1、Designation: D7727 111Standard 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.1NOTEEditorial corrections made throughout in March 2014.1. Scope1.1 This practice applies to the c
3、alculation of the doseequivalent to133Xe in the reactor coolant of nuclear powerreactors resulting from the radioactivity of all noble gas fissionproducts.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units
4、that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the
5、 applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D3648 Practices for the Measurement of RadioactivityD7282 Practice for Set-up, Calibration, and Quality Controlof Instruments Used for Radioactivity Measurements3. Terminology3.1 Definitions:3.1.1 DOSE-
6、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,88Kr,131mXe,133mXe,133Xe,135mXe,135Xe, and138Xe actuallypresent.3.1.1.1 DiscussionThis is the
7、 general definition of DEX.Each utility may have adopted modifications to this definitionthrough agreement with the U.S. Nuclear Regulatory Commis-sion (U.S. NRC). The definition as approved for each utility bythe U.S. NRC is the one that should be applied to thecalculations in this practice.4. Summ
8、ary 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 dose to that of133Xe. This practiceis to replace the previous practice of
9、 calculating the reactorcoolant calculation 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 (LCO) that more closely relates thenon-iodine RCS activity limits to the
10、 dose consequence analy-ses which form their bases.NOTE 1It 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 dose consequence analysis usedby the plant in their dose calculation manual
11、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 vent the location of the site boundary, the calculatedreactor coolant ac
12、tivity 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 requiringaction on plant operation by the operators.5.2 The determination of DEX i
13、s 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, and138Xe which aresignificant in terms of contribution to whole body dose.
14、5.3 It is important to note that only fission gases areincluded in this calculation, and only the ones noted in Table 1.1This practice is under the jurisdiction of ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.04 on Methods of RadiochemicalAnalysis.Current edition a
15、pproved May 15, 2011. Published June 2011. DOI: 10.1520/D7727-11E01.2For referenced ASTM standards, 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 w
16、ebsite.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1For example83mKr is not included even though its half life is1.86 hours. The reason for this is that this radionuclide cannotbe easily determined by gamma spectrometry (low energy
17、X-rays at 32 and 9 keV) and its dose consequence is vanish-ingly small compared to the other, more prevalent kryptonradionuclides.5.4 Activity from41Ar,19F,16N, and11C, all of whichpredominantly will be in gaseous forms in the RCS, are notincluded in this calculation.5.5 If a specific noble-gas radi
18、onuclide is not detected, itshould be assumed to be present at the minimum-detectableactivity. The determination of DOSE-EQUIVALENT XE-133shall be performed using effective dose-conversion factors forair submersion listed in Table III.1 of EPA Federal GuidanceReport No. 12 (1),3or the average gamma-
19、disintegrationenergies as provided in ICRP Publication 38 (“RadionuclideTransformations”) or similar source.6. Interferences6.1 The analytical determination of the radionuclides usedfor this calculation is made by gamma ray spectrometry.Commercially available software is generally used to performthe
20、 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 select the appropriate interference free gamma rayenergy for each radionuclide in order to determine accuratelythe activit
21、y of each radionuclide.6.2 The short half-lives of several of the noble gasradionuclides, the low abundance of their gamma rays, andhigh background activity at their principal gamma ray energies,may require that separation of the gases from the reactorcoolant liquid be performed in order to reliably
22、 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 treatment process preceding this sample point (that is,prior to letdown demineralization).7.2 Containers used for containing the n
23、oble 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 (for example, gas expansion into anevacuated container) as long as the sample line remainspressurized until degasification c
24、an 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 Practices D3648 and D7282 and in accor-dance with the manufacturersspecifications for the gamma rayspectrometry system u
25、sed 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 gamma rayspectrometry within a short period of time after the samplebeing taken from the reactor coolant system.9.2 A
26、n 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 separated gas sample is counted, the method usedshould ensure that noble gas radionuclides are no retained bythe
27、 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 hours later for accurate determination oflonger lived noble gas radionuclides.9.5 Tabulate the concentrations, u
28、niformly 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 performing DEX gamma ray spectrometry analyses shouldbe consistent from sample to sample so that the ingrowth frompro
29、genitors 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 = an activity concentration equivalent to133Xe by allnoble gas fission products from Table 1, Ci/g,AI= the activity
30、 of the individual radionuclide identifiedin Table 1, Ci/g, andDFI= the ratio of the dose conversion factor each radionu-clide to the dose conversion factor for133Xe (listed inTable 1), dimensionless.3The boldface numbers in parentheses refer to a list of references at the end ofthis standard.TABLE
31、1 Table of Equivalence Factors for Noble Gas FissionProductsNumber 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 111210.2 If a radionuclide listed in Table 1 is not detected, t
32、heminimum 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 liquidcontains gas activity, the activity for each individual radionu-clide sha
33、ll be added to the gas phase activity of thatradionuclide, respectively, in Eq 1.11. Keywords11.1 DEX; dose correction; dose equivalent xenon; noblegasesREFERENCES(1) “External Exposure to Radionuclides in Air, Water and Soil,” FederalGuidance Report No. 12, EPA-402-R-93-081.(2) “Calculation of Dist
34、ance Factors for Power and Test Reactor Sites,”Table III of TID-14844, AEC, 1962.(3) “Calculation of Annual Doses to Man from Routine releases ofReactor Effluents for the Purpose of Evaluating Compliance with10CFR Part 50,Appendix I,” U.S. NRC Regulatory Guide 1.109, Rev.1, Table E-7, 1977.(4) “Comm
35、itted Dose Equivalent in Target Organs or Tissues per Intakeof Unit Activity,” ICRP 30, Supplement to Part 1, pp. 192212.(5) “Standard Radiological Effluent Technical Specifications For Pressur-ized Water Reactors,” U.S. NRC NUREG-0472, Rev 3, 1983.(6) 10CFR50 Domestic Licensing of Production and Ut
36、ilizationFacilities, Appendix I.(7) 10CFR100 Reactor Site Criteria.(8) “Deletion of E Bar Definition and Revision to RCS Specific ActivityTechnical Specification,” TSTF-490, Rev 0 ADAMS NumberML052630462, 2007.ASTM International takes no position respecting the validity of any patent rights asserted
37、 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, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the
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39、areful 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 by ASTM Internati
40、onal, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D7727 1113
