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ASTM E266-07
Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Aluminum
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Разработчик:
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ICS:
17.240 Radiation. Including dosimetry / Измерения параметров излучений27.120.30 Fissile. Including raw materials / Делящиеся ядерные вещества. Включая сырье
Сборник (ASTM):
12.02 Nuclear (II), Solar, and Geothermal Energy; Radiation Processing / Ядерная энергия (II), Солнечная, и Геотермическая Энергия; Радиационная обработка
Тематика:
Nuclear Technology
Описание
Значение и использование

Refer to Guide E 844 for the selection, irradiation, and quality control of neutron dosimeters.

Refer to Practice E 261 for a general discussion of the determination of fast-neutron fluence rate with threshold detectors.

Pure aluminum in the form of foil or wire is readily available and easily handled.

24Na has a half-life of 14.951 h (1)3 and emits gamma rays with energies of 1.368.633 and 2.754028 MeV (2).

Fig. 1 shows a plot of cross section versus neutron energy for the fast-neutron reaction 27Al(n,α)24Na from the IRDF2002 dosimetry cross section library(3). This figure is for illustrative purposes only to indicate the range of response of the 27Al(n,α) reaction. Refer to Guide E 1018 for descriptions of recommended tabulated dosimetry cross sections.

Two competing activities, 28Al and 27Mg, are formed in the reactions 27Al(n,γ) 28Al and 27Al(n,p) 27Mg, respectively, but these can be eliminated by waiting 2 h before counting.


FIG. 1 27Al(n,α)24Na Cross Section

Область применения

1.1 This test method covers procedures measuring reaction rates by the activation reaction 27Al(n,)24Na.

1.2 This activation reaction is useful for measuring neutrons with energies above approximately 6.5 MeV and for irradiation times up to about 2 days (for longer irradiations, see Practice E 261).

1.3 With suitable techniques, fission-neutron fluence rates above 106cm2s1 can be determined.

1.4 Detailed procedures for other fast neutron detectors are referenced in Practice E 261.

This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Ключевые слова:
activation; activation reaction; aluminum; cross section; dosimetry; fast-neutron monitor; neutron metrology; pressure vessel surveillance; reaction rate