1、Designation: C1295 05C1295 13Standard 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. It is intended to provide a method for demonstrating compliance with UF6 specifications C787and C996 and uranyl nitrate specification C788.1.2 The lower limit of detection is 5000 MeV Bq/kg (MeV/kg per second) of urani
4、um 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 pure, agednatural uranium (ANU) solution. The value is dependent upon detector efficiency and background.1.3 The nuclides to be measured ar
5、e 106Ru/106Rh, 103Ru,137Cs, 144Ce, 144Pr, 141Ce, 95Zr, 95Nb, and 125Sb. Other gamma energy-emitting fission nuclides present in the spectrum atdetectable levels should be identified and quantified as required by the data quality objectives.1.4 The values stated in SI units are to be regarded as stan
6、dard. No other units of measurement are included in this 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 app
7、licability of regulatorylimitations prior to use.2. Referenced 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
8、Nuclear-Grade Uranyl Nitrate Solution or CrystalsC996 Specification for Uranium Hexafluoride Enriched to Less Than 5 % 235UD3649 Practice for High-Resolution Gamma-Ray Spectrometry of Water3. Summary of Test Method3.1 A solution of the uranium sample is counted on a high-resolution gamma-ray spectro
9、scopyspectrometry system. Theresulting spectrum is analyzed to determine the identity and activity of the gamma-ray-emitting radioactive fission and decayproducts. The number of counts recorded from one or more of the peaks identified with each fission nuclide is converted todisintegrations of that
10、nuclide per second (Bq).The gamma-ray energy for a fission nuclide is calculated by multiplying the numberof disintegrations per second of the nuclide by the mean gamma-ray energy emission rate of the nuclide. The calculated gamma-rayenergy emission rates for all observed fission nuclides are summed
11、, then divided by the mass of the uranium in the sample tocalculate the overall rate of gamma energy production in units of million electron volts per second per kilogram of uranium. Decayproduct nuclides will be separately quantified and reported based on specific needs.4. Significance and Use4.1 T
12、heSpecific gamma-ray emitting fission products radionuclides in UF6 are identified and quantified using a high-resolutiongamma-ray energy analysis system, which includes a high-resolution germanium detector. This test method shall be used to meet1 This test method is under the jurisdiction of ASTM C
13、ommittee C26 on Nuclear Fuel Cycle and is the direct responsibility of Subcommittee C26.05 on Methods of Test.Current edition approved July 1, 2005Feb. 15, 2013. Published August 2005March 2013. Originally approved in 1995. Last previous edition approved in 19982005 asC1295 98.C1295 05. DOI: 10.1520
14、/C1295-05.10.1520/C1295-13.2 For referencedASTM standards, visit theASTM website, 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 stand
15、ard and is intended only to provide the user of an ASTM standard an indication of 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
16、 only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1the health and safety specifications of C787, C788, and C996 regarding applicable
17、fission products in reprocessed uraniumsolutions. This test method may also be used to provide information to parties such as conversion facilities on the level of uraniumdecay products in such materials.5. Apparatus5.1 High-Resolution Gamma-Ray Spectrometry System, as specified in Practice D3649.5.
18、2 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-heigh
19、t sample container with a diameter slightly smaller than the detectorbeing used.5.3 Sample Holder, shall be used to position the sample container such that the detector view of the sample is reproducible. Tominimizereduce the effects of coincident summing, the sample holder shall provide a minimum s
20、eparation of 5 mm between thesample container and the detector end cap.6. Calibration and Standardization of Detector6.1 Prepare a mixed radionuclide calibration standard stock solution covering the energy range of approximately 50 to 2000keV.6.1.1 Commercial calibration standards are available. ava
21、ilable which are traceable to NIST or other national standardslaboratories.6.2 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.6.3 Transfer a known, suitable activity of the mixed nuclide calibration standard s
22、tock solution (40 to 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. Practice D3649 provides information on calibration ofdetector
23、 energy, efficiency, resolution, and other parameters.6.4 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 up
24、 to 1 h thatincludes all the gamma photopeaks in the energy range up to ;2000 keV. All counting conditions (except count time)duration)must be identical to those that will be used for analysis of the actual sample.6.5 Determine the net counts under each peak of every nuclide in the mixed radionuclid
25、e standard, then divide by the counttimeduration (live time) to determine the rate in counts per second for each radionuclide. If a background count on the detectorshows any net peak area for the peaks of interest, these must be subtracted from the standard counts per second.6.6 Divide the observed
26、count 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).TABLE 1 Gamma-Ray-Emitting Fission Products Found in UF6colwidth=“0.83in“/COLSPECNuclide Half-LifeDecayConstant(I)MeasurementPeaks,Me
27、VAbundanceGamma/Disintegration(GI)Mean GammaEnergyDisintegration,MeVBq (EI)103Ru/103Rh 39.35d 0.01761/d 0.4971 0.889 0.484103Ru/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 0.209106Ru/106Rh 366.5d 0.001891/d 0.5119 0.207 0.2090.62220.0981141Ce 32.55
28、d 0.02129/d 0.1454 0.484 0.0718141Ce 32.55d 0.02129/d 0.1454 0.484 0.0718144Ce/144Pr 284.5d 0.002436/d 0.1335 0.1110 0.0518144Ce/144Pr 284.5d 0.002436/d 0.1335 0.1110 0.0518137Cs/137Ba 30.17y 0.02297/y 0.6616 0.851 0.5655137Cs/137Ba 30.17y 0.02297/y 0.6616 0.851 0.565595Nb 34.97d 0.01982/d 0.7658 1.
29、000 0.76695Nb 34.97d 0.01982/d 0.7658 1.000 0.76695Zr 63.98d 0.01083/d 0.7242 0.444 0.73795Zr 63.98d 0.01083/d 0.7242 0.444 0.7370.7567 0.549125Sb 2.71y 0.256/y 0.4279 0.294 0.433125Sb 2.71y 0.256/y 0.4279 0.294 0.4330.6008 0.178C1295 1326.6.1 Calculation of the gamma emission rate for each peak fro
30、m the mixed calibration standard must account for the following:6.6.1.1 Activity 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.6.6.1.2 Volume of each isotopic s
31、tandard taken for the mixed standard and the final volume of the mixed standard.6.6.1.3 Fraction of the volume of the mixed standard taken for counting.6.6.1.4 Decay of the activity of each isotope in the standard between its date of standardization and the date of countingaccording to the equation:
32、Ai 5Ai0e2it (1)where:Ai = activity of isotope i on the date of counting 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
33、time between the calibration reference date and the date of counting. Time units must be the same as in the decayconstant.6.6.1.5 The abundance of gamma rays of the energy of interest emitted by each disintegration (see Table 1).6.7 Plot a detector efficiency curve of counts/gamma versus gamma energ
34、y. Most multichannel analyzers and data reductionprograms associated software are able to store individual values from this curve or the equation of the curve for later use.6.8 This efficiency calibration will remain valid provided none of the sample or instrument parameters are changed (forexample,
35、 volume of sample, container geometry, distance from detector, and detector) 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 6.3 with the geometry as used
36、 during detector efficiency calibration. Tenmeasurements of the control standard solution are made. The calculated data for the fission products is used to establish precisionand bias of the test method.7.1.1 Most multichannel analyzers and associated software have automatic routines for determining
37、 the net counts under singlepeaks and double peaks that are not resolved. If the available analyzer does not have such capabilities, refer to Reilly3 forsingle-peak analysis methods and 7.2.1 and 7.2.2 for double-peak problems that are likely to be encountered.7.1.2 Peaks that are determined for thi
38、s analysis are listed in Table 1,4 along with the abundance factors, decay constants, andthe mean gamma energy per disintegration for each nuclide. Needed information for uranium decay products can be found inReference 44 or other available sources.7.2 While most full-energy gamma emissions are gene
39、rally characteristic of specific radionuclides, it is possible that unresolvedmultiplets may produce biased peak areas. Determination of the following peak areas may cause problems during calibration orsample measurements.7.2.1 The peak produced by the 765.9-keV gamma ray of 95Nb is not resolved fro
40、m the peak produced by the 766.4-keV gammaray of 234mPa, a daughter progeny radionuclide of 238U. The following procedure is suggested to determine the count rate of 95Nbin the double peak.7.2.1.1 Perform a series of count measurements for periods up to 1 h of a sample of ANU under the same conditio
41、ns as thecalibration standard or sample. The counting period should be adjusted so that the counting errorsuncertainties are less than 1 %for the appropriate peaks of interest.7.2.1.2 For each measurement, determine the ratio of counts in the 234mPa peaks at 766.4 and 1001 keV using the equation:RPa
42、5C766 total/C1001 (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.7.2.1.3 Calculate the mean value for the ratio (RPa).7.2.1.4 Determine the 95Nb counts at 765.9 keV b
43、y use of the equation:CNb5C766 total2C1001!RHPa!# (3)3 Reilly, T. D., and Parker, J. L., A Guide to Gamma Ray Gamma-Ray Assay for Nuclear Materials Accountability, LA-5794M, Los Alamos National Laboratory, 1975.4 The information in Table 1 is from the Joint European File: 1 data file supplied by the
44、 Nuclear Energy Agency, Paris, France. The user may use other published data.C1295 133where:CNb = counts in the peak near 766 keV resulting from 765.9-keV gamma rays of 95Nb.7.2.2 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 o
45、f 235U. The following procedure is suggested to determine the count rate of 141Ce in the double peak.7.2.2.1 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.7.2.2.2 For each measurement, determine the ratio
46、 of counts in the 235U peaks at 143.8 and 185.7 keV 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.7.2.2.3 Calculate the mean va
47、lue for the ratio (RU).7.2.2.4 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.8. Procedure8.1 Hydrolyze the UF6 sample for counting as in Test Method C761 or prepare
48、the uranyl nitrate solution sample. Ensure thatsample preparation parameters (solution volume, uranium concentration, sample container, geometry, and so forth) are the sameas used during detector efficiency calibration. Note the mass of uranium (W) taken in grams.8.2 Place the container and sample i
49、nto the counter with the same geometry as used during detector efficiency calibration. Countthe sample for 60 min to collect a gamma spectrum of the sample.8.3 Determine the net counts under one or more peaks for each nuclide, then divide by the count timeduration (live time) todetermine the count rate for each gamma peak in counts per second. See 7.2.1 and 7.2.2 for methods to deal with unresolved doublepeaks.9. Calculation9.1 Determine the gamma energy release rate for each nuclide according to the following equation:Fi 51000W 3 CiEff3Gi3Ei (6)where:Fi = rate of
