1、Designation:C120602(Reapproved2010)Standard Test Method forPlutonium by Iron(II)/Chromium(VI)AmperometricTitration1This standard is issued under the fixed designation C1206;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of
2、last revision.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 test method covers the determination of plutoniumin unirradiated nuclear-grade plutonium dioxide,uranium-plutonium mix
3、ed oxides with uranium(U)/plutonium(Pu)ratios up to 21,plutonium metal,and plutonium nitratesolutions.Optimum quantities of plutonium to measure are 7 to15 mg.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard
4、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 determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Stand
5、ards:2C1168 Practice for Preparation and Dissolution of PlutoniumMaterials for Analysis3.Committee C-26 Safeguards Statement3.1 The materials nuclear-grade mixed oxides(U,Pu)O2powders,pellets,Pu metal,Pu oxides,and Pu nitrates to whichthis test method applies,are subject to nuclear safeguardsregulat
6、ions governing their possession and use.This analyticaltest method has been designated as technically acceptable forgenerating safeguards accountability measurement data forplutonium.3.2 When used in conjunction with appropriate standardreference material this test method can demonstrate traceabilit
7、yto the national measurement base.However,adherence to thistest method does not automatically guarantee regulatory accep-tance of the resulting safeguards measurements.It remains thesole responsibility of the user of this test method to ensure thatits application to safeguards has the approval of th
8、e properregulatory authorities.4.Summary of Test Method4.1 Amperometric titrations are based on the measuredchange in the current flow between two electrodes,held atconstant potential,when a titrant is added.The plutonium isfirst oxidized to the+6 oxidation state in a dilute sulfuric acidsolution wi
9、th argentic oxide.The excess oxidant is destroyedby heating,and the Pu(VI)is then reduced to Pu(IV)by excessFe(II)during the titration.The excess Fe(II)is titrated byCr(VI),and the Pu determined by difference from the quanti-ties of the two titrants.4.2 Oxide and metal samples are prepared to produc
10、e finalsolutions as a soluble sulfate.Plutonium-nitrate solutions canbe introduced directly at the beginning of the procedure and arelater diluted with sulfuric acid.Chlorides must be removed.5.Significance and Use5.1 All plutonium materials covered in this test method areused in the preparation of
11、nuclear-reactor fuels.In order to besuitable for this purpose,the materials must meet specifiedcriteria for plutonium content.This test method is used toverify the plutonium content.5.2 A primary standard dichromate such as that availablefrom National Institute of Standards and Technology(NIST)ora d
12、ichromate traceable to a primary standard such as NewBrunswick Laboratory(NBL)plutonium standard,is requiredfor this technique.6.Interferences6.1 Interference is caused by ions that are oxidized byargentic oxide and reduced by ferrous ion in sulfuric-acidsolution.Elements that may be present in plut
13、onium materialsand that will produce quantitative positive errors includevanadium(V),chromium(Cr),and manganese(Mn).Correc-tion can be made for these elements by calculation when theydo not individually exceed 200 g impurity elements per gramof plutonium.1This test method is under the jurisdiction o
14、fASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved Jan.1,2010.Published February 2010.Originallyapproved in 1991.Last previous edition approved in 2002 as C1206 02.DOI:10.1520/C1206-02R10.2For referenced ASTM st
15、andards,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 19428
16、-2959.United StatesNOTICE:This standard has either been superseded and replaced by a new version or withdrawn.Contact ASTM International(www.astm.org)for the latest information1 6.2 Other elements that will cause positive errors includecerium(Ce),ruthenium(Ru),gold(Au),rhodium(Rh),plati-num(Pt),lead(Pb),and neptunium(Np).Americium(Am)does not interfere because it is not oxidized to higher valencystates during the argentic oxidation.6.3 Thallium(Tl),selenium(Se),calcium(Ca),and barium(Ba)give low
