H was 4.3 and 7.4, ⁵⁴Mn was12 and 16.1, ⁶⁰Co was 12.6 and 14.2, ⁶⁵Zn was 12 and 27.9 and ¹³⁷Cs was 6.2 and 13.9, respectively.     

Thermodynamics of the System HNO3-UO2(NO3)2-H2O at 298.15 K

The sorption of ⁶⁰Co, ⁶⁵Zn, ⁷⁵Se, ¹⁰³Pd, ¹¹⁰Ag and ²⁰³Hg radionuclides by polyurethane foam (PUF) was investigated and optimized with respect to the selection of appropriate sorptive medium, metal, thiocyanate ions (except for ¹¹⁰Ag) and PUF concentration and equilibration time. The influence of common anions and cations on the sorption of each metal was examined. The sorption data subjected to different sorption isotherms have shown that the sorption of all the radionuclides followed Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms. The sorption capacity intensity and energy were evaluated for each element studied. The variation of sorption with temperature was monitored for all radionuclides except zinc and selenium. The values of H, S and G were estimated and found to be negative indicating exothermic and spontaneous nature of sorption. It was found that PUF is an effective and economical sorbent for traces of metal ions which can be used for the separation/preconcentration of these ions from their very dilute solutions and has useful applications in radioanalytical and environmental chemistry and in radioactive and industrial liquid waste management.