ASTM C1344-97
(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
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. This test method is adaptable to the determination of any uranium isotope.
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 specific 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 0.0001.
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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
Relations
Standards Content (Sample)
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: C 1344 – 97
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 C 1344; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This test method covers the isotopic analysis of uranium 3.1 Definitions of Terms Specific to This Standard:
hexafluoride (UF ) and may be used for the entire range of 3.1.1 drop through, n—a measurement of the amount of the
235 238 + 235 +
U isotopic compositions for which standards are available. UF ion beam that can be passed through the UF
5 5
235 +
1.2 This test method is applicable to the determination of collector slit and measured on the UF collector, stated as
238 +
the isotopic relationship between two UF samples. If the a percentage of the total UF signal.
6 5
abundance of a specific isotope of one sample (the standard) is 3.1.2 memory corrections, n—corrections applied to the
known, its abundance in the other can be determined. This test sample analysis results for memory effects.
method is flexible in that the number of times a given material 3.1.3 memory effect, n—the inability of the mass spectrom-
is admitted to the ion source may be adjusted to the minimum eter to omit completely the isotopic composition of the sample
required for a specified precision level. analyzed previously from attributing to the results of further
1.3 The sensitivity with which differences between two samples analyzed.
materials can be detected depends on the measuring system 3.1.4 normal isotopic abundance material, n—UF having a
used, but ratio-measuring devices can generally read ratio-of- value of 0.711 weight percent (wt %) U.
235 238
mol ratio differences as small as 0.0001. 3.1.5 ratio-of-mol-ratios, n—the mol ratio ( U/ U) of
1.4 The values stated in SI units are to be regarded as the the sample divided by the mol ratio of the standard, or the
standard. The values given in parentheses are for information inverse condition of the mol ratio of the standard divided by the
only. mol ratio of the sample.
1.5 This standard does not purport to address all of the
4. Summary of Test Method
safety concerns, if any, associated with its use. It is the
4.1 Test Method—The unknown sample and a standard with
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- an isotopic composition close to that of the sample are
+
introduced in sequence into the Neir mass spectrometer. UF
bility of regulatory limitations prior to use. Specific hazards
statements are given in Section 7. ions of the isotopes are focused through a mass-resolving
collector slit and onto a faraday cup collector. Measurements
235 + +
2. Referenced Documents
are made of UF to the total of the other UF isotopes.
5 5
2.1 ASTM Standards: With the known composition of the standard, calculation of the
C 787 Specification for Uranium Hexafluoride for Enrich- U composition of the sample can be determined.
ment
5. Significance and Use
C 996 Specification for Uranium Hexafluoride Enriched to
235 2
5.1 Uranium hexafluoride is a basic material used to prepare
Less Than 5 % U
2.2 Other Document: nuclear reactor fuel. To be suitable for this purpose, the
material must meet the criteria for isotopic composition. This
USEC-651, Uranium Hexafluoride: A Manual of Good
Handling Practices test method is designed to determine whether the material
meets the requirements described in Specifications C 787 and
C 996.
5.2 ASTM Committee C-26 Safeguards Statement:
5.2.1 The material (uranium hexafluoride) to which this test
This test method is under the jurisdiction of ASTM Committee C-26 on Nuclear
method applies is subject to the nuclear safeguards regulations
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
Test.
governing its possession and use. The analytical procedure in
Current edition approved Aug. 10, 1997. Published May 1997.
this test method has been designated as technically acceptable
Annual Book of ASTM Standards, Vol 12.01.
3 for generating safeguards accountability data.
Available from U.S. Enrichment Corporation, 6903 Rockledge Dr., Bethesda,
5.2.2 When used in conjunction with appropriate certified
MD 20817.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
C 1344
reference materials (CRMs), this procedure can demonstrate records data. Flexibility of the interactive program allows
traceability to the national measurement base. 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
It remains the sole responsibility of the user of this test method the data set, and a check of source pressure differences between
to ensure that its application to safeguards has the approval of the standard and sample that can be monitored by the computer
the proper regulatory authorities. program. Manifold valve actuation, conditioning time, and
pump-out time are features of the computer control program.
6. Apparatus
7. Hazards
6.1 Neir Mass Spectrometer, with the following features and
capabilities: 7.1 Since UF is radioactive, toxic, and highly reactive,
6.1.1 A single-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
8. Procedure
holders, to which UF containers can be attached, and the
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
system should be nickel or Monel for use with corrosive gases, 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 spectrometer must be considered. Ideally, the values obtained
−8
tube must maintain a pressure below 5 3 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 standards approximately 5 % apart (having a ratio of ratios of
−10
precision requirements. A high-current ion beam of 5 3 10 1.05) are suitable for most applications.
−9
to 1 3 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 A dual collector must be used, so that ions from one compared is 2.5 %. A series of working standards prepared at
5 % intervals and used for sample comparisons thus enables
isotope are passed through a resolving slit and focused on a
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
is by an automatic beam positioner circuit. A resolving slit with value of the working standard.
adjustable width features enhances the measurement of all 8.2 Sample Preparation:
isotopes but is not mandatory for isotopic measurements. 8.2.1 Attach tubes containing the appropriate working stan-
6.1.1.6 The amplified high- and low-current signals are fed dard, S, and the sample, X, to the spectrometer inlet system,
into a multimeter or other device capable of ratioing high- and and prepare the materials for introduction into the ion source,
low-current signals. If a multimeter is used, the multimeter as follows:
must have a minimum of 5.5 digits of resolution, a means of 8.2.1.1 If adequate sample and working standard are avail-
ratioing the high- and low-current signals, and interactive able, open all valves between the sample and working standard
communication capability with the controller. containers and the pumping system, except the valves on the
6.1.1.7 The memory effect of the spectrometer must be sample and working standard containers. If the amount of
consistent with the precision required since a high memory sample or working standard is limited, proceed to 8.2.2.
level is usually more variable than a low one. Memory values 8.2.1.2 Open the valve on the sample container, and then
of 2 to 3 % are typical, but up to 10 % memory can be close it quickly to vent gases to the pumping system.
tolerated. The memory characteristics of a spectrometer must 8.2.1.3 After the pumping system has evacuated the vented
be established from periodic measurement of the effect. Cur- gases, repeat the steps given in 8.2.1.2 a second time.
rent memory values usually will apply until the ion source is 8.2.1.4 Repeat the steps given in 8.2.1.2 and 8.2.1.3 for the
replaced, repairs are made on the sample inlet system, or the working standard.
instrument is refocused so the flow rate of UF is altered 8.2.2 Use the following alternative method of sample puri-
significantly. fication if the amount of the sample or working standard is
6.1.1.8 The computer control of the mass spectrometer must limited:
allow the operator to monitor parameters of the spectrometer 8.2.2.1 Operate the appropriate valves to remove air en-
and check other operating conditions. The development of an trapped in the connectors and to determine that there ar
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