The computer system in CNDC

With the development of the nuclear data work,Chinese Nuclear DataCenter(CNDC)has had own computer system. First,a PDP 11/70 computer with operating system RSX-11M was installedin 1983,it is connected with two RX02 8 inch floppy disk drivers,two TS111600 BPI magnetic tape units,two RP06 hard disk drivers(each has 176M bytesmemory),some terminals and plotters.With this computer,some applicationprogram system and data library have been developed by CNDC and its coopera-tion network.     

Critical phenomena of a nuclear system in alternative ZM models

Alternative versions of the ZM model are xtended to asymmetric nuclear matter by including ρ meson degree of freedom in the Lagrangian ,The extended models are then used to study the thermodynamical properties of asymmetric nuclear matter at finite temperature.The critical temperature for a liquid-gas phase transition in nuclear matter and its dependence on asymmetry parameter are calculated,The liniting temperature Tlim,which reflects Coulomb instability of hot nuclei,is studied.The calculated results are compared with that given by the original ZM model.     

Considerations of uncertainties in evaluating dynamic reliability by GO-FLOW methodology – example study of reliability monitor for PWR safety system in the risk-monitor system

The uncertainty analyses have been considered as a relevant topic since WASH-1400 and analysis was performed for identifying the risk measure, e.g. plant- and core-damage frequency or the frequency of a large early release of radioactivity in the probabilistic safety assessment (PSA) or probabilistic risk assessment. There are two main sources of uncertainty such as aleatory uncertainty and epistemic uncertainty (parameter uncertainty, model uncertainty and completeness uncertainty) for risk analysis in PSA or risk-monitor system. A sensitivity analysis is related field to uncertainty, which can provide information of the most effective on those inputs of PSA, which are mostly contributed to the uncertainty.

In this paper, uncertainty analysis (epistemic) has been conducted in the evaluation of dynamic reliability of safety-related subsystem for risk analysis. GO-FLOW methodology has been employed for the procedure of uncertainty analysis alternatively to Fault Tree Analysis and Even Tree because it is success-oriented system-analysis technique and comparatively easy to conduct the reliability analysis of the complex system. The method used sample data from Monte Carlo simulation to quantify uncertainty in terms of appropriate estimates for analysis results. Pressurized water reactor containment spray system has been taken as an example of safety-related subsystem. The results of this paper show that the uncertainty analysis is an important part for the practical evaluation of the system dynamic reliability and makes the reliability prediction more accurate compared with the result without the uncertainty analysis. The GO-FLOW methodology can be employed easily for uncertainty analysis with its advance functions.     

Flashing and flashing coupled density wave oscillation in natural circulation system

The phenomeon and mechainsm of different kinds of two-phase flow instabilities,namely geysering,flashing instability and flashing coupled density wave instability are firstly well interpreted by the experiment performed on the test loop(HRTL-5) simulating the 5-MW reactor.The flashing coupled density wave instability is analyzed by using an onedimensional non-thermoequilibrium two-phase flow drift model computer code.Calculation results are in good agreement with the experimetal.     

Numerical study of the radio-frequency biased accelerating system in ion thrusters

A 2D-3V implicit immersed-finite-element particle-in-cell(IFE-PIC) model is introduced to investigate the radio-frequency(RF) self-bias accelerating system applied in the RF ion thruster.A set of holes in a two-grid system with slit apertures is simulated in Cartesian coordinates. The characteristics of the plasma plume, such as the ion density, the neutralization rate and the ion and electron current density were investigated for different RF voltage amplitudes(600-1200V) and frequencies(6-30 M...     

Bifurcation and hysteresis phenomena in the two－phase natural circulation system

The static bifurcation of the two-phase natural circulation (TPNC) system was studied theoretically and numerically.By the DERPAR algorthm the solution diagram was calculated,which shows that the static bifurcation occurs under some conditions in the TPNC systems.Also,it shows that the static bifurcation occurs under some conditions in the TPNC systems.Also,it shows that,in a region of multiple solutions.the static instability may occur.It is defined as a region of thermal-siphon instability induced flow rate jumping.By means of the solution diagram,the stability margin can be determined in this region.Furthermore.the heat input at the peak of the solution diagram is defined as the maximum capacity of heating load that can be used to judge the capacity of the TPNC of a given geometry topological structure,Meanwhile,it is interesting that the TPNC systems have the hystersis phenomenon defined as thermal-siphon hysteresis.Some parametric effects related were also studied.     

Stopping power in a cylindrical system by the modified Bessel function’s method

On the basis of the general theory of stopping power for a system, where their electronic distributions are able to be treated as cylindrically symmetric, we derive the log-type formulae which are applied in the non-relativistic high-energy region. As well as the case of a free electron in a homogeneous system, we obtain analytically instructive solutions of stopping power in an inhomogeneous system of many-electrons, in which an effective impact parameter averaged over scattering angles is introduced. Numerical calculations are performed for fast protons into a Au〈1 0 0〉 string.     

Automatic spectrum recognition system for charge state analysis in electron cyclotron resonance ion sources

The Electron Cyclotron Resonance(ECR) ion source is a critical device for producing highly charged ion beams in various applications. Analyzing the charge-state distribution of the ion beams is essential, but the manual analysis is labor-intensive and prone to inaccuracies due to impurity ions. An automatic spectrum recognition system based on intelligent algorithms was proposed for rapid and accurate chargestate analysis of ECR ion sources. The system employs an adaptive window-length Savitzky–...     

Experimental observations of naturally occurring dust using a high-speed vacuum ultraviolet imaging system in EAST

In the ELMy H-mode experiment, naturally occurring dust originating at the high-field side is clearly observed using the high-speed vacuum ultraviolet imaging system developed on the Experimental Advanced Superconducting Tokamak(EAST). The main ablation cloud shape is similar to the classical shape observed in pellet fueling experiments. However, during the dust penetration, an erupted secondary cloudlet with a bent ‘cigar’ shape is observed and moves upwards along the direction perpendicular to...     

100 kA/10kV thyristor stack design for the quench protection system in CRAFT

Thyristors have longer lifetimes, higher reliability, and very high voltage and current ratings and they require less maintenance than other high-power semiconductor devices. As a result, they are particularly suitable for quench protection systems(QPSs), which protect the superconducting magnets in large fusion devices from damage. In this paper, we propose a design for a 100 k A/10 k V thyristor stack supported by both theoretical and simulation-based analyses as well as experimental verificat...     

The effect of adrenergic receptor—adenyl cyclase system on myocardial ischemic preconditioning in rats

In order to study the effects of every part of adrenergic reccptor-adenyl cyclase system on ischemic preconditioning of myocardium in rats in vivo, SD rats were divided into three groups: IP group, I/R group and CON group. Rats were received surgical procedure and undergone left coronary artery occlusion and reperfu-sion. Hearts were extracted to analyze the infarct size by TTC staining, to measure serum myocardial enzymes, to study β-AR Bmax and Kd by radioligand binding assay of receptors (RAB), and to check the activity of AC and the content of cAMP by ra-dioimmunoassay (RIA). The infarct area was found much smaller in IP group than I/R group (p <0.001); CK,CK-MB and LDH were found significantly higher in I/R group (p <0.001). The Bmax of β-AR in IP group were higher than in I/R group (p <0.001). No difference of Kd could be seen between IP and I/R group. In IP group, the activity of AC and the content of cAMP were higher than I/R group (p <0.05 and 0.001, respectively). It is concluded that ischemi     

The study of aeroball system for measuring 3D neutron flux distribution in reactor core

Aeroball system is attractive in several aspects because it can easily transport the map of neutron flux distribution to be measured from incore to outside of a reactor vessel.However,before the aeroball system is put to practical use in the heating reactor.there are four topics that have to be further studied.They are the stability of the activated positions,enhancement of signal/noise(S/N)ratio,distributed control and data-acquisition system and on-lin nbeutron flux distribution reconstruction.Besides describing the rasons for them,this paper gives out the theory,concept and solution about the first two topics and it is helptul to give the possibility to enhance the reactor-power.     

Solubility studies,thermodynamics and electrical conductivity in the Th1−xSrxO2 system

A polymeric gel combustion method was employed for the lower temperature synthesis of 1, 2, 3, 5, 7.5, 10 and 15 mol.% SrO doped ThO₂ solid solutions. After final sintering of these samples at 1573 K in Ar, the solubility limit was found to be 1 mol.%, giving rise to a composition-independent value of (559.84±0.02) pm (at 300 K) for the CaF₂-type unit cell. AC impedance measurements carried out on discs of 1, 2, 3 and 5 mol.% SrO in ThO₂ discs in flowing Ar, yielded values of 116, 115, 128 and 96 kJ/mol, respectively as the activation energies for the bulk ionic conductivity. The thermodynamic activities of SrO in the 1, 2 and 3 mol.% solid solutions were measured using [SrO]_ThO2,SrF₂,O₂,Pt as the test electrodes and SrZrO₃,ZrO₂,SrF₂,O₂,Pt as the reference with sintered SrF₂ as the electrolyte over the range of approximately 650–800 K. The activity values differed marginally from each other, but were indicative of the combined (and not free) state of SrO. Hence, only a limiting value of a_SrO for the just saturated (mole fraction of SrO=0.01) thoria solid solution could be derived as log a_SrO=0.36−4602/T (K).     

Simulation of multi-atomic interactions in H–O–W system with the MD code CADAC

For future tokamak reactors, chemical erosion of tungsten armour surfaces under impact of hot deuterium–tritium plasma that contains impurities, for instance oxygen, is an important issue. Oxygen can form volatile molecular complexes O_xW_y at the surface, and the retained H-atoms form the volatile complexes H_xO_y, which mitigates the erosion (H states for hydrogen isotopes). The plasma impact can substantially destroy the complexes.To describe this H–O–W system, the molecular dynamics (MD) code CADAC was earlier developed using only pair–atomic interactions. Now CADAC is extended for multi-body forces to simulate molecular organization of atoms near the tungsten surface. The approach uses the Abell's model of empirical bond-order potentials in addition combined, for the first time, with a valence concept. CADAC simulates chemical features using atomic valences and the Morse potentials. The new model is introduced and model parameters are estimated.     

Distribution of trace impurities of fluorocarbons in the condensed phase – vapor system based on uranium hexafluoride in equilibrium and during evaporation

The results of investigations of the distribution of fluorocarbons in two-phase solid phase–gas and liquid–vapor systems based on uranium hexafluoride are presented. The systems are studied under equilibrium conditions, under which a constant distribution of fluorocarbons is established between the phases in a closed volume, and under nonequilibrium conditions created with stationary removal of the gas phase from the volume with liquid or solid uranium hexafluoride. The investigations were performed on specially prepared standard mixtures of uranium hexafluoride with fluorocarbon fraction from 10^–4 to 10^–1%. The special features of the evaporation processes in the two-phase systems studied are shown, the distribution laws of the fluorocarbons between phases of the main substance are established, and the regimes of evaporation of the mixtures with the smallest disruptions in the uniformity of the fluorocarbon inflow with the flow of the evaporated uranium hexafluoride are determined.     

Interaction between point defects in the Si–SiO2 system during the process of its formation

The results of the studies of the point defect generation kinetics in the Si–SiO₂ system by means of electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) are presented. It has been established that the EPR and NMR signal intensities change non-monotonously with oxide film thickness and the maximum of the EPR and minimum of the NMR signals occur at the same oxidation time. This can be connected with the competition between the generation and transformation of the point defects, the formation of Si–O bonds and strained bonds rupture in the Si–SiO₂ system during the process of its formation. The defect structure of the Si–SiO₂ system depends on the point defects density in initial wafers. A possible mechanism to explain this interdependence has been discussed.     

“Stand B” reactor-laser system

A reactor-laser system, consisting of a BARS-6 double-core aperiodic pulsed reactor operating on fast neutrons and equipment for performing investigations of the laser radiation generation by direct nuclear pumping, is described. The neutron-physical characteristics of the reactor and the laser unit as well as the reactor-laser unit system are presented. The special features of the formation of fission pulses and the parameters of the pulses are indicated. 8 figures, 1 table, 12 references. Translated from Atomnaya énergiya, Vol. 88, No. 5, pp. 337–342, May, 2000.