Значение и использование

Aluminum oxide pellets are used in a reactor core as filler or spacers within fuel, burnable poison, or control rods. In order to be suitable for this purpose, the material must meet certain criteria for impurity content. These test methods are designed to show whether or not a given material meets the specifications for these items as described in Specification C 785.

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

Aluminum oxide-boron carbide composite pellets are used in a reactor core as a component in neutron absorber rods. In order to be suitable for this purpose, the material must meet certain criteria for boron content, isotopic composition, and impurity content as described in Specification C 784.

3.2.1 The material is assayed for boron to determine whether the boron content is as specified by the purchaser.

3.2.2 Determination of the isotopic content of the boron is made to establish whether the ¹⁰B concentration is in compliance with the purchaser’specifications.

3.2.3 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 aluminum oxide and aluminum oxide-boron carbide composite pellets to determine compliance with specifications.

1.2 The analytical procedures appear in the following order:

Sections Boron by Titrimetry 7 to 13 Separation of Boron for Mass Spectrometry14 to 19 Isotopic Composition by Mass Spectrometry20 to 23 Separation of Halides by Pyrohydrolysis24 to 27 Fluoride by Ion-Selective Electrode28 to 30 Chloride, Bromide, and Iodide by Amperometric Microtitrimetry31 to 33 Trace Elements by Emission Spectroscopy34 to 46

1.3 The values stated in SI units are to be regarded as the 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 and health practices and determine the applicability of regulatory limitations prior to use. (For specific precautionary statements, see Section 5.)

7.1 This test method covers the determination of boron in aluminum oxide-boron carbide composites. As an alternative, the procedure for total boron by titrimetry detailed in Test Methods C791 may be used.

14.1 This test method covers the separation of boron from aluminum and other impurities. The isotopic composition of the separated boron is measured using another test method found herein.

20.1 This test method covers the determination of the isotopic composition of boron in nuclear-grade aluminum oxide/boron carbide composite pellets containing natural to highly enriched boron.

24.1 This test method covers the separation of up to 100 μg of halides per gram of sample. The separated halides are measured using other test methods found herein.

28.1 This test method can determine as low as 2-μg of F/g sample in condensate containing all the halogens.

31.1 This test method covers the determination of halogens, except fluorine, as separated by pyrohydrolysis. The detection limit is 1.5 μg Cl/g sample.

34.1 This spectrochemical test method provides for the determination of 14 impurity elements. The elements and concentration ranges are as follows:

ElementsConcentration Range, ppm Boron10 to 10 000 Calcium 10 to 10 000 Chromium10 to 10 000 Dysprosium30 to 10 000 Europium10 to 10 000 Gadolinium30 to 10 000 Hafnium 30 to 10 000 Iron 10 to 10 000 Magnesium10 to 10 000 Nickel 10 to 10 000 Samarium10 to 10 000 Silicon 10 to 10 000 Sodium 10 to 10 000 Titanium10 to 10 000

34.2 The test method can also be extended to cover the determination of other elements of interest.