[en] The critical mass of the reactor RP-0 of the Peruvian Institute of Nuclear Energy is determined by using the Fermi model of diffusion and age in connection with an experimental subcritical neutron population. A desk computer HP9825 is used with a program in HP4. The observed discrepancy between the calculated and the measured mass is 5%

[en] The problem of slowing-down density of neutrons in a spherical symmetry with different sources of neutrons in it with exact boundary conditions in the age theory has been solved. Solutions for the approximate boundary conditions have been derived as special cases. (author)

[en] A companion paper has presented a generalized age theory expression for the scalar flux Phi/sup G//sub O/ (x, u) due to a plane isotropic source emitting neutrons in an infinite medium with cross sections that are constant in energy. The range of validity for this generalized age theory expression has also been determined as p = x/(2u) ≤ R(A), where R(A), the range of validity, is a function of the scatterer's mass. The purpose of this paper is to present the expression for the scalar flux Phi/sup G//sub O/ (x,u) in the complementary region in phase space, i.e., where p > R(A)

[en] The problem of slowing-down density of neutrons for cylindrical shell of finite height with exact boundary conditions on all the surfaces in the age theory has been solved by operational method. (author)

[en] The general problem of neutron noise in an infinite heterogeneous reactor consisting of plate-type fuel elements of identical nuclear properties embedded in a moderator is formulated in the two-group diffusion theory by using the source-sink method of Feinberg and Galanin. After linearizing the neutronic stochastic differential equations, the heterogeneous kinetic adjoint equations are formulated and solved by assuming that the detectors are only sensitive to thermal neutrons. It is shown that in a heterogeneous analysis, a localized noise source will give rise to additional local noise components in the response of a near-by detector. These components have very similar properties to the conventional local component of the homogeneous two-group theory but their existence is due to the attenuation of the signal in the pure moderator and is not directly related to the number of energy groups used in the analysis. (author)

[en] In this paper, the first transcendental approximation as a very good Fermi formula improvement is presented. The first transcendental approximation exactness and application is discussed. (author)

[en] Neutron moderation in an infinite homogeneous medium with constant cross sections, which is traditionally treated by Taylor series approximation methods, bears a close correspondence with the exact transcendental equation approach, as has been demonstrated by reducing the exact result to approximate forms. In this paper we give an alternative approach in which the convergence of the approximations to the exact result is derived by allowing the order of approximation to increase indefinitely. The approach is based on the fact that the usual approximations do not give a self consistent definition of the effective mass parameter. The present result can hence be considered as the slowing down counterpart of Davison's treatment of the one speed equation in the Psub(l) approximation. (auth.)

[en] An attempt has been made to study the neutron diffusion through a finite hollow elliptic cylindrical pile with the help of the solution of Fermi age equation in cylindrical geometry and with capture of neutrons. The use has been made of the modified Mathieu transform to solve the corresponding Fermi age equation in elliptic coordinates. The solution obtained is further used to study the critical state. (author)

[en] The Green's function of the noise is determined using continuous slowing-down theory. An infinite number of roots are found and a definition of the global and local components, that is independent of the number of roots, is given. The local component of age theory is confronted with that of the synthetic kernel (two-group theory) approach and insufficiency of the latter in determining the diffusion length from local-noise measurements is suggested. (author)

No abstract available