ASTM C1854-17

Standard Test Method for Determination of Hydrogen (total from all sources) in Mixed Oxide ((U, Pu)O<inf>2</inf>) Sintered Pellets by the Inert Gas Fusion Technique Followed by Thermal Conductivity Measurement

SIGNIFICANCE AND USE
5.1 MOX is used as a nuclear-reactor fuel. This test method is designed to determine whether the hydrogen content of the pellets meet the requirements of fuel specification. Examples of these requirements are given in Specification C833. Other requirements may apply based on agreements between the supplier and the customer.  
5.2 This method is suitable for all sintered MOX pellets containing up to 15 weight % PuO2 when the UO2 and PuO2 meet the requirements of Specifications C753 and C757. The method uncertainty is related to the concentration of the hydrogen in the sample. At lower concentrations, the relative uncertainty increases. At hydrogen contents close to the typical hydrogen content specification limit (1.3 μg hydrogen/g U + Pu metal); the combined relative uncertainty at the 95 % confidence level (k = 2) is approximately 30 %.
SCOPE
1.1 This test method covers the determination of hydrogen in nuclear-grade mixed oxides of uranium and plutonium ((U, Pu)O2) sintered fuel pellets. This test method is an alternative to Test Method C698 for the determination of moisture in nuclear-grade sintered mixed oxide (MOX) fuel pellets. Test Method C698 describes the detection of moisture in mixed oxides using a coulometric, electrolytic moisture analyzer. Although the main source of H2 in the fuel pellets is moisture, there could be other sources. The MOX pellet Specification C833 specifies a limit for hydrogen from all sources, not only moisture. The inert gas fusion followed by thermal conductivity detector specified in this test method allows for detection of hydrogen from all sources. Therefore, this test method can be used to determine the limit specified in C833.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this 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 and health 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.

General Information

• Status: Published
• Publication Date: 31-May-2017
• ICS: 27.120.30 - Fissile materials and nuclear fuel technology
• Technical Committee: C26 - Nuclear Fuel Cycle
• Drafting Committee: C26.05 - Methods of Test

Relations

• Refers: ASTM C859-24 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Jan-2024
• Refers: ASTM C698-16 - Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Mixed Oxides ((U, Pu)O<inf>2</inf>)
• Effective Date: 01-Jun-2016
• Refers: ASTM C757-16 - Standard Specification for Nuclear-Grade Plutonium Dioxide Powder for Light Water Reactors
• Effective Date: 01-Apr-2016
• Refers: ASTM C753-16 - Standard Specification for Nuclear-Grade, Sinterable Uranium Dioxide Powder
• Effective Date: 01-Feb-2016
• Refers: ASTM C859-14a - Standard Terminology Relating to Nuclear Materials
• Effective Date: 15-Jun-2014
• Refers: ASTM C859-14 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 15-Jan-2014
• Refers: ASTM C859-13a - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Jun-2013
• Refers: ASTM C859-13 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-May-2013
• Refers: ASTM C833-13 - Standard Specification for Sintered (Uranium-Plutonium) Dioxide Pellets
• Effective Date: 01-Jan-2013
• Refers: ASTM C1068-03(2011) - Standard Guide for Qualification of Measurement Methods by a Laboratory Within the Nuclear Industry
• Effective Date: 01-Jun-2011
• Refers: ASTM C859-10b - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Nov-2010
• Refers: ASTM C859-10a - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Aug-2010
• Refers: ASTM C698-10 - Standard Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Mixed Oxides ((U, Pu)O₂)
• Effective Date: 01-Jun-2010
• Refers: ASTM C859-10 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 01-Feb-2010
• Refers: ASTM C859-09 - Standard Terminology Relating to Nuclear Materials
• Effective Date: 15-Feb-2009

Overview

ASTM C1854-17 is the internationally recognized standard test method for the determination of total hydrogen in mixed oxide ((U, Pu)O₂) sintered pellets, commonly known as MOX fuel. Developed by ASTM International, this method utilizes the inert gas fusion technique coupled with a thermal conductivity detector (TCD) to measure hydrogen content from all sources within MOX fuel pellets. Accurate hydrogen measurement is critical for ensuring compliance with fuel specifications and reliable performance in nuclear reactor applications.

MOX fuel, a blend of uranium oxide (UO₂) and plutonium oxide (PuO₂), is increasingly utilized in nuclear reactors. The presence of hydrogen-primarily introduced through moisture or chemical reactions-can affect fuel integrity and reactor safety. This standard provides clear procedural guidance for laboratories to identify and quantify hydrogen levels, complementing or providing an alternative to ASTM C698, which is focused on the detection of moisture.

Key Topics

• Scope and Suitability

  • Applicable to all sintered MOX pellets containing up to 15 wt% PuO₂, provided starting materials meet ASTM C753 (uranium dioxide) and C757 (plutonium dioxide) specifications.
  • Measures total hydrogen from all sources, not just moisture.

• Test Method Summary

  • Fusion of the MOX sample in a high-temperature electrode impulse furnace under a flow of nitrogen or argon gas.
  • Release of hydrogen, which is then filtered to remove interferences.
  • Quantification of hydrogen concentration using a thermal conductivity detector.

• Quality and Calibration

  • Use of blank analyses and certified reference materials for calibration.
  • Verification procedures before and after sample analysis to ensure data validity.
  • Guidance for laboratories to establish internal precision and bias limits due to the absence of matrix-matched reference materials.

• Safety and Regulatory Compliance

  • Procedures must be conducted in a controlled environment (such as glove boxes) to protect operators from radiological hazards.
  • Strict handling requirements for high-purity gases and hazardous chemicals.

Applications

• Nuclear Fuel Quality Assurance

  • Ensures hydrogen content in MOX fuel pellets meets the stringent limits set in fuel specification ASTM C833 or customer-specific agreements.
  • Provides essential data for fuel certification prior to reactor loading, supporting safe and efficient power plant operation.

• Alternative to Moisture Analysis

  • Offers an advanced approach for total hydrogen analysis compared to moisture-determination methods, including ASTM C698 (coulometric analysis).
  • Enables detection of hydrogen introduced through sources beyond moisture, improving overall quality control.

• Fuel Development and Research

  • Supports nuclear research laboratories and fuel manufacturers working with high-density uranium-plutonium oxide materials.
  • Facilitates process optimization by quantifying hydrogen uptake during various stages of pellet fabrication and handling.

Related Standards

• ASTM C698: Test Methods for Chemical, Mass Spectrometric, and Spectrochemical Analysis of Nuclear-Grade Mixed Oxides ((U,Pu)O₂)
• ASTM C753: Specification for Nuclear-Grade, Sinterable Uranium Dioxide Powder
• ASTM C757: Specification for Nuclear-Grade Plutonium Dioxide Powder for Light Water Reactors
• ASTM C833: Specification for Sintered (Uranium-Plutonium) Dioxide Pellets for Light Water Reactors
• ASTM C859: Terminology Relating to Nuclear Materials
• ASTM C1068: Guide for Qualification of Measurement Methods by a Laboratory Within the Nuclear Industry

Employing ASTM C1854-17 ensures precise and reliable hydrogen measurement in MOX fuel, underpinning the safety, quality, and regulatory compliance of nuclear fuel cycles worldwide.

Keywords: hydrogen content, MOX fuel, mixed oxide pellets, nuclear fuel analysis, ASTM C1854-17, inert gas fusion, thermal conductivity detector, uranium oxide, plutonium oxide, nuclear materials testing, hydrogen measurement, nuclear fuel quality assurance.

Standards Content (Sample)

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.
Designation: C1854 − 17
Standard Test Method for
Determination of Hydrogen (total from all sources) in Mixed
Oxide ((U, Pu)O ) Sintered Pellets by the Inert Gas Fusion
Technique Followed by Thermal Conductivity Measurement
This standard is issued under the fixed designation C1854; 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.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the determination of hydrogen
C698 Test Methods for Chemical, Mass Spectrometric, and
in nuclear-grade mixed oxides of uranium and plutonium ((U,
Spectrochemical Analysis of Nuclear-Grade Mixed Ox-
Pu)O ) sintered fuel pellets. This test method is an alternative
ides ((U, Pu)O )
to Test Method C698 for the determination of moisture in
C753 Specification for Nuclear-Grade, Sinterable Uranium
nuclear-grade sintered mixed oxide (MOX) fuel pellets. Test
Dioxide Powder
Method C698 describes the detection of moisture in mixed
C757 Specification for Nuclear-Grade Plutonium Dioxide
oxides using a coulometric, electrolytic moisture analyzer.
Powder for Light Water Reactors
Although the main source of H in the fuel pellets is moisture,
C833 Specification for Sintered (Uranium-Plutonium) Diox-
there could be other sources. The MOX pellet Specification
ide Pellets for Light Water Reactors
C833 specifies a limit for hydrogen from all sources, not only
C859 Terminology Relating to Nuclear Materials
moisture. The inert gas fusion followed by thermal conductiv-
C1068 Guide for Qualification of Measurement Methods by
ity detector specified in this test method allows for detection of
a Laboratory Within the Nuclear Industry
hydrogen from all sources. Therefore, this test method can be
3. Terminology
used to determine the limit specified in C833.
3.1 For definitions of terms used in this test method but not
1.2 The values stated in SI units are to be regarded as
defined herein, refer to Terminology C859.
standard. No other units of measurement are included in this
3.2 Definitions of Terms Specific to This Standard:
standard.
3.2.1 MOX—nuclearfuelcomposedofamixtureofuranium
1.3 This standard does not purport to address all of the
and plutonium oxides ((U, Pu)O ).
safety concerns, if any, associated with its use. It is the
3.2.2 reference material—material traceable to a reference
responsibility of the user of this standard to establish appro-
material from a national standards body such as the U.S.
priate safety and health practices and determine the applica-
National Institute for Standards and Technology (NIST) or
bility of regulatory limitations prior to use.
equivalent.
1.4 This international standard was developed in accor-
3.2.3 sintering—to increase the bonding in a mass of pow-
dance with internationally recognized principles on standard-
der or a compact by heating below the melting point of the
ization established in the Decision on Principles for the
main constituent.
Development of International Standards, Guides and Recom-
3.3 Acronyms:
mendations issued by the World Trade Organization Technical
3.3.1 LIMS—Laboratory Information Management System
Barriers to Trade (TBT) Committee.
3.3.2 TCD—Thermal Conductivity Detector
4. Summary of Test Method
4.1 Themethodforthedeterminationoftotalhydrogen(H )
fromallsourcespresentedinthistestmethodconsistsoffusion
This test method is under the jurisdiction ofASTM Committee C26 on Nuclear
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Test. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved June 1, 2017. Published June 2017. DOI: 10.1520/ Standards volume information, refer to the standard’s Document Summary page on
C1854-17. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1854 − 17
of the sample in an electrode impulse furnace in a stream of uncertainty increases.At hydrogen contents close to the typical
nitrogen (N ) or argon (Ar) gas at a temperature sufficient to hydrogencontentspecificationlimit(1.3µghydrogen/gU+Pu
release all hydrogen in the sample. The stream of gas carries metal); the combined relative uncertainty at the 95 % confi-
the released hydrogen through a series of filters to remove dence level (k = 2) is approximately 30 %.
interfering impurities and the hydrogen is measured by TCD.
6. Interferences
4.2 The specimen, a single MOX pellet weighing approxi-
6.1 After the sample fusion, the carrier gas containing the
mately 6 g, contained in a small single-use graphite crucible, is
carbon dioxide and other potentially interfering impurities
fused under a flowing nitrogen (N ) or argon (Ar) atmosphere
(sulfur, water, and small particulate matter) pass through a
and at a temperature greater than 1770°C. Hydrogen present in
series of filters and purifying reagents that remove these
the sample is released as molecular hydrogen into the flowing
impurities from the carrier gas stream leaving only H in the
carrier gas. Other gases are also liberated into the carrier gas,
stream at the detector. If the MOX pellets are made from UO
such as carbon monoxide, and need to be removed before they
and PuO that meet the requirements of Specifications C753
reach the thermal conductivity detector as they interfere with
and C757, all interferences are eliminated by the purification
the measurement. These sample impurities are swept by the
system.
carrier gas through a series of filters to remove dust and water
and then the gases flow through a quartz tube filled with 6.2 The crucibles, if they contain hydrogen, will yield
Schuetze reagent (see 8.3) and activated charcoal. The Schue- erroneously high results for the sample. The analytical method
tze reagent acts as an oxidizing agent to convert carbon requiresrunningblankstocorrectforthispotentialinterference
monoxide (CO) to carbon dioxide (CO ). The gas then flows in the calculation of the results (see 12.2).
through a molecular sieve to separate nitrogen from hydrogen
6.3 The nitrogen (N ) or argon (Ar) carrier gas could
by size, delaying the larger nitrogen molecule and allowing the
contain water and CO and is filtered prior to injection in the
hydrogen to reach the TCD before the nitrogen.
sample combustion chamber to remove these potentially inter-
4.3 The carrier gas, now free of interfering species then fering components.
flows through the measurement branch of the thermal conduc-
6.4 Weighing uncertainty of the samples is critical to the
tivity cell which is where the quantitative detection of the
method. If the balance meets the specification in 7.1,is
hydrogen released from the sample takes place. The hydrogen
calibrated in accordance with manufacturer’s guidance, and is
concentration in the carrier gas is measured by the TCD which
checked by procedure, the potential for the balance to be a
detects small changes in the thermal conductivity of the carrier
source of error is insignificant.
gas containing the liberated hydrogen gas compared to the
6.5 When using nitrogen gas with graphite crucible a
thermal conductivity of the carrier gas alone.
secondary reaction occurs at high temperatures (>3000°C)
4.4 The detector signal plotted versus time is a function of
where HCN is created, causing a bias that increases with
the concentration of the H in a carrier gas.The area below the
temperature.Argonascarriergasisusedathighertemperatures
curve (integral) corresponds to the total amount of hydrogen in
to avoid this reaction.
the sample. The peak is integrated by the software and the
concentration is calculated taking into account the calibration 7. Apparatus
factor, the blank analysis and the sample weight. The calibra-
7.1 Analytical Balance, with precision 60.1 mg.
tion of the analyzer is made by means of a reference material.
7.2 Graphite Crucibles—Use the crucibles of size recom-
Blank values are obtained from analyzing the empty crucibles.
mended by the manufacturer of the instrument. Crucibles shall
The blank results are stored. The final sample result is
be composed of high purity graphite.
corrected by the blank value and the results are expressed in µg
hydrogen/g MOX.
7.3 Hydrogen analyzer, consisting of an electrode impulse
furnace suitable for operation at 1770 to 2200°C, a TCD for
5. Significance and Use measuring H , a nitrogen or argon carrier gas injection system,
auxiliary gas purification systems, and a chiller to cool the
5.1 MOX is used as a nuclear-reactor fuel. This test method
electrodes. The analyzer typically has an integrated data
is designed to determine whether the hydrogen content of the
collectionandanalysissoftwaresystemthatallowsforefficient
pellets meet the requirements of fuel specification. Examples
collection and analysis of data.
of these requirements are given in Specification C833. Other
requirements may apply based on agreements between the 7.4 Tongs and Forceps, for handling crucibles.
supplier and the customer.
7.5 Stainless Steel Scoops and Spatulas, for handling pellets
and reference materials.
5.2 This method is suitable for all sintered MOX pellets
containing up to 15 weight % PuO when the UO and PuO
2 2 2
8. Reagents and Materials
meet the requirements of Specifications C753 and C757. The
method uncertainty is related to the concentration of the 8.1 Purity of Reagents—Reagent grade chemicals shall be
hydrogen in the sample. At lower concentrations, the relative used in all tests. Unless otherwise indicated, it is intended that
C1854 − 17
all reagents shall conform to the specifications of the Commit- gloves with hot surfaces. Typically these hot surfaces are
tee onAnalytical Reagents of theAmerican Chemical Society, guarded and inaccessible during the heating process and
where such specifications are available. Other grades may be therefore do not pose a risk to the operator.
used, provided it is first ascertained that the reagent is of
10.3 Exercise appropriate caution when working with com-
sufficiently high purity to permit its use without compromising
pressed gases.
the accuracy of the determination.
10.4 This procedure uses hazardous chemicals. Use appro-
8.2 Molecular Sieve (Zeolites of Silicon and Aluminum)—
priate precautions for handling corrosives, oxidizers, and
Captures CO from the carrier gas.
gases.
8.3 Schuetze Reagent (I O and SiO )—Oxidizes CO to
2 5 2
CO .
11. Preparation and Verification of Apparatus Prior to
Sample Analysis
NOTE 1—Schuetze reagent is commercially available and is typically
not prepared in-house. If the user of this test method wishes to prepare the
11.1 Turn on the analyzer and set the operating controls of
Schuetze reagent in house, a procedure is given in Appendix X1.
the instrument system according to the operating instructions
8.4 Activated Coal or Sodium Hydroxide (NaOH)—absorbs
for the specific equipment used.
CO before and after the CO and CO conversion.
2 2
11.2 Verification of the Gases—Carrier gas flow and system
8.5 Quartz Wool, for dust traps and to plug the reagent
pressurearetwoessentialparametersthatmustbecontrolledto
tubes.
ensure satisfactory performance of the instrument. Most ana-
lyzers are equipped with pressure regulation and electronic
8.6 Platinum Wire (if needed), for minimum furnace tem-
flow control.
perature verification, 1.0 mm diameter, 99.99 % trace metal
11.2.1 Ensure that the regulator valve is set to the correct
basis.
value for the nitrogen line per manufacturers’ recommenda-
8.7 Rhodium Wire (if needed), for maximum furnace tem-
tions.
perature verification, 1.0 mm diameter, 99.9 % trace metal
11.3 Verification of the Reagents—Change instrument col-
basis.
umn packing and reagents as recommended by manufacturer.
8.8 Nitrogen or Argon Carrier Gas, ≥99.999 % purity, inlet
11.3.1 The molecular sieve is usually changed or regener-
pressure: 200 kPa or as specified by the equipment manufac-
ated after eight hours of continuous analysis, but exact change
turer.
out times vary based on analyzer model and use.
8.9 Magnesium Perchlorate (Mg(ClO ) ), removes H O.
4 2 2 11.3.2 The Schuetze reagent and activated carbon should be
replaced approximately 40 % of the color of the Schuetze
9. Reference Materials
reagent changes from lemon yellow to pink or brown.
9.1 The calibration of the analyzer is made by measuring
11.3.3 The quartz wool should be replaced when visible
materials with hydrogen content in the range of concentration
particulate matter is observed.
expectedintheMOXpellet(~1.3ppm)traceabletoareference
11.3.4 At regular intervals and at each replacement of the
material from a national standards body such as the U.S.
reagents, the O-rings at the reagent tube holders must be
National Institute for Standards and Technology (NIST) or
inspected for wear and tear and replaced when appropriate.
equivalent. Suitable materials traceable to a reference material
11.4 Verification of the Furnace Temperature—In some
insteelmatrices(steelpins,steelrings,steelgranules,andsteel
cases, the furnace is designed with an automatic temperature
powder) are available and have been found satisfactory. Matrix
sensor or pyrometer. In these cases, temperature verification
matched reference materials for MOX pellets are not available.
can easily be performed per the manufacturer’s instructions. In
other cases where automatic temperature sensors are not
10. Precautions
available, it is necessary to use pure metal standards with
10.1 Because of the toxicity of plutonium, all operations
known melting points to verify furnace temperature above
should be performed within an approved glove box fitted with
1770°C and well below 2200°C. Metals such as platinum and
appropriate filters to contain any small particle of plutonium.A
rhodium can be used. For example, if platinum melts, and
detailed discussion of the necessary precautions is beyond the
rhodium does not melt, the verification is successful. If the
scope of this test method. Personnel involved in these analyses
sample is heated above 2200°C, significant amounts of carbon
should be familiar with safe handling practices for radiologi-
dioxide can be released as a result of the reduction of UO by
cally controlled materials.
the graphite crucible which could interfere with the detection
10.2 The furnace, sample tube and sample crucibles are
of the hydrogen by the TCD. Therefore avoiding temperatures
heated to >1770°C. Care should be taken to avoid contacting
near 2200°C is important.
11.5 Cleaning the Analyzer—It is typically recommended
that furnace cleaning should be performed after approximately
Reagent Chemicals, American Chemical Society Specifications, American
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
20sampleshavebeenanalyzed.Cleanthefurnaceaccordingto
listed by the American Chemical Society, see Analar Standards for Laboratory
the operating instructions for the specific equipment used.
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmac
...