ASTM_C_1000_-_11.pdf

Designation:C100011Standard Test Method forRadiochemical Determination of Uranium Isotopes in Soil byAlpha Spectrometry1This standard is issued under the fixed designation C1000;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of 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 alpha-emitting uranium isotopes in soil.This test method describesone acceptable approach to the determination of uraniumisotopes in soil.21.2 The test method is designed to analyze 10 g of soil;however,the sample size may be varied to 50 g depending onthe activity level.This test method may not be able tocompletely dissolve all forms of uranium in the soil matrix.Studies have indicated that the use of hydrofluoric acid todissolve soil has resulted in lower values than results usingtotal dissolution by fusion.1.3 The lower limit of detection is dependent on count time,sample size,detector,background,and tracer yield.Thechemical yield averaged 78%in a single laboratory evaluation,and 66%in an interlaboratory collaborative study.1.4 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.5 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 determine the applica-bility of regulatory limitations prior to use.A specific precau-tionary statement is given in Section 10.2.Referenced Documents2.1 ASTM Standards:3C859 Terminology Relating to Nuclear MaterialsC998 Practice for Sampling Surface Soil for RadionuclidesC999 Practice for Soil Sample Preparation for the Determi-nation of RadionuclidesC1163 Practice for Mounting Actinides for Alpha Spectrom-etry Using Neodymium FluorideC1284 Practice for Electrodeposition of the Actinides forAlpha SpectrometryD1193 Specification for Reagent WaterD3084 Practice for Alpha-Particle Spectrometry of WaterD3648 Practices for the Measurement of RadioactivityD7282 Practice for Set-up,Calibration,and Quality Controlof Instruments Used for Radioactivity Measurements3.Summary of Test Method3.1 A soil sample with uranium-232 tracer added is heatedto destroy organic matter and dissolved with a mixture ofhydrofluoric acid and nitric acid.The uranium is coprecipitatedwith ferric hydroxide and the precipitate is dissolved withhydrochloric acid.Iron is removed by extraction with isopropylether,and plutonium,radium,and thorium are separated fromuranium by anion exchange.Uranium is electrodeposited on astainless steel disk and determined by alpha spectrometry.Asan option,the uranium may be prepared for alpha spectromet-ric measurement by using coprecipitation with neodymiumfluoride.4.Significance and Use4.1 This test method is used to analyze soil for alpha-emitting uranium isotopes.It can be used to establish baselineuranium levels and to monitor depositions from nuclear facili-ties.5.Interferences5.1 Protactinium-231 may not be completely separated bythe procedure and could interfere with the determination ofuranium-233 or uranium-234 because it has the followingalpha energies in MeV:5.06,5.03,5.01,4.95 and 4.73(seeAppendix X1).If neptunium is present in the sample in the plusfour oxidation state,it will co-elute with the uranium.5.2 Since uranium-232 is added as a tracer,it can not bedetermined in soil.Uranium-232 is rarely present in soilsamples.If present in significant quantities relative to the1This test method is under the jurisdiction ofASTM Committee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved Feb.1,2011.Published February 2011.Originallyapproved in 1983.Last previous edition approved in 2005 as C1000 05.DOI:10.1520/C1000-11.2Casella,V.A.,Bishop,C.T.,and Glosby,A.A.,“Radiometric Method for theDetermination of Uranium in Soil and Air,”U.S.Environmental Protection Agency,EPA-600/7-80-019,Las Vegas,NV,February 1980;and in Practices D3084 andD3648.3For referenced ASTM standards,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 19428-2959.United States1 activity of uranium-232 tracer added,uranium-232 will lead toan overestimation of the chemical yield and a low bias inuranium results.6.Apparatus6.1 Alpha Pulse Height Analysis System:26.1.1 A system consisting of a charged particle detectorcapable of 50 keV or less resolution on samples electrodepos-ited on a flat mirror-finished stainless steel disk is required.6.1.2 The resolution is defined