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1.
《中国核科技报告》1997,(Z3)
Introduction The γ-production data are very important for the nuclear engineering, especially for the calculations of the radiation shielding. Because the experimental values of the γ-production data can not satisfy the needs of the nuclear engineering both in the quantity of the nuclei and in the energy region covered by them, as the supplement, the theoretical calculations of the γ-production data are indispensable. The γ-production data in the nuclear reactions induced by neutrons include the γ-production cross sections, the γ-energy spectra, the γ-multiplicities and the reaction cross sections of the (n,γ) and the (n,xγ) reactions, where the (n,xγ) reactions mean 相似文献
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G. L. Ponomarenko 《Atomic Energy》1999,87(3):663-667
A comparative analysis is made of the deterministic and statistical methods of taking into account the effect of the curvature of VVéR-1000 fuel assemblies on the power of fuel elements. The fuel-element distribution of the energy release in the core for any random distribution of the gaps between the fuel assemblies is simulated, using the MEX code, on the basis of precise calculations (MCU code) and design calculations (BIPR-7 and PERMAK codes). The Monte Carlo method (Zazor code) was used to model the nominal density distribution of gaps in the core for different degrees of curvature of the fuel assemblies. It is shown that the power gain, obtained for the fuel elements by the probabilistic-statistical method, due to the curvature of the fuel assemblies is smaller and makes it possible to substantiate core safety with large perturbations, in contrast to the deterministic “maximum gaps near the most-energy stressed fuel element” method. 5 figures, 1 table, 3 references. Special Design Office “Gidropress.” Translated from Atomnaya énergiya, Vol. 87, No. 3, pp. 210–213, September, 1999. 相似文献
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L. Bettadj A. Surzhykov S. Fritzsche 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2010,268(23):3509-3516
The intensity ratio of the to photon emission is analyzed for hydrogen-like Fe25+ ions if their excitation arises in a plasma not only from the electron impact but also due to the radiative recombination (RR) of initially bare Fe26+ ions. Under such conditions, the intensity ratio and the (degree of) linear polarization of the Ly-α1 line are explored for collisions with an electron beam over a wide range of kinetic energies up to 50 keV. Apart from the direct population of the 2p1/2,3/2 levels via the RR of bare ions, the contributions from radiative cascades and higher multipoles are taken into account by applying a fully relativistic theory for the motion of the electrons and the electron-photon coupling. Our calculations show an overall small effect of the RR upon the degree of the Ly-α1 polarization as well as the intensity ratio under usual plasma conditions. However, the effects from the RR of initially bare ions may become significant at electron beam energies , for plasma conditions far away from ionization equilibrium with a relatively large proportion of bare Fe ions, as it may be realized in electron-beam ion trap experiments. 相似文献
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TANG Long WANG Bin 《中国原子能科学研究院年报》2005,(1):8-8
The coolant of the primary loop and secondary loop of CEFR is sodium. The reaction of sodium with water during the leakage of SG will induce the water hammer in the secondary loop. The water hammer in the loop would cause the pipeline to swing, the support of the pipeline to snap, the pipeline to break, even the nuclear power station to shutdown directly. The water hammer is an important issue of the design and safe analysis of CEFR. 相似文献
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《中国原子能科学研究院年报(英文版)》2005,(1)
The coolant of the primary loop and secondary loop of CEFR is sodium. The reaction of sodium with water during the leakage of SG will induce the water hammer in the secondary loop. The water hammer in the loop would cause the pipeline to swing, the suppor… 相似文献
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V. N. Asnovskii S. I. Rovnyi S. P. Glazkov Yu. V. Fedorenko S. L. Levunin M. P. Tsevelev M. G. Kozhanov V. I. Bulanenko L. V. Bidulya 《Atomic Energy》2008,105(5):340-343
The results of investigations of the nuclear safety of the masonry in the AI uranium–graphite (Industrial Association Mayak)
reactor are presented. It is concluded on the basis of these results that the masonry is nuclear safe and a radiation certificate
is composed. The radiation examination made it possible to determine the level, composition, and distribution of the radioactive
contamination of the masonry as well as the level and distribution of the neutron and γ radiation, and to construct a forecast
of the change in the activity of radionuclides in graphite as a function of the holding time. These data are necessary for
safety analysis and for making decisions about the subsequent stages of decommissioning of the reactor.
Translated from Atomnaya énergiya, Vol. 105, No. 5, pp. 266–269, November, 2008. 相似文献
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This letter focuses on a possible pitfall that can occur in the DFT calculation of graphite–hydrogen interactions under tokamaks conditions. Calculations based on the BLYP functional, in fact, result in a stable –C2H3 group that other functionals (OLYP, XLYP, PBE and BP) do not confirm. 相似文献
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E. I. Sirotinin 《Atomic Energy》1963,13(6):1159-1162
The evaporation model is used to solve the problem of the spectrum of neutrons emitted by fission Fragments at angIes of 0, 45, and 90° to the direction of flight of the fragments. It is assumed that the neutrons are emitted isotropically in a coordinate system associated with the fragment. The spectra calculated are in good agreement with the experimental data.Translated from Atomnaya Énergiya, Vol. 13, No. 6, pp. 530–533, December, 1962 相似文献
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The theoretical approach to the influence of granulation of samples on the measured thermal neutron absorption cross-section has been verified in an experiment on samples containing irregular grains. The neutron absorption heterogeneity effect is defined as the ratio G of the absorption cross-section of the grained sample to the cross-section of the corresponding homogenised medium. The parameter G=1 when the heterogeneity of a material does not influence the thermal neutron transport, otherwise G<1. The theoretical limit, for the “sufficiently small” grains, G→1, has been experimentally confirmed on samples of pure silicon. For the complex media: diabase grains (size from 6.3 to 12.8 mm) embedded in aqueous solutions of boric acid (1.3–2.5% weight concentration), the G parameter achieves values between 0.9 and 0.8. The observed effect can be result in an underestimation of the absorption cross-sections measured on samples insufficiently crumbled. 相似文献
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1 Overview of the data acquisi-tion system for BES IIIAfter having run successfully for more than tenyears, the BEPC e+ e- collider will be upgradedfor higher luminosity, which will be increased to1033 cm-2 ·sec-1 [1]. Therefore, its detector BESII willbe upgraded to BESIII in order to take advantage ofthis increased luminosity, named BESIII.Trigger rate and event size define the performance re-quirements for the data acquisition (DAQ) system. Forpeak luminosity, we expect a L1 t… 相似文献
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A. G. Shokod'ko 《Atomic Energy》2002,93(5):880-886
Certain contradictions and inaccuracies in the classical theory of the -Rossi stochastic neutron method are pointed out. An alternative theory which is almost free of contradictions and deficiencies of the classical theory is presented.A new implementation regime for the method is proposed to eliminate any influence of the prestart dip on the correlated amplitude in the -Rossi method using modern time-delay analyzers – the scaled start regime, consisting in triggerings of the time-delay analyzer scaled by two, three, or more signals from the starting neutron detector. It is shown that the correlated amplitude contains the ratio of the first and second moments of the number of prompt neutrons in a chain.A new expression is obtained for taking account of the spatial-energy effect in the -Rossi method. The effect differs from the well-known one not only by the energy component but also by a large range of possible values.The possibilities of the -Rossi method for determining the physical parameters of multiplying and nonmultiplying media are considered: , k
p, k, eff, F, F
s, and D. 相似文献
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《中国核科技报告》1989,(Z1)
The following five programs are improved for present second edition in 1988.Program CBWFIT,written by Lu Guoxiong,Qiu Guochun and Shen Shunying,is designed to analyse resonance cross section by means of SLBW formula withthe correction of multileyel effect(1).The interference parameters(U,V)are ob-tained.A simply method for optimum paramerters is created. 相似文献
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《中国原子能科学研究院年报(英文版)》2005,(1)
The extrapolating critical program is an important sub-program of the CEFR’s physical startup software. After the physics startup software is finished, each of the sub-program is verified separately. This text will do a brevity presentation about the cou… 相似文献
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V. V. Avgustov A. A. Kuchmagra O. S. Molchanov G. I. Odinokin V. N. Shcherbin 《Atomic Energy》2002,92(2):165-170
A substantiation is given for the choice of threshold values of the neutron flux density (threshold-1 – Attention and threshold-2 – Danger), and formulas are derived for calculating these values for systems which are being designed and are currently in operation for monitoring the state of fuel-containing materials in the object Cover at the Chernobyl nuclear power plant. 相似文献
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《中国核科技报告》1994,(Z3)
The maximum entropy method of analysis is successful in fitting experimental data.In order to reveal the underlying physics,this method is applied in comparison with the conventional approach,i.e the exciton model plus the master equation,to three cases.It is found that both approaches produce almost equally good fits to spectra,and yield almost the same average exciton numbers. This implies that there must be similar physical ideas behind the two approaches,and it should be safe to use the maximum entropy method of analysis to fit data or to estimate reaction cross sections. 相似文献
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FAN Zhen-dong 《中国原子能科学研究院年报》2005,(1):9-9
The extrapolating critical program is an important sub-program of the CEFR's physical startup software. After the physics startup software is finished, each of the sub-program is verified separately. This text will do a brevity presentation about the course of verification off-line for extrapolating critical program 相似文献