Adjustment of the Parameters in the Calculations of the γ-Production Data

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     

Effects of the radiative recombination on the intensity and polarization of the Ly-α emission of hydrogen-like ions

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 2p_1/2,3/2 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.     

Analysis of the Water Hammer in the Secondary Loop of CEFR

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.     

Analysis of the Water Hammer in the Secondary Loop of CEFR

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…     

Accident Analysis of the Large Leakage in the SG of CEFR

ThisreportwasfinishedinAugust,1999,whichgivestheaccidentanalysisofsodium-waterreactionunderlargeleakagecaseintheSG(steamgenerator)ofCEFR.Themainresultsincludetemperatureandpressureschangeofsecondaryloopequipmentunderthisaccidentcase,andthepossibleaccident…     

Investigation of the radiation characteristics of the masonry in the ai uranium–graphite reactor

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.     

The Influence of the Shape of BGO Crystal to the Energy Resolution

BGOcrystalisoftenusedforComptonsuppressionintheHPGedetectorsystemforgammaspectrummeasurement.Thehyperballsystemisdesignedandbuiltbythecoopera-tionbetweenChinaandJapan.TomeetthespecialneedsintheexperimentthreeirregularshapesofBGOcrystalhavebeenusedinthisde…     

Calculation of the spectra of fission neutrons emitted at angles of 0, 45, and 90° to the direction of flight of the fragments

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     

Influence of granulation of the sample on the thermal neutron Σa measurement

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.     

A Comparison of the Maximum Entropy Method of Analysis with the Exciton Model Plus the Master Equation

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.     

A Prototype of the Read-out Subsystem of the BESIII DAQ Based on PowerPC

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…     

Drawbacks of the Classical Theory of the α-Rossi Method and Its Alternative

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.     

Improvements of the Five Programs

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.     

Verification of the Extrapolating Critical Programme of CEFR

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…     

Substantiation of the Choice of Threshold Parameters for the System Monitoring the Fuel-Containing Materials in the Object “Cover”

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.