ASTM C1344-97(2008)e1
(Test Method)Standard Test Method for Isotopic Analysis of Uranium Hexafluoride by Single-Standard Gas Source Mass Spectrometer Method
Standard Test Method for Isotopic Analysis of Uranium Hexafluoride by Single-Standard Gas Source Mass Spectrometer Method
SIGNIFICANCE AND USE
Uranium hexafluoride is a basic material used to prepare nuclear reactor fuel. To be suitable for this purpose, the material must meet the criteria for isotopic composition. This test method is designed to determine whether the material meets the requirements described in Specifications C 787 and C 996.
ASTM Committee C-26 Safeguards Statement:
The material (uranium hexafluoride) to which this test method applies is subject to the nuclear safeguards regulations governing its possession and use. The analytical procedure in this test method has been designated as technically acceptable for generating safeguards accountability data.
When used in conjunction with appropriate certified reference materials (CRMs), this procedure can demonstrate traceability to the national measurement base. However, adherence to this procedure does not automatically guarantee regulatory acceptance of the regulatory safeguards measurements. It remains the sole responsibility of the user of this test method to ensure that its application to safeguards has the approval of the proper regulatory authorities.
SCOPE
1.1 This test method covers the isotopic analysis of uranium hexafluoride (UF6) and may be used for the entire range of 235U isotopic compositions for which standards are available.
1.2 This test method is applicable to the determination of the isotopic relationship between two UF6 samples. If the abundance of a specific isotope of one sample (the standard) is known, its abundance in the other can be determined. This test method is flexible in that the number of times a given material is admitted to the ion source may be adjusted to the minimum required for a specified precision level.
1.3 The sensitivity with which differences between two materials can be detected depends on the measuring system used, but ratio-measuring devices can generally read ratio-of-mol ratio differences as small as 0.0001.
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.5 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. Specific hazards statements are given in Section 7.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
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Designation:C1344 −97(Reapproved 2008)
Standard Test Method for
Isotopic Analysis of Uranium Hexafluoride by Single-
Standard Gas Source Mass Spectrometer Method
This standard is issued under the fixed designation C1344; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
´ NOTE—Section reference in Section 9.2 was corrected editorially in March 2009.
1. Scope C996Specification for Uranium Hexafluoride Enriched to
Less Than 5 % U
1.1 Thistestmethodcoverstheisotopicanalysisofuranium
hexafluoride (UF ) and may be used for the entire range of 2.2 Other Document:
U isotopic compositions for which standards are available. USEC-651, Uranium Hexafluoride: A Manual of Good
Handling Practices
1.2 This test method is applicable to the determination of
the isotopic relationship between two UF samples. If the
3. Terminology
abundance of a specific isotope of one sample (the standard) is
known, its abundance in the other can be determined.This test
3.1 Definitions of Terms Specific to This Standard:
method is flexible in that the number of times a given material
3.1.1 drop through, n—a measurement of the amount of the
238 + 235 +
is admitted to the ion source may be adjusted to the minimum
UF ion beam that can be passed through the UF
5 5
235 +
required for a specified precision level.
collector slit and measured on the UF collector, stated as
238 +
a percentage of the total UF signal.
1.3 The sensitivity with which differences between two 5
materials can be detected depends on the measuring system
3.1.2 memory corrections, n—corrections applied to the
used, but ratio-measuring devices can generally read ratio-of-
sample analysis results for memory effects.
mol ratio differences as small as 0.0001.
3.1.3 memory effect, n—the inability of the mass spectrom-
1.4 The values stated in SI units are to be regarded as
eter to omit completely the isotopic composition of the sample
standard. No other units of measurement are included in this
analyzed previously from attributing to the results of further
standard.
samples analyzed.
1.5 This standard does not purport to address all of the
3.1.4 normal isotopic abundance material, n—UF havinga
safety concerns, if any, associated with its use. It is the
value of 0.711 weight percent (wt%) U.
responsibility of the user of this standard to establish appro-
235 238
3.1.5 ratio-of-mol-ratios, n—the mol ratio ( U/ U) of
priate safety and health practices and determine the applica-
the sample divided by the mol ratio of the standard, or the
bility of regulatory limitations prior to use. Specific hazards
inverseconditionofthemolratioofthestandarddividedbythe
statements are given in Section 7.
mol ratio of the sample.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
C787Specification for Uranium Hexafluoride for Enrich-
4.1 Test Method—The unknown sample and a standard with
ment an isotopic composition close to that of the sample are
+
introduced in sequence into the Neir mass spectrometer. UF
ions of the isotopes are focused through a mass-resolving
collector slit and onto a faraday cup collector. Measurements
ThistestmethodisunderthejurisdictionofASTMCommitteeC26onNuclear
235 + +
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
are made of UF to the total of the other UF isotopes.
5 5
Test.
Withtheknowncompositionofthestandard,calculationofthe
Current edition approved Dec. 1, 2008. Published January 2009. Originally
U composition of the sample can be determined.
approved in 1997. Last previous edition approved in 2003 as C1344–97 (2003).
DOI: 10.1520/C1344-97R08E01.
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 Available from U.S. Enrichment Corporation, 6903 Rockledge Dr., Bethesda,
the ASTM website. MD 20817, http://www.usec.com.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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C1344−97 (2008)
5. Significance and Use 6.1.1.7 The memory effect of the spectrometer must be
consistent with the precision required since a high memory
5.1 Uraniumhexafluorideisabasicmaterialusedtoprepare
level is usually more variable than a low one. Memory values
nuclear reactor fuel. To be suitable for this purpose, the
of 2 to 3% are typical, but up to 10% memory can be
material must meet the criteria for isotopic composition. This
tolerated. The memory characteristics of a spectrometer must
test method is designed to determine whether the material
be established from periodic measurement of the effect. Cur-
meets the requirements described in Specifications C787 and
rent memory values usually will apply until the ion source is
C996.
replaced, repairs are made on the sample inlet system, or the
5.2 ASTM Committee C-26 Safeguards Statement:
instrument is refocused so the flow rate of UF is altered
5.2.1 The material (uranium hexafluoride) to which this test
significantly.
method applies is subject to the nuclear safeguards regulations
6.1.1.8 Thecomputercontrolofthemassspectrometermust
governing its possession and use. The analytical procedure in
allow the operator to monitor parameters of the spectrometer
this test method has been designated as technically acceptable
and check other operating conditions. The development of an
for generating safeguards accountability data.
interactive program allows input of sample information, per-
5.2.2 When used in conjunction with appropriate certified
forms necessary calculations, makes memory corrections, and
reference materials (CRMs), this procedure can demonstrate
records data. Flexibility of the interactive program allows
traceabilitytothenationalmeasurementbase.However,adher-
pausing of the instrument for adjustment or restart capability,
ence to this procedure does not automatically guarantee regu-
or both. Suggested methods of analysis checks include the
latory acceptance of the regulatory safeguards measurements.
standard deviation (SD) on individual data points, linearity of
Itremainsthesoleresponsibilityoftheuserofthistestmethod
thedataset,andacheckofsourcepressuredifferencesbetween
to ensure that its application to safeguards has the approval of
thestandardandsamplethatcanbemonitoredbythecomputer
the proper regulatory authorities.
program. Manifold valve actuation, conditioning time, and
pump-out time are features of the computer control program.
6. Apparatus
6.1 Neir Mass Spectrometer,withthefollowingfeaturesand
7. Hazards
capabilities:
7.1 Since UF is radioactive, toxic, and highly reactive,
6.1.1 Asingle-focusing spectrometer, with a 127-mm mini-
especially with reducing substances and moisture (see USEC-
mum deflection radius, is satisfactory when equipped and
651), appropriate facilities and practices for analysis must be
focused as follows:
provided.
6.1.1.1 The sample inlet system must have two sample
holders, to which UF containers can be attached, and the
8. Procedure
necessary valves to evacuate the sample lines through which
8.1 Calibration of Isotopic Standards:
the sample and standard are introduced. The sample inlet
8.1.1 One working standard is required for the analysis of a
systemshouldbenickelorMonelforusewithcorrosivegases,
sample at any specific concentration of any isotope. Two
and should have minimum volume.
working standards are required to determine memory correc-
6.1.1.2 A single adjustable leak, operated by an automatic
tions. Memory can be measured more precisely with a large
leak control mechanism for admitting the sample into the
difference between two working standards, but the adverse
spectrometer ion source, is preferred.
effect of introducing wide concentration ranges into the mass
6.1.1.3 The pumping system of the spectrometer analyzer
−8 spectrometer must be considered. Ideally, the values obtained
tube must maintain a pressure below 5×10 torr with sample
from the high- and low-memory standards should symmetri-
flowing into the ion source.
cally bracket those of the sample to be corrected. Working
6.1.1.4 Focus the instrument for resolution consistent with
−10 standards approximately 5% apart (having a ratio of ratios of
precision requirements. A high-current ion beam of 5×10
−9 1.05) are suitable for most applications.
to 1×10 amps is necessary, with a signal-to-noise ratio
8.1.2 A reasonable limit for the relative e between the
greater than 3000 in the low-current amplifier system.
unknown sample and the working standard to which it is
6.1.1.5 Adual collector must be used, so that ions from one
compared is 2.5%. A series of working standards prepared at
isotope are passed through a resolving slit and focused on a
5% intervals and used for sample comparisons thus enables
low-current collector, and ions from all other isotopes are
this 2.5% limit.
focused on a high-current collector. The preferred method of
8.1.3 Prepare a working standard, and standardize against
maintaining the low-current ion beam within the collector slit
an oxide blend of CRM standards that is within 0.02% of the
isbyanautomaticbeampositionercircuit.Aresolvingslitwith
value of the working standard.
adjustable width features enhances the measurement of all
isotopes but is not mandatory for isotopic measurements. 8.2 Sample Preparation:
6.1.1.6 The amplified high- and low-current signals are fed 8.2.1 Attach tubes containing the appropriate working
into a multimeter or other device capable of ratioing high- and standard,S,andthesample,X,tothespectrometerinletsystem,
low-current signals. If a multimeter is used, the multimeter and prepare the materials for introduction into the ion source,
must have a minimum of 5.5 digits of resolution, a means of as follows:
ratioing the high- and low-current signals, and interactive 8.2.1.1 If adequate sample and working standard are
communication capability with the controller. available, open all valves between the sample and working
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C1344−97 (2008)
standard containersandthepumpingsystem,exceptthevalves are recorded, precedes the determination to make the sample-
on the sample and working standard containers. If the amount standard interaction more unifo
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