ASTM E 264 : 2019

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

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

Note 1: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).

1.2This 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, provided that the analysis methods described in Practice E261 are followed. If dosimeters are analyzed after irradiation periods longer than 200 days, the information inferred about the fluence during irradiation periods more than 200 days before the end of the irradiation should not be relied upon without supporting data from dosimeters withdrawn earlier.

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

1.4Detailed procedures for other fast-neutron detectors are referenced in Practice E261.

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

1.6This 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.7This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.