1、Designation: C1295 14Standard Test Method forGamma Energy Emission from Fission and Decay Productsin Uranium Hexafluoride and Uranyl Nitrate Solution1This standard is issued under the fixed designation C1295; 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 covers the measurement of gammaenergy emitted from fission and
3、decay products in uraniumhexafluoride (UF6) and uranyl nitrate solution. It is intended toprovide a method for demonstrating compliance with UF6specifications C787 and C996, uranyl nitrate specificationC788, and uranium ore concentrate specification C967.1.2 The lower limit of detection is 5000 MeV
4、Bq/kg(MeV/kg per second) of uranium and is the square root of thesum of the squares of the individual reporting limits of thenuclides to be measured. The limit of detection was determinedon a pure, aged natural uranium (ANU) solution. The value isdependent upon detector efficiency and background.1.3
5、 The fission product nuclides to be measured are106Ru/106Rh,103Ru,137Cs,144Ce,144Pr,141Ce,95Zr,95Nb, and125Sb.Among the uranium decay product nuclides that may bemeasured is231Pa. Other gamma energy-emitting fission anduranium decay nuclides present in the spectrum at detectablelevels should be iden
6、tified and quantified as required by thedata quality objectives.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is
7、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 Standards:2C761 Test Methods for Chemical, Mass Spectrometric,Spectrochemical, Nuclear, and Rad
8、iochemicalAnalysis ofUranium HexafluorideC787 Specification for Uranium Hexafluoride for Enrich-mentC788 Specification for Nuclear-Grade Uranyl Nitrate Solu-tion or CrystalsC967 Specification for Uranium Ore ConcentrateC996 Specification for Uranium Hexafluoride Enriched toLess Than 5 %235UC1022 Tes
9、t Methods for Chemical and Atomic AbsorptionAnalysis of Uranium-Ore ConcentrateD3649 Practice for High-Resolution Gamma-Ray Spectrom-etry of Water3. Summary of Test Method3.1 A solution of the uranium sample is counted on ahigh-resolution gamma-ray spectrometry system. The resultingspectrum is analy
10、zed to determine the identity and activity ofthe gamma-ray-emitting radioactive fission and decay prod-ucts. The number of counts recorded from one or more of thepeaks identified with each fission nuclide is converted todisintegrations of that nuclide per second (Bq). The gamma-rayenergy for a fissi
11、on nuclide is calculated by multiplying thenumber of disintegrations per second of the nuclide by themean gamma-ray energy emission rate of the nuclide. Thecalculated gamma-ray energy emission rates for all observedfission nuclides are summed, then divided by the mass of theuranium in the sample to
12、calculate the overall rate of gammaenergy production in units of million electron volts per secondper kilogram of uranium. Decay product nuclides such as231Pawill be separately quantified and reported based on specificneeds.4. Significance and Use4.1 Specific gamma-ray emitting radionuclides in UF6a
13、reidentified and quantified using a high-resolution gamma-rayenergy analysis system, which includes a high-resolutiongermanium detector. This test method shall be used to meet thehealth and safety specifications of C787, C788, and C996regarding applicable fission products in reprocessed uraniumsolut
14、ions. This test method may also be used to provideinformation to parties such as conversion facilities on the level1This 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
15、June 15, 2014. Published July 2014. Originallyapproved in 1995. Last previous edition approved in 2013 as C1295 13. DOI:10.1520/C1295-14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume i
16、nformation, 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 States1of uranium decay products in such materials. Pa-231 is aspecific uranium decay product that may be present in
17、uraniumore concentrate and is amenable to analysis by gamma spec-trometry.5. Apparatus5.1 High-Resolution Gamma-Ray Spectrometry System, asspecified in Practice D3649. The energy response range of thespectrometry system may need to be tailored to address all theneeded fission and uranium decay produ
18、ct nuclides that need tobe analyzed for.5.2 Sample Container with Fitted CapAleak-proof plasticcontainer capable of holding the required sample volume. Thedimensions must be consistent between containers used forsamples and standard to keep the counting geometry constant.The greatest detection effic
19、iency will be achieved with alow-height sample container with a diameter slightly smallerthan the detector being used.5.3 Sample Holder, shall be used to position the samplecontainer such that the detector view of the sample is repro-ducible. To reduce the effects of coincident summing, thesample ho
20、lder shall provide a minimum separation of 5 mmbetween the sample container and the detector end cap.6. Calibration and Standardization of Detector6.1 Prepare a mixed radionuclide calibration standard stocksolution covering the energy range of approximately 50 to2000 keV.6.1.1 Commercial calibration
21、 standards are available whichare traceable to NIST or other national standards laboratories.6.2 Prepare a solution of ANU at 6.74 gU/100 g. Theuranium and its progenys relationship must not have beenaltered for at least eight months.6.3 Transfer a known, suitable activity of the mixed nuclidecalibr
22、ation standard stock solution (40 to 50 kBq) to acontainer identical to that used for the sample measurement.Add ANU solution to the mixed nuclide standard so that thefinal volume and uranium concentration match those expectedin the sample measurement. Practice D3649 provides informa-tion on calibra
23、tion of detector energy, efficiency, resolution,and other parameters.6.4 The detector energy scale and efficiency are calibratedby placing the container with the mixed nuclide calibrationstandard in a sample holder that provides a reproduciblegeometry relative to the detector. Collect a spectrum ove
24、r aperiod up to 1 h that includes all the gamma photopeaks in theenergy range up to ;2000 keV.All counting conditions (exceptcount duration) must be identical to those that will be used foranalysis of the actual sample.6.5 Determine the net counts under each peak of everynuclide in the mixed radionu
25、clide standard, then divide by thecount duration (live time) to determine the rate in counts persecond for each radionuclide. If a background count on thedetector shows any net peak area for the peaks of interest, thesemust be subtracted from the standard counts per second.6.6 Divide the observed co
26、unt rate determined for eachgamma peak by the calculated emission rate of the gamma raythat produced the peak in the mixed calibration standard(gammas per second).6.6.1 Calculation of the gamma emission rate for each peakfrom the mixed calibration standard must account for thefollowing:6.6.1.1 Activ
27、ity of the nuclide that produces the peak in itsoriginal standard (disintegrations/second/unit volume). This istaken from the standard certificate of measurement suppliedwith the standard.6.6.1.2 Volume of each isotopic standard taken for themixed standard and the final volume of the mixed standard.
28、6.6.1.3 Fraction of the volume of the mixed standard takenfor counting.6.6.1.4 Decay of the activity of each isotope in the standardbetween its date of standardization and the date of countingaccording to the equation:Ai5 Ai0e2it(1)TABLE 1 Gamma-Ray-Emitting Fission and Decay Products Found in UF6Nu
29、clideHalf-LifeDecayConstant(I)MeasurementPeaks,MeVAbundanceGamma/Disintegration(GI)Mean GammaEnergyDisintegration,MeVBq (EI)103Ru/103Rh 39.35d 0.01761/d 0.4971 0.889 0.4840.6103 0.056106Ru/106Rh 366.5d 0.001891/d 0.5119 0.207 0.2090.6222 0.0981141Ce 32.55d 0.02129/d 0.1454 0.484 0.0718144Ce/144Pr 28
30、4.5d 0.002436/d 0.1335 0.1110 0.0518137Cs/137Ba 30.17y 0.02297/y 0.6616 0.851 0.565595Nb 34.97d 0.01982/d 0.7658 1.000 0.76695Zr 63.98d 0.01083/d 0.7242 0.444 0.7370.7567 0.549125Sb 2.71y 0.256/y 0.4279 0.294 0.4330.6008 0.178231Pa 32760y 2.1158E-05/y 0.002736 0.103 n/aC1295 142where:Ai= activity of
31、 isotope i on the date of counting in Bq,Ai0= activity of isotope i on the date of standard character-ization in Bq,i= decay constant of isotope i in units of inverse time(values for some isotopes of interest may be found incolumn 3 of Table 1), andt = elapsed time between the calibration reference
32、dateand the date of counting. Time units must be the sameas in the decay constant.6.6.1.5 The abundance of gamma rays of the energy ofinterest emitted by each disintegration (see Table 1).6.7 Plot a detector efficiency curve of counts/gamma versusgamma energy. Most multichannel analyzers and associa
33、tedsoftware are able to store individual values from this curve orthe equation of the curve for later use.6.8 This efficiency calibration will remain valid providednone of the sample or instrument parameters are changed (forexample, volume of sample, container geometry, distance fromdetector, and de
34、tector) and instrument response to the controlstandard remains within the statistical limits established.7. Measurement of Control Standard Solution7.1 Measure the control standard solution prepared in 6.3with the geometry as used during detector efficiency calibra-tion. Ten measurements of the cont
35、rol standard solution aremade. The calculated data for the fission products is used toestablish precision and bias of the test method.7.1.1 Most multichannel analyzers and associated softwarehave automatic routines for determining the net counts undersingle peaks and double peaks that are not resolv
36、ed. If theavailable analyzer does not have such capabilities, refer toReilly3for single-peak analysis methods and 7.2.1 and 7.2.2for double-peak problems that are likely to be encountered.7.1.2 Peaks that are determined for this analysis are listed inTable 1,4along with the abundance factors, decay
37、constants,and the mean gamma energy per disintegration for eachnuclide. Needed information for uranium decay products canbe found in Reference 44or other available sources.7.2 While most full-energy gamma emissions are generallycharacteristic of specific radionuclides, it is possible thatunresolved
38、multiplets may produce biased peak areas. Deter-mination of the following peak areas may cause problemsduring calibration or sample measurements.7.2.1 The peak produced by the 765.9-keV gamma rayof95Nb is not resolved from the peak produced by the766.4-keV gamma ray of234mPa, a progeny radionuclide
39、of238U. The following procedure is suggested to determine thecount rate of95Nb in the double peak.7.2.1.1 Perform a series of count measurements for periodsupto1hofasample ofANU under the same conditions as thecalibration standard or sample. The counting period should beadjusted so that the counting
40、 uncertainties are less than 1 % forthe appropriate peaks of interest.7.2.1.2 For each measurement, determine the ratio of countsin the234mPa peaks at 766.4 and 1001 keV using the equation:RPa5 C766 total/C1001(2)where:RPa= ratio of counts in the 766.4 and 1001-keV peaksof234mPa,C766 total= total co
41、unts in the double peak near 766 keV, andC1001= counts in the 1001-keV peak of234mPa.7.2.1.3 Calculate the mean value for the ratio (RPa).7.2.1.4 Determine the95Nb counts at 765.9 keV by use ofthe equation:CNb5 C766 total2 C1001!RHPa!# (3)where:CNb= counts in the peak near 766 keV resulting from765.
42、9-keV gamma rays of95Nb.7.2.2 The peak produced by the 145.4-keV gamma rayof141Ce is not resolved from the peak produced by the143.8-keV gamma ray of235U. The following procedure issuggested to determine the count rate of141Ce in the doublepeak.7.2.2.1 Perform a series of measurements of up to 1-hco
43、unting time of a sample of ANU under the same conditionsas the calibration standard or sample.7.2.2.2 For each measurement, determine the ratio of countsin the235U peaks at 143.8 and 185.7 keV using the equation:RU5 C144 total/C185.7(4)where:RU= ratio of counts in the 143.8 and 185.7-keV peaksof235U
44、,C144 total= total counts in the double peak near 144 keV, andC185.7= counts in the 185.7-keV peak of235U.7.2.2.3 Calculate the mean value for the ratio (RU).7.2.2.4 Determine the141Ce counts at 145.4 keV by use ofthe equation:CCe5 C144 total2 C185!RHU!# (5)where:CCe= counts in the peak near 144 keV
45、 resulting from145.4-keV gamma rays of141Ce.8. Procedure8.1 Hydrolyze a UF6sample as in Test Method C761,dissolve a uranium ore concentrate sample using suitableapproach in Test Method C1022, or prepare the uranyl nitratesolution sample. Ensure that sample preparation parameters(solution volume, ura
46、nium concentration, sample container,geometry, and so forth) are the same as used during detectorefficiency calibration. Note the mass of uranium (W) taken ingrams.3Reilly, T. D., and Parker, J. L., A Guide to Gamma-Ray Assay for NuclearMaterials Accountability, LA-5794M, Los Alamos National Laborat
47、ory, 1975.4The information in Table 1 for fission products is from the Joint European File:1 data file supplied by the Nuclear Energy Agency, Paris, France. The user may useother published data. The uranium decay product information in Table 1 is from L.P.Ekstrm and R.B. Firestone, WWWTable of Radio
48、active Isotopes, database version2/28/99 from URL http:/ie.lbl.gov/toi/index.htm. The user may use other publisheddata for uranium decay products.C1295 1438.2 Place the container and sample into the counter with thesame geometry as used during detector efficiency calibration.Count the sample for 60
49、min to collect a gamma spectrum ofthe sample.8.3 Determine the net counts under one or more peaks foreach nuclide, then divide by the count duration (live time) todetermine the count rate for each gamma peak in counts persecond. See 7.2.1 and 7.2.2 for methods to deal with unre-solved double peaks.9. Calculation9.1 Determine the gamma energy release rate for eachnuclide according to the following equation:Fi51000W3CiEff3Gi3Ei(6)where:Fi= rate of energy released in gamma radiation as a resultof fission nuclide i decay in MeV Bq/kg U (MeV/kgper second),Ci= count rate
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1