1、Designation: C1638 06 (Reapproved 2013)Standard Guide for theDetermination of Iodine-129 In Uranium Oxide1This standard is issued under the fixed designation C1638; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This method covers the determination of iodine-129(129I) in uranium oxide by gamma-ray spectrometry. Themethod could also be
3、 applicable to the determination of129Iinaqueous matrices.1.2 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and to determine theapplicabi
4、lity of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2C1402 Guide for High-Resolution Gamma-Ray Spectrom-etry of Soil SamplesD1193 Specification for Reagent WaterD3648 Practices for the Measurement of RadioactivityD3649 Practice for High-Resolution Gamma-Ray Spectrom
5、-etry of Water3. Summary of Practice3.1 An aliquot of uranium oxide is dissolved in dilute nitricacid and the iodine is selectively extracted via liquid-liquidextraction. The iodine is further purified by selective precipi-tation and counted by gamma-ray spectrometry.3.2 Gravimetric tracer recoverie
6、s using this method aretypically between 75 and 90 %.3.3 The minimum detectable activity (MDA) will vary withchemical yield, sample size, instrument background, countingtime and counting efficiency. For a sample size of 100 mg Uoxide, using a well shielded detector, a 1000 minute countingtime, and 3
7、2 % detector efficiency at 30 keV, a MDA of 0.74Bq/g (20 pCi/g) oxide was achieved.4. Significance and Use4.1 The determination of129I is not typically requested innuclear fuel specifications however it is commonly requestedfor disposal of the spent fuel, or for disposal of excess uraniumfrom nation
8、al weapon complexes. This practice can provideresults of sufficient quality for waste disposal repositories.5. Interferences5.1 Incomplete removal of uranium and its234Th/234mPadaughters could lead to elevated Compton background in thelow energy region of the gamma-ray spectrum, where the129Ix-rays
9、are counted.5.2 Because the iodine yield monitor is added after theoxide dissolution, any loss of129I during the dissolution stepwill not be monitored and may lead to results that are biasedlow. To minimize any iodine loss, avoid prolonged heating ofthe sample and minimize the time the sample is in
10、an acidicstate.6. Instrumentation6.1 Extended-range or low-energy gamma ray spectrometrysystem. See C1402, D3648 or D3649 for a general descriptionof gamma-ray spectrometry systems. The system used tomeasure the low-energy x-rays from129I should have a thinwindow to allow the efficient penetration a
11、nd measurement ofthe low-energy x-rays.7. Terms and Definitions7.1 ROI: Region-of-Interest; the channels, or region, in thespectra in which the counts due to a specific radioisotopeappear on a functioning, calibrated gamma-ray spectrometrysystem.7.2 Reagent blank: reagent water processed the same as
12、 thesamples; used in the determination of the minimum detectableactivity.8. Apparatus8.1 Plastic bottles, 30 and 60-ml, or separatory funnels8.2 Filter paper25-mm diameter, 0.45m pore size8.3 Vacuum filter apparatus8.4 pH paper with unit resolution1This guide is under the jurisdiction of ASTM Commit
13、tee C26 on the NuclearFuel Cycle and is the direct responsibility of subcommittee C26.05 on Methods ofTest.Current edition approved Jan. 1, 2013. Published January 2013. Originallyapproved in 2006. Last previous edition approved in 2006 as C1638 06. DOI:10.1520/C1638-06R13.2For referenced ASTM stand
14、ards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA
15、 19428-2959. United States19. Reagents and Materials9.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where
16、 such specifications are available3.9.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean Type I water as defined inSpecification D1193.9.3 1M Hydroxylamine-hydrochloridecommerciallyavailable solution or dissolve 70 g of the powder in 500 mL ofwater, dilute to
17、 1 litre final volume.9.4 Iodide carrier, 20 mg I-per millilitre as KI.9.5 Nitric Acid, concentrated, ;16M9.6 0.1M Nitric AcidAdd ;6 mL of concentrated HNO3to 950 mL of water, dilute with water to a final volume of 1litre.9.7 8M Nitric AcidAdd 500 mL of concentrated HNO3to450 mL of water; dilute wit
18、h water to a final volume of 1 litre.9.8 p-xylene.9.9 Palladium carrier;10 mg/mL, dilute a commerciallyprepared solution to the correct concentration9.10 Sodium bisulfite, 0.1Mdissolve 10.4 g of powder in500 mL of water, dilute to a final volume of 1 litre9.11 Sodium Carbonate, 2Mdissolve 212 g of p
19、owder in500 mL of water, dilute to 1 litre final volume.9.12 Sodium Hydroxide, 4Mdilute a commercially pre-pared solution or dissolve 160 g of pellets in 700 mL of water,dilute to a final volume of 1 litre. This is a very exothermicreaction. The use of an ice bath can mitigate the magnitude ofthe ex
20、othermicity.9.13 Sodium Hypochlorite.10. Calibration and Standardization10.1 The gamma-ray spectrometry system should be cali-brated for energy, resolution and efficiency according to themanufacturer instructions. The background counting rate forthe instrument should be measured at a frequency deter
21、minedby the user. See C1402, D3648 or D3649 for additionalinformation. A typical spectrum for129I is shown in Fig. 1.10.2 Confirm the concentration of the I-carrier by adding1.00 mL of the carrier solution to 15 mL of water. Add 1 mLof the 0.1M NaHSO3, mix, heat gently and then add 2 mL ofthe Pd+2ca
22、rrier. Collect the precipitate (PdI2) on a tared 25-mmfilter paper. Dry and reweigh the filter paper to confirm theexpected precipitate weight. Repeat this confirmation severaltimes to increase the precision of the determination.10.3 Prepare an efficiency curve for the 30 keV x-rayscomparing the rel
23、ative efficiency versus weight of PdI2byprecipitating equal quantities of129I with various weights ofPdI2. A typical curve for a Ge well detector is shown in Fig. 2;note that this curve shows the net count rate versus weight ofPdI2rather than calculated efficiency (the129I activity used toprepare th
24、is graph was 2.2 Bq (60 pCi).3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and
25、 the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Low-Energy Photon Spectrum of I-129 on a Ge Well Detec-torC1638 06 (2013)211. Procedure11.1 Weigh out no more than 100 mg of uranium oxide intoa small beaker.11.2 Dissolve the oxide
26、 in about 20 mL of 0.1M HNO3.Heat gently, if required, to complete the dissolution.NOTE 1Avoid prolonged heating to minimize any iodine volatilizationand possibly avoid heating altogether if only a small portion of the sampleremains undissolved. Also, proceed directly to the next steps to minimizeth
27、e time the sample is held under acidic conditions without the tracerpresent. Addition of the tracer prior to dissolution may not be appropriatesince the sample iodine may not be in the same form and oxidation stateas the tracer iodine.11.3 Add 1 mL of the 4M NaOH. Swirl the solution to mixand check
28、the pH. The solution should be strongly basic.11.4 Add 1 mL of the 2M NaCO3. Swirl to mix the solution11.5 Add 1.00 mL of the 20 mg/mL I-carrier. Swirl to mix.11.6 Add 1 mL of the NaHClO3solution to the beaker tooxidize the iodine to periodate (IO4-). Swirl to mix. Place thebeaker on a hotplate and
29、heat the solution to just below boiling.Remove from the hotplate and cool to room temperature.CAUTION: The beaker and solution must be cool prior tothe next step.11.7 Carefully add 1 mL of the 8M HNO3. Swirl thesolution then check the pH. The solution should be stronglyacidic.11.8 Transfer the solut
30、ion to a 60-mL plastic bottle orseparatory funnel. Rinse the beaker a few times with smallportions of water and add to the bottle.11.9 Add 10 mL of p-xylene to the bottle.11.10 Add 3 mL of 1M NH2OH-HCl to the bottle to reducethe periodate to iodine (I2). Swirl to mix. The solution shouldbe red-purpl
31、e in color at this point.11.11 Cap the bottle and shake for several minutes to extractthe iodine into the organic layer. Let the solution stand andallow the organic layer to separate from the aqueous layer.11.12 Remove the cap and draw off the top, organic layerwith a disposable pipette. Transfer th
32、e organic layer to a 30-mLplastic bottle or clean separatory funnel.11.13 Add 15 mL of water to the organic in the 30-mLbottle. Add 1 mL of the 0.1M NaHSO3to the bottle to reducethe iodine to iodide (I-). Cap the bottle and shake for oneminute until the organic layer is colorless. Let the solutionst
33、and and allow the organic layer to separate from the aqueouslayer.11.14 Draw off the upper, organic layer and discard.11.15 Transfer the aqueous layer to a 100-mL beaker andgently warm the solution on a hotplate.11.16 Add 2 mL of the Pd+2carrier solution to the beaker.11.17 Allow the PdI2to precipit
34、ate and then filter thesolution through a tared 25-mm filter paper.11.18 Allow the filter paper to dry and then reweigh todetermine the chemical yield of the separation.11.19 Count the filter on an extended range or low-energygamma-ray spectrometry system for the length of time requiredto meet the r
35、equested detection limit. Set the ROI for129Itomonitor the 29-34 keV Xe K x rays.12. Calculation12.1 CALCULATION OF CHEMICAL YIELDY = mg PdI2recovered/mg PdI2expected based on calibra-tion (10.2)12.2 CALCULATION OF ACTIVITYAi5 Gi2 Bi!/Y*E*ABi*W!# (1)FIG. 2 Self-Adsorption of 30 keV X-ray versus Weig
36、ht of PdI2H2OC1638 06 (2013)3whereAi= activity of129I in Bq per gram U oxideGI= gross counts per second in the129I ROIBi= background counts per second in the129I ROIY = yield calculated above expressed as a fractionE = detector efficiency for the 29-34 keV x-rays, ex-pressed as a fraction, based on
37、the weight of the PdI2ABi= branching ratio for129I, expressed as a fractionW = weight of U oxide analyzed in gramsIf the weight of uranium per gram of oxide is known thesample activity may be reported as Bq of129I per gram ofuranium by multiplying by the correct ratio.12.3 CALCULATION OF MINIMUM DET
38、ECTABLEAC-TIVITYMDAi5 4.65*sB12.71!/E*Y*T*ABi*W! (2)whereMDAi= minimum detectable activity (Bq/g)sB= standard deviation of the reagent blank counts intime TT = sample counting time in seconds13. Keywords13.1 Gamma-ray spectrometry; liquid-liquid extraction;x-rayASTM International takes no position r
39、especting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.Thi
40、s standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM Inte
41、rnational Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown
42、below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).C1638 06 (2013)4
