摘要:

AbstractOne-velocity treatments of thermal neutron transport have proved inadequate whereas multigroup methods may be so time consuming as to become impractical. The few thermal group calculations investigated here lie between these extremes. Few group calculations in typical power peaking and control rod worth studies are found to be both rapid and accurate, particularly when the rods are represented by boundary conditions. Boundary conditions for use with theP-3 and doubleP-1 approximations are derived and discussed.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25962

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractThe slowing-down equation for the infinite homogeneous moderator is solved exactly. The solution is obtained in analytical form. The calculated collision density and the escape probability are compared with the approximate Wigner formulas in the case of resonance no wider than one collision interval.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25963

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractThe temperature distributions within plate or thin tubular fuel elements with bonded end closures are determined with an eigen-function expansion. A one-term approximation is given for end caps longer than the plate thickness. Numerical examples are included for uranium fuel elements with Zircaloy cladding and bonded Zircaloy end caps whose lengths are twice, once, and one-fifth the thickness of the fuel plate. For these examples the ratios of the maximum exterior end cap temperature to the maximum temperature of the fuel material (coolant temperature considered as the base temperature) were 0.38, 0.68, and 0.954, respectively.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25964

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractA new approach to the chemical reprocessing of contaminated Th—U—O slurry-type reactor fuels is suggested which avoids the complete dissolution of the slurry particles. The method is based on the elution of adsorbed contaminants from specially treated surface of the slurry particles using hot dilute nitric acid. In particular, the adsorption and elution properties of this type of slurry with respect to 0.004Mcerium were determined.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25965

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractMeasurements ofρ28, the ratio of epithermal to thermal neutron radiative capture in U238, has been carried out in the plate fuel geometry planned for the second Shippingport Pressurized Water Reactor (PWR-2). The experimental results have been compared with two-dimensional diffusion theory analyses, and the agreement is considered satisfactory.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25966

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractThe critical condition is obtained for a system consisting of a ring ofNequally spaced identical cylindrical rods in a reflected cylindrical reactor. The fluxes in each region are expressed in terms of a Fourier Series expansion of the angular dependence of the flux about each rod. The imposition of the boundary conditions gives a set of linear homogeneous equations, from which the critical determinant is deduced. Matrix theory is used throughout, which facilitates the treatment of the problem, and which in the case of a bare reactor provides a method of elimination of constants alternative to that given by Avery. The derivation is also valid for a system containing a ring ofNmultiplying or nonmultiplying zones. A little modification of this theory leads, without difficulty, to the solution of the problem of a ring ofNcontrol rods, which are“black”to thermal neutrons.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25967

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractThe fast, potentially hazardous chemical reaction between a metal and water can occur in a nuclear reactor only above the melting point of the metal,Tm. There is a critical temperatureθ>Tm, at which the process changes over from the slow corrosion-like reaction to one which proceeds with explosive speed and violence. For the alkali metals,θis only slightly greater thanTm. The critical temperatureθhas been experimentally determined for three high melting point metals, Al, Zr, and U; and it is shown thatθis approximately equal to the temperature at which the metal vapor pressure is 0.15 mmfor these cases. This relation suggests that the initiation of the violent metal-water reaction for refractory metals may be a vapor phase phenomenon. On the basis of this hypothesis, and the empirical correlations developed, predictions of the value ofθare presented for a number of other metals for which experimental data are not presently available.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25968

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractSome basic theorems of the geometric theory of differential equations are reviewed, without proofs, in an attempt to clarify: (a) what relationship exists between the general solution of a set of nonlinear differential equations and the solution of its linear approximation and under what conditions this relationship can be used; and (b) how the geometric theory can be used to find properties of boundedness, stability, and periodicity of the solutions of nonlinear differential systems.These theorems are illustrated by means of two-third order examples. The first is the xenon controlled reactor and the second a two-region reactor with two temperature coefficients of reactivity. It is shown without involved computations or any approximations that: (a)Xenon controlled reactor—when the reactivity controlled by xenon is smaller than the prompt xenon yield, the reactor power is always bounded but periodic oscillations may arise. When the reactivity controlled by xenon is greater than the prompt xenon yield the reactor power is unbounded; (b)Two-region reactor—this reactor does not admit periodic solutions. When the temperature coeffi.cients are of opposite sign, conditions are derived for the reactor power to be bounded.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25969

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractSeveral calculational models for the treatment of transient fluid flow through reactor coolant channels have been studied in order to determine their suitability for digital computer application. A momentum integral model has been judged most appropriate for a wide class of intermediate speed transients on the basis of balancing adequacy of physical description against numerical simplicity and computer time requirements.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25970

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor

摘要:

AbstractA method for joining Zircaloy-2 with stainless steel, using controlled expansion transition sections, is described.The transition sections consist of nickel-iron elements of the Invar type and range from low expansion rate 43% nickel-iron, at the Zircaloy-2 end, to high expansion rate 60% nickel-iron, at the stainless steel end. Problems encountered in producing suitable mechanical joints between Zircaloy-2 and 43 % nickel-iron and in preparing and welding the various grades of nickel-iron to each other and to stainless steel are discussed.

ISSN:0029-5639    

DOI:10.13182/NSE61-A25971

出版商:Taylor&Francis    

年代:1961

数据来源: Taylor