ASTM_D_7727_-_11e1.pdf

Designation:D7727111Standard 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 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 calculation 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 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 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-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 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.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 dose to that of133Xe.This practiceis to replace the previous practice of 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 dose consequence analy-ses which form their bases.NOTE1It 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 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 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 requiringaction 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,and138Xe 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 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 approved 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 website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 For 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 energyX-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