ASTM C1457-18

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Designation: C1457 − 00 (Reapproved 2010) C1457 − 18
Standard Test Method for
Determination of Total Hydrogen Content of Uranium Oxide
Powders and Pellets by Carrier Gas Extraction
This standard is issued under the fixed designation C1457; 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.
ε NOTE—Editorial corrections were made throughout in June 2010.
1. Scope
1.1 This test method applies to the determination of hydrogen in nuclear-grade uranium oxide powders and pellets to determine
compliance with specifications. Gadolinium oxide (Gd O ) and gadolinium oxide-uranium oxide powders and pellets may also be
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analyzed using this test method.
1.2 This standard describes a procedure for measuring the total hydrogen content of uranium oxides. The total hydrogen content
results from absorbed water, water of crystallization, hydro-carbides and other hydrogenated compounds which may exist as fuel’s
impurities.
1.3 This test method covers the determination of 0.05 to 200 μg of residual hydrogen.
1.4 This test method describes an electrode furnace carrier gas combustion system equipped with a thermal conductivity
detector.
1.5 The preferred system of units is micrograms hydrogen per gram of sample (μg/g sample) or micrograms hydrogen per gram
of uranium (μg/g U).
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For specific hazard statements, see Section 9.
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.
2. Referenced Documents
2.1 ASTM Standards:
C753 Specification for Nuclear-Grade, Sinterable Uranium Dioxide Powder
C776 Specification for Sintered Uranium Dioxide Pellets for Light Water Reactors
C859 Terminology Relating to Nuclear Materials
C888 Specification for Nuclear-Grade Gadolinium Oxide (Gd O ) Powder
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C922 Specification for Sintered Gadolinium Oxide-Uranium Dioxide Pellets
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms relating to the nuclear fuel cycle, refer to Terminology C859.
4. Summary of Test Method
4.1 The total hydrogen content is determined using a hydrogen analyzer. The hydrogen analyzer is based on the carrier gas
method using argon or nitrogen as carrier gas. The actual configuration of the system may vary with vendor and model.
This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.
Current edition approved June 1, 2010Feb. 1, 2018. Published June 2010February 2018. Originally approved in 2000. Last previous edition approved in 20052010 as
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C1457 – 00 (2005).(2010) . DOI: 10.1520/C1457-00R10E01.10.1520/C1457-18.
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.
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C1457 − 18
4.2 The samples to be analyzed are dropped into a preheated graphite crucible, and then, heated up to a temperature of more
than 1700°C in a graphite crucible. At that temperature hydrogen, oxygen, nitrogen, and carbon monoxide (oxygen is converted
to CO when it reacts with the crucible) are released. The release gas is purified in the carrier gas stream by oxidation and absorption
columns. The hydrogen is separated by chromatographic means and analyzed in a thermal conductivity detector.
5. Significance and Use
5.1 Uranium dioxide is used as a nuclear-reactor fuel. Gadolinium oxide is used as an additive to uranium dioxide. In order to
be suitable for this purpose, these materials must meet certain criteria for impurity content. This test method is designed to
determine whether the hydrogen content meets Specifications C753, C776, C888, and C922.
6. Interferences
6.1 Contamination of carrier gas, crucibles, or samples with extraneous sources of hydrogen may cause a positive bias. A blank
correction will help to minimize the bias from carrier gas and crucibles. Interference from adsorbed hydrogen on samples may be
eliminated by keeping the sample in an inert atmosphere or vacuum.
6.2 The purification system typically associated with the recommended combustion and detection equipment is designed to
minimize other expected sources of interferences, such as sulfur, halogens, carbon monoxide, carbon dioxide, and water.
6.2.1 The nitrogen and hydrogen peaks are close together and must be well-separated to prevent falsely high result from the
nitrogen. The molecular sieve must be sufficiently long to separate the peaks and must be changed when the column becomes
loaded with contaminants that prevent proper peak separation.
6.3 The temperature of >1700–1800°C must be reached. If not, the decomposition of the released water to hydrogen and carbon
monoxide may not be complete. The temperature will depend upon the instrument and type of graphite crucible used. Single wall
crucibles will require a lower temperature (power) than double wall crucibles.
6.4 Incomplete fusion may result in partial or a late release of hydrogen resulting in low results.
6.5 At temperatures of more than 2200°C uranium metal may be formed, and carbon dioxide released because of reduction of
UO by the graphite crucible.
6.5.1 Carbon dioxide will interfere with the thermal conductivity measurement. This interference can be minimized by use of
chemical absorption, or a molecular sieve column, or both.
6.5.2 Excess temperature, from too much power, crucible hot spots, or from misaligned electrodes may cause analysis errors.
Uranium samples should be evenly fused, fall out freely of the crucibles and contain very little uranium metal.
7. Apparatus
7.1 Hydrogen Analyzer, consisting of an electrode furnace capable of operation at least up to 2200 to 2500°C, a thermal
conductivity detector for measuring, and auxiliary purification systems.
7.2 Balance, with precision of 6 1 mg.
8. Reagents and Materials
8.1 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
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 determination.
8.2 Carrier Gas—Nitrogen ≥99.998 % or Argon ≥99.995 %.
8.3 Carrier Gas Purifiers:
8.3.1 Copper Oxide, or rare earth copper oxide (converts H to H O), or
8.3.2 Copper Turnings, or granules.
8.4 Molecular Sieve-Sodium Hydroxide, on a fiber support (sodium hydroxide reacts with CO to yield water; the molecular
sieve separates N and H ).
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8.5 Schutze Reagent, iodine pentoxide over silica gel (converts CO to CO ).
8.6 Magnesium Perchlorate—removes water.
8.7 Silicone Vacuum Grease.
8.8 Tin Flux, if Zr or Ti hydride standards are to be used.
Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed by
the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and National
Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
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