核动力工程

Nuclear Conceptual Design of Spent Fuel Pool Reactor Loaded With Spent Fuels of Daya Bay Nuclear Power Station

CAI De-chang, WANG Kan, YAO Zeng-hua

2004, 25(5): 385-389.

Abstract(6)

Abstract:
This work calculates the required assembly number of spent fuel pool reactor loaded with spent fuels of Daya Bay Nuclear Power Station, and analyses the influence of Xe-135, Sm-149 and Pu-241 on reactivity and the relationships between cycle length and spent fuel storage time. A way of prolonging cycle length by drawing all gadolinium rods is also given, and then a core layout is designed. Nuclear analysis of this layout further shows that this type of reactor is realizable.

Transport-Burnup Code System and Its Application for IAEA ADS Benchmark

JIANG Xiao-feng, XIE Zhong-sheng

2004, 25(5): 390-394,412.

Abstract(6)

Abstract:
In order to investigate the neutron economy and safety of Accelerator Driven System, IAEA launched the Co-ordinated Researched Program （CRP）, and issued an ADS benchmark. This ADS bench-mark was divided into several stages, and the 1^st stage devoted to analyzing the neutron performances of ADS and validating the nuclear databases and the codes. The burnup code system ANISN-DOT4.2-ORIGEN2 is developed. Initial enrichments of ²³³U which correspond to all given initial （BOL） k_eff values are calculated. and then, the spatial distributions of power density （BOL）, the void reactiv-ity effects, the spallation source effectiveness φ^*, and the evolution curves of k_eff and source as function of time are also calculated for every given k_eff （BOL）. The numerical results are in a good agreement with those of various countries.

Spherical-Harmonics Method for Neutron Transport Equation Based on Unstructured-Meshes

CAO Liang-zhi, WU Hong-chun

2004, 25(5): 395-398,416.

Abstract(5)

Abstract:
The spherical harmonics method for neutron transport equation on unstructured-meshes is derived based on a new second order neutron transport equation, self-adjoint angular flux （SAAF） equation. The spherical harmonics function is used to expand the angular flux. A set of differential equations about the spatial variables, which are coupled with each other, can be obtained. They are solved iteratively by using the finite element method on unstructured-meshes. A two-dimension transport calculation code is programmed according to the model. The numerical results of some benchmark problems demonstrate that this method can give high precision result and avoid the ray effect very well.

Dynamic Analysis of Power Regulation System for China Experiment Fast Reactor

GUO Wen-qi, CENG Hai

2004, 25(5): 399-402.

Abstract(6)

Abstract:
Power regulation system of China Experiment Fast Reactor （CEFR） consists of ionization chamber, regulation amplifier, dead zone and limiter, power amplifier and stepping motor, reducer, and regulation rod. In this paper, the mathematical models of the parts of the system are introduced, and the dynamic analysis of system is carried out. The analysis results show that the application of proportional rule to system is feasible. When K_N is less than 5000, the system is stable. When step reactivity disturbance is input to the system, the maximum overshoot of the system increases with the disturbance amplitude, and is independent of K_N. Time delay is disadvantageous to the system, but just has a little effect on it. K_N can be within the range of 300 to 600. When K_N is 300, and ñ is 8×10^-5/s, the maximum overshoot of system is less than 3%P_D, and setting time less than 7s. When ñ is 4×10^-4 step disturbance, the maximum overshoot of system is less than 8%P_D, and setting time is less than 5s. If K_N is less than 5000, and without limiter, the dynamic characteristic of system is better.

Application of Calculation Fluid Dynamic in Thermal Hydraulic Analysis of the Fuel Assembles and Design of the Spacer Grid

CHEN Bing-de, XIONG Wan-yu, WANG Xiao-jun

2004, 25(5): 403-407.

Abstract(3)

Abstract:
The time and cost for the analysis and design can be decreased greatly by using of Calculation Fluid Dynamic （CFD） methodology in thermal performance analysis of fuel assemble and the design of spacer grid. In the middle of 1990s, the commercial CFD code has been used to analyze the 3D flow and temperature fields of the fuel in foreign countries. It was successful to design the spacer grid with the verified methodology. In the Laboratory of Bubble Physics and Natural Circulation, the CFX code was employed to calculate the fluid field of a rod bundle with spacers in the end of 1990s. The structure simulation of complex small size geometry, the selection of the proper boundary conditions and the evaluation of CFX applicability have been studied and problems were solved. Then the calculation of flow field of the single-phase and air-water two-phase has been carried out and compared with experiment results. The steam-water two-phase flow has been studied and the design of new spacer has been carried out. It is desired to develop a CFD analysis and design methodology, which can predict not only the flow and temperature fields in rod bundle with spacers, but also the surface temperature of the rods.
The results show that it can compare the turbulence, eddy and fluid temperature near rod of single-phase flow to evaluate the mixing characteristics of a spacer to fluid. The spring and dimple of the spacer have evidently effect on flow and it is necessary to simulate. In order to ensure the correctness of prediction results, it suggests to take a benchmark exercise before the analysis of CFD thermal hydraulic analysis for a fuel assemble with spacers.

Numerical Calculation for Vertical Annular Two-Phase Flow Boiling with Presence of Nucleate Boiling

YANG Dong, LI Bin, CHEN Ting-kuan

2004, 25(5): 408-412.

Abstract(5)

Abstract:
A new model is proposed for the prediction of saturated flow boiling heat transfer inside vertical tubes. The model assumes the forced convection and nucleate boiling coexist in the annular flow regime. Conservation of mass, momentum, and energy are used to solve for the liquid film thickness, velocity, and temperature. The heat transfer due to nucleate boiling is determined from the frequency and diameter of bubble departure, the density of active nucleation sites, and suppression factor. The overall heat transfer coefficients are calculated from the total heat flux partitioned into the two components of forced convection and nucleate boiling. Predictions of the model agree with the experimental data within the error of ±20%. The numerical results indicate that the nucleate boiling contribution to the overall heat transfer coefficients decreases from 20% to 1% with quality increasing.

Critical Heat Flux for Convective Boiling of Sub-cooled Water Jet Impingement on a Stagnation Zone

TONG Tie-feng, LIU Zhen-hua

2004, 25(5): 413-416.

Abstract(4)

Abstract:
A steady heat transfer experiment was carried out for predicting the critical heat flux （CHF） of convective boiling for a round sub-cooled water jet impingement on the jet stagnation zone of a hot surface. The effects of sub-cooling, jet velocity and jet diameter on the critical heat flux were fully investigated. An empirical correlation was proposed for predicating CHF using the preset experimental data. The study found that the CHF is a function of the sub-cooling, the jet velocity and the jet diameter. In especial, the sub-cooling has a significant effect on the CHF. Finally, a correlation was proposed for predicting CHF of convective boiling for sub-cooled water jet impinging on the jet stagnation zone, and the correlation agreed with the existing experimental data.

Study of Void Fraction in Flow Sub-cooled Boiling

YAN Chang-qi, LÜ Xiang-bo, SUN Li-cheng

2004, 25(5): 417-420,429.

Abstract(3)

Abstract:
The factors with effects on the sub-cooled boiling heat transfer are vapor quality and system pressure. System pressure is with direct effects on the bubble size of the heated surface, and the heat transfer from heated surface to liquid. The thermodynamic quality in sub-cooled boiling region is calculated based on the thermodynamic parameters and flow parameters, and then the void fraction at certain point is calculated. The calculation correlations for the void fraction in sub-cooled boiling channel are given. It is proved that the correlations coincide with the experimental dada within the given experimental parameters.

Simulation Study for the Influences of Fluid Physical Properties on Void Fraction of Moderator Cell of Cold Neutron Source

LI Xiao-ming, BI Qin-cheng, FENG Quan-ke, CHEN Ting-kuan, DU She-jiao

2004, 25(5): 421-425.

Abstract(6)

Abstract:
The void fraction at different heights in the annular channel of moderator cell mockup was measured with a differential pressure transducer. The tests proved that the ratio of surface tension to density of liquid phase is the main factor that determines the physical properties on void fraction. The larger the ratio, the smaller the void fraction. The ratio of surface tension to density of Freon 113 is lower than that of liquid hydrogen. Therefore, Freon 113 can be used as working fluid to study the void fraction in the hydrogen two-phase thermo-siphon loop in the cold neutron source （CNS） of China Advanced Research Reactor （CARR）), and the results are conservative.

Dynamic Analysis of Reactor Containment Subjected to Aircraft Impact Loading

LI Xiao-tian, HE Shu-yan

2004, 25(5): 426-429.

Abstract(5)

Abstract:
In this paper, dynamic character of reactor containment subjected to aircraft impact loading is analyzed with MSC.DYTRAN program. The displacement of concrete and velocity curve of airplane is obtained. The results of the different material model are compared with empirical formula. It is concluded that reasonable result can be obtained using cap model for concrete.

Study of Engineering Treatment of Failure Assessment Curves of Cracked Structure Based on Double-parameter J～Q criterion

ZHANG Min, MA Bo, LI Xiao-rui

2004, 25(5): 430-433,451.

Abstract(4)

Abstract:
Considering the influence of stress-triaxiality on stress-strain field near crack tip, the theory that used to access the integrity of homogeneous materials has been discussed in this paper. In addition, the failure assessment curves of cracked structure based on double-parameter J～Q criterion are founded. By utilizing the finite element numerical results, the engineering treatment methods of each factor in the failure assessment curves are obtained. In the end, calculatiion approach for the failure assessment curves set up in this paper has been compared with the available procedure.

Localized Nonlinear Buckling of Pressure Vessel under Internal Pressure Caused by Initial Geometric Imperfections

WAN Li, TAO Wei-ming, WU Xin-xin, HE Shu-yan

2004, 25(5): 434-438.

Abstract(6)

Abstract:
This paper focuses on the localized nonlinear buckling of pressure vessel under internal pres-sure caused by initial geometric imperfection. The localized plastic buckling occurred in the transition region in the torispherical end closure of a pressure vessel has been analyzed by FEM. By introducing two types of initial geometrical imperfections, the arc-length method of modified-Riks/Ramm procedure is employed to simulate the deformation process during loading. The first type of imperfection is determined from the elastostatic displacements, into the zone where it is circumferentially compressed. The second type of imperfection is the irregular thickness of the vessel, also into the zone where it is circumferentially com-pressed. The buckling point is captured from the load-deflection curve of a typical point within the buckled zone, and the corresponding buckling load is calculated. The results show that after the first buckling initiated, the succeeding loading will lead to more wrinkles within the compressive transition region, which agree well with the results of experiments.

Study of Delayed Hydride Cracking In CANDU and RBMK Pressure Tubes

GOU Yuan, LI Yan-rong, CHEN Hong-tong, WANG Yun-hui, XUE Shu-juan

2004, 25(5): 439-443.

Abstract(3)

Abstract:
Using Compact tension specimen （CT）, delayed hydride cracking （DHC） tests were implemented to determine cracking velocities in CANDU Zr-2.5Nb pressure tube and RBMK standard pressure tube under constant loading and different temperature and different hydrogen contents. The DHC fracture surface and hydride distribution were observed by SEM. The results of the tests show that crack growth dis-plays stairs shape, probably due to hydrogen accumulating and diffusing at crack tip. The highest DHC velocity is inherent in the CANDU pressure tubes. The DHC velocity in the RBMK pressure tubes is lower by an order and even more. This difference in the DHC velocities owes to different yield strength of CANDU Zr-2.5Nb pressure tube and RBMK standard pressure tube.

Experimental Study on Uniaxial Ratcheting Deformation and Failure Behavior of 304 Stainless Steel

YANG Xian-jie, GAO Qing, CAI Li-xun, LIU Yu-jie

2004, 25(5): 444-451.

Abstract(5)

Abstract:
In the paper, the tests of cyclic strain ratcheting and low cycle fatigue for 304 stainless steel under uniaxial cyclic straining were carried out to systematically explore the deformation and failure behavior of the material. The experimental study shows that the cyclic strain ratcheting deformation behavior of the material is different from either the uniaxial monotonic tensile one or the cyclic deformation one under the symmetrical cyclic straining with the same strain amplitude, and the strain ratcheting deformation and failure behaviors depend on both the plastic strain amplitude and the strain increment at the cyclic maximum strain. Some significant results were observed.

Study of Corrosion Mechanism under High Temperature and Pressure Watersteam with Overheating for Titanium Alloy

YU Zhen-tao, LI Dong, WU Wei-lu, QIU Shao-yu, WANG Xing-wang

2004, 25(5): 452-456,480.

Abstract(6)

Abstract:
This paper has studied the regular pattern of oxidization corrosion of T225NG and T42NG anium alloy under high-temperature and high-pressure with long time. The element of the oxide film on surface, constitution and microstructures have been tested and analyzed, and the model of corrosion dynamical for T225NG and T42NG alloys has been tested and analyzed. The same time, the corrosion mechanism has been analyzed briefly .The results indicate that the main element Ti oxides first, and element Al and the impurity elements such as Fe, N, H, C promote corrosion behavior. All of this shows typical crystallographic character. The corrosion dynamics pattern of these two alloys all submits Para-curve in Wagner theory.

Application of Nickel Nano-particles in the Diffusion Bonding of Titanium Alloy and Stainless steel

QIN Bin, SHENG Guang-min, HUANG Jia-wei, ZHOU Bo, QIU Shao-yu, LI Cong

2004, 25(5): 457-462.

Abstract(5)

Abstract:
Direct diffusion bonding and nickel nano-particles layer diffusion bonding of titanium alloy- stainless steel were investigated by diffusion welding at certain temperature and pressure, diffusion welding under pulsatile pressure and phase transformation super-plastic diffusion welding. Result gained by rigidity testing, rupture observation and micro-structure analysis showed that the strength of bonding gained by diffusion welding at certain temperature and pressure is lower, while the joint obtained by diffusion welding under pulsatile pressure is higher. The degree of diffusion in direct welding affected the strength of the bonding greatly. Better joint was gained by diffusion welding with nickel nano-particles layer, with its strength up to 213MPa, but the density of the nickel nano-particles layer is not high enough, which limited the strength of the joint.

Design of Non-uniform Heating tube in 5×5 Full-scale Bundle

LANG Xue-mei

2004, 25(5): 463-465,480.

Abstract(5)

Abstract:
A general design principle and design method of non-uniform heating tube used in the critical heat flux （CHF） experiment with axial non-uniform heat flux distribution in full-scale bundle was introduced in this paper. Non-uniform heating tube in 5×5 full-scale bundle was designed according to this design principle and method. In fact the design of non-uniform heating tube is an optimizing design process considering various conditions such as the demand of power system, experiment technology, fabrication ability and welding technology. The final design result shall meet the needs of experiment as well as technological requirements. The non-uniform heating tube in 5×5 full-scale bundle according to this design principle has applied successfully in the experiment on CHF of fuel assembly.

Improvement of RSW Secondary Strainer

LI Ling-mao

2004, 25(5): 466-469.

Abstract(5)

Abstract:
This paper describes the structure of RSW secondary strainer in QinShan Phase III Nuclear Power Plant, analyzes the origin for frequent failure about strainer drive chain hole leaking, and describes the improvement of the strainer. Operational results indicate that the improved secondary strainer can prevent the leaking failure effectively, improve the operation life, and ensure the safe operation of the nuclear power plant.

Study on Method of Internal Dose Assessment and Development of Software, According to 1990 ICRP’Re-commendation

CHEN Bao-wei, AN Yong-feng, MA Ru-wei, WU Jin-hai

2004, 25(5): 470-474.

Abstract(7)

Abstract:
The new computer software system INDO2000 used for personal assessment of occupational exposure due to intakes of radionuclides is described in this paper. This software system refers to metabolic models and parameters from the ICRP series Publications 56,66,67,68,69,71,78 and etc. This system adopts matrix algorithm that is adapted to run on microcomputer. VC++ is taken for compiling this software, which can run under Win95 or higher microsoft's operating system. This system can convert the measured values into intake, effective dose and other quantities used in assessment. It is applicable for routine individual internal dose assessment for radiation workers. This system uses new models and parameters. It can be used to solve recycling and non-recycling compartment models directly and can be used to estimate and assess individual internal dose accord with ICRP ’s recommendation in 1990 and international basic safety standards for protection against ionizing radiation and for the safety of radiation sources in 1997. Furthermore, this software runs under windows’ operating system, and graphic interface makes it friendly and more convenient.

Study on ²³⁵U Transfer Depth in the Rubber

SHUAI Zhen-qing, TONG Chun-han, ZHANG Dong, GAO Guo-lin, ZHU Shi-fu, ZHAO Bei-jun, TAN Zhao-yi

2004, 25(5): 475-477.

Abstract(7)

Abstract:
The neutron activation analysis technology and γ spectrum analysis methods have been used to measure ²³⁵U relative intensity in the rubber and cable in the storage of uranium. This is the first time to make study on ²³⁵U transfer depth in the rubber and cable. The result shows that ²³⁵U migration depth be-tween tens and hundreds micrometers. ²³⁵U transfer depths are different from different materials and places. The results from the neutron activation analysis is as the same as that from of γspectrum analysis

Non-conformity Control in Nuclear Equipment Manufacturing

LIU Jian-cheng

2004, 25(5): 478-480.

Abstract(6)

Abstract:
Non-Conformity Control is very important for the successfully manufacturing of nuclear equipment. Taking the non-conformity control in the manufacturing of the nuclear island main components for Guangdong Ling’ao Nuclear Power Station (2× 1000MW PWR) by Dongfang Boiler Group Co. Ltd. as an example, this paper expounds the principles and procedures of the non-conformity control in nuclear equipment manufacturing. It can provide a reference for the concerned personnel engaged in the quality assurance in the nuclear equipment manufacturing industry in China.

2004 Vol. 25, No. 5