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ASTM E264-08

Historical Revision

Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Nickel

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1.1 This test method covers procedures for measuring reaction rates by the activation reaction 58Ni(n,p)58Co.

1.2 This activation reaction is useful for measuring neutrons with energies above approximately 2.1 MeV and for irradiation times up to about 200 days in the absence of high thermal neutron fluence rates (for longer irradiations, see Practice E 261).

1.3 With suitable techniques fission-neutron fluence rates densities above 107 cm−2·s−1 can be determined.

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

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 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.


Note—The burnup corrections were computed using effective burn-up cross sections of 1650 b for 58Co(n,γ) and 1.4E5 b for 58mCo(n,γ).

FIG. 1 R Correction Values as a Function of Irradiation Time and Neutron Flux

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 nickel in the form of foil or wire is readily available, and easily handled.

58Co has a half-life of 70.86 days and emits a gamma ray with an energy of 0.8107593-MeV.

Competing activities 65Ni(2.5172 h) and 57Ni(35.60 h) are formed by the reactions 64Ni(n,γ) 65Ni, and 58Ni(n,2n)57Ni, respectively.

A second 9.04 h isomer, 58mCo, is formed that decays to 70.86-day 58Co. Loss of 58Co and 58mCo by thermal-neutron burnout will occur in environments , having thermal fluence rates of 3 × 1012 cm−2·s−1 and above. Burnout correction factors, R, are plotted as a function of time for several thermal fluxes in Fig. 1. Tabulated values for a continuous irradiation time are provided in Hogg, et al.

Fig. 2 shows a plot of cross section versus energy for the fast-neutron reaction 58Ni(n,p) 58Co. This figure is for illustrative purposes only to indicate the range of response of the 58Ni(n,p) reaction. Refer to Guide E 1018 for descriptions of recommended tabulated dosimetry cross sections.

Note 1—The data is taken from the Evaluated Nuclear Data File, ENDF/B-VI, rather than the later ENDF/B-VII. This is in accordance with E 1018, section 6.1, since the later ENDF/B-VII data files do not include covariance information. For more details see Section H of reference 8.


FIG. 2 58Ni(n,p)58Co Cross Section
SDO ASTM: ASTM International
Document Number E264
Publication Date July 1, 2008
Language en - English
Page Count 3
Revision Level 08
Supercedes
Committee E10.05
Publish Date Document Id Type View
April 1, 2019 E0264-19 Revision
July 1, 2008 E0264-08 Revision
June 10, 2002 E0264-02 Revision
Jan. 1, 1992 E0264-92 Revision
Jan. 1, 2013 E0264-08R13 Reaffirmation
Jan. 1, 1996 E0264-92R96 Reaffirmation