ASTM E 262 : 2013
Superseded
A superseded Standard is one, which is fully replaced by another Standard, which is a new edition of the same Standard.
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Standard Test Method for Determining Thermal Neutron Reaction Rates and Thermal Neutron Fluence Rates by Radioactivation Techniques
Hardcopy , PDF
05-20-2024
English
01-01-2013
Committee |
E 10
|
DocumentType |
Test Method
|
Pages |
11
|
PublisherName |
American Society for Testing and Materials
|
Status |
Superseded
|
SupersededBy | |
Supersedes |
1.1The purpose of this test method is to define a general procedure for determining an unknown thermal-neutron fluence rate by neutron activation techniques. It is not practicable to describe completely a technique applicable to the large number of experimental situations that require the measurement of a thermal-neutron fluence rate. Therefore, this method is presented so that the user may adapt to his particular situation the fundamental procedures of the following techniques.
1.2The techniques presented are limited to measurements at room temperatures. However, special problems when making thermal-neutron fluence rate measurements in high-temperature environments are discussed in 9.2. For those circumstances where the use of cadmium as a thermal shield is undesirable because of potential spectrum perturbations or of temperatures above the melting point of cadmium, the method described in Test Method E481 can be used in some cases. Alternatively, gadolinium filters may be used instead of cadmium. For high temperature applications in which aluminum alloys are unsuitable, other alloys such as cobalt-nickel or cobalt-vanadium have been used.
1.3This test method may be used to determine the equivalent 2200 m/s fluence rate. The accurate determination of the actual thermal neutron fluence rate requires knowledge of the neutron temperature, and determination of the neutron temperature is not within the scope of the standard.
1.4The techniques presented are suitable only for neutron fields having a significant thermal neutron component, in which moderating materials are present, and for which the average scattering cross section is large compared to the average absorption cross section in the thermal neutron energy range.
1.5Table 1 indicates the useful neutron-fluence ranges for each detector material.
Foil Material | Form | ≈ Useful Range (neutrons/cm 2) |
Indium | pure or alloyed with aluminum | 103 to 1012 |
Gold | pure or alloyed with aluminum | 107 to 1014 |
Dysprosium | pure or alloyed with aluminum | 103 to 1010 |
Cobalt | pure or alloyed with aluminum | 1014 to 1020 |
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