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

Importancia y uso:

5.1 Refer to Guide E844 for the selection, irradiation, and quality control of neutron dosimeters.

5.2 Refer to Practice E261 for a general discussion of the determination of fast-neutron fluence rate with threshold detectors.

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

5.4 ⁵⁸Co has a half-life of 70.85 (3) days (1, 2)3 and emits a gamma ray with an energy of 810.7602 (20) keV (2, 3).

5.5 Competing activities ⁶⁵Ni(2.5172 h) and ⁵⁷Ni(35.9 (3) h (2) are formed by the reactions ⁶⁴Ni(n,γ) ⁶⁵Ni and ⁵⁸Ni(n,2n)⁵⁷Ni, respectively.

5.6 A second 9.04 h isomer, ^58mCo, is formed that decays to 70.85 day ⁵⁸Co. Loss of ⁵⁸Co and ^58mCo by thermal-neutron burnout will occur in environments (4, 5) 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. (5).

Note 1: The data is taken from the International Reactor Dosimetry and Fusion File (IRDFF-II, the legend of the above plot to be updated). For more details, see Ref (7).

Subcomité:

E10.05

Referida por:

F0980-16R24, E0720-23, E0721-22, F1190-24, E2005-21, E0798-24, E1854-19, E0261-16R21, E1005-21, E0944-19

Volúmen:

12.02

Número ICS:

17.240 (Radiation measurements), 27.120.30 (Fissile materials and nuclear fuel technology)

Palabras clave:

activation; activation reaction; cross section; dosimetry; fast-neutron monitor; neutron metrology; nickel; pressure vessel surveillance; reaction rate;