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Standard Test Method for Measuring Reaction Rates by Radioactivation of Neptunium-237 (Includes all amendments And changes 12/31/2018).
Automatische name übersetzung:
Standard Test Methode zur Messung der Reaktionsgeschwindigkeit von Radioaktivierungs von Neptunium-237
NORM herausgegeben am 1.8.2013
Bezeichnung normen: ASTM E705-13a
Anmerkung: UNGÜLTIG
Ausgabedatum normen: 1.8.2013
SKU: NS-47733
Zahl der Seiten: 5
Gewicht ca.: 15 g (0.03 Pfund)
Land: Amerikanische technische Norm
Kategorie: Technische Normen ASTM
Keywords:
fission dosimeter, fission product, fission reaction rates, Neptunium-237, ICS Number Code 17.240 (Radiation measurements), 27.120.30 (Fissile materials and nuclear fuel technology)
Significance and Use | ||||||||||||||||||||||
5.1 Refer to Practice E261 for a general discussion of the determination of fast-neutron fluence rate with fission detectors. 5.2 237Np is available as metal foil, wire, or oxide powder. For further information, see Guide E844. It is usually encapsulated in a suitable container to prevent loss of, and contamination by, the 237Np and its fission products.5.3 One or more fission products can be assayed. Pertinent data for relevant fission products are given in 5.3.1 137Cs-137mBa is chosen frequently for long irradiations. Radioactive products 134Cs and 136Cs may be present, which can interfere with the counting of the 0.662 MeV 137Cs-137mBa gamma ray (see Test Methods E320). 5.3.2 140Ba-140La is chosen frequently for short irradiations (see Test Method E393). 5.3.3 95Zr can be counted directly, following chemical separation, or with its daughter 95Nb, using a high-resolution gamma detector system. 5.3.4 144Ce is a high-yield fission product applicable to 2- to 3-year irradiations. 5.4 It is necessary to surround the 237Np monitor with a thermal neutron absorber to minimize fission product production from trace quantities of fissionable nuclides in the 237Np target and from 238Np and 238Pu from (n,γ) reactions in the 237Np material. Assay of 238Pu and 239Pu concentration is recommended when a significant contribution is expected. 5.4.1 Fission product production in a light-water reactor by neutron activation products 238Np and 238Pu has been calculated to be insignificant (1.2 %), compared to that from 237Np(n,f), for an irradiation period of 12 years at a fast neutron (E > 1 MeV) fluence rate of 1 × 1011 cm−2 ·s−1, provided the 237Np is shielded from thermal neutrons (see Fig. 2 of Guide E844). 5.4.2 Fission product production from photonuclear reactions, that is, (γ,f) reactions, while negligible near-power and research reactor cores, can be large for deep-water penetrations (1).5 5.5 Good agreement between neutron fluence measured by 237Np fission and the 54Fe(n,p) 54Mn reaction has been demonstrated 5.6 The 237Np fission neutron spectrum-averaged cross section in several benchmark neutron fields are given in Table 3 of Practice E261. Sources for the latest recommended cross sections are given in Guide E1018. In the case of the 237Np(n,f)F.P. reaction, the recommended cross section source is the ENDF/B-VI cross section (MAT = 9346) revision 1 1.1 This test method covers procedures for measuring reaction rates by assaying a fission product (F.P.) from the fission reaction 237Np(n,f)F.P. 1.2 The reaction is useful for measuring neutrons with energies from approximately 0.7 to 6 MeV and for irradiation times up to 30 to 40 years. 1.3 Equivalent fission neutron fluence rates as defined in Practice E261 can be determined. 1.4 Detailed procedures for other fast-neutron detectors are referenced in Practice E261. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.6 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 and health practices and determine the applicability of regulatory limitations prior to use. |
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2. Referenced Documents | ||||||||||||||||||||||
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Historisch
1.6.2011
Historisch
1.6.2011
Historisch
1.1.2008
Historisch
1.6.2010
Historisch
1.6.2010
Historisch
15.6.2014
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