核动力工程

Probability Analysis for External Reactor Vessel Cooling Effectiveness under Severe Accident

CAO Ke-mei, XU Yi-quan, SHI Guo-bao, CAI Jian-ping

2009, 30(1): 1-4.

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There are many uncertainties in severe accident phenomena which affect the effectiveness of External Reactor Vessel Cooling （ERVC） measurement. The uncertainties of In-Vessel Retention （IVR） issue are analyzed based on Risk-Oriented Accident Analysis method, and the probability distribution of ERVC effectiveness is obtained. The calculation results using VTA sampling program show that if the melt pool in lower head achieves final bounding state, the success probability of core debris IVR is over 99% for 8 kinds of severe accident sequences, supposing a postulated severe accident occurs in Chashma-2 Nuclear power plant and ERVC is performed successfully.

Study on Reliability of Redundant Standby Pumps in Nuclear-Powered Systems

HUANG Tao, CAI Qi, ZHAO Xin-wen, SHANG Xue-li

2009, 30(1): 5-7.

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According to the work conditions of the component cooling pumps in nuclear-powered sys-tems, the check valve in redundant pumps is taken as two redundant valves. Reliability chart was drawn and reliability analysis model was built up. Based on the example of equipment cooling pumps in nuclear-powered systems, the reliability of pumps in three conditions was separately calculated. Final results show that the re-liability of two-component redundancy is much higher than that of single component, but the dependent fail-ures between pumps and valves in redundancy decrease the reliability.

CFD Analysis on Hydrogen Risk in Qinshan II NPP

XIONG Jin-biao, YANG Yan-hua

2009, 30(1): 8-13.

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The computational fluid dynamics code GASFLOW is applied to simulate the steam/hydrogen behavior inside the containment of Qinshan II NPP, installed with 22 Passive Automatic Recombiners （PAR）, during the first 7 000 seconds of a postulated surge line Large Break LOCA accident. The results imply that the structures remove large amount of heat from the containment atmosphere and that the pressure variation is controlled by the inventory of gas （mainly steam） and the temperature. Two typical flow patterns and hydro-gen strafication are found in the containment during the accident. The stable recombination capability of the given arrangement is about 20 g/s. The possibility of flame acceleration is indicated.

Analysis of Environmental Influence in Maximum Hypothetical Accident of CFBR-II Reactor

LI Mao-hui, YANG Cheng-de, DENG Men-cai

2009, 30(1): 14-16,35.

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Scale of accident and data of radioelement on CFBR-II reactor are calculated and analyzed based on the principle used in its determination in the fast pulsed reactors in foreign countries. According to analysis of gas-dispersion mode, aerodynamic diffusion mode and source of individual effective dose, the individual effective dose of public and operator on the representative position in a conservative estimate is obtained. Compared with the national standards, it is not necessary to take emergency measurements such as for the public and operators to take iodine, shield and evacuate when maximum hypothetical accident does occurred.

Effect of Ractivity Addition Rate and Neutron Source Intensity Effect on Criticality Accidents Magnitude

ZHENG Chun

2009, 30(1): 17-19.

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The energy released （or the excursion power） at a real nuclear excursion is more than that pre-dicted by reactor kinetics because of the time delay of the first persist fission chain. In order to provide refer-ence for the development of startup procedure for the reactor and reducing the scale for the criticality accident, the energy released model at the nuclear excursion is established in this paper. Due to the time difference for the first persist fission chain occurred, the excursion power of a systems with no neutron source or only weak source is higher than that of a system with stranger neutron source, and the excursion power increases as the reactivity addition rate increases.

Quantitative Evaluation of Physical Protection System in Nuclear Power Plant

SUN Ya-hua, LI Shi-ju, LI Bin

2009, 30(1): 20-25.

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Based on the prompt detection analysis,this paper introduced one analysis model of intrusion path in nuclear power plant by means of morphology analysis and developed the evaluation software for path model analysis of physical protection system. Quantitative analysis on three elements （detection, delay, and response） of physical protection system was presented with an imaginary intrusionevent example in Mac Ar-thur nuclear center. The results indicated that the path prompt detection analysis worked effectively to find the weak point of the physical protection system in NPP,and meantime we can also get the high cost-effectiveness improved measures. It is an effective approach to evaluate the overall performance of the system.

Software Development for Risk Monitor in Nuclear Power Plants

WANG Hai-tao, WU Yi-can, LI Ya-zhou, HU Li-qin, LIU Ping, YUAN Run, CAO Xing-huan, LI Yuan-yuan

2009, 30(1): 26-30.

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Based on wide survey and analysis of the development of the current international Risk Moni-tors and its key techniques, a risk monitor named Risk Angel has been developed. An overview of the archi-tecture and functions of Risk Angel is presented in this paper, as well as the key algorithms and the testing. Test results show that Risk Angel meets the requirements on the speed for calculating the risk in a Risk Monitor.

Experiment on Fragmentation of Melt Drop Interacted with Water

LIN Qian, TONG Li-li, CAO Xue-wu, KRIVENTSEV Vladimir

2009, 30(1): 31-35.

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In order to understand the complicated fuel-coolant interaction and steam explosion during severe accident of nuclear reastors, the fragmentation process of high temperature molten metal drop interacted with water is investigated by experiment. The influences of initial temperature of melt drop, the temperature of water, the release distance of melt drop and the property of the materials are analyzed by comparing the appearance of the debris generated during interaction. The fragmentation process of melt drop is observed by high-speed camera. The results show that the initial temperature of melt drop, the temperature of water and the property of the materials are sensitive parameters for the fragmentation, but the release distance of melt drop is not an important parameter under the conditions of this experiment.

Dimensionless Analysis of Natural Circulation Characteristics of Nuclear Installations under Ocean Condition

YAN Bing-huo, YU Lei, ZHANG Yang-wei, GUI Xue-wen, XIE Hai-yan

2009, 30(1): 36-39,77.

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The dimensionless analysis is used to deduce the expression of natural circulation flow of nu-clear installations under ocean condition and the natural circulation flow equation in the steady state. The theoretical results are consistent with the experiment values. The expression between rolling amplitude and rolling period is also been deduced by the dimensionless analysis, with the limit that the fluctuation of natural circulation flow cannot cause the response of the control rods. The relation between the rolling amplitude and period is quadratic. The theory results are also consistent with the Code results. The responses of control rods depend on the maximum rolling acceleration, and have nothing to do with the maximum rolling angular ve-locity.

Development and Validation of Thermal-Hydraulic and Safety Analysis Code for CARR （TSACC）

TIAN Wen-xi, QIU Sui-zheng, SU Guang-hui, JIA Dou-nan, LIU Xing-min, ZHANG Jian-wei

2009, 30(1): 40-44.

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A Thermal-hydraulic and Safety Analysis Code for CARR（TSACC） was developed using For-tran Language. The adoption of modular programming techniques enables TASCC to be applied to other re-actors by easily modifying the corresponding function modules. Based on the principle of code validation, the Loss of Off-site Power（LOP） accident was analyzed using both TSACC and RELAP5/Mod3. Some important thermal-hydraulic parameters, such as coolant flowrate, temperature and MDNBR, in the mean channel and hot channel were obtained. The comparison between the computation results by TSACC and RELA5/Mod3 showed a good agreement in spite of a little larger difference during the coolant inverse flow process. The larger local difference is mainly caused by the adoption of different heat transfer correlations under low flow condition in the two codes. The code validation proves the applicability and accuracy of TSACC.

Boiling Phenomenon and Heat Transfer in Bead-packed Porous Structure

ZHANG Xiao-jie, ZHU Yan-lei, BAI Bo-feng, YAN Xiao, XIAO Ze-jun

2009, 30(1): 45-49,73.

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A visual study on pool boiling behavior and phase distribution was conducted on the porous structures made of staggered glass beads at atmospheric pressure. The bead-packed structure was heated on the bottom. The investigations were carried out respectively at different glass bead diameters which were 4mm, 6mm and 8mm. The results show that during subcooled boiling, small isolated bubbles are formed on the heated surface and combine into main-bubbles, the dispersion frequency of the main-bubbles is low and the small bubbles scatter in the bead-packed porous structures. At the initial stage of saturated boiling, the bubble growth rate, the volume of main-bubbles and the range of continuous vapor phase increase. The dispersion frequency of main-bubbles increases with the increasing of heat flux. During film boiling, the heated surface is absolutely covered with vapor film and the porous structure is full of liquid. The larger the diameter of beads is, the higher heat flux is needed for the same phenomenon, and the higher maximum value of heat transfer coefficient will be. During the whole saturated boiling, and the heat transfer enhanced firstly and then weakened. Being opposite to that of the diameters of 4mm and 8mm, the heat transfer coefficient in the 6mm-bead-packed porous structure decreases with the increasing of the heat flux.

Numerical Study on Turbulent Mixed Convection in Inclined Rectangular Channels

XIE Zheng-rui, YANG Yan-hua, GU Han-yang, CHENG Xu

2009, 30(1): 50-55.

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In literatures, the analysis of turbulent flows and heat transfer with buoyant effects mainly fo-cus on the study on vertical channel. Although the flows in inclined channel can be encountered everywhere in engineering condition, it has not drawn much attention. In this paper, numerical study on turbulent mixed convection in inclined plane channel has been made to examine the effect of inclination on fluid flow and heat transfer distributions. The inclination angle is changed from 15°to 90°. The turbulent air flows upward or downward into the duct with one wall heated from below. Calculation results with several kind of k-ε type turbulence models （called k-ε model） have been used to compare with the experimental data in opening lit-eratures to determine which is the most suitable model to adopt. The dependents of Nusselt number on the inclination angle of both the buoyancy-aided and buoyancy-opposed flow are discussed.

Measurement of ²³⁵U Mass and Burnup in Fuel Assembly in Research Reactors

LI Run-dong, A. V. Bushyev, A. F. Korin

2009, 30(1): 56-59.

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The method for measurement of ²³⁵U mass and burnup in fuel assembly in research reactors with comparison γ-Spectrum after irradiation is introduced in this paper. It also described the equipment, con-dition and experimental process of measurement IRT-3M fuel assembly in reactor IRT-MIFI in Russia, and presented relevant experiment result and its estimate of uncertainty. The result indicates the probability to ob-tain data of ²³⁵U mass in concentrated fuel assembly with uncertainty less than 2% by application of this method.

Hydromechanics Calculation for Micro Sphere UO₂ Fuel Producted by Sol-Gelation Method

JIN Xin, LIANG Tong-xiang, GUO Wen-li, ZHAO Xing-yu, HAO Shao-chang

2009, 30(1): 60-63.

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Relation between the jet steam velocity in nozzle and height of glue solution level and rela-tion between the jet steam velocity in nozzle and the pressure of glue solution level in pressure kettle are es-tablished with Bernoulli equation. The result calculated from this relations shows that the flow of gelation solution is of laminar, the effect of the height of solution level on the the jet steam velocity in nozzle is little and the maximum error for diameter of micro global UO₂, resulting from the height of solution level, is far more less than the control error.

Study on Surface Grain Refinement of Zircaloy-4

ZHANG Qiang, ZHANG Xi-yan, LI Cong, QIU Shao-yu

2009, 30(1): 64-67.

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A refined structure was obtained on Zircaloy-4 through ultra-sonic shot peening （USSP） treat-ment and characterized by optical microscopy （OM）, X-ray diffraction （XRD） and field-emission gun scan-ning electron microscopy （FEG-SEM）. It has been found that the treated sample consists of three grain struc-tures: surface nanocrystalline （60μm thick）, ultrafine grain （160μm thick） and the matrix. The grain refine-ment mechanism is attributed to severe plastic deformation （SPD） during the USSP treatment, which includes: formation of twins and dislocations, formation of dislocation tangles, subdivision by dislocation cells, orientation randomization.

Structure and Properties of C/C-SiC Prepared by Reactive Melt Infiltration

TANG Rui, WANG Ji-ping, LONG Chong-sheng, JIN Zhi-hao

2009, 30(1): 68-73.

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C/C materials were prepared by liquid-vaporized and thermal-gradient CVI, and C/C-SiC composite with a density of 2.13～2.28 g/cm³ was prepared by reactive melt infiltration（RMI） in this paper. The microstructure of C/C-SiC was examined using XRD and OM, and its mechanical properties （flexural strength, compressive strength, hardness and fracture ductility）, friction and wear characteristics were investi-gated. The results show that C/C-SiC is composed of C, SiC and Si. The lower the density of C/C, the higher the density of corresponding C/C-SiC. By graphitization, the flexural strength of C/C-SiC decreased from 203～275 MPa to150～210 MPa and the compressive strength decreased from463～607 MPa to 403～536 MPa, but the fracture ductility increased from 6.6～8.5 MPa·m^1/2 to 7.3～9.2 MPa · m^1/2. During the sliding friction of C/C-SiC disc to SiC pin, the friction coeffici～ent was about 0.19. By graphitization, the friction coefficient decreased to 0.14～0.15, but the average volume loss rate increased from 3.4×10^-3～5.0×10^-3mm³/h to 7.9×10^-3～9.8×10^-3mm³/h.

Neutron Multiplicity Counting and Analysis for Uranium Material

LIU Xiao-bo, HU Qian, XIAO Jian-guo

2009, 30(1): 74-77.

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Neutron multiplicity counting technique is a new method to greatly improve the measurement precision and reduce the measurement bias. The relatively considerable bias of active coincidence counting is analyzed, and the theoretical equation of active multiplicity counting is introduced in this paper. The data processing method is presented, and in this method, the sample multiplication is obtained based on the meas-ured data, and the reaction coefficient is obtained from the emperical relationship, and thus the sample mass is obtained.

Effect of Surface Self-Nanocry Stallization on Diffusion Bonding between Titanium Alloy and Stainless Steel

ZHOU Xiao-ling, SHENG Guang-min, HAN Jing, YAN Jing, HU Guo-xiong

2009, 30(1): 78-81.

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Direct diffusion bonding between a TA17 near α- titanium alloy and an 0Cr18Ni9Ti stainless steel at constant temperature and pressure has been carried out in vacuum. Titanium alloy and stainless steel had been treated by surface mechanical atrrition treatment before diffusion bonding.The tensile strength was tested by using the hydraumatic universal testing machine. SEM observation and EDS determination were employed to investigate the structure of the joint and phases on the fracture.The result show that the inter-face-structure of titanium alloy/stainless steel joint have different layered structures on the bonding inter-face.The bonding interfaces are with the same forms of the interface-structure at the different temperature; Comparing with non-treated materials, the diffusion velocity of atoms around the interface was faster,bonding time was shorter and the joint strength was higher under self-nanocrystallization condition.

Application of Digital Technology and Its Engineering Adaptation in Reactor Control System in Ling’Ao Phase II NPP

LIU Jiong

2009, 30(1): 82-85.

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Reactor control system is one of the important I＆C systems in NPP. In Ling’Ao Phase II project, many aspects of design shall be re-considered and adapted to meet the new requirements from advanced digital technology. Based on the studies for the application of digital technology, this paper states the new engineering requirements, new design features and new adaptation research results about digital reactor control system.

Data Process for Time-to-Amplitude ²⁵²Cf Randomly Pulsed Neutron Source System

ZHOU Hao-jun, SONG Ling-li, LI Jian-sheng, JIN Yu

2009, 30(1): 86-89,94.

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Data process is an important step for the final determination of propmt neutron decay constant in ²⁵²Cf randomly pulsed neutron source method. Comparison between the simulated and the experiment data shows that the single exponential dcay mode of least-square fittings shall be used. The initial channel shall avoid the high-order term attenuation effect, and shall be with enough statistic counting.

Development of Eddy Current Test System for Fuel Element Based on LabVIEW

CHENG Ting-ting, SONG Wen-ai, CHEN Yi-fang, ZHANG Shi-xiong

2009, 30(1): 90-94.

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Fuel element plays an important role in high temperature gas-cooled reactor-pebble-bed mod-ule. For adjusting the fuel element precisely, an eddy current test system based on LabVIEW was developed to count the plumbago ball precisely and select the defective balls. The system was composed of the hardware circuit, the computer, the data acquisition card and relative softwares. The design of the excitation source, head amplifier circuit and the phase-sensitive detector was introduced in detail. The plumbago balls were counted and defects were tested by this system, and the results showed that the system is with good test capa-bility.

Identification of Aging and Damage of Neutron Measurement Probe of RPN System in Daya Bay Nuclear Power Station

HU Ping, ZHAO Fu-yu

2009, 30(1): 95-99.

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The source range probe of RPN system in Daya Bay Nuclear Power Station is a boron-lined proportional counter. The middle range probe and the power range probe are boron-lined compensation ionization chambers. This paper introduces the relationship between different characteristic curves and aging of probes, and presents the way to identify the aging and malfunction of the neutron measurment probes in detail. For source range probe, if ΔC （aging extension of flat reigon in discrimative curve）＞60%, and the high voltage curve with aging trend by comparing with history curves, the probe has to be replaced. For middle range probe, the saturation curve of high voltage and electric current shall be drawn firstly, and then the coefficents P and V₀ are established. When the curve changes greatly or V₀ ＞ 70 V, it means that the probe is becoming aging, and it is necessary to draw the saturation curves every 3 months in order to monitor the aging.If the curve changes continuously or V₀ ＞140 V and P ＞ 6%,the probe has to be replaced. For power range probe,when the curve changes greatly or V₀ ＞ 30 V, it means that the probe is becoming aging, and it is recommended to draw the saturation curves every 3 months. If the curve changes continuously or V₀ ＞ 60 V and P ＞ 1.5%, the probe has to be replaced.

Analysis and Computation for Corrugated Plates Dryer Considering Reentrainment

LI Jia, HUANG Su-yi, WANG Xiao-mo

2009, 30(1): 100-103.

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Reentrainment is a very important factor for the separation performance of corrugated plates dryer. The formation process of second droplet is analyzed in this paper. The separation efficiency in the cold condition and actual operation state of corrugated plates dryer is simulated by the FLUENT and the results of numerical computation and experiment are compared. It could be concluded that the two-hook corrugated plate outperforms the one-hook when reentrainment is existed.

Research on Compliance Coefficient Calculation for Heterogeneity Material Bolted Joints of Reactor Internal

LI Qing, REN Xin, ZHANG Kang-da

2009, 30(1): 104-108.

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Using the finite element method, calculation and test are conducted on the bolted joints of four different diameters, and the existing calculation method for bolt compliance coefficient is analyzed. The re-sults indicate that the calculated and test results by finite element method are agreed well, and value D/t_f and β have a linear relation.

Reliable Analysis for Pressure Vessel Based on ANSYS

PENG Cui-ling, AI Hua-ning, LIU Qing-song, XIANG Wen-yuan

2009, 30(1): 109-111.

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With the PDS of ANSYS procedure, the ramdomicity of the actually structure design parameters is simulated, by taking thewall thickness, pressure load and elastic module as input random variables. Based on the reliablity analysis of the pressure vessel by Monte-Carlo procedure, the stress probability distribution of this finite element analysis model and the sensitivity of the design parameters such as the pressure load and wall thickness to the stress distribution are obtained

Algorithm of Artificial Time Histories Meeting Requirements of Both Fitting of Response Spectrum and Envelop of Power Spectral Density

WANG Hai-tao, HE Shu-yan, ZHANG Zheng-ming, YU Su-yuan

2009, 30(1): 112-115.

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Artificial time histories are key data inputs for the calculation of floor spectra of the contain-ment building in nuclear power plants. The application of the single-ground-motion analysis method shall meet the requirements of envelop of the power spectral density as well as fitting of the target response spec-trum. This paper presents a generation algorithm of artificial time histories in order to meet the needs of both fitting of the target response spectrum and envelop of the power spectral density. The Fourier amplitude spec-trum is modified within the effective frequency bandwidths defined for the target response spectrum and power spectral density respectively in this algorithm, and iterations are used in order to meet the correspond-ing requirements. The numerical examples demonstrate that the artificial time history generated by this algo-rithm reaches high fitting precisions to the target response spectrum and meets the need of envelop of the power spectral density.

Analysis of Field Coordination on Heat Exchanger Shell Side with Different Diameter Tubes and Holding Structure

LI Jing, LIU Min-shan, DONG Qi-wu

2009, 30(1): 116-120.

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In order to overcome the disadvantages of the rod-baffle heat exchanger, which achieves the high heat transfer efficiency only at high flow velocity, and which with non compact layout of tubes and is weak in the resistance of operation mode changes, this paper proposed two sizes of heat exchange tubes and holding and support structures to replace the traditional rod-baffle support unit, to increase the heat exchange coefficient on shell side and the heat exchange effectiveness. Three-dimensional numerical simulation was conducted on theshellside flow field and heat exchange field by the CFD software, and the calculation method was proposed for the included angle for the shellside velocity-temperature gradient fields of the vertical flow heat exchanger with complex structure. The quantitative relationship of the field coordination angle for the shellside velocity field and temperature gradient field was obtained and it is proved that the new structure is with better field coordination relation.

Primary Analysis of Critical Assembly Operation Personnel

ZHENG Chun

2009, 30(1): 121-123,128.

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Based on the analysis of the critical assembly operation characteristics and procedures as well as the criticality accidents because of the errors by operators, the operation personnel of a critical assembly at least include the head of the operation personnel, reactor physics engineer, controls engineer and health physics engineer. The critical assembly operation experience is important to the head of the operation per-sonnel; and the head shall not make any arbitrary decision, or turn a deaf ear to any opinion, and shall not be overconfident. The head and reactor physics engineer shall make judgement independently.

Behavior of Tritium Release from Liquid LiPb Alloy

XIE Bo, HU Rui

2009, 30(1): 124-128.

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The liquid lithium lead alloy is a prominent breeder material for the fusion reactor tritium blanket. For an effective calculation of the knowledge of kinetics of tritium release behavior from liquid LiPb alloy, a mathematical model is built by taking into consideration the theory of metals and hydrogen and the design of the bubble tritium extraction system from the liquid Lithium-Lead module for fusion reactor. The calculation data of tritium release-behavior from liquid LiPb under different operating conditions of tempera-ture and tritium partial pressures and helium gas flow-rates and mass transfer coefficients are obtained. These results have shown that the overall release process, even though including five sub-processes （transport of the tritium by diffusion and convection, transport of the tritium by diffusion through a layer of eutectic adjacent to the gas-eutectic interface, heterogeneous reaction at the interface of the tritium atoms recombination, diffusion of the tritium through the gas-phase boundary layer, transport of the gaseous tritium by diffusion and convec-tion from the gas phase boundary layer）, is governed by the diffusion of tritium atoms in the LiPb and by the heterogeneous reaction at the gas-eutectic interface of the tritium atoms recombination in the desorptiong temperature vary from 633 to 723 K.

2009 Vol. 30, No. 1