1、Designation: C1539 08 (Reapproved 2014)Standard Test Method forDetermination of Technetium-99 in Uranium Hexafluoride byLiquid Scintillation Counting1This standard is issued under the fixed designation C1539; the number immediately following the designation indicates the year oforiginal adoption or,
2、 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 is a quantitative method used todetermine technetium-99 (99Tc)
3、in uranium hexafluoride (UF6)by liquid scintillation counting.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 does not purport to address all of thesafety concerns, if any, associated with its use. It is th
4、eresponsibility 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 Standards:2C787 Specification for Uranium Hexafluoride for Enrich-mentC996 Specification for Uran
5、ium Hexafluoride Enriched toLess Than 5 %235UC1215 Guide for Preparing and Interpreting Precision andBias Statements in Test Method Standards Used in theNuclear Industry2.2 Other Document:USEC-651 Uranium Hexafluoride: A Manual of GoodHandling Practices33. Terminology3.1 Definitions:3.1.1 quench sta
6、ndard curvea relationship betweensample quench and detection efficiency. A quench curve for anisotope in a given cocktail and vial combination is developedby counting a series of standards containing the same activityof that isotope, but each with different quench. Sample quenchis typically quantifi
7、ed by a variety of parameters.4. Summary of Test Method4.1 Ameasured portion of hydrolyzed uranium hexafluoride(UF6) containing approximately 0.8 to 1.2 g of uranium or avolume of sample less than or equal to 30 mL is transferred toa centrifuge tube. The uranium is precipitated using ammo-nium hydro
8、xide.After centrifuging, the decanted supernatant isacidified with sulfuric acid and extracted with tributyl phos-phate. An aliquot of the extract is transferred to a scintillationvial, where stannous chloride in hydrochloric acid and liquidscintillation cocktail are added. The99Tc beta activity is
9、thendetermined by liquid scintillation counting.5. Significance and Use5.1 Uranium hexafluoride is a basic material used to preparenuclear reactor fuel. To be suitable for this purpose, thematerial must meet the criteria for technetium composition.This test method is designed to determine whether th
10、e materialmeets the requirements described in Specifications C787 andC996.5.2 Using the specified instrumentation and parameters, thismethod has a lower detection limit of 0.0004 gTc/gU.NOTE 1Different instrumentation or parameters may provide varyingdetection limits, as calculated in 11.4.6. Appara
11、tus6.1 Liquid Scintillation Counter,4with alpha/beta discrimi-nation and enhanced low level discrimination over the entireenergy range of 0 to 2000 keV.6.2 Centrifuge.6.3 Analytical Balance, 1 mg sensitivity.6.4 Separatory Funnel, 125 mL volume.1This test method is under the jurisdiction ofASTM Comm
12、ittee C26 on NuclearFuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods ofTest.Current edition approved June 1, 2014. Published June 2014. Originallyapproved in 2002. Last previous edition approved in 2008 as C1539 08. DOI:10.1520/C1539-08R14.2For referenced ASTM standards,
13、 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.3Available from U.S. Enrichment Corporation, 6903 Rockledge Drive,Bethesda, MD 20817.4The so
14、le source of supply of the apparatus known to the committee at this timeis Packard Tri-Carb Model 1905 AB/LA. If you are aware of alternative suppliers,please provide this information to ASTM International Headquarters. Your com-ments will receive careful consideration at a meeting of the responsibl
15、e technicalcommittee,1which you may attend.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States16.5 Liquid Scintillation Vials, 20 mL.6.6 Centrifuge Tubes with Caps, 50 mL.6.7 Laboratory Wipes, lint free disposable.7. Reagents and Material
16、s7.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee ofAnalytical Reagents of the American Chemical Society wherespecifications are available.57.2 Purity of WaterUnless oth
17、erwise indicated, referencesto water shall be understood to mean laboratory accepteddeionized water.7.3 Ammonium Hydroxide (NH4OH), concentrated (14.5M).7.4 Hydrochloric Acid (HCl), concentrated (12M).7.5 Hydrochloric Acid (HCl), (1M). Add 82 mL of concen-trated (12 M) HCl to 900 mL of water, dilute
18、 to a final volumeof 1000 mL, and mix.7.6 Liquid Scintillation Cocktail.67.7 Potassium Permanganate (KMnO4), 1 % W/V in water.Dissolve1gofKMnO4in 100 mL of water, and mix.7.8 Stannous Chloride (SnCl2), 20 % (W/V) SnCl2in con-centrated hydrochloric acid. Dissolve 20 g of SnCl2in 100 mLof concentrated
19、 hydrochloric acid, and mix.7.9 Sulfuric Acid (H2SO4), concentrated 18M.7.10 Sulfuric Acid (H2SO4), 9M. Add 500 mL concentratedH2SO4(18 M) to 400 mL water, dilute to a final volume of1000 mL, and mix.7.11 Sulfuric Acid (H2SO4), 3M. Add 168 mL of concen-trated H2SO4(18M) to 800 mL of water, dilute to
20、 a finalvolume of 1000 mL, and mix.7.12 Sulfuric Acid (H2SO4), 1M.Add 56 mLof concentratedH2SO4(18M) to 900 mL of water, dilute to a final volume of1000 mL, and mix.7.13 Technetium Standard(s) in a Basic Aqueous Solution.7.14 Tributyl Phosphate (TBP C12H27O4P), saturated solu-tion. Equilibrate 500 m
21、L TBP with 500 mL 3M H2SO4. Shakefor approximately 2 min. Allow to separate and discardaqueous layer.8. Hazards8.1 Since UF6is radioactive, toxic, and highly reactive,especially when reducing substances and moisture are present(see USEC-651), appropriate facilities and practices must beprovided.9. P
22、rocedure9.1 Transfer an aliquot up to 30 mL of one of the followingsolutions, as applicable, to a 50 mL centrifuge tube:9.1.1 Hydrolyzed UF6SampleUnknown UF6sample hy-drolyzed in water.9.1.2 StandardLaboratory control sample with a known99Tc concentration.9.1.3 Spike SolutionUF6sample spiked with a
23、knownconcentration of99Tc (approximately ten times the sampleactivity).9.2 Add 2 drops of potassium permanganate solution (1 %W/V) and swirl to mix.9.3 Dilute with water to approximately 35 mL and swirl tomix.9.4 Add 5 mL concentrated ammonium hydroxide to pre-cipitate uranium.9.5 Dilute with deioni
24、zed water to 50 mL.9.6 Cap and shake vigorously to break up large particles ofammonium diuranate.9.7 Centrifuge for approximately 10 min at approximately1500 rpm.9.8 Add 25 mL 9M H2SO4to a clean 125-mL separatoryfunnel.9.9 Decant the supernatant containing the technetium intothe 125-mL separatory fu
25、nnel.NOTE 2The precipitated uranium remains in the centrifuge tube.9.10 Add 5 mL of TBP solution to the separatory funnel.9.11 Stopper or cap the funnel and shake for approximately60 s.9.12 Allow phases to separate a minimum of 5 min.9.13 Drain off aqueous (lower) phase into a waste beaker.9.14 Add
26、20 mL of 3M H2SO4.9.15 Stopper or cap the funnel and shake for approximately30 to 45 s.9.16 Allow phases to separate for a minimum of 5 min.9.17 Drain off aqueous (lower) phase into a waste beaker.9.18 Pipette up to 4 mL of the extract from the funnel intoa 20 mL scintillation vial.9.19 Pipette 0.2
27、mL stannous chloride solution into the vial.9.20 Pipette 12 mL liquid scintillation cocktail into the vial.NOTE 3This test method has proven acceptable for 12 mL of liquidscintillation cocktail, but up to 16 mL can be added depending on theusers instrumentation.9.21 Cap the vial and shake vigorously
28、 for approximately 5to 10 s.9.22 Wipe the outside of the vial with a damp laboratorywipe to remove static electricity, if necessary.9.23 Place the vial in the liquid scintillation counter.9.24 Allow vial to stand for approximately 15 min prior tocounting.5Reagent Chemicals, American Chemical Society
29、 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 the United States Pharmacopeia andNational Formulary, U.S. Pharmacopeial C
30、onvention, Inc. (USPC), Rockville, MD,or equivalent.6The sole source of supply of the apparatus known to the committee at this timeis Insta-Gel (trademarked). If you are aware of alternative suppliers, please providethis information to ASTM International Headquarters. Your comments will receivecaref
31、ul consideration at a meeting of the responsible technical committee,1whichyou may attend.C1539 08 (2014)210. Counting10.1 Program the liquid scintillation counter according tothe manufacturers guidelines.710.2 Place reagent blank in position one and allow instru-ment to subtract background counts t
32、o obtain net counts perminute (cpm), as needed.10.3 Count vial for three consecutive 10 min counts, andaverage (avg).10.4 Calculate counting efficiency by spiking a knownamount of99Tc into vial containing 4 mL of TBP, 0.2 mL ofSnCl2, and 12 mL of liquid scintillation cocktail.Net cpmdpm of the known
33、 reference value5 Efficiency expressed as a decimal!(1)where:dpm 5 disintegrations per minute10.5 Convert cpm to dpm for the unspiked samples prior toperforming calculations.Avg dpm 5Avg cpmEfficiency expressed as a decimal!(2)11. Calculations11.1 Calculate the99Tc concentration:g99TcgU5A 3yB 3Aliq!
34、 3C 337830(3)where:A = volume (mL) of TBP added to the separatoryfunnel in 9.10,B = uranium concentration in gU/mLof the hydrolyzedUF6,C = aliquot (mL) of extract taken from the separatoryfunnel in 9.18,Aliq = sample (mL) from 9.1.1,37830 = specific activity of99Tc in dpm/g99Tc, andy = average dpm o
35、f sample as obtained in 10.4 and10.5.11.2 Manual Calculation of Spike Recovery8Spike Recovery %! 5Spiked Sampledpm! 2 Sampledpm!#Spike Concentrationdpm!3100(4)11.3 Calculate the minimum detectable activity (MDA)when the background and sample run times are equal.MDA 5314.66 3 =gross counts# 3AT 3B 3A
36、liq 3C 337830 3K5g99TcgU(5)where:4.66 = Curries Factor (a constant to achieve 2error),T = time in min,gross counts = background cpm T, andK = counting yield or counting efficiency ex-pressed as a decimal.NOTE 4Below is an example of some typical values. Please note thatsome values will vary dependin
37、g on the instrumentation used, instrumentsetup, cocktail used, and lower detection limits.T = 30 min as designated in 10.3K = 0.93 to 0.95B = 0.8 to 1.2 g of uranium or a volume of sample 30 mLC =4mL11.4 Calculate the minimum detectable activity (MDA)when the background and sample run times are not
38、equal.MDA 5313.29 3 =Rbtg11tg/tb!# 3Atg3B 3Aliq 3C 337830 K5g99TcgU(6)where:Rb= background, cpm,tg= gross counting time, min, andtb= background counting time, min.12. Precision and Bias12.1 Data9Data are presented for three99Tc controlshaving certified reference values traceable to recognized na-tio
39、nal standards. The three standards were 229 6 3.05dpm99Tc, 1146 6 15.24 dpm99Tc, and 1923 6 21.92 dpm99Tc,where the 6 quantities are at the 2 error for the referencevalues. The standard designations, function, reference valuesand uncertainties are listed in Table 1. The lowest (229 dpm)and highest (
40、1923 dpm) controls were each prepared as alaboratory control sample (LCS) in deionized water to assessthe overall process for an inherent bias. In addition, the 1146dpm99Tc control was prepared as a spike in UF6samples toindicate the appropriateness of the method by measuring99Tcrecovery in UF6. The
41、 UF6samples contained uranium concen-trations ranging from 0.0493 to 0.0675 gU/mL and99Tcconcentrations (prior to spiking) ranging from 0.0001 to 0.0301g99Tc/gU. Each of the three standards was analyzed over twomonths by different analysts in the same laboratory resulting ina total of at least 30 te
42、st results for each standard. Threedifferent analysts analyzed the 229 dpm99Tc and 1923 dpm99Tc7Packard Tri-Carb Model 1905 AB/LA uses a 0.8 to 293 keV counting window.8Spike Recovery is used for Laboratory QA/QC purposes to monitor the qualityof the analysis.9Supporting data, including raw data and
43、 statistical analysis, have been filed atASTM International Headquarters and may be obtained by requesting ResearchReport RR:C26-1011.TABLE 1 Reference ValuesIdentity Function Value Uncertainty (2)SRM 4288A (NIST) LCSA1923 dpm99Tc 1.14 %Amersham LabsBLCS 229 dpm99Tc 1.33 %Amersham Labs UF6spike 1146
44、 dpm99Tc 1.33 %ALCS = laboratory control sample.BAmersham Laboratories meets quality assurance requirements of NuclearRegulatory Commission for achieving implicit traceability.C1539 08 (2014)3laboratory control standards, with five different analysts ana-lyzing the 1146 dpm99Tc laboratory control sa
45、mple. The datawere used to quantify precision and bias.12.2 Due to difficulties in movement and ownership ofnuclear materials, as referred to in section 1.4 of Guide C1215,interlaboratory testing is not practical. The reproducibility wasobtained by treating the analysts as different laboratories. Th
46、isshould be taken into account when considering the reproduc-ibility results.12.3 PrecisionTable 2 summarizes the statistical resultsfor precision, giving both the repeatability and reproducibilityresults obtained using standard analysis of variance (ANOVA)techniques. The absolute standard deviation
47、 increases with99Tc concentration indicating the precision is a function of thetest results (in this case, the relative standard deviation is themore appropriate measure of precision). The relative repeat-ability standard deviation (single analyst) has been determinedto be 2.14 % (averaged over the
48、three standards) while thereproducibility standard deviation (between analysts) was de-termined to be 2.30 % in the same manner. The betweenanalysts variation was not statistically significant at the 99 %level.12.4 BiasTable 2 also summarizes the statistical resultsfor bias estimation. The relative
49、difference of the mean resulton each standard from its reference value, averaged over thethree standards, is 2.94 %, indicating an average recovery of97.1 % on the standards. This difference is an indication ofbias.13. Keywords13.1 scintillation counter; technetium-99; uraniumhexafluorideASTM International takes no position respecting 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, an
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