ASTM C1638-06

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Designation: C1638 − 06
StandardGuide for the
Determination of Iodine-129 In Uranium Oxide
This standard is issued under the fixed designation C1638; 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 4. Significance and Use
1.1 This method covers the determination of iodine-129 4.1 The determination of I is not typically requested in
( I) in uranium oxide by gamma-ray spectrometry. The nuclear fuel specifications however it is commonly requested
method could also be applicable to the determination of Iin for disposal of the spent fuel, or for disposal of excess uranium
aqueous matrices. from national weapon complexes. This practice can provide
results of sufficient quality for waste disposal repositories.
1.2 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Interferences
responsibility of the user of this standard to establish appro-
234 234m
priate safety and health practices and to determine the 5.1 Incomplete removal of uranium and its Th/ Pa
applicability of regulatory limitations prior to use.
daughters could lead to elevated Compton background in the
low energy region of the gamma-ray spectrum, where the I
2. Referenced Documents
x-rays are counted.
2.1 ASTM Standards:
5.2 Because the iodine yield monitor is added after the
C1402 Guide for High-Resolution Gamma-Ray Spectrom-
oxide dissolution, any loss of I during the dissolution step
etry of Soil Samples
will not be monitored and may lead to results that are biased
D1193 Specification for Reagent Water
low. To minimize any iodine loss, avoid prolonged heating of
D3648 Practices for the Measurement of Radioactivity
the sample and minimize the time the sample is in an acidic
D3649 PracticeforHigh-ResolutionGamma-RaySpectrom-
state.
etry of Water
6. Instrumentation
3. Summary of Practice
6.1 Extended-range or low-energy gamma ray spectrometry
3.1 An aliquot of uranium oxide is dissolved in dilute nitric
system. See C1402, D3648 or D3649 for a general description
acid and the iodine is selectively extracted via liquid-liquid
of gamma-ray spectrometry systems. The system used to
extraction. The iodine is further purified by selective precipi-
measure the low-energy x-rays from I should have a thin
tation and counted by gamma-ray spectrometry.
window to allow the efficient penetration and measurement of
the low-energy x-rays.
3.2 Gravimetric tracer recoveries using this method are
typically between 75 and 90 %.
7. Terms and Definitions
3.3 The minimum detectable activity (MDA) will vary with
7.1 ROI: Region-of-Interest; the channels, or region, in the
chemical yield, sample size, instrument background, counting
spectra in which the counts due to a specific radioisotope
time and counting efficiency. For a sample size of 100 mg U
appear on a functioning, calibrated gamma-ray spectrometry
oxide, using a well shielded detector, a 1000 minute counting
system.
time, and 32 % detector efficiency at 30 keV, a MDAof ≤0.74
Bq/g (20 pCi/g) oxide was achieved.
7.2 Reagent blank: reagent water processed the same as the
samples; used in the determination of the minimum detectable
activity.
This guide is under the jurisdiction of ASTM Committee C26 on the Nuclear
Fuel Cycle and is the direct responsibility of subcommittee C26.05 on Methods of
8. Apparatus
Test.
8.1 Plastic bottles, 30 and 60-ml, or separatory funnels
Current edition approved Jan. 1, 2006. Published February 2006. DOI: 10.1520/
C1638-06.
8.2 Filter paper—25-mm diameter, 0.45µm pore size
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
8.3 Vacuum filter apparatus
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 8.4 pH paper with unit resolution
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C1638 − 06
FIG. 1 Low-Energy Photon Spectrum of I-129 on a Ge Well Detec-
tor
9. Reagents and Materials 9.11 Sodium Carbonate, 2M—dissolve 212 g of powder in
500 mL of water, dilute to 1 litre final volume.
9.1 Purity of Reagents—Reagent grade chemicals shall be
used in all tests. Unless otherwise indicated, it is intended that
9.12 Sodium Hydroxide, 4M—dilute a commercially pre-
all reagents shall conform to the specifications of the Commit-
pared solution or dissolve 160 g of pellets in 700 mLof water,
tee onAnalytical Reagents of theAmerican Chemical Society,
dilute to a final volume of 1 litre. This is a very exothermic
where such specifications are available .
reaction. The use of an ice bath can mitigate the magnitude of
9.2 Purity of Water—Unless otherwise indicated, references
the exothermicity.
towatershallbeunderstoodtomeanTypeIwaterasdefinedin
9.13 Sodium Hypochlorite.
Specification D1193.
9.3 1M Hydroxylamine-hydrochloride—commercially
10. Calibration and Standardization
available solution or dissolve 70 g of the powder in 500 mLof
water, dilute to 1 litre final volume. 10.1 The gamma-ray spectrometry system should be cali-
-
brated for energy, resolution and efficiency according to the
9.4 Iodide carrier, 20 mg I per millilitre as KI.
manufacturer instructions. The background counting rate for
9.5 Nitric Acid, concentrated, ;16M
the instrument should be measured at a frequency determined
9.6 0.1M Nitric Acid—Add ;6 mL of concentrated HNO
3 by the user. See C1402, D3648 or D3649 for additional
to 950 mL of water, dilute with water to a final volume of 1
information. A typical spectrum for I is shown in Fig. 1.
litre.
-
10.2 Confirm the concentration of the I carrier by adding
9.7 8M Nitric Acid—Add 500 mL of concentrated HNO to
1.00 mL of the carrier solution to 15 mL of water. Add 1 mL
450 mLof water; dilute with water to a final volume of 1 litre.
of the 0.1M NaHSO , mix, heat gently and then add 2 mL of
+2
9.8 p-xylene.
thePd carrier.Collecttheprecipitate(PdI )onatared25-mm
filter paper. Dry and reweigh the filter paper to confirm the
9.9 Palladium carrier—;10 mg/mL, dilute a commercially
expected precipitate weight. Repeat this confirmation several
prepared solution to the cor
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