Значение и использование

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 C750 and C751.

An assay is performed to determine whether the material has the specified boron content.

Determination of the isotopic content of the boron is made to establish whether the content is in compliance with the purchaser’s specifications.

Impurity content is determined to ensure that the maximum concentration limit of certain impurity elements is not exceeded.

Область применения

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.

1.2 The analytical procedures appear in the following order:

Sections Total Carbon by Combustion in an Inductive Furnace and Infrared Measurement 7-16 Total Boron by Titrimetry and ICP OES17-27 Isotopic Composition by Mass Spectrometry28-32 Pyrohydrolysis33-40 Chloride by Constant-Current Coulometry41-49 Chloride and Fluoride by Ion-Selective Electrode50-58 Water by Constant-Voltage Coulometry and Weight Loss on Drying59-62 Metallic Impurities63 and 64 Soluble Boron by Titrimetry and ICP OES65-79 Free Carbon by a Coulometric Method80-89

7.1 This method covers the determination of total carbon in nuclear-grade boron carbide in either powder or pellet form.

17.1 This method covers the determination of total boron in samples of boron carbide powder and pellets by titrimetry and ICP OES. The recommended amount of boron for each titration is 100 ± 10 mg.

28.1 This method covers the determination of the isotopic composition of boron in nuclear-grade boron carbide, in powder and pellet form, containing natural to highly enriched boron.

33.1 This method covers the separation of up to 100 μg of halides per gram of boron carbide. The separated halides are measured using other methods found in this standard. It also covers the sample preparation for the determination of isotopic composition by ICP MS.    

41.1 This method covers the measurement of chloride after separation from boron carbide by pyrohydrolysis. The lower limit of the method is about 2 μg of chloride per titration.

50.1 This method covers the measurement of chloride and fluoride after separation from boron carbide by pyrohydrolysis. The limit of detection for chloride and fluoride in the boron carbide sample is 3 mg/kg and 2 mg/kg, respectively.    

60.1 This method covers the determination of water in boron carbide in either powder or pellet form. The lower limit of the method is 5 μg of water. The lower limit of the weight loss on drying method is 20 mg/kg for a sample mass of 5 g.

65.1 This method covers the determination of soluble boron in boron carbide. Soluble boron is defined as that boron dissolved under the conditions of the test.

80.1 This method covers the determination of free carbon (also called soluble carbon) in boron carbide powders and shaped or sintered bodies of boron carbide after crushing. This method is applicable to mass fractions of free carbon of 0.01 % to 10 %.