Nuclear Structural Engineering最新文献

The limit pressure has been calculated approximately for a cylindrical nozzle in a plain spherical shell and also for a pad reinforced shell. It is shown how the results may be used in the design of reinforcements for nozzles. Tests were run to confirm the validity of the analysis and good agreement was found.

The distribution of temperature and thermal stresses arising from the absorption of nuclear radiation in thick annular concrete shields is analysed. Design criteria are developed relating maximum allowable incident energy fluxes to maximum allowable compression or tension stresses. A typical result for a $\text{4}\text{1}\text{2}$ ft thick shield is a maximum allowable indicent energy flux of 85 Btu/hr-ft², resulting in a maximum temperature rise of 95°F in a shield cooled by plant container air on both inner and outer surfaces. The results are virtually independent of the nature of the incident radiation whether medium or high energy gammas, or neutrons.

Stature, a Fortran digital computer code for the study of thermal stresses arising from the absorption of nuclear radiation in both steel and concrete annuli is described. Use of Stature allows detailed calculation of the temperature and stress distributions in a shield within 12 sec when the computation is performed with the IBM 7090 digital computer.

A method of determination of the temperature and thermal stress distributions in a plane reactor shell is derived. The transient operation of the reactor is considered. It is assumed that the material of the shell is homogeneous and isotropic and satisfies the Boltzmann principle of superposition. As an example of application of the derived method two problems: elastic shell and viscoelastic shell, are solved for the case of reactor shutdown. The effects of inertia forces are taken into account.

Radioactive methods based on the registration of gamma-radiation from concealed sources are widely used in building practice for laboratory and field research, production testing and automatic regulation of product quality, and technological processes involving changes in volume weight and moisture content.

Very often parameters of radioactive installations and apparatus for concrete testing are selected at random. As a result the possibilities offered by the method are not evaluated properly, the sensitivity and accuracy of measurements are underestimated, whereas biological danger is unwarrantably overestimated.

The present paper deals with the selection of basic parameters for concrete testing and some problems of radioactive installation and apparatus calibration. The material of the report can be used for making up standards of radioactive testing methods.

The temperature distributions in bonded end caps of solid cylindrical reactor fuel elements with an internal, uniform heat source are determined theoretically. The solution for the temperature distributions is expressed by products of Bessel functions with hyperbolic functions. An illustrative example is chosen for enriched uranium oxide fuel elements with zircaloy cladding and bonded zircaloy end caps. The lengths of the end caps are 0.5, 1.0 and 1.5 times the fuel-rod radius. The results of the example indicate that relatively long end caps have somewhat lower maximum temperatures and lower radial temperature gradients than short end caps. These maximum temperatures and radial temperature gradients tend to approach constants as the lengths of the end caps increase. The maximum surface temperature of the end caps is checked against the corrosion temperature limit of zircaloy in water coolant of nuclear reactors.

An analysis of a cylindrical shell subjected to an axisymmetric temperature distribution which varies along the axis and linearly through the thickness is presented. The differential equation pertinent to the analysis is derived, and all of the stress components are set forth for a particular form of the temperature distribution. The analysis is of sufficient generality to be applicable to almost any axisymmetrically, thermally loaded cylindrical shell.

This paper gives a description of a newly developed technique for determination of both groundwater movement and the relative displacement of isotopes through porous media. The device automatically times the drift of a small radioisotope injection over a certain distance by means of four counting tubes. The flow direction is obtained from the time ratio between the peaks in the time-activity record. The velocity can furthermore be deduced knowing the direction and the distance from injection point to the center of the counting tubes distance which is constant. Measurement capability with this device is possible between 1 and 200 cm per day, giving an error within acceptable limits. Field and laboratory tests executed with this device were compared and calibrated by existing methods. Finally, some other applications are given.