Standard Test Method for Measuring Fast-Neutron Reaction Rates by Radioactivation of Iron
NORMA vydaná dňa 1.12.2018
Označenie normy: ASTM E263-18
Dátum vydania normy: 1.12.2018
Kód tovaru: NS-910513
Počet strán: 5
Približná hmotnosť: 15 g (0.03 libier)
Krajina: Americká technická norma
Kategória: Technické normy ASTM
fast neutron detector, iron activation, reaction rate, 54Fe(n,p),, ICS Number Code 17.240 (Radiation measurements), 27.120.30 (Fissile materials and nuclear fuel technology)
|Significance and Use|
5.1 Refer to Guide for guidance on the selection, irradiation, and quality control of neutron dosimeters.
5.2 Refer to Practice for a general discussion of the determination of fast-neutron fluence rate with threshold detectors.
5.3 Pure iron in the form of foil or wire is readily available and easily handled.
5.4 shows a plot of cross section as a function of neutron energy for the fast-neutron reaction 54Fe(n,p)54Mn FIG. 1 54Fe(n,p)54Mn Cross Section
5.5 54Mn has a half-life of 312.19 (3) days5.6 Interfering activities generated by neutron activation arising from thermal or fast neutron interactions are 2.57878 (46)-h 56Mn, 44.494 (12) days 59Fe, and 5.2711 (8) years 60Co (. (Consult the latest version of Ref , )5.7 The vapor pressures of manganese and iron are such that manganese diffusion losses from iron can become significant at temperatures above about 700°C. Therefore, precautions must be taken to avoid the diffusion loss of 54Mn from iron dosimeters at high temperature. Encapsulating the iron dosimeter in quartz or vanadium will contain the manganese at temperatures up to about 900°C.
5.8 Sections , and that follow were specifically written to describe the method of chemical separation and subsequent counting of the 54Mn activity. When one elects to count the iron dosimeters directly, those portions of Sections , and that pertain to radiochemical separation should be disregarded.
Note 1: The following portions of this test method apply also to direct sample-counting methods: , , , , , , , and .
1.1 This test method describes procedures for measuring reaction rates by the activation reaction 54Fe(n,p)54Mn.
1.2 This activation reaction is useful for measuring neutrons with energies above approximately 2.2 MeV and for irradiation times up to about three years, provided that the analysis methods described in Practice are followed. If dosimeters are analyzed after irradiation periods longer than three years, the information inferred about the fluence during irradiation periods more than three years before the end of the irradiation should not be relied upon without supporting data from dosimeters withdrawn earlier.
1.3 With suitable techniques, fission-neutron fluence rates above 108 cm−2·s−1 can be determined. However, in the presence of a high thermal-neutron fluence rate (for example, >2 × 1014 cm−2·s −1) 54Mn depletion should be investigated.
1.4 Detailed procedures describing the use of other fast-neutron detectors are referenced in Practice .
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.7 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. Referenced Documents|
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