ASTM E263-18

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Designation: E263 − 13 E263 − 18
Standard Test Method for
Measuring Fast-Neutron Reaction Rates by Radioactivation
of Iron
This standard is issued under the fixed designation E263; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
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1.1 This test method describes procedures for measuring reaction rates by the activation reaction Fe(n,p) Mn.
1.2 This activation reaction is useful for measuring neutrons with energies above approximately 2.2 MeV and for irradiation
times up to about 3 years (for longer irradiations, see three years, provided that the analysis methods described in Practice E261).
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from dosimeters withdrawn earlier.
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1.3 With suitable techniques, fission-neutron fluence rates above 10 cm ·s can be determined. However, in the presence of
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a high thermal-neutron fluence rate (for example, >2 × 10 cm ·s ) Mn depletion should be investigated.
1.4 Detailed procedures describing the use of 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 safety, health, and healthenvironmental 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
2.1 ASTM Standards:
D1193 Specification for Reagent Water
E170 Terminology Relating to Radiation Measurements and Dosimetry
E181 Test Methods for Detector Calibration and Analysis of Radionuclides
E261 Practice for Determining Neutron Fluence, Fluence Rate, and Spectra by Radioactivation Techniques
E844 Guide for Sensor Set Design and Irradiation for Reactor Surveillance
E944 Guide for Application of Neutron Spectrum Adjustment Methods in Reactor Surveillance
E1005 Test Method for Application and Analysis of Radiometric Monitors for Reactor Vessel Surveillance
E1018 Guide for Application of ASTM Evaluated Cross Section Data File
3. Terminology
3.1 Definitions:
3.1.1 Refer to Terminology E170 for definitions of terms relating to radiation measurements and neutron dosimetry.
This test method is under the jurisdiction of ASTM Committee E10 on Nuclear Technology and Applications and is the direct responsibility of Subcommittee E10.05
on Nuclear Radiation Metrology.
Current edition approved June 1, 2013Dec. 1, 2018. Published July 2013January 2019. Originally approved in 1965 as E263 – 65 T. Last previous edition approved in
20092013 as E263 – 09.E263 – 13. DOI: 10.1520/E0263-13.10.1520/E0263-18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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4. Summary of Test Method
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4.1 High-purity iron is irradiated in a neutron field, thereby producing radioactive Mn from the Fe(n,p) Mn activation
reaction.
4.2 The gamma rays emitted by the radioactive decay of
Mn are counted in accordance with Test Methods E181. The reaction rate, as defined by Practice E261, is calculated from the
decay rate and irradiation conditions.
4.3 Radioassay of the Mn activity may be accomplished by directly counting the irradiated iron dosimeter, or by first
chemically separating the Mn activity prior to counting.
4.4 The neutron fluence rate above about 2.2 MeV can then be calculated from the spectral-weighted neutron activation cross
section as defined by Practice E261.
5. Significance and Use
5.1 Refer to Guide E844 for guidance on 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 iron in the form of foil or wire is readily available and easily handled.
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5.4 Fig. 1 shows a plot of cross section as a function of neutron energy for the fast-neutron reaction Fe(n,p) Mn (1). This
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figure is for illustrative purposes only to indicate the range of response of the Fe(n,p) Mn reaction. Refer to Guide E1018 for
descriptions of recommended tabulated dosimetry cross sections.
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5.5 Mn has a half-life of 312.13312.19 (3) days (2) and emits a gamma ray with an energy of 834.838 (5)834.855 (3) keV
(2).
5.6 Interfering activities generated by neutron activation arising from thermal or fast neutron interactions are 2.5789
56 59 60
(1)-h2.57878 (46)-h Mn, 44.495 (9) day44.494 (12) days Fe, and 1925.28 (1) day5.2711 (8) years Co (2,3). (Consult the latest
version of Ref (2) for more precise values currently accepted for the half-lives.) Interference from Mn can be eliminated by
waiting 48 h before counting. Although chemical separation of Mn from the irradiated iron is the most effective method for
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eliminating Fe and Co, direct counting of iron for Mn is possible using high-resolution detector systems or unfolding or
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FIG. 1 Fe(n,p) Mn Cross Section
The boldface numbers in parentheses refer to the list of references located at the end of this test method.
The un-bolded number in parenthesis after the unit indicates the uncertainty in the least significant digits. For example, 1.89 (2) keV would indicate a value of 1.89 keV
6 0.02 keV.
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stripping techniques, especially if the dosimeter was covered with cadmium or boron during irradiation. Altering the isotopic
composition of the iron dosimeter is another useful technique for eliminating interference from extraneous activities when direct
sample counting is to be employed.
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 Mn 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 6, 7 and 8 that follow were specifically written to describe the method of chemical separation and subsequent
counting of the Mn activity. When one elects to count the iron dosimeters directly, those portions of Sections 6, 7 and 8 that
pertain to radiochemical separation should be disregarded.
NOTE 1—The following portions of this test method apply also to direct sample-counting methods: 6.1 – 6.3, 7.4, 7.9, 7.10, 8.1 – 8.5, 8.18, 8.19, and
9 – 12.
6. Apparatus (Note 1)
6.1 High–Resolution Gamma-Ray Spectrometer, because of its high resolution, the germanium detector is useful when
contaminant activities are present. See Test Methods E181 and E1005.
6.2 Precision Balance, able to achieve the required accuracy.
6.3 Digital Computer, useful for data analysis (optional).
6.4 Chemical Separation Cylinder, borosilicate glass, about 25-mL capacity, equipped with stopcock and funnel. This apparatus
is illustrated in Fig. 2.
6.5 Beakers, borosilicate glass, 50 mL; volumetric flasks, 25 and 50 mL, and volumetric pipets, 1 mL.
7. Reagents and Materials (Note 1)
7.1 Purity of Reagents—Reagent-grade chemicals shall be used in all tests. Unless otherwise indicated, it is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
FIG. 2 Ion-Exchange Separation Apparatus
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such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use without lessening the accuracy of the activity determination.
7.2 Purity of Water— Unless otherwise indicated, references to water shall be understood to mean reagent-grade water
conforming to Specification D1193.
7.3 Anion Exchange Resin, strongly basic type, 100 to 200 mesh size.
7.4 Iron Foil or Wire, high purity.
7.5 Hydrochloric Acid (sp gr 1.19, 1190 kg/m )—Concentrated hydrochloric acid (HCl).
7.6 Hydrochloric Acid (1 + 3)—Mix 1 volume of concentrated HCl (sp gr 1.19) with 3 volumes of water.
7.7 Manganese Carrier Solution (10 mg MnCl /cm ).
7.8 Nitric Acid (sp gr 1.42, 1420 kg/m )—Concentrated nitric acid (HNO ).
7.9 Encapsulating Materials—Brass, stainless steel, copper, aluminum, quartz, or vanadium have been used as primary
encapsulating materials. The container should be constructed in such a manner that it will not create a significant flux perturbation
and that it may be opened easily, especially if the capsule is to be opened remotely. (See Guide E844.)
7.10 The purity of the iron is important in that no impurities should be present which produce long-lived radionuclides that
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interfere with the Mn radioassay. This condition includes species that will accompany Mn through the separation scheme and
that have gamma rays, of energy 0.6 MeV or higher. The presence of impurities may be determined either by emission spect
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