1、Designation:C163806(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 revisio
2、n.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 applicable t
3、o the determination of129I inaqueous 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 theapplicability of regulat
4、ory 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-etry of Water3.
5、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 recoveries using this metho
6、d 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 32%detector efficiency at 30
7、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 national weapon complexes.This practice c
8、an 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 are counted.5.2 Because the iodine yie
9、ld 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 an acidicstate.6.Instrumentation6.1 Exten
10、ded-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 and measurement ofthe low-energy x-rays.7.Term
11、s 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 thesamples;used in the determination of the minimum
12、 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 Committee C26 on the NuclearFuel Cycle and is the direct respon
13、sibility 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 standards,visit the ASTM website,www.astm.org,orcontact ASTM Custome
14、r 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 19428-2959.United States1 9.Reagents and Materials9.1 Purity of Reagent
15、sReagent 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 such specifications are available3.9.2 Purity of WaterUnless otherwise ind
16、icated,referencesto water shall be understood to mean Type I water as defined inSpecification D1193.9.3 1MHydroxylamine-hydrochloridecommerciallyavailable solution or dissolve 70 g of the powder in 500 mL ofwater,dilute to 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
