Potřebujeme váš souhlas k využití jednotlivých dat, aby se vám mimo jiné mohly ukazovat informace týkající se vašich zájmů. Souhlas udělíte kliknutím na tlačítko „OK“.
Standard Test Method for Measuring Neutron Fluence Rate by Radioactivation of Cobalt and Silver
Automaticky přeložený název:
Standardní zkušební metoda pro měření neutronového Fluence sazbu o Radioactivation kobaltu a stříbra
NORMA vydána dne 1.1.2010
Označení normy: ASTM E481-10
Poznámka: NEPLATNÁ
Datum vydání normy: 1.1.2010
Kód zboží: NS-46943
Počet stran: 7
Přibližná hmotnost: 21 g (0.05 liber)
Země: Americká technická norma
Kategorie: Technické normy ASTM
Keywords:
activation, cobalt, dosimetry, foil, silver, thermal neutron, Cobalt- and silver-foil monitors, Fluence, Neutron activation reactions, Neutron flux/fluence, Radioactivation--fast neutron flux, Silver-foil monitors, Thermal neutron flux, ICS Number Code 17.240 (Radiation measurements), 27.120.30 (Fissile materials and nuclear fuel technology)
Significance and Use | ||||||||||
The pertinent data for these two reactions are given in Table 1. This test method uses one monitor (cobalt) with a nearly 1/v absorption cross-section curve and a second monitor (silver) with a large resonance peak so that its resonance integral is large compared to the thermal cross section. The equations are based on the Westcott formalism (2, 3) and determine a Westcott 2200 m/s neutron fluence rate nv0 and the Westcott epithermal index parameter r |
||||||||||
1. Scope | ||||||||||
1.1 This test method covers a suitable means of obtaining the thermal neutron fluence rate, or fluence, in well moderated nuclear reactor environments where the use of cadmium, as a thermal neutron shield as described in Method E262, is undesirable because of potential spectrum perturbations or of temperatures above the melting point of cadmium. 1.2 This test method describes a means of measuring a Westcott neutron fluence rate (Note 1) by activation of cobalt- and silver-foil monitors (See Terminology E170). The reaction 59Co(n,γ)60Co results in a well-defined gamma emitter having a half-life of 1925.28 days (1). The reaction 109Ag(n,˙γ) 110mAg results in a nuclide with a complex decay scheme which is well known and having a half-life of 249.76 days (1). Both cobalt and silver are available either in very pure form or alloyed with other metals such as aluminum. A reference source of cobalt in aluminum alloy to serve as a neutron fluence rate monitor wire standard is available from the National Institute of Standards and Technology (NIST) as Standard Reference Material 953. The competing activities from neutron activation of other isotopes are eliminated, for the most part, by waiting for the short-lived products to die out before counting. With suitable techniques, thermal neutron fluence rate in the range from 109 cm−2 · s−1 to 3 × 1015 cm−2 · s−1 can be measured. For this method to be applicable, the reactor must be well moderated and be well represented by a Maxwellian low-energy distribution and an (1/E) epithermal distribution. These conditions are usually met in positions surrounded by hydrogenous moderator without nearby strongly absorbing materials. Otherwise the true spectrum must be calculated to obtain effective activation cross sections over all energies. |
||||||||||
2. Referenced Documents | ||||||||||
|
Poslední aktualizace: 22.12.2024 (Počet položek: 2 217 000)
© Copyright 2024 NORMSERVIS s.r.o.