Author: Wilmot N. Hess
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 46

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Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 11

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Book Description
In many systems, it is imperative to have accurate knowledge of all significant sources of neutrons due to the decay of radionuclides. These sources can include neutrons resulting from the spontaneous fission of actinides, the interaction of actinide decay [alpha]-particles in ([alpha], n) reactions with low- or medium-Z nuclides, and/or delayed neutrons from the fission products of actinides. Numerous systems exist in which these neutron sources could be important. These include, but are not limited to, clean and spent nuclear fuel (UO2, ThO2, MOX, etc.), enrichment plant operations (UF6, PuF4, etc.), waste tank studies, waste products in borosilicate glass or glass-ceramic mixtures, and weapons-grade plutonium in storage containers. SOURCES-3A is a computer code that determines neutron production rates and spectra from ([alpha], n) reactions, spontaneous fission, and delayed neutron emission due to the decay of radionuclides in homogeneous media (i.e., a mixture of [alpha]-emitting source material and low-Z target material) and in interface problems (i.e., a slab of [alpha]-emitting source material in contact with a slab of low-Z target material). The code is also capable of calculating the neutron production rates due to ([alpha], n) reactions induced by a monoenergetic beam of [alpha]-particles incident on a slab of target material. Spontaneous fission spectra are calculated with evaluated half-life, spontaneous fission branching, and Watt spectrum parameters for 43 actinides. The ([alpha], n) spectra are calculated using an assumed isotropic angular distribution in the center-of-mass system with a library of 89 nuclide decay [alpha]-particle spectra, 24 sets of measured and/or evaluated ([alpha], n) cross sections and product nuclide level branching fractions, and functional [alpha]-particle stopping cross sections for Z

Author: Raymond L. Walker
Publisher:
ISBN:
Category : Boron
Languages : en
Pages : 14

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Book Description

Author: Henry Herman Barschall
Publisher: Pergamon
ISBN:
Category : Science
Languages : en
Pages : 378

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Book Description

Author: James H. Roberts
Publisher:
ISBN:
Category : Alpha rays
Languages : en
Pages : 22

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Book Description

Author: U.S. Atomic Energy Commission
Publisher:
ISBN:
Category : Polonium
Languages : en
Pages : 24

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Book Description

Author: F. G. P. Seidl
Publisher:
ISBN:
Category : Beryllium
Languages : en
Pages : 12

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Book Description

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
A method is presented for measuring the average energy of the neutrons from a source. The attenuation of the neutrons by polyethylene is measured by the use of a long counter in good geometry. The attenuation length is a sensitive function of the neutron energy. The average neutron energies from several (alpha, n) sources were measwed and agree well with values obtained by other techniques. (auth).

Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Book Description
One component of the neutron source associated with the decay of actinide nuclides in many environments is due to the interaction of decay [alpha] particles in ([alpha], n) reactions on low Z nuclides. Measurements of ([alpha], n) thick target neutron yields and associated neutron spectra have been made for only a few combinations of [alpha] energy and target nuclide or mixtures of actinide and target nuclides. Calculations of thick target neutron yields and spectra with the SOURCES code require [alpha]-energy-dependent cross sections for ([alpha], n) reactions, as well as branching fractions leading to the energetically possible levels of the product nuclides. A library of these data has been accumulated for target nuclides of Z d"15 using that available from measurements and from recent GNASH code calculations. SOURCES, assuming neutrons to be emitted isotopically in the center-of-mass system, uses libraries of [alpha] stopping cross sections, ([alpha], n) reaction cross reactions, product nuclide level branching fractions, and actinide decay [alpha] spectra to calculate thick target ([alpha], n) yields and neutron spectra for homogeneous combinations of nuclides. The code also calculates the thick target yield and angle intergrated neutron spectrum produced by [alpha]-particle beams on targets of homogeneous mixtures of nuclides. Illustrative calculated results are given and comparisons are made with measured thick target yields and spectra. 50 refs., 1 fig., 2 tabs.

Author: H. Ullmaier
Publisher: Springer
ISBN: 9783540514350
Category : Science
Languages : en
Pages : 0

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Book Description
Atomic or point defects are disturbances of the periodicity of the crystal lattice extending over only a few atomic distances. Many physical and mechanical properties of solids are sensitive to their presence. Furthermore other defects which are crucial to material behaviour are influenced by their interaction with atomic defects. A detailed knowledge of production mechanisms and properties of point defects is therefore essential for assessing and for understanding the atomistic as well as the macroscopic behaviour of materials. As a result of the use of new research methods in recent years, such information is now available for almost all pure metals, for many dilute alloys and for some concentrated alloys. However, a critical and comprehensive collection of these data has so far been missing. The aim of the present volume is to close this gap by sifting, evaluating and compiling data on vacancies and self-interstitial atoms in solid metals. A chapter on the element helium is included because of the exeptional position of He as an "alloying" element and its role in radiation damage phenomena.