共查询到20条相似文献,搜索用时 687 毫秒
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P. P. Boldyrev A. I. Bortash V. A. Zagryadskii A. S. Zakharov V. I. Nikolaev M. A. Proshin D. Yu. Chuvilin A. V. Shatrov S. P. Vesnovskii 《Atomic Energy》2012,111(6):422-427
A scheme for producing the α-emitters 212Pb and 212Bi, to be used in a promising method of diagnostics and therapy in oncology – radioimmunotherapy, is proposed. The technology
is based on two generators operating in tandem: 228Th/212Pb and 212Pb/212Bi. The first one is based on separation from an initial solution containing thorium isotopes and gaseous 220Rn, which secures the purity of the desired products 212Pb and 212Bi. For a 228Th/212Pb model generator, the efficiency of 220Rn extraction from solution was ~60%. After conditioning, the 212Pb solution from the 228Th/212Pb generator was used to charge a column, which functioned as a 212Pb/212Bi generator, with a cation exchanger. 相似文献
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Computational results, obtained by analyzing possible schemes of nuclear transformations of each of four threshold fission
radiators 238U, 232Th, 237Np, and 231Pa, for fission ionization chambers are presented. The influence of the nuclear reactions (n, ƒ), (n, γ), and (n, 2n) on the characteristics of fission ionization chambers is taken into account in the nuclear transformation schemes for all
four radiators. The results are presented in the form of a dependence of the sensitivity of the fission ionization chambers
on the neutron fluence in the range 1021–1024 cm−2. The effect of 0.2 and 1 g/cm2 thick boron screens is examined.
Translated from Atomnaya énergiya, Vol. 106, No. 1, pp. 42–47, January, 2009. 相似文献
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It is suggested that γ radiation with E
γ > 4900 keV from short-lived fission products produced by thermal neutrons be used to detect 235U and 239Pu in samples. A time regime is substantiated: 120 sec irradiation, 60 sec holding time, and 120 sec measurement time. The contribution of the reaction (n, p) on fast neutrons is studied.__________Translated from Atomnaya Energiya, Vol. 98, No. 5, pp. 365–370, May 2005. 相似文献
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V. M. Maslov 《Atomic Energy》2007,103(2):633-640
Calculations of 239Pu(n, F) prompt fission neutron spectra have been performed for neutron energy up to 20 MeV. The exclusive spectra of pre-fission
neutron reactions (n, xnf) were calculated on the basis of the Hauser-Feshbach model simultaneously with the cross sections
of (n, F) and (n, 2n) reactions. The spectra of neutrons emitted by fission fragments were approximated by a sum of two Watt
distributions. The components of the prompt fission neutron spectra due to pre-fission neutrons are manifested in the prompt
fission neutron spectra and the average neutron energy. A correlation is established between this effect in the contribution
of emissive fission (n, xnf) in the fission cross-section of 239Pu(n, F) and 235U(n, F). It is shown that the 239Pu(n, F) prompt fission neutron spectra used in applied calculations do not correspond to the experimental differential data
and the systematic regularities in the spectra and their average energy found for the most carefully studied nuclei 235,238U and 232Th.
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Translated from Atomnaya énergiya, Vol. 103, No. 2, pp. 119–124, August, 2007. 相似文献
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A. A. Pustovalov V. V. Gusev V. V. Zaddé N. S. Petrenko L. A. Tsvetkov A. V. Tikhomirov 《Atomic Energy》2007,103(6):939-945
The possibility of developing a β-electric atomic battery with microwatt power based on 63Ni with a lifetime of at least 30 years is analyzed. A method is proposed for large-scale commercial production of 63Ni with concentration 80–90% in the final product. A design of a β-electric transducer based on macroporous silicon with optimized configuration and macropore depth (microchannels) is presented
and analyzed. 63Ni is deposited on the inner surface of the microchannels.
A laboratory model of an atomic battery based on 63Ni has been fabricated. The working parameters and the current-voltage characteristics of a 500 μW(e) atomic battery based
63Ni (90% concentration) are presented.
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Translated from Atomnaya énergiya, Vol. 103, No. 6, pp. 353–356, December, 2007. 相似文献
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The methods and results of benchmark experiments and calculations of the transport of 137Cs, 60Co, and 22Na photons in iron, lead, bismuth, tungsten, and uranium are described. The results are photon spectra which served as the basis for determining the photon absorption coefficients in a wide geometry and the accumulation factors. A comprehensive analysis of the experimental and computational results revealed the regularities in the differences between the experimental and computational photon absorption coefficients in a wide geometry.Translated from Atomnaya Ènergiya, Vol. 97, No. 4, pp. 293–299, October, 2004. 相似文献
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The possibilities of reagent-based processing of sandy soil contaminated with 137Cs are examined. To attain a high decontamination factor, the process is conducted in several steps. First, water-gravity
separation is used to separate finely dispersed matter (first step). The main goal of the next (second) reagent-based processing
step is to destroy the strongly bound fragments and hydroxide films with which a part of the finely dispersed fraction is
bound. At the next step, part of the 137Cs is extracted into the reagent solution from the purely sandy fraction; repeated water-gravity separation (third step) makes
it possible to completely separate the finely dispersed substance. The subsequent steps of reagent-based processing give 137Cs concentration in the sandy fraction of the initial soils that meets the sanitary norms. 相似文献
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Reactions resulting in the accumulation of 3He and 6Li, whose thermal neutron capture cross-section is large, occur under the action of neutron radiation in the beryllium blocks
of the MIR reactor core. When a neutron absorber accumulates in the moderator of a reactor, important physical characteristics
change: reactivity access, efficiency of safety and control rods, and reactivity effects; in addition, energy release is redistributed.
An algorithm for calculating 3H, 3He, and 6Li in each beryllium block of the core has been developed and implemented. This algorithm makes it possible to follow the
change in the concentration of these nuclides during reactor operation and shutdown. The 3He and 6Li concentrations are used as initial data for calculating the neutron-physical characteristics of the MIR reactor using the
MCU and BERCLI programs. The computational results for the effect of the accumulation of the nuclides indicated on the neutron-physical
characteristics of the core are presented.
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Translated from Atomnaya énergiya, Vol. 104, No. 2, pp. 84–88, February, 2008. 相似文献
11.
The radiochemical purity of a 131Cs solution used in brachytherapy is studied. After separating 131Cs from the neutron irradiated targets BaO, Ba(NO3)2, and BaCO3, the contribution of impurities was evaluated: 0.015% for 124Sb and 0.012% for 132Cs. The contribution of the parent 131Ba to cesium solutions was, on average, 0.0067% for BaO, 0.01% for Ba(NO3)2, and 0.011% for BaCO3. 相似文献
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A. A. Alekseev A. A. Bergman A. I. Berlev E. A. Koptelov A. S. Egorov B. F. Samylin B. I. Fursov V. S. Shorin 《Atomic Energy》2012,111(6):428-438
The SVZ-100 lead moderation time neutron spectrometer at the Institute of Nuclear Physics of the Russian Academy of Sciences
was used to measure the fission cross section for 243Am in the neutron energy range En = 0.3 eV – 10 keV. The resonance fission integrals and the area and fission width of the resolved resonances were calculated.
The properties of the intermediate-structure resonances were evaluated. The results were compared with existing data and recommended
evaluations. 相似文献
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Analysis of data obtained in 1990 and 2000 on the 137Cs contamination of the bottom of the Tsimlyanskoe reservoir near the dam has revealed the salient variations of this contamination.
The global fallout enters the water in the section near the dam from side tributaries and as a result of erosion from the
closest water catchment areas. The fallout due to the accident at the Chernobyl nuclear power plant is added primarily with
the solid runoff from the more highly contaminated catchment basins of the Don River. It is shown that shore abrasion, flows,
and removal of sediment through the water outflow area influence the distribution of the 137Cs content over the zones and the characteristics of the variation of this distribution in time.
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Translated from Atomnaya énergiya, Vol. 103, No. 4, pp. 260–263, October, 2007. 相似文献
16.
The status and the problems of world 99Mo production are presented. A comparative analysis is made of reactor methods of 99Mo production. It is noted that the currently used technologies and research reactors are not satisfying the growing demand
in medicine for this isotope. It is underscored that the role of alternative production technologies has grown. In the development
of new 99Mo production technologies, the experimental results obtained on the basis of research program conducted on the MSRE reactor
with molten-salt fluoride fuel have been analyzed. The analysis revealed a special behavior of certain fission products including
99Mo: they leave the melt spontaneously and enter the gas phase. The authors hypothesize that highly volatile fluorides of the
indicated products are formed in the melt; this explains the effect indicated. The effect is used as a basis to propose a
new reactor method of producing fissionproduced 99Mo. Concrete examples of a way to implement the new method of producing fission-produced 99Mo using molten-salt fluoride nuclear fuel are presented. 相似文献
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The particulars of radioactive contamination of concrete wastes by 137Cs were studied. x-Ray phase analysis and chemical analysis show that clayey materials, including Al2O3, Fe2O3, K2O, and MgO, on which 137Cs sorption is possible, were present in the concrete wastes. The content and form in which 137Cs was found in radioactive concrete wastes from nuclear power facilities as well as in model samples were determined. When
the wastes were treated with nitric acid the binder dissolved and a polydisperse suspension formed. The suspension consisted
of three phases: solution, fine suspension, and rapidly settling precipitate of heavy filler particles. x-Ray phase analysis
was performed and the 137Cs mass ratio and distribution in the phases were determined. The possibility of decontaminating the concrete by a reagent
method was evaluated. 相似文献
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The cross sections for radiative capture and fission for 236U in the neutron energy ranges 1–2000 eV and 1–1000 eV, respectively, have been measured. The measurements were performed
on a flight baseline 5.2 m of the FAKEL linear electron accelerator at the National Research Center Kurchatov Institute using
a method based on measuring the distribution of the number of particles emitted by an excited nucleus with simultaneous measurement
of the energy of each particle. The spectrum of the neutrons incident on a sample was measured by detecting the reaction 10B(n, α)7Li. The cross sections were normalized with respect to the resonance in 236U at 5.45 eV. The data obtained are compared with the results of other experiments and evaluated data. 相似文献