scope:

This test method covers procedures for measuring reaction rates by the activation reaction ^natTi(n,X)⁴⁶Sc. The "X" designation represents any combination of light particles associated with the production of the residual ⁴⁶Sc product. Within the applicable neutron energy range for fission reactor applications, this reaction is a properly normalized combination of three different reaction channels: ⁴⁶Ti(n,p)⁴⁶Sc; ⁴⁷Ti(n, np)⁴⁶Sc; and ⁴⁷Ti(n,d)⁴⁶Sc.

NOTE 1-The ⁴⁷Ti(n,np)⁴⁶Sc reaction, ENDF-6 format file/reaction identifier MF=3, MT=28, is distinguished from the ⁴⁷Ti(n,d)⁴⁶Sc reaction, ENDF-6 format file/reaction identifier MF=3/MT=104, even though it leads to the same residual product (1).² The combined reaction, in the IRDFF-II library, has the file/reaction identifier MF=10/MT=5.

NOTE 2-The cross section for the combined ⁴⁷Ti(n,np:d) reaction is relatively small for energies less than 12 MeV and, in fission reactor spectra, the production of the residual ⁴⁶Sc is not easily distinguished from that due to the ⁴⁶Ti(n,p) reaction.

The reaction is useful for measuring neutrons with energies above approximately 4.4 MeV and for irradiation times, under uniform power, up to about 250 days (for longer irradiations, or for varying power levels, see Practice E261).

With suitable techniques, fission-neutron fluence rates above 10⁹ cm^-2·s^-1 can be determined. However, in the presence of a high thermal-neutron fluence rate, ⁴⁶Sc depletion should be investigated.

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

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

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

This 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.

² The boldface numbers in parentheses refer to a list of references at the end of this standard.