“Pattern recognition” from the U<Emphasis Type="Italic">L</Emphasis> emission spectra as a method for identifying the likeness and difference of uranium state in compounds

The UL X-ray emission spectra of a wide range of uranium compounds were systematically studied. The chemical and isotope (^{233, 235, 238}U) shifts in the L transitions were estimated. The suitability of these data for identifying the U state in real compounds and minerals was assessed. The experimental results were compared with the theoretical predictions based on the Hartree-Fock-Dirac method.Translated from Radiokhimiya, Vol. 46, No. 6, 2004, pp. 494–502.Original Russian Text Copyright © 2004 by Makarov, Solomennikov.     

Current radiation situation in near area of air nuclear explosion conducted at Totskoe Testing Ground (Orenburg oblast) on September 14, 1954

Results obtained in 1996–2000 at the Radium Institute on the radiation situation in the epicenter and near trace areas of nuclear explosion conducted at the Totskoe Testing Ground (Orenburg oblast) in 1954 are reviewed, including analysis of available data on the Totskoe 1954 war games and also on global fallout levels typical of the Orenburg oblast. The specific activities of long-lived radionuclides (⁹⁰Sr, ¹³⁷Cs, and ^{239 + 240}Pu) in the soil are determined. At the epicenter, the specific activities of induced radionuclides (⁶⁰Co and ¹⁵²Eu) are determined. The surface and vertical distributions of radionuclides are studied. The contamination levels of the epicenter and near trace areas with explosion-derived radionuclides are estimated taking into account the global fallout levels characteristic of the Orenburg region. For the first time, a comprehensive regular-grid examination of radiation situation in the indicated territory is made. The isotopic composition of Pu in the soil corresponds to that of the global fallout, but not to weapons-grade Pu, suggesting the lack of contamination with long-lived fission products derived from Totskoe 1954 explosion, or indicating that the contamination levels with these products are within the fluctuations typical of the global fallout.Translated from Radiokhimiya, Vol. 46, No. 6, 2004, pp. 564–568.Original Russian Text Copyright © 2004 by Dubasov, Trifonov, Arshanskii, Skovorodkin, Smirnova.     

Results of measuring the content of actinide, neodymium, and cesium isotopes and the burn-up in a sample of high-burn-up WWER-1000 fuel by destructive methods

Experimental data on the content of U, Pu, Np, Am, Cm, Nd, and Cs isotopes in a sample of WWER-1000 (1000 MW water-cooled water-moderated energy reactor) spent nuclear fuel with the burn-up of up to 70 GW day (t U)^?1 are reported. The data were mainly obtained by isotope dilution followed by mass-spectrometric determination. The burn-up was determined from the weight fractions of ¹⁴⁸Nd and ^134,137Cs in U. The data obtained can be used for the development of low-waste cost-saving technolofy for reprocessing highburn-up SNF and for the improvement of calculation methods and programs intended for calculation of the burn-up and nuclide composition of SNF from WWER reactors.     

Distribution of <Superscript>137</Superscript>Cs, <Superscript>90</Superscript>Sr, <Superscript>239 + 240</Superscript>Pu, <Superscript>241</Superscript>Am,and <Superscript>244</Superscript>Cm among Components of Organic Matter of Soils in Near Exclusion Zone of the Chernobyl NPP

Distribution of Chernobyl-derived ¹³⁷Cs, ⁹⁰Sr, ^{239 + 240}Pu, ²⁴¹Am, and ²⁴⁴Cm among organic fractions of soddy-podzolic, sandy, soddy-meadow, and peat soils collected from the Chernobyl Exclusion Zone along the North-Western radioactive fallout track was determined. Regardless of the soil type, 80–85% of ¹³⁷Cs is tightly fixed on the mineral fraction of the soil. Depending on the soil type, 50–70% of ⁹⁰Sr and 15– 45% of ²⁴¹Am are associated with fulvic acid fractions. ²⁴¹Am and ²⁴⁴Cu are similarly distributed among the organic acid fractions. In all the soil types studied, ^{239 + 240}Pu is associated essentially with humic acid fractions. Natural ^{230, 232}Th and technogenic ^{239 + 240}Pu are similarly distributed among the organic fractions.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 91–96.Original Russian Text Copyright © 2005 by Odintsov, Pazukhin, Sazhenyuk.     

Extraction of U(VI), Th(IV), Pu(IV), Am(III), and rare-earth elements from nitric acid solutions with diphenyl(dialkylcarbamoylmethyl)phosphine oxides substituted in the methylene bridge

The extractive power and selectivity of diphenyl(dialkylcarbamoylmethyl)phosphine oxides in extraction of U(VI), Th(IV), Pu(IV), Am(III), and rare-earth elements from nitric acid solutions was studied, as influenced by substitution of one or two hydrogen atoms in the methylene bridge with alkyl, cycloalkyl, CH₂P(O)Ph₂, and CH₂C(O)NBu₂ groups.Translated from Radiokhimiya, Vol. 46, No. 5, 2004, pp. 427–432.Original Russian Text Copyright © 2004 by Turanov, Karandashev, Yarkevich, Safronova, Kharitonov, Radygina, Fedoseev.     

Investigation of SHS processes using laser hardening

Using the titanium-boron system as an example, a procedure for ultrafast hardening (10⁶–10⁷ K/sec) of the SHS reaction using pulse laser radiation is developed. The dynamic scheme of the component interaction is obtained on the basis of metallographical and micro X-ray spectrum analysis. It is shown that under conditions of high-speed heating mass transfer on the interfaces has a pronounced convective character, ensuring an increased interaction rate.Institute of Structural Macrokinetics of the Russian Academy of Sciences, Tomsk Branch. Scientific-Research Institute of Applied Mathematics and Mechanics. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 5, pp. 598–601, November, 1993.     

Determination of the radionuclide composition and burn-up of high-burn-up WWER-1000 fuel by destructive methods

A sample of WWER-1000 spent nuclear fuel (SNF) with the burn-up of approximately 50 GW day (t U)^?1 was studied by methods of destructive analysis. Data on the content of isotopes of U, Pu, Am, Cm, Nd, and Cs are given. The methods used are briefly described. These include anion exchange and extraction chromatography, thermal ionization mass spectrometry, luminescence analysis, and ??- and ??-ray spectrometry. The main method of the study is isotope dilution followed by mass-spectrometric analysis. The data obtained will be used for developing of a low-waste and low-cost technology for preprocessing of highburn-up SNF and also for checking the accuracy of calculation of heavy actinide content in SNF and for improving computation methods and programs intended for calculation of the SNF nuclide composition in relation to the fuel burn-up in WWER-type reactors. The Nd and Cs isotopes were used as burn-up monitors.     

Destructive analysis of the nuclide composition of spent fuel of WWER-440, WWER-1000, and RBMK-1000 reactors

The results of analysis of spent nuclear fuel (SNF) by destructive methods, carried out systematically at the Khlopin Radium Institute for over 20 years till the mid-1990s, are presented. These data constitute the experimental base for the development of nondestructive methods, correction of calculation programs, substantiation of correlation techniques of determination of individual components of SNF, and for some other purposes. The isotope compositions of U, Pu, Am, and Cm and the fuel burn-up values are presented for 81 SNF samples from WWER-440, WWER-1000, and RBMK-1000 reactors. The burn-up values are determined with ¹⁴⁸Nd, ^{145 + 146}Nd, and ¹³⁷Cs monitors. The utilized methods, including ion-exchange and distribution chromatography, electromigration, and coprecipitation, as well as α-ray spectrometry, luminescence analysis, and mass spectrometry, are briefly discussed. The principal method utilized is isotope dilution α-ray spectrometry or isotope dilution mass spectrometry. A number of isotopes certified as reference samples of different categories, prepared at the Radium Institute, served as spikes. A combination of these methods allows the isotope composition to be estimated accurately to within ≤0.15% for U, ≤0.5% for Pu, and 3–5% for Am and Cm. The accumulated data set for the SNF from WWER and RBMK reactors is presented.     

Kinetics and Mechanism of Pu(VI) Reduction with Acetaldoxime in Nitric Acid Solution

Reduction of Pu(VI) to Pu(III) with acetaldoxime (CH₃CHNOH) in an HNO₃ solution involves three consecutive steps Pu(VI) → Pu(V) → Pu(IV) → Pu(III), and also reproportionation of Pu(IV). Complete kinetics equations of these steps were derived and the rate constants and activation energies of these steps were determined by computer treatment of the experimental kinetic data for all Pu valence forms. The mechanisms of these reaction steps based on the experimental results were discussed.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 67–71.Original Russian Text Copyright © 2005 by V. Koltunov, Pastushchak, Mezhov, G. Koltunov.     

Procedure for Simultaneous Determination of Uranium and Transuranium Elements in Groundwater and Liquid Radioactive Wastes from the Shelter

An ion-exchange procedure for simultaneous determination of ²³⁴U, ²³⁵U, ²³⁶U, ²³⁸U, ²³⁸Pu, ^{239 + 240}Pu, ²⁴¹Am, and ²⁴⁴Cm in groundwater and liquid radioactive wastes is described. The concentration and separation of U and Pu are performed on AV-17 anion exchanger in the chloride form from 9 M HCl. Am and Cm are separated from rare-earth elements by step-by-step elution from KU-2 cation-exchange resin in the NH ₄ ⁺ form with α-hydroxyisobutyric acid (pH 4.75). Finally, U, Pu, Am, and Cm are determined α-spectrometrically.     

Use of a High-Resolution Infrared Fourier Spectrometer for Detection of Ultrasmall Impurities in Liquids and Gases

An experimental setup created on the basis of an infrared Fourier spectrometer and intended for an analysis of ultrasmall impurities in liquids and gases is described. Results of experimental studies of the vapor of ultrapure ammonium and nonsymmetric dimethylhydrazine are reported. It is shown that the limiting mole concentration of the detected impurities amounts to about (3–9)·10^–4% for different types of gases.     

Membrane Methods for Treating Liquid Radioactive Wastes from the Shelter To Remove Transuranic Elements

The possibility is studied of membrane treatment of liquid radioactive wastes from the inside premises of the Shelter to remove transuranic elements using ultra- and nanofiltration methods. The highest degree of decontamination (about 100%) was obtained for Pu and Am, and the lowest one, for Cs; for U and Sr, the values were intermediate. The effect of characteristics of a nanofiltration membrane on the LRW treatment efficiency is studied.__________Translated from Radiokhimiya, Vol. 47, No. 1, 2005, pp. 85–88.Original Russian Text Copyright © 2005 by Rudenko, Khan.     

Simultaneous determination of Np, Pu and Am in HNO3 solution by combining extraction, liquid scintillation counting, and α spectrometry

α Spectrometry is one of the most important and sensitive techniques for the assay of α-emitting nuclides, but various complicated procedures are often required for preparation of uniform thin plate source. Liquid scintillation counting (LSC) with pulse shape analysis (PSA) combining extraction is much simpler, more rapid and accurate technique, but the extraction processes are often very long. By combining extraction, LSC with PSA, and α spectrometry, we proposed a new approach to determine ²³⁷Np, ^238–240Pu and ²⁴¹Am. The new approach includes an extraction process of three steps for blind samples or of only one step for those samples without tailing interference with α spectra. Moreover, no complicated procedure is required for α plate source preparation because even non-uniform plate source is feasible for the new approach. The approach has taken advantages of high counting efficiency (nearly 100%) of LSC for α-radiation, high energy resolution of α spectrometry and high recovery yield of actinides by trialkylphosphine oxide (TRPO) extraction. The approach with one step extraction can be expected to determine ²³⁷Np, ^238–240Pu, ²⁴¹Am and ²⁴⁴Cm simultaneously.     

Model Assessment of the Migration Capability of Transuranium Radionuclides (<Superscript>241</Superscript>Am and Pu Isotopes) and <Superscript>152</Superscript>Eu in the System Bottom Sediments-Yenisei River Water by Chemical Fractionation Technique

Sorption of radiotracers ²⁴¹Am and ²⁴²Pu and weighable amounts of uranium and stable Eu on bottom sediments in the simulated system bottom sediments—Yenisei river water was studied. At a contact time of 40 min these metals are completely sorbed on the bottom sediments, presumably via association with organomineral complexes and hydrated gels. Along with sorption, these metals can form soluble complexes and stable colloids (pseudocolloids). The distribution factors of ²⁴¹Am and ²⁴²Pu, and stable Eu in the simulated system between bottom sediments and liquid phases were calculated from the results of sorption experiments. The introduced ²⁴¹Am and ¹⁵²Eu initially present in radioactively contaminated bottom sediments of the Yenisei river show similar pattern of distribution over differently mobile fractions. The distribution of weighable amounts of stable Eu significantly differs from that of initially present ¹⁵²Eu and tracer ²⁴¹Am due to decelerated sorption of stable Eu and its considerably higher concentration. A significant part of ²⁴²Pu, ²⁴¹Am, and ¹⁵²Eu is associated with mobile fractions of bottom sediments, which, under certain environmental conditions, can pass into river water as migrating species.__________Translated from Radiokhimiya, Vol. 47, No. 4, 2005, pp. 379–384.Original Russian Text Copyright © 2005 by Bondareva, Bolsunovskii, Sukhorukov, Kazbanov, Makarova, Legler.     

Synthesis of new crystalline Pu(V) compounds from solutions: I. Structure and characteristics of a double Pu(V) phthalate with [Co(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>]<Superscript>3+</Superscript> in the outer sphere

The conditions of synthesis of Pu(V) phthalates by conversion of Pu(VI) into the pentavalent state with addition of H₂O₂ in the presence of excess of phthalate ions (L) were determined. Subsequent addition of [Co(NH₃)₆]Cl₃ allowed isolation of crystalline [Co(NH₃)₆][PuO₂L₂]2H₂O isostructural with [Co(NH₃)₆][NpO₂L₂]2H₂O studied previously. The thermal behavior and IR spectra of both compounds were studied.Translated from Radiokhimiya, Vol. 46, No. 6, 2004, pp. 516–520.Original Russian Text Copyright © 2004 by Krot, Bessonov, Grigorev, Charushnikova, Makarenkov.     

International program to improve decay data for transactinium nuclides

To help meet an identified need for precise decay data, in 1977 the IAEA organized an international Coordinated Research Program (CRP) to measure and evaluate half-lives and γ- and α-emission probabilities for selected transactinium nuclides of importance for reactor technology. The CRP goals were (1) to determine a list of data that needed improvement, (2) to encourage new measurements, and (3) to evaluate the available data. All three phases of this work are now complete. Our participation in this effort has involved the measurement of γ-ray emission probabilities for ^232,233,235U, ^{238,239,240,241}Pu, ²²⁹Th and ²³³Pa, as well as participating in the data evaluation. The γ-emission probabilities were determined from the measurement of γ-emission rates with the goal of obtaining uncertainties of ≤ 1%. γ-measurements were made on calibrated Ge detectors. These calibrations were done by standard methods, generally involving measurements at ∼ 60 γ-ray energies from 14 to 2700 keV. The efficiency-calibration functions were assigned uncertainties ranging from 2% below 50 keV to 0.50% from 400 to 1400 keV. The determination of the decay rates of the various sources involved several techniques. The ²³⁸Pu, ²³⁹Pu and ²⁴⁰Pu samples were calibrated by gross α-emission-rate measurements at NBS. The ²³⁵U sample was taken from an NBS-calibrated spike solution. The ²⁴¹Pu and ²³³U samples were calibrated by isotope-dilution mass spectrometry based on spikes of the calibrated ²³⁹Pu, ²⁴⁰Pu and ²³⁵U materials. Some of our results are given, together with a comparison of some present and previous results.     

РH process as a technology for reprocessing mixed uranium–plutonium fuel from BREST-OD-300 reactor

A technology for reprocessing mixed uranium–plutonium nitride fiel (MUPN) from BREST reactor is considered. The technology should ensure reprocessing of spent nuclear fuel with the storage time after irradiation of no more than 1 year, 10–15% content of fissile materials (FM), and burn-up of 10% of heavy atoms. The target product of the technology is a mixture of actinide oxides separated from fission products with the separation factor of ~10⁶. A PH (Pyro–Hydro) process was suggested for MUPN SNF reprocessing. It involves pyroelectrochemical fuel reprocessing with separation of U, Np, and Pu from the major fraction of fission products responsible for the heat release from the fuel and for the radiation load on process media, a series of hydrometallurgical operations for final purification of the target products (U–Pu–Np–Am), and radioactive waste (RW) management. The PH process is being developed since 2011 by the teams from the Bochvar High-Tech Research Institute of Inorganic Materials, Khlopin Radium Institute, and Research Institute of Atomic Reactors with active participation of the Leading Research Institute of Chemical Technology, Siberian Chemical Combine, and institutes of the Russian Academy of Sciences, primarily Frumkin Institute of Physical Chemistry and Electrochemistry and Vernadsky Institute of Geochemistry and Analytical Chemistry.     

Coulometric methods for uranium and plutonium determination

Data on coulometric methods for U and Pu determination in various nuclear materials are presented, analyzed, and summarized. Coulometric determination methods at controlled current and controlled potential are considered. The main principles of the U and Pu determination procedures based on the use of the UO₂ ²⁺/U⁴⁺, Pu⁴⁺/Pu³⁺, and PuO₂ ²⁺/Pu⁴⁺ redox couples are presented. Various methodical factors influencing the error of the U and Pu determination, such as sample weight; supporting electrolyte composition; oxidation and reduction potentials; current; electrode material, shape, and activation procedure; impurity elements, etc., are discussed. Procedures for joint coulometric determination of U and Pu are considered separately. The main methods used by the authors for eliminating the mutual effect of U and Pu in their joint determination are described.     

Extraction of U(VI) with poly(ethylene glycol) in two-phase aqueous systems containing various anions

The distribution of U(VI) between the phase of poly(ethylene glycol) (PEG) of various molecular weights (1500, 4000, 6000, and polydisperse PEG115) and aqueous phosphate, sulfate, and carbonate solutions was studied at pH 3– 13. With increasing PEG molecular weight, the distribution factor of U(VI) increases. The extraction isotherms of U(VI) at 20°C were obtained. The scattering of laser radiation in U(VI)-containing poly(ethylene glycol) solutions showed no colloid formation. Along with U(VI), the extraction of several other metals with PEG was studied. The mechanisms of extraction of U(VI) with PEG are discussed.Translated from Radiokhimiya, Vol. 46, No. 5, 2004, pp. 423–426.Original Russian Text Copyright © 2004 by Safiulina, Tananaev.     

A model of growth of an intermediate phase in bi- and polycrystals

An analytically solvable model of the growth of an intermediate phase between low-soluble components on diffusion at grain boundaries involving outflow is suggested. Criteria for a transition from the Fisher regime t^1/4 to a parabolic one are established. The formalism suggested is extended to the case of the growth of a solid-state solution with an exponential concentration dependence of the diffusion coefficient.Cherkassy Engineering-Technological Institute, Cherkassy Pedagogical Institute. Institute of Metallurgy, Russian Academy of Sciences, Moscow. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 65, No. 3, pp. 311–316, September, 1993.