Experiment for the Flow Distribution in the CARR Fuel Assembly

CARR fuel assembly is a plate type fuel element, which has twenty rectangle coolant channels formatted by twenty-one fuel plates. The breadths of channel are symmetrically distribution along the     

Heat transfer analysis of the bent cooling channels in SSRF light-blocked components

The front end light-blocked components of the third generation of synchrotron radiation facility,which are subjected to high heat load,are cooled with flowing water through the cooling channels.The convective heat transfer coefficient and the flow resistance(or pressure drop) are two important parameters for evaluating the heat transfer performance of the cooling channels and should be strictly quantified.In this research,two typical bent cooling channels in Shanghai Synchrotron Radiation Facility(SSRF) were modeled and their in-pipe turbulent flows were simulated.The two criteria obtained under different channel water velocities met the SSRF technical requirements.To reduce the total pressure drop,arc transitions were proposed to replace the right angle transitions in the cooling channels.At the same time,an experiment was performed to measure the convective heat transfer coefficient of a typical bent channel unit.The experimental results were in good agreement with the simulation ones.     

Out-of-pile Hydraulic Stability Test of CARR Control Rod Assembly

The CARR control rod assembly consists of the neutron absorber, the fuel follower, and the drivingstructure which are linked each other by the linking latches as shown in Fig. 1. The out-of-pile hydraulic stability test of control rod assembly has been done in order to examine     

The Welding Process of the Small In-pile Testing Fuel Assembly

The small in-pile testing fuel assembly is designed for high performance fuel assembly study. It has two parts of which are four fuel element with double layer cladding and a detect system for measurement of testing pressure and temperature. The fuel element is composed of UO2 pellets, the stainless steel cladding and end caps. The detect system is direct contact with the fuel element by electron beam welding. In the fabrication of the assembly, some special welding technologies are     

The Plasma Channel Evolution Characteristics of Pulsed Flashlamps Working in an Array

This work is devoted to the study of plasma channel evolution characteristics in pulsed xenon flashlamps working in an array. Influencing factors on the plasma channel evolution process are studied, including pre-ionization pulse and neighbor flashlamps. It has been found that neighbor flashlamps affect the plasma channel by shaping the electric potential distribution, rather than by Lorentz force. Branching is observed in the plasma channels of the flashlamps in the middle of the array. Inconsistency also exists in the plasma channels of these flashlamps in different tests. The branching and inconsistency are both caused by the unique electric field distribution in these flashlamps. Besides, the pre-ionization pulse can help the main pulse plasma channel to develop more smoothly and faster, which will weaken the shock wave and benefit the mechanical strength of the flashlamp.     

Research on Power Ramp Testing Method for PWR Fuel Rod at Research Reactor

In order to develop high performance fuel assembly for domestic nuclear power plant, it is necessary to master some fundamental test technology. So the research on the power ramp testing methods is proposed. A tentative power ramp test for short PWR fuel rod has been conducted at the heavy water research reactor (HWRR) in China Institute of Atomic Energy (CIAE) in May of 2001. The in-pile test rig was placed into the central channel of the reactor . The test rig consists of pressure pipe assembly, thimble, solid neutron absorbing screen and its driving parts, etc.. The test     

Simulation of quenching in horizontal geometry channel

<正>Two tests of refilling and reflooding in the horizontal geometry channel under different pressure conditions,respectively,are conducted to understand the thermal hydraulics behavior during a LOCA in the CANDU reactor.One case of refilling a hot horizontal tube test and four cases of reflooding a horizontal fuel channel test series (35%and 60%break size of reactor inlet header with single-end injection or both-end injection,respectively) have been simulated.The horizontal channel is simulated with the model splitting as parallel pipes with cross flow junction component.The simulation results have been compared with the tests in terms of wall temperature or heated-pin surface temperature.The results are reasonably acceptable and it shows that the code is applicable on horizontal channel quenching.     

IRIS reactor core with thorium fuel

This work is aimed at running the first IRIS reactor core with mixed thorium dioxide fuel（ThO₂-UO₂ and ThO₂-PuO₂）.Calculations are performed by using Dragon 4.0.4 and Citation codes.The results show the multiplication factor(K_eff) for central and peripheral assemblies as a function of burnup.To ensure the proliferation resistance,the value of ²³⁵U enrichment is < 20%.The K_eff is calculated using Dragon 4.0.4 for a single fuel rod and the model developed to fuel assembly,while the whole core was calculated using Citation code.For a fuel burnup,the use of increased enrichment fuel in the IRIS core leads to high reserve of reactivity,which is compensated with an integral fuel burnable absorber.The self-shielding of boron is in an IRIS reactor fuel.The effect of increased enrichment to the burn-up rates,and burnable poison distribution on the reactor performance,are evaluated.The equipment used in traditional light water reactors is evaluated for designing a small unit IRIS reactor.     

Neutron Radioactive Capture Cross Section Calculations of Natural Zr in the Incident Energy Region from 0.01 to 20 MeV

The neutron radiate capture cross sections of natural Zr are calculated in the neutron incident energy region from 0.01 MeV to 20 MeV. In the calculations, photon transmission coefficients of the compound statistical processes are calculated by solving the cascade gamma deexcitation processes of the compound nucleus. The nonstatistical effects of the neutron radiate captures, the radiate captures in the shape elastic scattering channels and the compound elastic scattering channels as well as the direct-semidirect captures are considered carefully in the calculated energy region. The calculated results are in better agreement with the experimental values.     

A versatile 16-channel front-end integrated circuit for semiconductor radiation detectors

A CMOS front-end integrated circuit consisting of 16 identical analog channels is proposed for semiconductor radiation detectors. Each of the 16 channels has a low noise charge sensitive amplifier, a pulse shaper, a peak detect and hold circuit and a discriminator, while analog voltage and channel address are routed off the chip. It can accommodate both electron and hole collection with selectable gain and peaking time. Sequential and sparse readout, combining with self-trigger and external trigger, makes four readout modes. The circuit is implemented in a 0.35 μm DP4M (double-poly-quad-metal) CMOS technology with an area of 2.5×1.54 mm2 and power dissipation of 60 mW. A single channel chip is tested with Verigy 93000. The gain is adjustable from 13 to 130 mV·fC–1 while the peaking time varies between 0.7 and 1.6 μs. The linearity is more than 99% and the equivalent noise charge is about 600e.     

Progress of Annular Fuel R&D

正1Introduction As a new type of fuel rod composes of inner and outer claddings and annular fuel pellet,the annular fuel has a coolant channel inside the fuel rod,which increases the heat transfer area,power density,and the economics of nuclear power compared with the traditional fuel rod.Lower fuel temperature and stored energy are features of annular fuel,which can reduce fission gas released     

Development and Integration of a Data Acquisition System for SST-1 Phase-1 Plasma Diagnostics

Long pulse(of the order of 1000 s or more) SST-1 tokamak experiments demand a data acquisition system that is capable of acquiring data from various diagnostics channels without losing useful data(and hence physics information) while avoiding unnecessary generation of a large volume data.SST-1 Phase-1 tokamak operation has been envisaged with data acquisition of several essential diagnostics channels.These channels demand data acquisition at a sampling rate ranging from 1 kilo samples per second(KSPS) to 1 mega samples per second(MSPS).Considering the technical characteristics and requirements of the diagnostics,a data acquisition system based on PXI and CAMAC has been developed for SST-1 plasma diagnostics.Both these data acquisition systems are scalable.Present data acquisition needs involving slow plasma diagnostics are catered by the PXI based data acquisition system.On the other hand,CAMAC data acquisition hardware meets all requirements of the SST-1 Phase-1 fast plasma diagnostics channels.A graphical user interface for both data acquisition systems(PXI and CAMAC) has been developed using LabVIEW application development software.The collected data on the local hard disk are directly streaming to the central server through a dedicated network for post-shot data analysis.This paper describes the development and integration of the data acquisition system for SST-1 Phase-1 plasma diagnostics.The integrated testing of the developed data acquisition system has been performed using SST-1 central control and diagnostics signal conditioning units.In the absence of plasma shots,the integrated testing of the data acquisition system for the initial diagnostics of SST-1 Phase-1 operation has been performed with simulated physical signals.The primary engineering objective of this integrated testing is to validate the performance of the developed data acquisition system under simulated conditions close to that of actual tokamak operation.The data acquisition is synchronized with a clock and trigger provided by the central timing system.     

Absorption-fluorescence-Raman Spectroscopic Study on Complexation of Uranyl Ion with Fluoride

<正>The coordination chemisty and speciation of uranyl in aqueous solutions are of great importance in nuclear fuel cycle.In nuclear fuel manufacturing and spent fuel reprocessing,the thermodynamic properties of uranyl complexes are needed for processes design and operation control.For waste disposal,the speciation of uranyl under associated conditions is the base for depicting and controlling the migration of uranium.     

Mechanism of ONB based on nonequilibrium thermodynamics of natural circulation in narrow channels

Based on the experiment of onset of nucleate boiling （ONB） in natural circulation and the nonequilibrium thermodynamics dissipative theory, the mechanism of ONB in narrow rectangle channels of natural circulation is proposed. It points out that the onset of nucleate boiling is influenced by the degree of superheat and the special conditions of narrow channels. Under the conditions of both density difference in natural circulation and narrow rectangle channels, the prediction model of ONB in natural circulation of narrow channels based on fluctuating is established. The experimental results show that the present model can be used to predict the heat flux of ONB in narrow rectangle channels. Features of ONB in natural circulation narrow rectangle channels are as follows： heating power is the incentive of the happen of ONB; the higher the heating power is, the higher the degree of superheat is, and the earlier the ONB will appear. With the pressurizing, the appearance of ONB will be delayed. The higher the degree of supercooling is, the later the ONB appears. The ONB will happen easier when there are noncondensable gases and roughness in the channels.     

Analysis on MHD Stability of Free Surface Jet flow in a Gradient Magnetic Fields

The simplified modeling for analysis on MHD stability of free surface jet flow in a gradient magnetic fields is based on the theoretical and experimental results on channel liquid metal MHD flow, especially, the results of MHD flow velocity distribution in cross-section of channels (rectangular duct and circular pipe), and the expected results from the modeling are well agreed with the recent experimental data obtained. It is the first modeling which can efficiently explain the experimental results of liquid-metal free surface jet flow.     

Numerical Analyses of Electromagnetic Forces on the ITER Blanket Module Shield Block During Major Disruptions

Electromagnetic（EM） load is one of the key design drivers for the blanket shield block（SB） and other in-vessel components. In this article, an EM analysis method was developed to address the EM force on the SB. The plasma currents, which vary spatially and temporally,are loaded as a filament at each time point. The standard blanket module No.04（BM04） under major disruption（MD） is selected to perform the analyses. The analyses results are validated by comparing currents on the passive structure. To better understand the effects of cooling channels and slits on the EM force, the case of SB without cooling channel and the case without slits are calculated to make comparisons. The results show that the slits play an important role in controlling the EM load on SB.     

Interactions between multiple filaments and bacterial biofilms on the surface of an apple

In this paper, the interactions between two dielectric barrier discharge(DBD) filaments and three bacterial biofilms are simulated. The modeling of a DBD streamer is studied by means of 2D finite element calculation. The model is described by the proper governing equations of air DBD at atmospheric pressure and room temperature. The electric field in the computing domain and the self-consistent transportation of reactive species between a cathode and biofilms on the surface of an apple are realized by solving a Poisson equation and continuity equations. The electron temperature is solved by the electron energy conservation equation. The conductivity and permittivity of bacterial biofilms are considered, and the shapes of the bacterial biofilms are irregular in the uncertainty and randomness of colony growth. The distribution of the electrons suggests that two plasma channels divide into three plasma channels when the streamer are 1 mm from the biofilms. The toe-shapes of the biofilms and the simultaneous effect of two streamer heads result in a high electric field around the biofilms, therefore the stronger ionization facilitates the major part of two streamers combined into one streamer and three streamers arise.The distribution of the reactive oxygen species and the reactive nitrogen species captured by time fluences are non-uniform due to the toe-shaped bacterial biofilms. However, the plasma can intrude into the cavities in the adjacent biofilms due to the μm-scale mean free path. The two streamers case has a larger treatment area and realizes the simultaneous treatment of three biofilms compared with one streamer case.     

Parameters Distribution Along the Channel Axis in the Scaling Designed Stationary Plasma Thruster

The study of the parameters＇ distribution along the channel axis in a stationary plasma thruster（SPT） helps One to understand the physical characteristics of the SPT＇s operation. In this paper, the axial distribution of the desired SPT parameters are predicted by combining the improved scaling theory and a one-dimensional hybrid model. The simulation indicates that the SPT parameters＇ distribution along the channel axis changes with scaling index variable ~. If ~ is set properly, the similarity of the parameters~ axial distribution between the model and a desired thruster can be ensured. In addition, the operation characteristics of the desired thruster, such as the ionization and acceleration processes, are also similar to those of the model. When ζ is set, the improved SPT scaling theory and the one-dimensional hybrid model can be used to predict the axial distribution of the desired SPT parameters with the same propellant （such as Xe）.     

Management of Waste from the Fusion Experimental Breeder

Fusion breeder might be an essential intermediate application of fusion energy at earlier term, which has the potential to provide plenty of commercial fissile fuel. Based on fusion physics and technologies available at present and in near future, the realistic Fusion Experimental Breeder, FEB-E was designed. The obiectives of the FEB-E are to demonstrate the engineering feasibility of     

Simulation of the effect of a magnetically insulated anode on a low-power cylindrical Hall thruster

The intersection point of the characteristic magnetic field line (CMFL) crossing the anode boundary with the discharge channel wall,and its influence on thruster performance and the energy and flux of ions bombarding the channel wall,have been studied numerically.The simulation results demonstrate that with the increase in distance from the crossover point of the CMFL with the channel wall to the bottom of the thruster channel,the ionization rate in the discharge channel gradually increases;meanwhile,the ion energy and ion current density bombarding the channel wall decreases.When the point of the CMFL with the channel wall is at the channel outlet,the thrust,specific impulse,and efficiency are at a maximum,while the ion energy and ion current density bombarding the channel wall are at a minimum.Therefore,to improve the performance and lifetime of the thruster,it is important to control the point of intersection of the CMFL with the channel wall.