Isolation of myo-inositol from a mixture of isomers

The transfer reaction of phosphatidylcholine and aqueous solutions of inositols that is catalyzed by phospholipase D is studied. Optimal conditions for synthesis of posphatidylinositol in a water—organicsolvent heterogeneous system are found. Addition of the alcoholic substrate methanol to the reaction medium is demonstrated to liberate myo-inositol from the phosphatidylinositol in hexane—water. Myo-inositol is isolated from a mixture of isomers by carrying out the double transfer reaction using phospholipase D.Mirzo Ulugbek National University of Uzbekistan. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 160–163, March–April, 2000.     

Specific activities of radioactive elements from fission product mixtures

Specific activities of radioactive elements at the time of chemical separation from fission product mixtures produced by thermal neutron fission of²³⁵U were computed byBateman's and other equations on an electronic computer. Computations were made for two fission times: fission was assumed to be complete in a few minutes in one case, and over a period of a year in the other case. It was also assumed that each element was separated instantly after allowing the fission products to decay for 1∼10 000 000 hrs (1 140 years). The computations were applied to 12 important elements: Ru, Zr, Nb, Cs, Sr, Pm, Tc, Ba, La, Ce, Kr and Y. Results are given as a diagram for each element. The diagrams are intended to be helpful in the chemical processing of a large quantity of fission products, and industrial or tracer application of these elements.     

Separation of radionuclides from a fission product solution by ion exchange on alumina

The distribution of different radionuclides depends on their speciation in the real fission product solution and the electric charge of the alumina. The pH-value is the main parameter that influences the disyribution coefficient. By combination of an acidic adsorption and an alkaline desorption process, the interesting fission molybdenum can be separated. The distribution ratios of the relevant radionuclides are described.     

Study of fission product loaded aerosols from core melting experiments

A severe nuclear reactor accident may result in the meltdown of the reactor core. The formation of the core melt is accompanied by the appearance of aerosols consisting of vaporized and recondensed core constituents. The investigation of aerosol samples, which were generated in a laboratory scale core melting experiment and collected during a temperature range Of 1200–1900°C of the melting charge, was performed using X-ray Photoelectron Spectroscopy (XPS) and revealed silver, cadmium, indium, tellurium, iodine and cesium as constituents of the aerosol surface. The metal components were present as either oxides or hydroxides with the exception of silver, which remained in its metallic state.     

Chemical separation of molybdenum from uranium and fission product nuclides

A very rapid method for the separation of molybdenum(VI) from neutron irradiated uranium and its fission products is described. The procedure is based on the selective extraction of molybdenum(VI) by a 0.1M solution of 2-hexylpyridine in benzene from 4M HCl+0.04M KSCN. Decontamination factors were estimated to be >10⁴ for the radionuclides of niobium, zirconium, ruthenium, lanthanum, cerium, promethium, yttrium, strontium and barium.     

Separation of 99Mo from a simulated fission product solution by precipitation with a-benzoinoxime

The formation property of Mo precipitate was investigated and improved the existing process was using H₂O₂ that acts as an interfering compound in a subsequent alumina adsorption process. The property of the Mo precipitate was investigated by using SEM, FTIR, TG-DTA, and XRD. The simulated solution consisted of 1M nitric acid containing seven elements (Mo, I, Ru, Zr, Ce, Nd, Sr) and their radioactive tracers. As a result, the precipitate was composed of the Mo precipitate and re-precipitated a-benzoinoxime which was added excessively for increasing the precipitation efficiency. It was confirmed that the Mo precipitate was formed by the reaction of two a-benzoinoxime molecules and one MoO₂ ²⁺. Molybdenum precipitate was dissolved in 0.4M NaOH solution within 5 minutes without H₂O₂. Hydrogen peroxide induced only the rapid dissolution of the a-benzoinoxime re-precipitate. Also, the dissolution method without H₂O₂ was favorable in the purification aspect because Zr and Ru were contained as a small fraction of 1.3% and 7.7%, respectively, in the dissolving solution.     

Rapid activation product separations from fission products and soil matrixes

A rapid method for the separation and qualitative analysis of several neutron activation products (¹⁹⁸Au, ¹⁹²Ir, ⁷²Ga, ⁵¹Cr, ^191/195m/197Pt, ⁵⁴Mn, ⁵⁷Co, and ⁵⁹Fe) from fission products and soil matrixes has been developed. Analytes were isolated within 20 h using ion exchange chromatography. After separation, the activation products were characterized by γ-spectroscopy and inductively coupled plasma-optical emission spectroscopy. Validation experiments demonstrated versatility of the method, showing that the activation products could be isolated from fresh fission products and other contaminants associated with complex soil matrixes.

     

Monitoring of fission product release in a boiling water reactor

A comprehensive analysis of routine radiochemistry data obtained at a BWR plant has been performed. The variation of fission product release levels as well as the characteristics of the release pattern were evaluated. The number of defective fuel bundles and the exposures of the defective fuel are correctly predicted from the results of data analyses.     

Migration of fission product137Cs in mud near a nuclear reactor

Due to the mismanagement of nuclear waste as well as heat exchanger degradation for the primary coolant of the one megawatt nuclear research reactor, the fission product¹³⁷Cs has been leaking to the environment ever since 1969. In the past thirty years, the long-lived¹³⁷Cs was accumulated and eventually trapped in the mud of the discharge pond right in front of the waste storage and the reactor facility. The distribution of¹³⁷Cs in mud was measured and contour-mapped to reveal the migration of trace levels of¹³⁷Cs in a period of three decades.     

Perspectives of laser-chemical isotope separation of a long-lived fission product: cesium-135

The cesium isotope ¹³⁵Cs has an extremely long half-life (τ_1/2 = 2.3 · 10⁶ y) and its high water solubility leads to the anxiety of exudation to ground water during geological disposal. Such a LLFP ¹³⁵Cs would be converted into ¹³⁶Cs (Its half-life is 13.16 d and it becomes stable ¹³⁶Ba) by neutron capture reaction. However intermingling ¹³³Cs of which the natural abundance is 100% disturbs this nuclear converting reaction because ¹³³Cs also absorbs neutrons and produces ¹³⁵Cs again. For separating ¹³⁵Cs from other cesium isotopes, laser-chemical isotope separation (LCIS) is believed to be suitable mainly due to the light absorption and emission stability. Isotope separation of alkali metal ⁸⁵Rb/⁸⁷Rb was successfully achieved, showed 23.9 of head separation factor by LCIS. The measured isotope shift of Cs D₂ line is within the reach of available semiconductor lasers having emission line width of less than 1 MHz, which shows that the selective excitation of ¹³⁵Cs may turn to be possible. It is known that cesium excited to the 6²P_3/2 state may forms cesium hydride while ground-state cesium does not. Therefore if the lifetime of 6²P_3/2 state is sufficiently longer than the inverse rate of the chemical reaction, ¹³⁵Cs can be extracted as cesium hydride. Applicability of the Doppler-free two-photon absorption method for selective excitation and further evaluation on Rydberg states and ionization should be investigated.     

Separation of some radionuclides from fission product elements by adsorption on diethylene glycol succinate

Separation of adsorbed radionuclides on diethylene glycol succinate (DGS) by diethylenetriaminepentaacetic acid (DTPA) was quantitatively performed. Adsorption between the radionuclides studied and DGS was attained at pH 5±0.5. Individual separations of⁶⁰cobalt (II),⁹⁰strontium (II),¹⁴⁴cerium (III),²³³uranium (VI) and²³⁹plutonium (IV) were done by 25 ml of 10⁻⁴M of DTPA, as eluting agent, at different pH values.     

Determination of gamma impurities in fission product99Mo

The methodology is given for determination of very low quantities of gamma impurities:⁹⁵Zr,⁹⁵Nb,¹⁰³Ru,¹³¹I,¹³²Te,¹³²I,¹⁴⁰Ba,¹⁴⁰La,¹⁴¹Ce,¹⁴⁴Ce in⁹⁹Mo produced by separation from other fission products, by means of different measurement conditions such as initial activity, decay time and attenuation with lead.Presented as a poster at the International Conference on Nuclear and Radiochemistry, Beijing, P.R. China, September, 1986.     

Migration of radiocesium in a zeolite-solution system

Some properties of natural zeolite from Zaloka gorica, Slovenia, Yugoslavia were investigated to establish its applicability in solidification and for storage purposes of radioactive waste. It was found that this material is a rather good sorber for cesium, with a capacity of about 0.6 meq g^–1. The migration rate of Cs⁺ in a system ion exchanger-aqueous solution was investigated and correlated with the sorption behaviour of cesium in a system. The leaching rate of cesium from concrete containing zeolite was measured.     

Separation of rare-earth fission product elements from106Ru and137Cs by chloride sublimation

The possibility has been investigated of separating rare-earth fission fragment elements from¹⁰⁶Ru and¹³⁷Cs by high-temperature sublimation (950°C) of chlorides, with their subsequent gas adsorption separation in a quartz tube under a temperature gradient in a flow of the carrier-gas Ar+SOCl₂. The temperature corresponding to the maxima of the element precipitation zones are: 630–660°C (¹⁴⁴Ce), 770–780°C (0.7–6 μg¹⁴⁰La+La), 920°C (1.5 mg Ce or La), 420–450°C (¹⁰⁶Ru), 280–300°C (¹³⁷Cs). The coefficients of element separation have been calculated. For the separation of indicator amounts of rare-earth elements and¹⁰⁶Ru and¹³⁷Cs, fractional sublimation of the chlorides of the latter at 650°C has been used. Rate constants and effective activation energies of the overall processes of chlorination-sublimation of the elements have been determined.     

Isolation and partial characterization of a biosurfactant mixture produced by Sphingobacterium sp. isolated from soil

The concentration decay curves for the adsorption of phenol on organobentonite were obtained in an agitated tank batch adsorber. The experimental adsorption rate data were interpreted with diffusional models as well as first-order, second-order and Langmuir kinetic models. The surface diffusion model adjusted the data quite well, revealing that the overall rate of adsorption was controlled by surface diffusion. Furthermore, the surface diffusion coefficient increased raising the mass of phenol adsorbed at equilibrium and was independent of the particle diameter in the range 0.042-0.0126 cm. It was demonstrated that the overall rate of adsorption was essentially not affected by the external mass transfer. The second-order and the Langmuir kinetic models fitted the experimental data quite well; however, the kinetic constants of both models varied without any physical meaning while increasing the particle size and the mass of phenol adsorbed at equilibrium.