Nuclear Structural Engineering最新文献

This paper presents results of an analytical investigation of stresses and displacements in perforrated plates, these results being of interest in such applications as tube sheets and grid plates in boilers, heat exchangers, and nuclear power reactors. The results are felt to be more comprehensive and detailed than those which can be obtained through the use of ligament theory.

The plates are assumed to be uniform in thickness and of infinite extent in both directions and to have an infinite number of circular holes uniformly distributed in a regular triangular array. The investigation considers the plane stress problem within the usual assumptions of classical elasticity theory. Some remarks on the applicability of these results to the approximate solution of normal bending problems are included.

Corresponding results for the normal bending problems of perforated plates are not given at the present time. However, in the absence of these solutions and pending their acquisition, the results for the plane stress problems given in the present paper might be used to deduce approximate results for the related pure bending and pure twisting problems.

Method of analysis of the problem of designing a homogeneous two-material spherical reactor shield of minimum weight, treating radiation attenuation in plane geometry. The optimization procedure is illustrated by the outline of an example calculation for a reactor shield consisting of a hydrogeneous material (organic plastic) loaded with lead where the space-variable volume fraction of lead is optimized to give a shield of minimum overall weight.

A preliminary study was carried out regarding the relation between hardness and brittleness in steels. The temperature dependence of Vickers hardness on the steels was studied over a range from −196°C to 100°C. It was found that the logarithmic hardness versus the reciprocal of absolute temperature can be described by several linear stages. If the intersection of the two lowest temperature stages is defined as a hardness ductile-brittle transition temperature, the increase in the transition temperature during irradiation was approximately consistent with data obtained with the Charpy impact test. By obtaining the temperature dependence of hardness one should be able to detect easily embrittlement in steel.

Double reactor containment buildings with associated use of filtration and washout systems are very efficient for the retention of fission products under accident conditions. An analytical treatment of teh activity release from such a containment system is given. A numerical example estimates the influence of a second containment on the release of the particularly dangerous isotopes iodine-131, and the results are compared with the release from a reactor system enclosed only by a single containment shell.

A calculational procedure for prediction of the attenuation of thermal and fast neutrons in straight air-filled annular ducts is described. The underlying theory, not presented here, takes into consideration arbitrary angular distributions of the source flux and treats both collided and uncollided contributions to the air gap flux. The procedure works also at short distances from the duct mouth.

The equilibrium of a disk with variable thickness, symmetrical with respect to both its axis and its midplane, is analyzed, under the action of centrifugal and thermal loading. Introducing the customary assumption of plane stress, and neglecting the influence of shear stresses, the differential equilibrium equation is integrated, and stress analysis methods are derived. A digital computer program based on these methods is described briefly. Results of a typical numerical problem are presented. The method provides a very useful tool for the rapid investigation of the cost and performance of families of turbo-machines for coolant circulation in gas-cooled power reactors.

An experimental study on the response of a nuclear reactor building under earthquake loading was done by model testing on a random shaking table and a field test by blasting in order to get some data for aseismic design. In the case in which the basement is founded on firm rock, the lobar modes with natural frequency 3 ∼ 4 c/s are predominant at the container shell and the outer concrete shield.

This description of the design of the (BONUS) containment structure places emphasis on the design of the reinforced concrete foundation slab, since design of an unsymmetrically loaded mat on an elastic foundation is one of the more complex problems in structural engineering.

A brief description of the steel shell superstructure is also included for completeness.

Transmission of gamma rays from ⁶⁰Co and ¹³⁷Cs line isotropic sources through a steel pipe wall was measured as a function of the wall thickness. The measurement was carried out with two alternative arrangements: a point isotropic source and a long cylindrical ionization chamber, and also a moving point isotropic source on the pipe axis and a small spherical ionization chamber.

Comparing the build-up factor obtained by this experiment with that for similar geometry calculated from the results obtained by Goldstein and Wilkins for an infinite homogeneous medium using the method of moments, the ratio of the former to the latter was 0.90 for ⁶⁰Co and 0.87 for ¹³⁷Cs, respectively, for the wall thickness larger than 1.5 cm.

The objectives of this paper are to briefly outline a quality control program for the design and fabrication of a nuclear reactor pressure vessel which will meet all nuclear and safety requirements, and to show how nondestructive testing can help to achieve the broad objective.

Failure in materials, components, and assembly has demonstrated that our present techniques of fabrication are not sufficient alone to assure repeated reliability in critical components. Flaws and inhomogeneities occur even when using the best processes and properly controlled procedures. Thus an adequate and well integrated nondestructive testing program is necessary to assure the quality level required in a nuclear reactor pressure vessel. The principal nondestructive methods used in the fabrication of reactor pressure vessels are: visual, X-ray and gamma radiography, ultrasonics, magnetic particle, and liquid penetrant. The nondestructive testing program must include the inspection of plate material, forging, casting, cladding, and welds. Various methods and their application to the nondestructive testing of pressure vessels and components will be illustrated and discussed.