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

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 measurement of fast neutron fluence rate with threshold detectors. The general shape of the ⁶³Cu(n,α) ⁶⁰Co cross section is also shown in Fig. 1 (3, 4, 5) along with a comparison to the current experimental database (6). This figure is for illustrative purposes only to indicate the range of the response of the ⁶³Cu(n,α)⁶⁰Co reaction. Refer to Guide E1018 for descriptions of recommended tabulated dosimetry cross sections.

FIG. 1 ⁶³Cu(n,α)⁶⁰Co Cross Section with EXFOR Experimental Data

Note 1: The cross section appropriate for use under this standard is from the IRDFF-II library (5) which, up to an incident neutron energy of 20 MeV, is drawn from the RRDF-2002 library (3) and is identical to the adopted cross section in the IRDF-2002 library (4). See Guide E1018.

5.3 The major advantages of copper for measuring fast-neutron fluence rate are that it has good strength, is easily fabricated, has excellent corrosion resistance, has a melting temperature of 1083°C, and can be obtained in high purity. The half-life of   ⁶⁰ Co is long and its decay scheme is simple and well known.

5.4 The disadvantages of copper for measuring fast neutron fluence rate are the high reaction apparent threshold of 4.5 MeV, the possible interference from cobalt impurity (>1 μg/g), the reported possible thermal component of the (n,α) reaction, and the possibly significant cross sections for thermal neutrons for   ⁶³Cu and ⁶⁰Co [that is, 4.50(2) and 2.0(2) barns, respectively], (7), which will require burnout corrections at high fluences.

Subcomité:

E10.05

Referida por:

E0721-22, E2005-21, 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; copper; cross section; dosimetry; fast-neutron monitor; neutron metrology; pressure vessel surveillance; reaction rate; ⁶³Cu(n,α)⁶⁰Co;