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5.1 This practice provides a way to estimate the average grain size of polycrystalline materials. It is based on EBSD measurements of crystallographic orientation which are inherently quantitative in nature. This method has specific advantage over traditional optical grain size measurements in some materials, where it is difficult to find appropriate metallographic preparation procedures to adequately delineate grain boundaries.1.1 This practice is used to determine grain size from measurements of grain areas from automated electron backscatter diffraction (EBSD) scans of polycrystalline materials.1.2 The intent of this practice is to standardize operation of an automated EBSD instrument to measure ASTM G directly from crystal orientation. The guidelines and caveats of E112 apply here, but the focus of this standard is on EBSD practice.1.3 This practice is only applicable to fully recrystallized materials.1.4 This practice is applicable to any crystalline material which produces EBSD patterns of sufficient quality that a high percentage of the patterns can be reliably indexed using automated indexing software.1.5 The practice is applicable to any type of grain structure or grain size distribution.1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.7 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.1.8 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.

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5.1 Refer to Practice E261 for a general discussion of the measurement of fast-neutron fluence rates with threshold detectors.5.5.1 Fig. 5 (2) shows how the neutron energy depends upon the angle of scattering in the laboratory coordinate system when the incident deuteron has an energy of 150 keV and is incident on a thick and a thin tritiated target. For thick targets, the incident deuteron loses energy as it penetrates the target and produces neutrons of lower energy. A thick target is defined as a target thick enough to completely stop the incident deuteron. The two curves in Fig. 5, for both thick and thin targets, come from different sources. The dashed line calculations come from Ref (3); the solid curve calculations come from Ref (4); and the measured data come from Ref (5). The dash-dot curve and the right-hand axis give the difference between the calculated neutron energies for thin and thick targets. Computer codes are available to assist in calculating the expected thick and thin target yield and neutron spectrum for various incident deuteron energies (6).FIG. 5 Dependence of 3H(d,n)4He Neutron Energy on Angle (2)5.6 The Q-value for the primary 3H(d,n)4He reaction is +17.59 MeV. When the incident deuteron energy exceeds 3.71 MeV and 4.92 MeV, the break-up reactions 3H(d,np)3H and 3H(d,2n)3He, respectively, become energetically possible. Thus, at high deuteron energies (>3.71 MeV) this reaction is no longer monoenergetic. Monoenergetic neutron beams with energies from about 14.8 to 20.4 MeV can be produced by this reaction at forward laboratory angles (7).5.7 It is recommended that the dosimetry sensors be fielded in the exact positions where the dosimetry results are wanted. There are a number of factors that can affect the monochromaticity or energy spread of the neutron beam (7, 8). These factors include the energy regulation of the incident deuteron energy, energy loss in retaining windows if a gas target is used or energy loss within the target if a solid tritiated target is used, the irradiation geometry, and background neutrons from scattering with the walls and floors within the irradiation chamber.1.1 This test method covers a general procedure for the measurement of the fast-neutron fluence rate produced by neutron generators utilizing the 3H(d,n)4He reaction. Neutrons so produced are usually referred to as 14-MeV neutrons, but range in energy depending on a number of factors. This test method does not adequately cover fusion sources where the velocity of the plasma may be an important consideration.1.2 This test method uses threshold activation reactions to determine the average energy of the neutrons and the neutron fluence at that energy. At least three activities, chosen from an appropriate set of dosimetry reactions, are required to characterize the average energy and fluence. The required activities are typically measured by gamma-ray spectroscopy.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 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.1.5 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.

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5.1 This practice is useful for the determination of the average energy per disintegration of the isotopic mixture found in the reactor-coolant system of a nuclear reactor (1).5 The value is used to calculate a site-specific activity limit for the reactor coolant system, generally identified as: where: K   =   a power reactor site specific constant (usually in the range of 50 to 200). The activity of the reactor coolant system is routinely measured, then compared to the value of Alimiting. If the reactor coolant activity value is less than Alimiting then the 2-h radiation dose, measured at the plant boundary, will not exceed an appropriately small fraction of the Code of Federal Regulations, Title 10, part 100 dose guidelines. It is important to note that the measurement of the reactor coolant system radioactivity is determined at a set frequency by use of gamma spectrometry only. Thus, the radionuclides that go into the calculation of and subsequently Alimiting are only those that are measured using gamma spectrometry. 5.2 In calculating , the energy dissipated by beta particles (negatrons and positrons) and photons from nuclear decay of beta-gamma emitters includes the energy released in the form of extra-nuclear transitions such as X-rays, Auger electrons, and conversion electrons. However, not all radionuclides present in a sample are included in the calculation of . 5.3 Individual nuclear reactor technical specifications vary and each nuclear operator must be aware of limitations affecting plant operation. Typically, iodine radionuclides with half-lives of less than 10 min (except those in equilibrium with the parent) and those radionuclides identified using gamma spectrometry with less than 95 % confidence level are not included in the calculation. However, technical requirements specify that the reported activity must account for at least 95 % of the activity after excluding radioiodines and short-lived radionuclides. There are individual bases for each exclusion. 5.3.1 Radioiodines are typically excluded from the calculation of because United States commercial nuclear reactors are required to operate under a more conservative restriction of 1 μCi (37 kBq) per gram dose equivalent 131I (DEI) in the reactor coolant. 5.3.2 Beta-only-emitting radio isotopes (for example, 90Sr or 63Ni) and alpha emitting radioisotopes (for example, 241Am or 239Pu) which comprise a small fraction of the activity, are not included in the E-bar calculation. These isotopes are not routinely analyzed for in the reactor coolant and, thus, their inclusion in the E-bar calculation is not representative of what is used to assess the 10 CFR 100 dose limits. Tritium, also a beta-only emitter, should not be included in the calculation. Tritium has the largest activity concentration in the reactor coolant system but the lowest beta particle energy. Thus, its dose contribution is always negligible. However, its inclusion in the E-bar calculation would raise the value of Alimiting, yielding a non-conservative value for dose assessment. 5.3.3 Excluding radionuclides with half-lives less than 10 min, except those in equilibrium with the parent, has several bases. 5.3.3.1 The first basis considers the nuclear characteristics of a typical reactor coolant. The radionuclides in a typical reactor coolant have half-lives of less than 4 min or have half-lives greater than 14 min. This natural separation provides a distinct window for choosing a 10-min half-life cutoff. 5.3.3.2 The second consideration is the predictable time delay, approximately 30 min, which occurs between the release of the radioactivity from the reactor coolant to its release to the environment and transport to the site boundary. In this time, the short-lived radionuclides have undergone the decay associated with several half-lives and are no longer considered a significant contributor to . 5.3.3.3 A final practical basis is the difficulty associated with identifying short-lived radionuclides in a sample that requires some significant time, relative to 10 min, to collect, transport, and analyze. 5.3.4 The value of E-bar is usually calculated once every 6 months. However, any time a significant increase in the activity of the reactor coolant occurs, the value of E-bar should be reassessed to ensure compliance with 10 CFR 100. Such reassessment should be done any time there is a significant fuel defect that would alter the value and affect Alimiting. The two possible causes to reassess the value of would be: (1) A significant fuel defect has occurred where the noble gas activity has increased. (2) A significant corrosion product increase has occurred. For the case of a fuel defect, the plant staff may need to include new radionuclides not normally used in the calculation of such as 239U and 239Np. 1.1 This practice applies to the calculation of the average energy per disintegration ( ) for a mixture of radionuclides in reactor coolant water. 1.2 The microcurie (µCi) is the standard unit of measurement for this standard. The values given in parentheses are mathematical conversions to SI units, which are provided for information only and are not considered standard. 1.3 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. 1.4 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.

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5.1 These test methods cover procedures for determining the mean grain size, and the distribution of grain intercept lengths or grain areas, for polycrystalline metals and nonmetallic materials with equiaxed or deformed grain shapes, with uniform or duplex grain size distributions, and for single phase or multiphase grain structures.5.2 The measurements are performed using semiautomatic digitizing tablet image analyzers or automatic image analyzers. These devices relieve much of the tedium associated with manual measurements, thus permitting collection of a larger amount of data and more extensive sampling which will produce better statistical definition of the grain size than by manual methods.5.3 The precision and relative accuracy of the test results depend on the representativeness of the specimen or specimens, quality of specimen preparation, clarity of the grain boundaries (etch technique and etchant used), the number of grains measured or the measurement area, errors in detecting grain boundaries or grain interiors, errors due to detecting other features (carbides, inclusions, twin boundaries, and so forth), the representativeness of the fields measured, and programming errors.5.4 Results from these test methods may be used to qualify material for shipment in accordance with guidelines agreed upon between purchaser and manufacturer, to compare different manufacturing processes or process variations, or to provide data for structure-property-behavior studies.1.1 These test methods are used to determine grain size from measurements of grain intercept lengths, intercept counts, intersection counts, grain boundary length, and grain areas.1.2 These measurements are made with a semiautomatic digitizing tablet or by automatic image analysis using an image of the grain structure produced by a microscope.1.3 These test methods are applicable to any type of grain structure or grain size distribution as long as the grain boundaries can be clearly delineated by etching and subsequent image processing, if necessary.1.4 These test methods are applicable to measurement of other grain-like microstructures, such as cell structures.1.5 This standard deals only with the recommended test methods and nothing in it should be construed as defining or establishing limits of acceptability or fitness for purpose of the materials tested.1.6 The sections appear in the following order:Section Section  1Referenced Documents  2Terminology  3 Definitions  3.1 Definitions of Terms Specific to This Standard  3.2 Symbols  3.3Summary of Test Method  4  5Interferences  6Apparatus  7Sampling  8Test Specimens  9Specimen Preparation 10Calibration 11Procedure:   Semiautomatic Digitizing Tablet 12 Intercept Lengths 12.3 Intercept and Intersection Counts 12.4 Grain Counts 12.5 Grain Areas 12.6 ALA Grain Size 12.6.1 Two-Phase Grain Structures 12.7Procedure:   Automatic Image Analysis 13 Grain Boundary Length 13.5 Intersection Counts 13.6 Mean Chord (Intercept) Length/Field 13.7.2 Individual Chord (Intercept) Lengths 13.7.4 Grain Counts 13.8 Mean Grain Area/Field 13.9 Individual Grain Areas 13.9.4 ALA Grain Size 13.9.8 Two-Phase Grain Structures 13.10Calculation of Results 14Test Report 15Precision and Bias 16Grain Size of Non-Equiaxed Grain Structure Specimens Annex A1Examples of Proper and Improper Grain Boundary Delineation Annex A21.7 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.1.8 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.

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