Transient thermal stress intensity factors for Mode I edge-cracks

Stress intensity factors are analytically derived for an edge-cracked circular disk subjected to transient thermal stresses using symplectic technique. The transient temperature function for the time independent boundary conditions is obtained by a generalized symplectic approach and the method of separation of variables. From the obtained temperature function, quasi-static solutions of the thermoelasticity problem are derived analytically. The stress intensity factors together with the close form solutions for both displacements and stresses are found simultaneously. The results obtained are in good accordance with those cited in the literature for some special cases of steady state problem. In addition, a parametric study is performed in the numerical examples.     

Vent clearing analysis of a Mark III pressure suppression containment

An analysis of the vent clearing transient in a Mark III pressure suppression containment after a hypothetical LOCA is carried out. A two-dimensional numerical model solving the transient fluid dynamic equations is used. The geometry of the pressure suppression pool is represented and the pressure and velocity fields in the pool are obtained from the moment the LOCA occurs until the first vent in the drywell wall clears. The results are compared to those obtained with the one-dimensional model used for containment design, with special interest on two-dimensional effects. Some conclusions concerning the effect of the water discharged into the suppression pool through the vents on submerged structures are obtained. Future improvements to the model are suggested.     

Cylindrical Dritt Chambers with Two Dimsional Readout

We have built and used a set of three cylindrical drift chambers with delay line readout. The azimuthal coordinate is obtained in the conventional way; the resolution obtained is about 300 microns. The axial coordinate is obtained fran signals induced on printed circuit delay lines with a resolution of ±5 mn FWHM. The chambers are 120 cm long and have diamters of 29.3 cm, 70.1 cm and 118.5.     

Electrothermal Breakdown Mechanisms for Multilayer Insulation

The problem of the electrothermal breakdown of thin bilayer dielectric insulation used in nuclear-power systems is examined. Analytical expressions relating the parameters at the breakdown boundary are obtained for certain limiting cases. It is shown that the best electric strength qualities are obtained at the same current density in both layers of insulation in the most highly stressed section when several distributed sources of e.m.f. are present. These conditions can be obtained by adjusting the resistances of the layers or using auxiliary shunts, including short-circuiting in one of the layers.     

Comparison Between Discrete Magnetic Coils and Multipole Coils for Measurement of Plasma Displacement in IR-T1 Tokamak

We have expressed two different methods to determine the plasma positions in the IR-T1 tokamak. An array of magnetic probes are placed polidally outside the chamber surface and their signals are plugged in the displacement equation and horizontal displacement of plasma column is obtained. The results of this measurement are compared with the experimental data obtained from sensors of multipole moment. It was detected a fluctuation in plasma displacement obtained with discrete magnetic coils, so the method of multiple moments is better than the discrete magnetic coils for the determination plasma displacement that used for feed back control.     

Method of nondestructive monitoring of fuel-element seal tightness

A method of monitoring the seal tightness of fuel elements is described. The method is based on determining leaks of gaseous fission products during annealing of preirradiated samples. The basic steps using this method are described and mathematical expressions for determining the constants of the activation model of the leakage of gaseous fission products, which is used for processing and analyzing experimental results, are presented. The measurements results obtained using the method develop are compared with the results obtained in reactor tests of spherical fuel elements. An example using the technique is described: simulators, for which the temperature dependence of ¹³⁵Xe leakage (to 1400 K) is obtained and a quantitative relation between the number of microfuel elements with damaged coatings and leakage of gaseous fuel products, are tested. It is found that technological contamination of graphite of the simulators by uranium is present.     

铀氢锆堆物理计算及燃料管理软件包

建立了一套铀氢锆堆物计算软件包，首先考虑氢化锆中的热化特殊性，按ＷＭＳ格式制作 了氢化锆 氢的６９群群常数并入ＷＩＭＳ－Ｄ／４数据库中，形成了ＷＩＭＳ－Ｎ１库和ＷＩＭＳ－Ｎ２库；应用ＷＩＭＳ－Ｎ２库和国际通用的ＷＩＭＳ－Ｄ／４程序包计算了铀氢锆堆各类栅元的群常数，应用差分程序ＣＩＴＡＴＩＯＮ和六角形节块和ＳＩＸＴＵＳ进行扩散计算，同时在ＳＩＸＴＵＳ－２程序的基础上编制了燃料管理程序和ＸＰＲ－ＩＣＦ     

核反应堆控制棒转动装置用轴承磨损寿命分析方法研究

为建立核反应堆控制棒转动装置用轴承磨损寿命分析方法,以优化现有以试验为主的转动装置用轴承磨损寿命分析手段,通过构建运行工况下的轴承力学分析模型得到滚道-滚动体接触力学特性,通过套圈控制理论,结合转动装置的运行特点,得到轴承滚动体与内外滚道间的运动特性,并基于Archard磨损模型构建转动装置运行工况下的轴承磨损分析模型,采用磨损迭代的方法得到轴承滚道与滚动体之间的磨损特性。研究结果表明,采用本文建立的轴承磨损寿命分析方法得到的轴承磨损寿命与试验结果符合较好,能够用于核反应堆控制棒转动装置用轴承磨损寿命分析。     

Research into keV N irradiated glycine

A set of experimental results obtained concerning glycine irradiated with N⁺ at an energy of 30 keV is obtained. The techniques used to get insight into the induced products are mass spectrometry, infrared spectrometry and ultraviolet visible spectrometry. The main non-volatile stable products obtained have been identified by combined gas chromatography mass spectrometry (GC/MS) and other modern instrumental analysis. The results were compared with those obtained with γ rays and show that more kinds of products are formed in keV ion irradiation. The combination of the implanted ion with glycine and nuclear collisions were thought to be probable processes to form the products. Some possible implications of the results are also suggested.     

Reliability of 2-out-of-3 System Considering Number of Spares and Exchange Time

The reliability of a simplified model of ractor instrumentation possessing redundancy in its system is studied. The unreliability is obtained for a 2-out-of-3 system with a limited number of spare units, for the case where the replacement of the failed unit by a spare unit is not instantaneous. Two methods for the solution are obtained. The results are then compared with that obtained from Jacobs' formula for a rate of false scrams, and the accuracy of Jacobs' formula is discussed. It is shown that Jacobs' formula can be used only when the duration of operation is larger than several times the reset time, which must be a constant. But in actuality this reset time depends on such factors as the number of spare units provided, and the time required for replacement.     

COBRA程序系列中的一个新版本：COBRAIIIC／MIT—2

一、前言二十多年来,在反应堆设计和安全分析领域内,随着计算机的普及和实验研究工作的开展,各种计算机程序应运而生。分析堆芯行为的程序更是层出不穷。其中美国太平洋西北实验室发展的COBRA程序系列是较好的一个。第一个版本COBRA-Ⅰ自1967年发表至今已二十多年,中间不断公布了改进的版本,如COBRA-Ⅱ,COBRA-Ⅲ等。1973年发表的COBRA-ⅢC采用了先进的横向动量方程,较逼真地描述了物理过程,还加强     

Improvement to the Calculation of Collision Probabilities in Annular System and Its Application to Cluster Geometry

A new method of calculating first-flight collision probabilities in cluster geometry is developed. The collision probabilities in an annular system as well as the transition probabilities for a neutron escaping from one subcell to reach other subcells are calculated and combined. The former is an improvement on Bonalumi's approximation and the latter is an extension of the Dancoff correction to subcells containing fuel rods and coolant. As applications of the present method, we calculate the collision probabilities in a hexagonal cluster with 7 fuel rods and in a square cluster with 28 fuel rods. Fairly good agreement is obtained by comparing the probabilities obtained from our method with the results obtained by the exact method. One-group calculations of the flux distribution are carried out in these systems.     

BGO组合测井仪物理方法研究

在实验室内,对BGO晶体在煤田测井中应用的可能性进行了较细致的实验。通过对BGO晶体的表面进行恰当的处理及选用较合适的光电倍增管,提高了BGO的光输出。采取尽可能与野外煤田测井相接近的实验条件,给出了BGO晶体用于煤田自然γ和散射γ测井的实验数据,并与NaI(Tl)进行了比较,测量了BGO晶体的光输出随温度的变化并采取了有效的温度补偿法,研制出了用于煤田测井的BGO组合测井仪。     

Round-robin activities on finite element analyses of elastic-plastic fracture in Japan

The establishment of the leak-before-break (LBB) concept requires a method to evaluate the fracture characteristics. The finite element method can be used for this purpose but the solution is more or less influenced by the method employed. In this study, two round-robin analyses are performed for three-dimensional crack problems. The first problem is for surface crack growth in a carbon steel plate subjected to tension loading. Ten solutions are obtained by ten participants, and calculated results are compared with each other as to the applied load, displacement and J-integral. Though the relation between applied load and displacement is affected by modeling of the stress-strain curve, fairly good agreement is obtained between the solutions. The second problem is for a circumferential part-through crack in a carbon steel pipe subjected to a bending moment. Nine solutions are obtained by eight participants. The difference between the solutions is relatively significant as to the relation between J-integral and load-point displacement. A discussion is made about the sources of difference between each solution.     

Asymptotic distributions and confidence regions of open loop transfer functions obtained by multivariate autoregressive modelling and application to a benchmark's simulation data

In this paper the asymptotic distributions of open loop transfer functions and noise sources transfer functions obtained my MAR analysis are established. The distributions are found to be normal and the covariance of the distributions is expressed in physical meaningful form. Numerical simulations are performed in order to test the theoretical findings. Also confidence regions obtained by the asymptotic distributions are constructed for the estimated transfer functions. These results are applied to the artificial data of nuclear reactor of Delft's university, known as benchmark data. It is also shown why the estimation of benchmark's transfer functions is not quite successful.     

High-Accuracy Position Measurements with Drift Chambers and Proportional Chambers

By constructing multiwire drift chambers with a uniform electric field saturating the drift velocity, a perfectly linear response is obtained over all the chamber. The accuracy is close to ? = 100 ?m. A similar accuracy is obtained for inclined tracks and in magnetic fields of the order of 1 tesla. By measuring the centre of gravity of avalanches a very high accuracy is obtained in the measurement of the two coordinates of avalanches in a single gap of a proportional chamber. The applications of the method to the mapping of spatial distributions of soft X-rays are discussed.     

Application of frequency domain analysis to transient response of nuclear containment structures

A combination of frequency domain and time domain analyses is proposed to obtain the dynamic responses of nuclear power plant containment structures. A soil-structure model of a boiling water reactor containment subjected to an assumed safety relief valve blowdown load is used as illustration. Linear time-invariant systems are analyzed using input forcing functions with varying frequency contents. Time domain analysis is performed using a synthesized input forcing function. The system characteristic function is generated in the frequency domain through Fourier transforms of the response time history and the synthesized input time history. The frequency response due to any other forcing function is obtained in frequency domain by using the system characteristic function, and the response time history is obtained by inverse Fourier transforms of the frequency response. The results obtained by the proposed method are in close agreement with the conventional time domain dynamic finite element analysis.     

Noise analysis of a zero power critical line reactor using Langevin's technique

Noise analysis of a critical, infinite-length, zero-power line reactor is given using the Langevin technique. A one-speed model is used and delayed neutrons are ignored. Stochastic analysis is carried out starting from the Boltzman equation with the assumption that neutrons move only in both directions in the line reactor. The power spectrum of neutron fluctuations is obtained and compared with that computed from diffusion approximation. Exact expressions for auto and cross-power spectrums of non-fission neutron detectors' outputs are also obtained.