ASTM C1429-99
(Test Method)Standard Test Method for Isotopic Analysis of Uranium Hexafluoride by Double-Standard Multi-Collector Gas Mass Spectrometer
Standard Test Method for Isotopic Analysis of Uranium Hexafluoride by Double-Standard Multi-Collector Gas Mass Spectrometer
SCOPE
1.1 This is a quantitative test method applicable to determine the mass percent of uranium isotopes in uranium hexafluoride (UF6) samples. This method as described is for concentrations of 235U between 0.1 and 10 mass percent, and 234U and 236U between 0.0001 to 0.1 mass percent.
1.2 This test method is for laboratory analysis by a gas mass spectrometer with a multi-collector.
1.3 This standard complements C 761, sections 35 through 40, the double-standard method for gas mass spectrometers using a single collector, by providing a method for spectrometers using a multi-collector.
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.
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Designation: C 1429 – 99
Standard Test Method for
Isotopic Analysis of Uranium Hexafluoride by Double—
Standard Multi—Collector Gas Mass Spectrometer
This standard is issued under the fixed designation C 1429; 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 3.1.1 A standard, n—the low-value standard of a standard
pair that brackets the sample.
1.1 This is a quantitative test method applicable to deter-
3.1.2 B standard, n—the high-value standard of a standard
mining the mass percent of uranium isotopes in uranium
pair that brackets the sample.
hexafluoride (UF ) samples. This method as described is for
3.1.3 determination, n—a single isotopic value, calculated
concentrations of U between 0.1 and 10 mass percent, and
234 236
from a sequence of ratios; the most basic isotopic value
U and U between 0.0001 and 0.1 mass percent.
calculated.
1.2 This test method is for laboratory analysis by a gas mass
3.1.4 Lagrange’s interpolation formula, n—a mathematical
spectrometer with a multi-collector.
equation designed to estimate values between two or more
1.3 This standard complements C 761, sections 35 through
known values.
40, the double-standard method for gas mass spectrometers
3.1.5 run, n—a completed, six-entry symmetrical sequence
using a single collector, by providing a method for spectrom-
consisting of A standard, sample, B standard, B standard,
eters using a multi-collector.
sample, and A standard from which a determination can be
1.4 This standard does not purport to address all of the
calculated for one or more isotopes.
safety concerns, if any, associated with its use. It is the
3.1.6 standard spread, n—the difference between the high
responsibility of the user of this standard to establish appro-
and low standards; sometimes called standard range.
priate safety and health practices and determine the applica-
3.1.7 test result, n—a reported value; the mean of two or
bility of regulatory limitations prior to use.
more determinations.
2. Referenced Documents
4. Summary of Test Method
2.1 ASTM Standards:
4.1 Uranium hexafluoride gas is introduced into an ioniza-
C 761 Test Methods for Chemical, Mass Spectrometric,
tion source. The resulting ions are accelerated down the flight
Spectrochemical, Nuclear, and Radiochemical Analysis of
tube into the magnetic field. The magnetic field separates the
Uranium Hexafluoride
ions into ion beams in accordance with the m/e ratio. Four
C 787 Specification for Uranium Hexafluoride for Enrich-
234 + 235 + 236 +
collectors are stationed so the UF , UF , UF , and
5 5 5
ment
238 +
UF ion beams strike individual collectors.
C 996 Specification for Uranium Hexafluoride to Less Than 5
235 2
4.2 Two standards are chosen whose values bracket the
5% U
desired isotope of the sample. The sample and two standards
C 1215 Guide for Preparing and Interpreting Precision and
are introduced in a six-entry, symmetrical sequence. Then,
Bias Statements in Test Method Standards Used in the
2 measurements are taken which give the mole ratio of the
Nuclear Industry
desired isotope to U.
3. Terminology 4.3 Through Lagrange’s interpolation formula, these mea-
surements are used to calculate the mass percent of the desired
3.1 Definitions of Terms Specific to This Standard:
isotope. If standards are available that bracket all isotopes, then
234 235 236
the U, U, and U mass percents are calculated from the
This test method is under the jurisdiction of ASTM Committee C–26 on
same six-entry run.
Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on
4.4 The results of two six-entry, symmetrical-sequence runs
Methods of Test.
are averaged to find test results for each isotope. The U mass
Current edition approved Jun. 10, 1999. Published September 1999.
Annual Book of ASTM Standards, Vol 12.01. percent is obtained by subtraction.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
C 1429
5. Significance and Use must bracket each of the three isotopes to permit calculation of
all isotopes for every run.
5.1 Uranium hexafluoride used to produce nuclear-reactor
7.1.2 If standards that bracket all isotopes are unavailable,
fuel must meet certain criteria for its isotopic composition.
analyze the isotope(s) bracketed by the originally selected
This test method may be used to help determine if sample
standards, then select other standards to run the remaining
materials meet the criteria described in Specifications C 787
isotope(s).
and C 996.
7.2 Prepare sample and standards:
7.2.1 Attach sample and standard containers to the spec-
6. Apparatus
trometer.
6.1 Mass spectrometer with the following features and
7.2.2 Open and close the appropriate valves to evacuate the
capabilities:
air from the inlet system.
6.1.1 An ion source with an accelerating voltage of approxi-
7.2.3 Open the sample and standard containers individually
mately 8 kV,
and vent the gas phase to the cold trap. This is to remove
6.1.2 A resolving power of greater than or equal to 500,
impurities that may bias the results or interfere with the
6.1.3 A minimum of three points of attachment for stan-
ionization. If necessary, freeze the UF with ice water or a
dards or samples,
mixture of crushed dry ice and isopropyl alcohol to permit
6.1.4 An ion collection system consisting of four collector
longer venting without losing large amounts of UF .
234 + 235 + 236 +
cups stationed to collect UF , UF , UF , and
5 5 5
7.2.4 Permit exhaust system pressure to recover.
238 +
UF ions,
7.2.5 Check to see if impurities have been sufficiently
6.1.5 An ion-current amplifier for each collector cup,
removed by introducing UF into the ion source and observing
6.1.6 A voltage-to-frequency (V-to-F) converter for each
pressure, or exhausting through the cold trap and observing
amplifier,
pressure on the other side, or any other suitable means.
6.1.7 A counter for each V-to-F converter, and
7.2.6 If necessary, repeat 7.2.3-7.2.5 until samples are clean.
6.1.8 Computer control over opening and closing valves, the
7.3 Prepare instrument:
timing, and the integration of analytical sequences.
7.3.1 Adjust instrument parameters to focus ion beams in
238 +
proper collectors and maximize the UF current reading.
7. Procedure
7.3.2 Enter standard values and other information if needed
7.1 Select standards: for calculations performed by computer.
7.1.1 Choose high and low standards which bracket the 7.3.3 Program the spectrometer to run two of the following
sample isotope(s) being evaluated. If the mass percent of six-entry, symmetrical sequences: low standard, sample, high
234 235 236
U, U, and U are all desired, then the two standards standard, high standard, sample, low standard.
C 1429
7.4 Run the analysis: 9. Precision and Bias
7.4.1 Obtain measurements from all four collectors during
9.1 Seven standards traceable to National Institute of Stan-
each entry.
dards and Technology (NIST) were selected as reference
values. Two pairs of standards, also traceable to NIST, were
234 235 236
8. Calculation
chosen to evaluate the U, U, and U mass percent values
of the seven reference standards. These standard pairs were
8.1 Perform the following operations for each of the U,
235 236
obtained by selecting a low standard and two high standards to
U, and U isotopes:
+ create one standard spread that was narrower for all three of the
8.1.1 For each entry, obtain a ratio by dividing the UF ion
238 + desired isotopes and one standard spread that was wider for all
count of the desired isotope by the UF ion count.
234 236
three of the desired isotopes. The U and U reference
8.1.2 Find the mean of the two low standard ratios and
values assigned to all of these standards were determined by
designate this
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