1、Designation: C1295 14C1295 15Standard 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 adop
2、tion 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 measurement of gamma energy emitted from fis
3、sion and decay products in uranium hexafluoride(UF6) and uranyl nitrate solution. This test method may also be used to measure the concentration of some uranium decay products.It is intended to provide a method for demonstrating compliance with UF6 specifications C787 and C996, uranyl nitratespecifi
4、cation C788, and uranium ore concentrate specification C967.1.2 The lower limit of detection is 5000 MeV Bq/kg (MeV/kg per second) of uranium and is the square root of the sum of thesquares of the individual reporting limits of the nuclides to be measured. The limit of detection was determined on a
5、pure, agednatural uranium (ANU) solution. The value is dependent upon detector efficiency and background.1.3 The fission product nuclides to be measured are 106Ru/106Rh, 103Ru, 137Cs, 144Ce, 144Pr, 141Ce, 95Zr, 95Nb, and 125Sb.Among the uranium decay product nuclides that may be measured is 231Pa. O
6、ther gamma energy-emitting fission and uraniumdecay nuclides present in the spectrum at detectable levels should be identified and quantified as required by the data qualityobjectives.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
7、 standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Refe
8、renced Documents2.1 ASTM Standards:2C761 Test Methods for Chemical, Mass Spectrometric, Spectrochemical, Nuclear, and Radiochemical Analysis of UraniumHexafluorideC787 Specification for Uranium Hexafluoride for EnrichmentC788 Specification for Nuclear-Grade Uranyl Nitrate Solution or CrystalsC859 Te
9、rminology Relating to Nuclear MaterialsC967 Specification for Uranium Ore ConcentrateC996 Specification for Uranium Hexafluoride Enriched to Less Than 5 % 235UC1022 Test Methods for Chemical and Atomic Absorption Analysis of Uranium-Ore ConcentrateD3649 Practice for High-Resolution Gamma-Ray Spectro
10、metry of WaterE181 Test Methods for Detector Calibration and Analysis of Radionuclides3. Terminology3.1 Except as otherwise defined herein, definitions of terms are as given in Terminology C859.4. Summary of Test Method4.1 A solution of the uranium sample is counted on a high-resolution gamma-ray sp
11、ectrometry system. The resulting spectrumis analyzed to determine the identity and activity of the gamma-ray-emitting radioactive fission and decay products. The number1 This test method is under the jurisdiction of ASTM Committee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcomm
12、ittee C26.05 on Methods of Test.Current edition approved June 15, 2014June 1, 2015. Published July 2014July 2015. Originally approved in 1995. Last previous edition approved in 20132014 asC1295 13.C1295 14. DOI: 10.1520/C1295-14.10.1520/C1295-15.2 For referencedASTM standards, visit theASTM website,
13、 www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of
14、 what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered
15、 the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1of counts recorded from one or more of the peaks identified with each fission nuclide is converted to disintegrations of that nuclideper second (Bq). The gamma-ray
16、 energy for a fission nuclide is calculated by multiplying the number of disintegrations per secondof the nuclide by the mean gamma-ray energy emission rate of the nuclide. The calculated gamma-ray energy emission rates forall observed fission nuclides are summed, then divided by the mass of the ura
17、nium in the sample to calculate the overall rate ofgamma energy production in units of million electron volts per second per kilogram of uranium. Decay product nuclides such as231Pa will be separately quantified and reported based on specific needs.5. Significance and Use5.1 Specific gamma-ray emitt
18、ing radionuclides in UF6 are identified and quantified using a high-resolution gamma-ray energyanalysis system, which includes a high-resolution germanium detector. This test method shall be used to meet the health and safetyspecifications of C787, C788, and C996 regarding applicable fission product
19、s in reprocessed uranium solutions. This test methodmay also be used to provide information to parties such as conversion facilities on the level of uranium decay products in suchmaterials. Pa-231 is a specific uranium decay product that may be present in uranium ore concentrate and is amenable to a
20、nalysisby gamma spectrometry.6. Apparatus6.1 High-Resolution Gamma-Ray Spectrometry System, as specified in Practice D3649. The energy response range of thespectrometry system may need to be tailored to address all the needed fission and uranium decay product nuclides that need to beanalyzed for.6.2
21、 Sample Container with Fitted CapA leak-proof plastic container capable of holding the required sample volume. Thedimensions must be consistent between containers used for samples and standard to keep the counting geometry constant. Thegreatest detection efficiency will be achieved with a low-height
22、 sample container with a diameter slightly smaller than the detectorbeing used.6.3 Sample Holder, shall be used to position the sample container such that the detector view of the sample is reproducible. Toreduce the effects of coincident summing, the sample holder shall provide a minimum separation
23、 of 5 mm between the samplecontainer and the detector end cap.7. Calibration and Standardization of Detector7.1 Prepare a mixed radionuclide calibration standard stock solution covering the energy range of approximately 50 to 2000keV.7.1.1 Commercial calibration standards are available which are tra
24、ceable to NIST or other national standards laboratories.7.2 Prepare a solution of ANU at 6.74 gU/100 g. The uranium and its progenys relationship must not have been altered for atleast eight months.7.3 Transfer a known, suitable activity of the mixed nuclide calibration standard stock solution (40 t
25、o 50 kBq) to a containeridentical to that used for the sample measurement. Add ANU solution to the mixed nuclide standard so that the final volume anduranium concentration match those expected in the sample measurement. Test Methods E181 and Practice D3649 providesinformation on calibration of detec
26、tor energy, efficiency, resolution, and other parameters.7.4 The detector energy scale and efficiency are calibrated by placing the container with the mixed nuclide calibration standardin a sample holder that provides a reproducible geometry relative to the detector. Collect a spectrum over a period
27、 up to 1 h thatincludes all the gamma photopeaks in the energy range up to ;2000 keV. All counting conditions (except count duration) mustbe identical to those that will be used for analysis of the actual sample.7.5 Determine the net counts under each peak of every nuclide in the mixed radionuclide
28、standard, then divide by the countduration (live time) to determine the rate in counts per second for each radionuclide. If a background count on the detector showsany net peak area for the peaks of interest, these must be subtracted from the standard counts per second.7.6 Divide the observed count
29、rate determined for each gamma peak by the calculated emission rate of the gamma ray thatproduced the peak in the mixed calibration standard (gammas per second).7.6.1 Calculation of the gamma emission rate for each peak from the mixed calibration standard must account for the following:7.6.1.1 Activ
30、ity of the nuclide that produces the peak in its original standard (disintegrations/second/unit volume). This is takenfrom the standard certificate of measurement supplied with the standard.7.6.1.2 Volume of each isotopic standard taken for the mixed standard and the final volume of the mixed standa
31、rd.7.6.1.3 Fraction of the volume of the mixed standard taken for counting.7.6.1.4 Decay of the activity of each isotope in the standard between its date of standardization and the date of countingaccording to the equation:Ai 5Ai0e2it (1)C1295 152where:Ai = activity of isotope i on the date of count
32、ing in Bq,Ai0 = activity of isotope i on the date of standard characterization in Bq,i = decay constant of isotope i in units of inverse time (values for some isotopes of interest may be found in column 3 of Table1), andt = elapsed time between the calibration reference date and the date of counting
33、. Time units must be the same as in the decayconstant.7.6.1.5 The abundance of gamma rays of the energy of interest emitted by each disintegration (see Table 1).7.7 Plot a detector efficiency curve of counts/gamma versus gamma energy. Most multichannel analyzers and associatedsoftware are able to st
34、ore individual values from this curve or the equation of the curve for later use.7.8 This efficiency calibration will remain valid provided none of the sample or instrument parameters are changed (forexample, volume of sample, container geometry, distance from detector, and detector) and instrument
35、response to the controlstandard remains within the statistical limits established.8. Measurement of Control Standard Solution8.1 Measure the control standard solution prepared in 6.37.3 with the geometry as used during detector efficiency calibration.Ten measurements of the control standard solution
36、 are made. The calculated data for the fission products is used to establishprecision and bias of the test method.8.1.1 Most multichannel analyzers and associated software have automatic routines for determining the net counts under singlepeaks and double peaks that are not resolved. If the availabl
37、e analyzer does not have such capabilities, refer to Reilly3 forsingle-peak analysis methods and 7.2.18.2.1 and 7.2.28.2.2 for double-peak problems that are likely to be encountered.8.1.2 Peaks that are determined for this analysis are listed in Table 1,4 along with the abundance factors, decay cons
38、tants, andthe mean gamma energy per disintegration for each nuclide. Needed information for uranium decay products can be found inReferenceFootnote 44 or other available sources.8.2 While most full-energy gamma emissions are generally characteristic of specific radionuclides, it is possible that unr
39、esolvedmultiplets may produce biased peak areas. Determination of the following peak areas may cause problems during calibration orsample measurements.8.2.1 The peak produced by the 765.9-keV gamma ray of 95Nb is not resolved from the peak produced by the 766.4-keV gammaray of 234mPa, a progeny radi
40、onuclide of 238U. The following procedure is suggested to determine the count rate of 95Nb in thedouble peak.8.2.1.1 Perform a series of count measurements for periods up to 1 h of a sample of ANU under the same conditions as thecalibration standard or sample. The counting period should be adjusted
41、so that the counting uncertainties are less than 1 % for theappropriate peaks of interest.8.2.1.2 For each measurement, determine the ratio of counts in the 234mPa peaks at 766.4 and 1001 keV using the equation:3 Reilly, T. D., and Parker, J. L., A Guide to Gamma-Ray Assay for Nuclear Materials Acco
42、untability, LA-5794M,LA-5794-M, Los Alamos National Laboratory, 1975.DOI: 10.2172/4210151.4 The information in Table 1 for fission products is from the Joint European File: 1 data file supplied by the Nuclear EnergyAgency, Paris, France. The user may use otherpublished data. The uranium decay produc
43、t information in Table 1 is from L.P. Ekstrm and R.B. Firestone, WWW Table of Radioactive Isotopes, database version 2/28/99from URL http:/ie.lbl.gov/toi/index.htm. The user may use other published data for uranium decay products.TABLE 1 Gamma-Ray-Emitting Fission and Decay Products Found in UF6Nucl
44、ide Half-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 284
45、.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 153RPa5C766 total/C1001 (
46、2)where:RPa = ratio of counts in the 766.4 and 1001-keV peaks of 234mPa,C766 total = total counts in the double peak near 766 keV, andC1001 = counts in the 1001-keV peak of 234mPa.8.2.1.3 Calculate the mean value for the ratio (RPa).8.2.1.4 Determine the 95Nb counts at 765.9 keV by use of the equati
47、on:CNb5C766 total2C1001!RHPa!# (3)where:CNb = counts in the peak near 766 keV resulting from 765.9-keV gamma rays of 95Nb.8.2.2 The peak produced by the 145.4-keV gamma ray of 141Ce is not resolved from the peak produced by the 143.8-keVgamma ray of 235U. The following procedure is suggested to dete
48、rmine the count rate of 141Ce in the double peak.8.2.2.1 Perform a series of measurements of up to 1-h counting time of a sample of ANU under the same conditions as thecalibration standard or sample.8.2.2.2 For each measurement, determine the ratio of counts in the 235U peaks at 143.8 and 185.7 keV
49、using the equation:RU5C144 total/C185.7 (4)where:RU = ratio of counts in the 143.8 and 185.7-keV peaks of 235U,C144 total = total counts in the double peak near 144 keV, andC185.7 = counts in the 185.7-keV peak of 235U.8.2.2.3 Calculate the mean value for the ratio (RU).8.2.2.4 Determine the 141Ce counts at 145.4 keV by use of the equation:CCe5C144 total2C185!RHU!# (5)where:CCe = counts in the peak near 144 keV resulting from 145.4-keV gamma rays of 141Ce.9. Procedure9.1 Hydrolyze a UF6 sample as in Test Method C761, dissolve a uranium ore concentrate sample usi
