Investigation of radiation effects caused by the interaction of β<Superscript>−</Superscript>-radiation with polyvinyl chloride

The dissipation of the energy of β⁻-radiation in polyvinyl chloride has been analyzed. The change in the properties of polyvinyl chloride under the action of β⁻-particles with an energy of 2.32 MeV has been characterized using the potentials of intermolecular and intramolecular interactions and the Bohr potential. The interrelation between certain micro-and macroproperties of polyvinyl chloride was determined and methods of their control with the use of β⁻-radiation were developed. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 80, No. 1, pp. 186–192, January–February, 2007.     

Leaching of<Superscript>60</Superscript>Co and<Superscript>137</Superscript>Cs from spent ion exchange resins in cement-bentonite clay matrix

The leaching rate of⁶⁰Co and¹³⁷Cs from the spent cation exchange resins in cement-bentonite matrix has been studied. The solidification matrix was a standard Portland cement mixed with 290–350 (kg/m³) spent cation exchange resins, with or without 2–5% of bentonite clay. The leaching rates from the cementbentonite matrix for⁶⁰Co : (4,2–7,0) × 10⁻⁵ (cm/d) and¹³⁷Cs : (3,2–6,6) × 10⁻⁴ (cm/d), after 125 days were measured. From the leaching data the apparent diffusivity of cobalt and cesium in cement-bentonite clay matrix with a waste load of 290–350 (kg/m³) spent cation exchange resins, was measured for⁶⁰Co : (1,1−4,0) × 10⁻⁶ (cm²/d) and¹³⁷Cs : (0,5–2,6) x× 10⁻⁴ (cm²/d), after 125 days. The results presented in this paper are part of the results obtained in a 20-year mortar and concrete testing project which will influence the design of radio-active waste management for a future Serbian radioactive waste disposal centre.     

Preparation of single-crystal <Superscript>29</Superscript>Si

A process has been developed for the preparation of single-crystal ²⁹Si from ²⁹Si-enriched silane. A silicon single crystal has been grown with a ²⁹Si content over 99.9 at %. The oxygen and carbon concentrations in the crystal are under 1 × 10¹⁶ cm⁻³, and its resistivity exceeds 1 kΩ cm.     

The standard base of Russia for measuring small direct-current in the 10<Superscript>−16</Superscript>–10<Superscript>−9</Superscript> a range

The present state of the standard base of Russia for measuring small direct-current in the 10⁻¹⁶–10⁻⁹ A range is considered, and the metrological characteristics of the state primary and transferable standards are given. __________ Translated from Izmeritel’naya Tekhnika, No. 11, pp. 40–42, November, 2007.     

Production and radiochemical separation of no-carrier-added <Superscript>88</Superscript>Y by liquid-liquid extraction

A method was suggested for the cyclotron production of ⁸⁸Y with liquid-liquid extraction. The sedimented ^natSrCO₃ target was irradiated with 18-MeV protons at current of 20 μA for 10 h. The ⁸⁸Y yields of about 1.326 MBq μA⁻¹ h⁻¹ were experimentally obtained. Solvent extraction of no-carrier-added ⁸⁸Y from irradiated strontium carbonate target in the hydrochloric acid solution was studied using di(2-ethylhexyl) hydrogen phosphate (HDEHP). The optimum separation was achieved in the system n-hexane/10% HDEHP-0.1 M HCl. Yttrium radionuclides were recovered from the HDEHP phase by stripping with 60 ml of 9 M HC1. Also, excitation functions of the proton, deuteron, and α-particle induced reactions of ⁸⁹Y, ⁸⁸Sr, ^natSr, and natRb were determined using computer codes and compared to the existing data.     

Nickel electrodeposition on copper substrate for cyclotron production of <Superscript>64</Superscript>Cu

Natural nickel electrodeposition on a copper substrate with a gold layer was studied with the aim of production of ⁶⁴Cu radionuclide. The electrodeposition experiments were carried out in acid plating baths. The operating parameters such as pH, temperature, and current density were optimized. The current efficiency was measured at different current densities. The optimum conditions of the nickel electrodeposition are as follows: 5.7 g 1⁻¹ nickel, pH 3–4, dc current density 85.54 mA cm⁻², and 55°C, with 97% current efficiency. SEM photomicrographs demonstrated fine-grained structure of the deposit obtained from the optimum bath. A 46-μm high-quality layer was deposited on a gold layer of the copper substrate.     

Recovery of <Superscript>131</Superscript>I and <Superscript>137</Superscript>Cs from a solution simulating NPP trap waters

Sorption of ¹³¹I and ¹³⁷Cs from a solution simulating NPP trap waters on various inorganic and organic sorbents was studied. The highest degree of ¹³¹I recovery (>99%) can be attained with Fizkhimin granulated sorbents based on coarsely porous silica gel containing Ag and Ni in 1: 4 ratio, with K _d for ¹³¹I exceeding 10⁵ ml g⁻¹ at V/m = 10³ ml g⁻¹ and contract time of the solid and liquid phases of 120 min. Elevation of the solution temperature to 40°C does not affect the degree of ¹³¹I and ¹³⁷Cs recovery. The degree of ¹³⁷Cs recovery in all the experiments did not exceed 35%. The degree of ¹³¹I recovery by coprecipitation with AgCl and Ag₄[Fe(CN)₆] was about ∼96% and only 65%, respectively.     

Diffusion coefficient of Fe<Superscript>2+</Superscript> in single-crystal ZnSe

The diffusion coefficient of Fe in single-crystal ZnSe has been measured in the temperature range 886–995°C. The 995°C diffusion coefficient is (47 ± 5) × 10⁻¹¹ cm²/s, and the average activation energy for Fe diffusion is 2.9 ± 0.3 eV.     

Effect of Pr<Superscript>3+</Superscript> on the stokes luminescence of YPO<Subscript>4</Subscript>:Nd<Superscript>3+</Superscript> under IR excitation

We have identified general relationships between the spectral and kinetic properties of the IR Stokes luminescence bands of Y_{1 − x − y} Nd _x Pr _y PO₄ solid solutions in the spectral range 0.86–1.40 μm under 0.810-μm laser excitation. The results have been used to formulate technical requirements for the purity of rare-earth oxides for the fabrication of efficient YPO₄:Nd³⁺ IR phosphors and to develop a fast YPO₄:Nd³⁺, Pr³⁺ IR phosphor that allows the decay time of the Nd³⁺ IR Stokes luminescence bands in the range 0.86–1.40 μm to be tuned from 50 to 170 μs by varying the ratio of the Nd³⁺ and Pr³⁺ concentrations.     

Effect of complexing anions on sorption of U(VI), <Superscript>90</Superscript>Sr,and <Superscript>90</Superscript>Y from aqueous solutions on layered double hydroxides of Mg,Al, and Nd

Sorption of ⁹⁰Sr and ⁹⁰Y from aqueous solutions on Mg-Al and Mg-Nd layered double hydroxides (LDHs) in various forms was studied. The distribution coefficients K _d of U(VI) and ⁹⁰Sr on LDH-Mg-Al-EDTA are 100–120 ml g⁻¹ in 15 min of contact of the solid and liquid phases at V/m = 50 ml g⁻¹. At the same time, under similar conditions, U(VI) and ⁹⁰Sr are not sorbed from aqueous solutions on LDH-Mg-Al-C₂O₄. The sorption of U(VI) from aqueous solutions containing H₂EDTA²⁻, C₂O₄²⁻, and CO₃²⁻ on LDH-Mg-Nd-CO₃ and LDH-Mg-Al-CO₃ strongly depends on the concentration of the complexing anions in the solution. In particular, for 10⁻³ M aqueous UO₂²⁺ solutions, with an increase in [C₂O₄²⁻] from 10⁻³ to 5 × 10⁻² M, K _d of U(VI) decreases from >5 × 10³ to 70 ml g⁻¹ for LDH-Mg-Al-CO₃ and from 170 to ∼0 ml g⁻¹ for LDH-Mg-Nd-CO₃. In the presence of 10⁻³ to 5 × 10⁻² M CO₃²⁻ in aqueous solution, U(VI) is not noticeably sorbed on LDH-Mg-Nd-CO₃ (K _d does not exceed 16 ml g⁻¹ at V/m = 50 ml g⁻¹), and on LDH-Mg-Al-CO₃ the sorption sharply decreases (K _d decreases from >5 × 10³ to ∼0 ml g⁻¹ at V/m = 50 ml g⁻¹). The presence of complexing anions in the solution does not appreciably affect the ⁹⁰Sr sorption, but noticeably affects the 90Y sorption. With an increase in their concentration, K _d of ⁹⁰Y appreciably decreases. The effect exerted by Sr²⁺ ions on the sorption of microamounts of U(VI) and by UO₂²⁺ ions on the sorption of microamounts of ⁹⁰Sr and ⁹⁰Y from aqueous solutions on LDH-Mg-Nd-CO₃ was also examined.     

Ultrapurification of <Superscript>76</Superscript>Ge-enriched GeH<Subscript>4</Subscript> by distillation

⁷⁶Ge-enriched germane has been ultrapurified by low-temperature distillation. The nature and concentration of molecular impurities in the germane samples were determined by gas chromatography/mass spectrometry, high-resolution Fourier transform IR spectroscopy, and gas chromatography. The distillate contains no more than 10⁻⁵ mol % hydrocarbons, 10⁻⁴ mol % carbon dioxide, 10⁻³ to 10⁻¹ mol % digermane and trigermane, and <3 × 10⁻⁵ mol % other impurities. A distinctive feature of the impurity composition of the isotopically enriched germane samples is the presence of silicon tetrafluoride and sulfur hexafluoride impurities.     

Behavior of plutonium in various oxidation states in aqueous solutions: I. Behavior of polymeric Pu(IV) and of Pu(VI) at 10<Superscript>−5</Superscript>–10<Superscript>−8</Superscript> M concentrations in solutions with pH ∼8

Pu(V) does not exist for a long time in solutions at pH ∼8 and concentrations of 10⁻⁵–10⁻⁸ M because of disproportionation to polymeric Pu(IV) and Pu(VI), which form a common polymeric structure that subsequently does not significantly change. Plutonium(III) at its concentrations from 10⁻⁵ to 10⁻⁸ M in solutions at pH ∼8 undergoes oxidation, transforming into polymeric Pu(IV). The data obtained can be useful for interpretation of the plutonium behavior under natural conditions.     

<Superscript>220</Superscript>Rn as an additional factor of radiation hazard in the Shelter

In 2003–2007, the content of ²¹²Pb (²²⁰Rn daughter product) inside the Shelter was, as a rule, in the range 0.5–5 Bq m⁻³. No seasonal and time dynamics of the ²¹²Pb concentration and no relationship with the technical activity were revealed. At simultaneous sampling of aerosols, the volume activities of ²¹²Pb in the bypass were higher by 1–2 orders of magnitude than in the surrounding medium (local zone). Hence, the sources of ²²⁰Rn emanation, in particular, ²³²U are inside the Shelter. Among 220 samples taken in the bypass, 94% had the activity median aerodynamic diameter of aerosol particles bearing ²²²Rn and ²²⁰Rn daughter products in the range from 0.05 to 0.4 μm. For the Shelter staff members, ²²²Rn and ²²⁰Rn daughter products, and also submicron size of their carriers are negative factors which were not taken into account previously when determining ionizing irradiation doses. The additional inhalation doses can reach tens of percents of the permissible annual dose.     

Synthesis and luminescence properties of Eu<Superscript>2+</Superscript>-doped Li<Subscript>2</Subscript>SrSiO<Subscript>4</Subscript>

We have studied the luminescence spectra of Li₂Sr_{1 − x} Eu _x SiO₄ (x = 0.0001–0.01) solid solutions prepared by solid-state reactions and a sol-gel process in a reducing atmosphere. The spectra show a broad band in the range 500–700 nm, centered at 578 nm, which is due to the 4f ⁶5d → 4f ⁷ transition. The luminescence excitation spectrum shows, in addition to bands due to Eu²⁺ 4f ⁷ → 4f ⁶5d transitions, a strong band centered at 174 nm, attributable to absorption in the SiO₄⁴⁻ group.     

Formation of Li<Superscript>+</Superscript> superionic crystals from the Li<Subscript>2</Subscript>S–P<Subscript>2</Subscript>S<Subscript>5</Subscript> melt-quenched glasses

The 70Li₂S·30P₂S₅ (mol%) glass was prepared by the melt quenching method and the glass–ceramic electrolytes were obtained by heating the prepared glass over crystallization temperatures. The superionic metastable Li₇P₃S₁₁ crystal was formed by heating the glass in the temperature range from 280 and 360 °C. The conductivity of the glass–ceramics was enhanced by the precipitation and growth of the Li₇P₃S₁₁ crystal, and the highest conductivity of 4.1 × 10⁻³ S cm⁻¹ at room temperature was achieved in the glass–ceramic heated at 360 °C for 1 h. The Li₇P₃S₁₁ crystal changed into the thermodynamically stable phase such as the Li₄P₂S₆ crystal with further increasing heat treatment temperature and holding time, resulting in lowering conductivities of the glass–ceramics.     

Adsorption of <Superscript>99<Emphasis Type="Italic">m</Emphasis></Superscript>Tc on aluminum oxide

Adsorption of ^99m Tc under static and dynamic conditions on aluminum oxides subjected to various acid treatments at pH from 7.29 to 1.26 (until the reaction of the oxide with the acid fully ceased) was studied. In batch experiments, the maximal adsorption of ^99m T_c, more than 30% of the radionuclide activity, is attained with the oxide that absorbed 2 × 10⁻⁴ mol g⁻¹ acid. The “rate” of linear migration of ^99m T_c in a chromatographic column in the course of elution with a 0.9% NaCl solution under the conditions of limiting saturation of the oxide with the acid is 0.49–0.52 cm ml⁻¹. It is concluded that the observed deceleration of the ^99m T_c elution from the generator column is due to its “braking” by active sites of the oxide. Upon reduction of ^99m T_c with bivalent tin, its adsorption increases to 93.53%. The results obtained are of interest for the development of procedures for depositing ^99m T_c onto the surface of nanosized colloidal particles of aluminum oxide for their subsequent use in medical diagnostics.     

Radioactivity calculations for production of <Superscript>131</Superscript>I by neutron irradiation of tellurium targets

The radioactivity of ¹³¹I as well as of the other radioisotopes, obtained from different nuclear reactions occurring during irradiation of natural tellurium including different decay branches, at the end of irradiation and after different cooling times was calculated. The optimum cooling time is 90 h. Published in Russian in Radiokhimiya, 2009, Vol. 51, No. 3, pp. 275–281. The text was submitted by the author in English.     

Enhanced Superconducting Properties of Air-Processed GdBa<Subscript>2</Subscript>Cu<Subscript>3</Subscript>O<Subscript>7-δ</Subscript> Single Domains with BaCO<Subscript>3</Subscript>/BaCuO<Subscript>2−<Emphasis Type="Italic">x</Emphasis></Subscript> Addition

Single domain GdBa₂Cu_7-δ (Gd123) bulk superconductors were fabricated in air by top-seeding melt-texture growth. Performance of the air-processed Gd123 was successfully enhanced by addition of both BaCO₃ and BaCuO_2−x , which suppress the formation of Gd_1+x Ba_2−x Cu₃O_7-δ solid solutions. The optimum doping amount ranges from 0.05 to 0.15, M BaCO₃ and 0.05 to 0.1, M BaCuO_2−x per molar Gd123. The distribution of the second phase particles was observed by scanning electron microscopy. A narrow band formed by Gd₂BaCuO₅ particle concentration appeared around the seeding zone in both a–b plane and c-growth sector in Gd123 single grain. Trapped magnetic field density reached 0.67, T for sample with 24 mm in diameter and 8, mm in thickness and a high critical current density J _c up to 91,200, A/cm² was achieved at 77, K under self-field.     

Application of FIBAN fibrous sorbents to concentrating <Superscript>90</Superscript>Sr from wastewater

Sorption of ⁹⁰Sr on FIBAN fibrous sorbents from wastewaters is studied. The performance of sorbents depends on pH: chelating sorbent FIBAN Kh-1 efficiently sorbs ⁹⁰Sr at pH 5–8, and strongly acidic sorbent FIBAN K-1, at pH 1–3. Strontium is readily desorbed from the sorbents with 2 M HCl. Conditions of sorption of strontium from various acidic wastewaters are optimized. FIBAN K-1 exhibits high sorption efficiency for ⁹⁰Sr and good kinetic characteristics. With this sorbent, about 90% of radiostrontium is recovered in a convenient form from wastewaters of various compositions. Original Russian Text A.A. Shunkevich, V.I. Grachek, I.I. Ugolev, S.V. Matveichuk, 2007, published in Radiokhimiya, 2007, Vol. 49, No. 6, pp. 554–556.     

Structural,optical and electrical properties of ZnTe<Subscript>1−<Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> thin films

ZnTe_1−x Se _x films were deposited on glass substrates kept at 200 °C by the electron beam evaporation technique. These films exhibited cubic structure and the lattice parameter increased with increase of Tellurium concentration in the films which confirmed the solid solution formation. The grain size is found to increase with Te content. The dislocation density and lattice strain show a decreasing trend with increasing of Te content. Band gap values of 2.73 eV, 2.63 eV, 2.52 eV and 2.41 eV have been calculated for the films of composition ‘x’ = 0.2, 0.4, 0.6 and 0.8, respectively, which confirmed the formation of solid solution between ZnSe and ZnTe. Refractive index of the films increased from 2.535 to 2.826 as the concentration of Te increased. All the films showed high resistivity values. Laser Raman spectral studies of ZnTe_1−x Se _x revealed LO phonon frequencies whose values are located in between the LO phonon frequencies of ZnSe and ZnTe.