ASTM C1477-08(2014)
(Test Method)Standard Test Method for Isotopic Abundance Analysis of Uranium Hexafluoride and Uranyl Nitrate Solutions by Multi-Collector, Inductively Coupled Plasma-Mass Spectrometry
Standard Test Method for Isotopic Abundance Analysis of Uranium Hexafluoride and Uranyl Nitrate Solutions by Multi-Collector, Inductively Coupled Plasma-Mass Spectrometry
SIGNIFICANCE AND USE
5.1 The test method is capable of measuring uranium isotopic abundances of 234U, 235U, 236U and 238U as required by Specifications C787 and C996.
SCOPE
1.1 This test method covers the isotopic abundance analysis of 234U, 235U, 236 U and 238U in samples of hydrolysed uranium hexafluoride (UF6) by inductively coupled plasma source, multicollector, mass spectrometry (ICP-MC-MS). The method applies to material with 235U abundance in the range of 0.2 to 6 % mass. This test method is also described in ASTM STP 1344.
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.
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Designation:C1477 −08 (Reapproved 2014)
Standard Test Method for
Isotopic Abundance Analysis of Uranium Hexafluoride and
Uranyl Nitrate Solutions by Multi-Collector, Inductively
Coupled Plasma-Mass Spectrometry
This standard is issued under the fixed designation C1477; 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 2.2 Other Document:
STP 1344 Applications of Inductively Coupled Plasma-
1.1 This test method covers the isotopic abundance analysis
234 235 236 238 Mass Spectrometry (ICP-MS) to Radionuclide Determi-
of U, U, U and U in samples of hydrolysed ura-
nations
nium hexafluoride (UF ) by inductively coupled plasma
source, multicollector, mass spectrometry (ICP-MC-MS). The
3. Terminology
methodappliestomaterialwith Uabundanceintherangeof
3.1 Acronyms:
0.2 to 6 % mass. This test method is also described in ASTM
3.1.1 amu—atomic mass unit
STP 1344.
3.1.2 ICP-MC-MS—Inductively Coupled Plasma Multi-
1.2 The values stated in SI units are to be regarded as
Collector Mass Spectrometer
standard. No other units of measurement are included in this
3.1.3 ICP-MS—Inductively Coupled Plasma Mass Spec-
standard.
trometer
1.3 This standard does not purport to address all of the
3.1.4 UIRM—Uranium Isotopic Reference Material
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
4. Summary of Test Method
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4.1 Samples are received either in the form of uranium
hexafluoride (UF ) or aqueous uranic solution. The UF
6 6
2. Referenced Documents
samples are hydrolysed, diluted and acidified with nitric acid.
2.1 ASTM Standards:
Uranic solution samples are diluted and acidified with nitric
C761 Test Methods for Chemical, Mass Spectrometric,
acid. If required, an internal reference of thorium isotopes can
Spectrochemical, Nuclear, and RadiochemicalAnalysis of
be subsequently added to each diluted sample. As detailed in
Uranium Hexafluoride
Section 8, isotope pairs of elements other than thorium could
C787 Specification for Uranium Hexafluoride for Enrich-
be used for an internal reference.
ment
4.2 The samples are contained in polypropylene tubes that
C996 Specification for Uranium Hexafluoride Enriched to
are inserted into the auto-sampler rack of the mass spectrom-
Less Than 5 % U
eter. Sample details are input to the computer and the instru-
D1193 Specification for Reagent Water
ment is prepared for measurement. The automatic measuring
sequence is initiated.
This test method is under the jurisdiction ofASTM Committee C26 on Nuclear
4.3 Uranium Isotopic Reference Materials (UIRMs) are
Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of
used to calibrate the instrument. Each UIRM is prepared in
Test.
Current edition approved Jan. 1, 2014. Published February 2014. Originally aqueous solution (acidified with nitric acid) and if required
approved in 2000. Last previous edition approved in 2008 as C1477 – 08. DOI:
spiked with the same internal reference as the samples. This
10.1520/C1477-08R14.
calibration solution is measured and a mass bias parameter is
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. Available from ASTM Headquarters.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1477−08 (2014)
calculatedthatisstoredandsubsequentlyimportedintoeachof solution and measuring the background U ion beam. The
the sample measurements to correct the measured uranium sample introduction system should be periodically disas-
isotopic ratios. sembled and cleaned, to minimise the background U ion
beam.
4.4 Measurements of isotopic ratios in the calibration solu-
6.4.2 A background correction is performed during the
tion and the subsequent samples are initiated by customised
measurement run by monitoring the analyte signals of the 0.3
software. The mass bias factor is computed from the measured
M nitric acid rinse solution. The background correction is
isotopic ratios in the calibration solution. This parameter is
measured prior to the mass calibration and is re-measured
then exported to correct the measured isotopic ratios of the
before each subsequent sample.
samples for mass bias. The corrected isotopic abundances are
expressed as % atomic and are converted to % mass prior to
7. Apparatus
reporting. Details of the mass bias correction are presented in
7.1 Mass Spectrometer:
Appendix X1.
7.1.1 The mass spectrometer has an inductively coupled
plasma (ICP) source and a double focusing electrostatic/
5. Significance and Use
magnetic sector analyser equipped with twelve Faraday detec-
5.1 The test method is capable of measuring uranium
tors and two ion counters.
234 235 236 238
isotopic abundances of U, U, U and U as required
7.1.2 The mass spectrometer is fully computer controlled
by Specifications C787 and C996.
using customised software and is equipped with an auto-
sampler.
6. Interferences
7.2 Polypropylene Sample Tubes, Screw-Cap, 50 mL.
6.1 Mass Bias—Electrostatic repulsion between uranium
ions causes a so-called “mass bias” effect. Mass bias is 7.3 Polypropylene Sample Tubes, Screw-Cap, 10 mL.
observed as an enhancement in the number of ions detected at
7.4 Positive Displacement Pipette, and Tips to Suit, 0.01
the collectors from the heavier uranium isotopes relative to the
mL.
lighter uranium isotopes. A calibration procedure is used to
7.5 Positive Displacement Pipette, and Tips to Suit, 1 mL.
correct the mass spectrometer for mass bias.
7.6 Variable-Volume Dispenser, 1 to 5 mL, fitted to a 1-L
6.2 Adjacent Isotopic Peaks—The abundance sensitivity of
glass storage bottle.
the ICP-MC-MS at mass 237 is specified to be less than 0.5
parts per million of the U ion beam. The method is limited
8. Reagents and Materials
to the measurement of U isotopic abundances below 6 %,
234 236
8.1 Purity of Water—Demineralised water as defined by
consequently interference effects with the U and U ion
Type I of Specification D1193.
beams are negligible.
8.2 High Purity 0.3 M Nitric Acid Solution (~x 50 dilution
6.3 IsobaricMolecularInterferences—Amolecularinterfer-
236 235
of the concentrated acid).
ence exists at mass 236 between U and a hydride of U,
which is formed in the plasma. This interference can be
8.3 Uranium Isotopic Reference Material (UIRMs)—
corrected by measuring the beam height of the U hydride at
UIRMsareusedtocalibratetheinstrumentformulti-collection
mass 239, and applying the correction defined in Eq 1,tothe
measurements. The Institute for Reference Materials and
236 5
measured U ion beam:
Measurements (IRMM) reference material IRMM-024 is used
for enriched samples and the New Brunswick Laboratory
UH
236 236 235
U 5 U 2 U 3 (1)
S D
c m Certified Reference Material CRM U005-Ais used for samples
U
of natural or depleted U abundances. The UIRMs are
where:
prepared as uranyl nitrate solutions containing 0.4 µg/mL of
236 236
U = the corrected U ion beam,
c uranium.
236 236
U = the measured U ion beam,
m 230
235 235 8.4 Optional—Internal Reference Solution containing Th
U = the measured U ion beam,
238 238
and Th isotopes (or isotopes of another suitable element).
UH = the measured U hydride ion beam, and
238 238
8.4.1 It has been found that the stability of the modern
U = the measured U ion beam.
ICP-MC-MS can be such that it is not necessary to use an
6.4 Memory Effects:
internal reference to monitor variations in mass bias. The data
6.4.1 Contamination of the sample introduction system
presented in this paper was obtained without the use of an
from previous samples produces memory interference effects.
Such effects are accentuated when samples that are depleted
in U are measured after enriched samples. Memory effects The data presented in the paper was obtained using a ‘Nu Plasma’ mass
spectrometer, manufactured by Nu Instruments (Nu Instruments Ltd, Unit 74
can be readily assessed by aspirating a 0.3 M nitric acid
Clywedog Road South, Wrexham LL13 9XS, North Wales, UK). The Nu Plasma
was supplied with the (optional) BIG80 vacuum pumping system to achieve
optimum sensitivity.
4 7
The uranium isotopic precision of measurement, limit of detection and Institute for Reference Materials and Measurement, Retieseweg, B-2440 Geel,
uncertainty of measurement are listed in Section 15 and Appendix X1. Belgium.
5 239 8
This correction can only be applied to samples which do not contain Pu (or NewBrunswickLaboratory,D-350,9800SouthCassAvenue,Argonne,Illinois
any other nuclides with mass 239). 60439.
C1477−08 (2014)
TABLE 1
Collector L6 L5 L4 IC1 L3 IC0 L2 L1 Ax H1 H2 H3 H4 H5
Separation 2U 1U 1U 1U 1U 1U 1U 1U 1U 1U 1U 2U 2U
230 232 234 235 236 238 238
Ion Th Th – U U U– U UH ––– – –
Beam
where:
Ax = Axial Faraday collector,
L and H = low and high mass Faraday collectors (with respect to the Axial collector),
IC = ion counters, and
U = unit mass dispersion for uranium isotopes.
internal reference. However, if the addition of an internal 10.1.3 Pour the hydrolysed UF into a 50 mL screw-cap
reference is deemed necessary then isotopes of thorium (230 polypropylene tube and dilute so that the final concentration of
and 232) can be used as a suitable internal reference material.
UF is 5 mg/mL. For example, if the weight of UF transferred
6 6
Theinternalreferencemustcontainatleastonepairofisotopes is 0.2 g, dilute to 40 mL with demineralised water.
in a fixed ratio. It is not necessary for this isotopic ratio to be
10.1.4 Using a positive displacement pipette, take a 0.01
accurately known as the same reference is added to both the
mLaliquot of solution and transfer to a clean 50 mLscrew-cap
calibration material and the subsequent samples. Minor fluc-
polypropylenetube.Dilutetoavolumeof42mLusinga0.3M
tuations in instrument calibration (mass bias) are reflected in
nitric acid solution. The resulting solution contains 1.2 µg/mL
the measured ratio of the internal reference in the samples.
of UF which is equivalent to 0.8 µg/mL of uranium.
Subsequent correction of the mass bias parameter using the
10.1.5 Pour 2 mL of solution into a 10 mL polypropylene
measured ratio of the internal reference provides the necessary
tube and double the volume to 4 mL using 0.3 M nitric acid
adjustment to the mass bias factor prior to result calculation.
solution, to reduce the uranic concentration to 0.4 µg/mL.
8.4.2 The internal reference material should be prepared
10.1.6 If required, add an aliquot of the thorium internal
with a dilution appropriate to the sensitivity of the mass
reference and mix the solution thoroughly (see 8.4).
spectrometer. If thorium is used as the internal reference then
10.1.7 Place the tube in the designated rack position in
a thorium to uranium ratio of approximately 1:2 should be
accordance with Section 13.
adequate.
NOTE 1—If an internal reference is added, then the uranic concentration
10.2 SamplesReceivedasAqueousUranylNitrateSolutions
ofthesamplesshouldbeadjustedsothattheuranicconcentrationrequired
of Known Uranic Concentration:
for the mass spectrometer is achieved following the addition of the
10.2.1 Dilute the sample with a 0.3 M nitric acid solution so
internal reference.
234 230
that the uranium concentration is 0.8 µg/mL.
NOTE 2—The decay of Uto Th may present a problem with the
analysis of aged-uranic solutions. This should not present a problem with
10.2.2 Proceed in accordance with 10.1.5 – 10.1.7.
uranium hexafluoride samples that are taken in the gaseous phase, as
gaseous UF separates from any non-volatile thorium compounds.
11. Preparation of Apparatus
9. Hazards
11.1 Many ICP-MC-MS designs require the Faraday collec-
9.1 A number of the materials used in this procedure are
tors to be mechanically positioned to align with the ion beams.
radioactive, toxic, corrosive or any combination of the three.
The instrument used for this work adopts a different approach,
Adequate laboratory facilities and safe handling procedures
where a “zoom lens” which alters the dispersion of the
must be used. A detailed discussion of all safety procedures is
instrument is used to focus the beams onto a fixed array of
beyond the scope of this method. Site specific practices for the
detectors.The zoom lens settings were adjusted under software
handling of radioactive materials and hazardous chemicals
control to achieve the configuration shown in Table 1.
should be followed.
11.2 To minimise measurement uncertainty, minor isotope
234 236
( U and U) abundances are measured with ion counters.
10. Sampling, Test Specimens, and Test Units
The analyser magnet must be calibrated across the mass range
10.1 Samples Received as UF :
230to238,however,theinstrumentmanufacturerrecommends
10.1.1 Transfer between 0.2 g and 0.25 g of UF gas into a
10 calibrating across the mass range 80 to 238 (achieved using the
glass sample tube cooled by liquid nitrogen.
beam from the Argon dimer). The magnet should be re-
10.1.2 Working in a fume cupboard, hydrolyse the UF
calibratedifthecalibrationdriftsbymorethan0.2atomicmass
using demineralised water from a wash bottle. The operator
units.
should keep the sample tube pointed away at all times since
some toxic HF gas is produced.
12. Calibration and Standardization
12.1 Calibration of the mass spectrometer using a UIRM
The sample dilutions specified in this section can be varied according to
producesamassbiasfactor.ThemassbiasfactorfortheUIRM
instrument requirements.
Subsampling of UF is detailed in ASTM Standard Test Method C761. in question is defined in Eq 2:
C1477−08 (2014)
235 b 3B
U ∆m
U 5 3100% mass (7)
quoted
~a 3A!1~b 3B!1~c 3C!1~d 3D!
U
Mass Bias Factor 5 (2)
U
where:
1 2
measured
U 234
a = U% atomic
b = U% atomic
where
c = U% atomic
∆m = ratio mass difference (that is, 3 in the case of
d = U% atomic
235 238
the U/ U ratio).
A = atomic weight of U (234.0409)
B = atomic weight of U (235.0439)
12.2 The mass bias factor is exported to all subsequent
C = atomic weight of U (236.0457)
sample measurements to correct for mass bias effects. Details
D = atomic weight of U (
...
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