1、Designation: D7727 11Standard Practice forCalculation of Dose Equivalent Xenon (DEX) for RadioactiveXenon Fission Products in Reactor Coolant1This standard is issued under the fixed designation D7727; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、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 practice applies to the calculation of the doseequivalent to133Xe in the reactor co
3、olant of nuclear powerreactors resulting from the radioactivity of all noble gas fissionproducts.1.2 The values given in parentheses are mathematical con-versions to SI units, which are provided for information onlyand are not considered standard.1.3 The values stated in inch-pound units are to be r
4、egardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.2. Referenced Documents2.1 ASTM Standards:D3648 Practices for the Measurement of RadioactivityD7282 Practice for Set-up, Calibration, and
5、Quality Controlof Instruments Used for Radioactivity Measurements3. Terminology3.13.1.1 DOSE-EQUIVALENT XE-133 (DEX), nshall be that133Xe concentration (microcuries per gram) that alone wouldproduce the same acute dose to the whole body as thecombined activities of noble-gas nuclides85mKr,85Kr,87Kr,
6、88Kr,131mXe,133mXe,133Xe,135mXe,135Xe, and138Xe actually present.NOTE 1This is the general definition of DEX. Each utility may haveadopted modifications to this definition through agreement with the USNuclear Regulatory Commission (USNRC). The definition as approvedfor each utility by the USNRC, is
7、the one that should be applied to thecalculations in this method.4. Summary of Practice4.1 A sample of fresh reactor coolant is analyzed for noblegas activities using gamma ray spectrometry. The individualactivity of each detectable radioactive fission gas is divided bya factor that normalizes its d
8、ose to that of133Xe. This practiceis to replace the previous practice of calculating the reactorcoolant Ecalculation when allowed by the plants revisedtechnical specifications. The quantity DEX is acceptable froma radiological dose perspective since it will result in a limitingcondition of operation
9、 (LCO) that more closely relates thenon-iodine RCS activity limits to the dose consequence analy-ses which form their bases.NOTE 2It is incumbent on the licensee to ensure that the doseconversion factors (DCFs) used in the determination of DEX are consis-tent with the DCFs used in the applicable dos
10、e consequence analysis usedby the plant in their dose calculation manual for radioactive releases.5. Significance and Use5.1 Each power reactor has a specific DEX value that istheir technical requirement limit. These values may vary fromabout 200 to about 900 Ci/g based upon the height of theirplant
11、 vent the location of the site boundary, the calculatedreactor coolant activity for a condition of 1% fuel defects, andgeneral atmospheric modeling that is ascribed to that particularplant site. Should the DEX measured activity exceed thetechnical requirement limit the plant enters an LCO requiringa
12、ction on plant operation by the operators.5.2 The determination of DEX is performed in a similarmanner to that used in determining DEI, except that thecalculation of DEX is based on the acute dose to the wholebody and considers the noble gases85mKr,85Kr,87Kr,88Kr,131mXe,133mXe,133Xe,135mXe,135Xe, an
13、d138Xe which aresignificant in terms of contribution to whole body dose.5.3 It is important to note that only fission gases areincluded in this calculation, and only the ones noted in. Forexample 83mKr is not included even though its half life is 1.86hours. The reason for this is that this radionucl
14、ide cannot beeasily determined by gamma spectrometry (low energy x-raysat 32 and 9 keV) and its dose consequence is vanishingly smallcompared to the other, more prevalent krypton radionuclides.5.4 Activity from41Ar,19F,16N, and11C, all of whichpredominantly will be in gaseous forms in the RCS, are n
15、otincluded in this calculation.5.5 If a specific noble-gas radionuclide is not detected, itshould be assumed to be present at the minimum-detectableactivity. The determination of DOSE-EQUIVALENT XE-1331This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibi
16、lity of Subcommittee D19.04 on Methods of RadiochemicalAnalysis.Current edition approved May 15, 2011. Published June 2011. DOI: 10.1520/D772711.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.shall be performed using effective dose-
17、conversion factors forair submersion listed in Table III.1 of EPA Federal GuidanceReport No. 12, or the average gamma-disintegration energiesas provided in ICRP Publication 38 (88Radionuclide Transfor-mations) or similar source.6. Interferences6.1 The analytical determination of the radionuclides us
18、edfor this calculation is made by gamma ray spectrometry.Commercially available software is generally used to performthe spectrum analysis and data reduction. However there canbe significant number of interferences from gamma ray emit-ters with multiple gamma ray emissions. The user mustcarefully se
19、lect the appropriate interference free gamma rayenergy for each radionuclide in order to determine accuratelythe activity of each radionuclide.6.2 The short half-lives of several of the noble gas radionu-clides, the low abundance of their gamma rays, and highbackground activity at their principal ga
20、mma ray energies, mayrequire that separation of the gases from the reactor coolantliquid be performed in order to reliably determine theirindividual activities.7. Sampling7.1 Separation of gases should be done at the sample pointfrom the reactor coolant system and there should be nochemical treatmen
21、t process preceding this sample point (i.e.prior to letdown demineralization).7.2 Containers used for containing the noble gases must“gas-tight” to ensure insignificant losses of radionuclidesduring sample counting.7.3 Separation may be achieved by any form of reactorcoolant degassing process (e.g.,
22、 gas expansion into an evacu-ated container) as long as the sample line remains pressurizeduntil degasification can occur.8. Calibration and Standardization8.1 Any calibrations and standardizations required in sup-port of this practice should be in accordance with the appli-cable sections of Practic
23、es D3648 and D7282 and in accor-dance with the manufacturersspecifications for the gamma rayspectrometry system used for analysis.8.2 Sample geometry and container size and physical com-position must be the same for sample and standards.9. Procedure9.1 A sample of reactor coolant is analyzed by gamm
24、a rayspectrometry within a short period of time after the samplebeing taken from the reactor coolant system.9.2 An appropriate aliquant of the sample is counted as apressurized liquid or degasified and the removed gas countedon a gamma ray spectrometer immediately after degasificationoccurs.9.3 If a
25、 separated gas sample is counted, the method usedshould ensure that noble gas radionuclides are no retained bythe liquid phase. If they are, then the concentration from theliquid phase should be included in the calculation in 10.1.9.4 A second count of the same aliquant of gas may berequired several
26、 hours later for accurate determination oflonger lived noble gas radionuclides.9.5 Tabulate the concentrations, uniformly measured inCi/cc (37 kBq/cc) or Ci/g (37 kBq/g), of all applicable noblegas radionuclides identified in the sample.9.6 The times between taking the reactor coolant sampleand perf
27、orming DEX gamma ray spectrometry analyses shouldbe consistent from sample to sample so that the ingrowth fromprogenitors and decay to progeny will be consistently ac-counted using the calculation in 10.1.10. Calculation10.1 The DEX value is calculated as follows:DEX1Cig5(1oi51AI3 DFI(1)Where:DEX =
28、an activity concentration equivalent to 133Xe by allnoble gas fission products from Table 1, Ci/gAI= the activity of the individual radionuclide identifiedin Table 1, Ci/gDFI= the ratio of the dose conversion factor each radio-nuclide to the dose conversion factor for133Xe(listed in Table 1), dimens
29、ionless10.2 If a radionuclide listed in Table 1 is not detected, theminimum detectable concentration for the gamma ray spec-trometry count time and sample volume (gas and liquid) usedfor analysis shall be the activity of that radionuclide.10.3 If the methodology to provide a degasified liquidcontain
30、s gas activity, the activity for each individual radionu-clide shall be added to the gas phase activity of that radionu-clide, respectively, in Equation 1.11. Keywords11.1 DEX; Dose correction; Dose Equivalent Xenon; NoblegasesTABLE 1 Table of Equivalence Factors for Noble Gas FissionProductsNumber
31、Radionuclide Factor1 Kr-85m 4.7962 Kr-85 0.0763 Kr-87 26.4034 Kr-88 65.3855 Xe-131m 0.2496 Xe-133m 0.8787 Xe-133 1.0008 Xe-135m 13.0779 Xe-135 7.62810 Xe-138 36.989D7727 112REFERENCES(1) Calculation of Distance Factors for Power and Test Reactor Sites9,Table III of TID- 14844, AEC (1962)(2) “Calcula
32、tion of Annual Doses to Man from Routine releases ofReactor Effluents for the Purpose of Evaluating Compliance with10CFR Part 50, Appendix I”, US NRC Regulatory Guide 1.109, Rev.1, Table E-7 (1977)(3) 9Committed Dose Equivalent in Target Organs or Tissues per Intake ofUnit Activity9, ICRP 30, Supple
33、ment to Part 1, page 192-212.(4) “Standard Radiological Effluent Technical Specifications For Pressur-ized Water Reactors”, US NRC NUREG-0472, Rev 3 (1983)(5) 10CFR50 Domestic Licensing of Production and Utilization Facilities,Appendix I(6) 10CFR100 Reactor Site Criteria(7) “External Exposure to Rad
34、ionuclides in Air, Water and Soil” , FederalGuidance report No. 12, EPA-402-R-93-081(8) 9Deletion of E Bar Definition and Revision to RCS Specific ActivityTechnical Specification9, TSTF-490, Rev 0 ADAMS NumberML052630462, (2007)ASTM International takes no position respecting the validity of any pate
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37、nts will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted
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