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适用范围：<p id="s00007">Boron carbide is used as a control material in nuclear reactors. In order to be suitable for this purpose, the material must meet certain criteria for assay, isotopic composition, and impurity content. These methods are designed to show whether or not a given material meets the specifications for these items as described in Specifications C 750 and C 751<astmref rid="a00001"><astmref rid="a00002">.</p> <p id="s00008">3.1.1 An assay is performed to determine whether the material has the specified boron content.</p> <p id="s00009">3.1.2 Determination of the isotopic content of the boron is made to establish whether the content is in compliance with the purchaserrsquo;specifications.</p> <p id="s00010">3.1.3 Impurity content is determined to ensure that the maximum concentration limit of certain impurity elements is not exceeded.</p><p>1.1 These test methods cover procedures for the chemical, mass spectrometric, and spectrochemical analysis of nuclear-grade boron carbide powder and pellets to determine compliance with specifications.</p><p>1.2 The analytical procedures appear in the following order:</p><table width=95%><TR><TD></TD><TD>Sections</TD></TR><TR><TD>Total Carbon by Combustion and Gravimetry</TD><TD>7-17</TD></TR><TR><TD>Total Boron by Titrimetry</TD><TD>18-28</TD></TR><TR><TD>Isotopic Composition by Mass Spectrometry</TD><TD>29-38</TD></TR><TR><TD>Chloride and Fluoride Separation by Pyrohydrolysis</TD><TD>39-45</TD></TR><TR><TD>Chloride by Constant-Current Coulometry</TD><TD>46-54</TD></TR><TR><TD>Fluoride by Ion-Selective Electrode</TD><TD>55-63</TD></TR><TR><TD>Water by Constant-Voltage Coulometry</TD><TD>64-72</TD></TR><TR><TD>Impurities by Spectrochemical Analysis</TD><TD>73-81</TD></TR><TR><TD>Soluble Boron by Titrimetry</TD><TD>82-95</TD></TR><TR><TD>Soluble Carbon by a Manometric Measurement</TD><TD>96-105</TD></TR><TR><TD>Metallic Impurities by a Direct Reader Spectrometric Method</TD><TD>106-114</TD></TR></table>