1、Designation: D 5411 05Standard Practice forCalculation of Average Energy Per Disintegration (E) for aMixture of Radionuclides in Reactor Coolant1This standard is issued under the fixed designation D 5411; the number immediately following the designation indicates the year oforiginal adoption or, in
2、the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice applies to the calculation of the averageenergy per disintegration (E
3、) for a mixture of radionuclides inreactor coolant water.1.2 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units, which are provided for informationonly and are not considered standard.1.3 This standard does not
4、 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
5、:2D 1066 Practice for Sampling SteamD 1129 Terminology Relating to WaterD 3370 Practices for Sampling Water from Closed ConduitsD 3648 Practices for the Measurement of Radioactivity2.2 Code of Federal Regulations:10CFR100 Reactor Cite Criteria33. Terminology3.1 DefinitionsFor definitions of terms us
6、ed in this prac-tice, refer to Terminology D 1129.4. Summary of Practice4.1 The average energy per disintegration, E(pronounced Ebar), for a mixture of radionuclides is calculated from theknown composition of the mixture. Eis computed by calcu-lating the total beta/gamma energy release rate, in MeV,
7、 anddividing it by the total disintegration rate. The resultant Ehasunits of MeV per disintegration.5. Significance and Use5.1 This practice is useful for the determination of theaverage energy per disintegration of the isotopic mixture foundin the coolant of a nuclear reactor (1).4The resultant val
8、ue isperiodically reported upon, by the operators of nuclear powerplants, in order to ensure that the 2-h radiation dose, measuredat the plant boundary, will not exceed an appropriately smallfraction of the Code of Federal Regulations, Title 10, part 100dose guidelines.5.2 In calculating E, all the
9、energy dissipated by chargedparticles and photons in each nuclear radioactive transforma-tion is included. This accounting includes the energy releasedin the form of beta particles and gamma rays as well as energyreleased from extra-nuclear transitions in the form of X-rays,Auger electrons, and conv
10、ersion electrons. However, not allradionuclides present in a sample are included in the calcula-tion of E.5.3 Individual, nuclear reactor, technical specifications varyand each nuclear operator must be aware of limitationsaffecting their operation. Typically, radio-iodines, radionu-clides with half
11、lives of less than 10 min (except those inequilibrium with the parent), and those radionuclides, identi-fied using gamma spectrometry, with less than a 95 % confi-dence level, are not typically included in the calculation.However, the operator must account for at least 95 % of theremaining activity.
12、 There are individual bases for each exclu-sion.5.3.1 Radio-iodines are typically excluded from the calcu-lation of Ebecause many commercial nuclear reactors arerequired to operate under a more conservative restriction of 1microCurie (37 kBq) per gram dose equivalent I-131 in thereactor coolant.5.3.
13、2 Excluding radionuclides with half-lives less than 10min, except those in equilibrium with the parent, has severalbases.5.3.2.1 The first basis considers the nuclear characteristicsof a typical reactor coolant. The radionuclides in a typical1This practice is under the jurisdiction of ASTM Committee
14、 D19 on Water andis the direct responsibility of Subcommittee D19.04 on Methods of RadiochemicalAnalysis.Current edition approved Dec. 1, 2005. Published December 2005. Originallyapproved in 1993. Last previous edition approved in 2005 as D 5411 93 (2005)e1.2For referenced ASTM standards, visit the
15、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.3Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia,
16、 PA 19111-5094, Attn: NPODS.4The boldface numbers in parentheses refer to a list of references at the end ofthis practice.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.reactor coolant have half-lives of less than 4 min or havehalf-
17、lives greater than 14 min. This natural separation providesa distinct window for choosing a 10 min half-life cutoff.5.3.2.2 The second consideration is the predictable timedelay, approximately 30 min, which occurs between the releaseof the radioactivity from the reactor coolant to its release to the
18、environment and transport to the site boundary. In this time, theshort-lived radionuclides have undergone the decay associatedwith several half-lives and are no longer considered a signifi-cant contributor to E.5.3.2.3 A final practical basis is the difficulty associatedwith identifying short-lived
19、radionuclides in a sample thatrequires some significant time, relative to 10 min, to collect,transport, and analyze.5.3.3 Radionuclides identified using less than a 95 % con-fidence level are not typically included in the calculation toimprove the accuracy of the calculation (2).6. Interferences6.1
20、There are no true interferences to this practice. How-ever, errors may result in the calculation of Efrom incorrectlyanalyzing the sample mixture.7. Sampling7.1 If samples are collected for analysis in support of thispractice they should be representative of the matrix, be ofsufficient volume to ens
21、ure adequate analysis, and be collectedin accordance with Practices D 1066, D 3370, and D 3648.7.2 In addition to the requirements of 7.1, if samples ofreactor coolant are required in support of this practice, theyshould typically be collected only after a minimum of 2effective full-power days and 2
22、0 days of power operation haveelapsed since the reactor was subcritical for 48 h or longer.Individual nuclear operator technical specifications vary andshould be reviewed to determine specific requirements.8. Calibration and Standardization8.1 Any calibrations and standardizations required in sup-po
23、rt of this practice should be in accordance with the appli-cable sections of Practice D 3648.9. Procedure9.1 Conduct all analyses in support of this practice inaccordance with the applicable sections of Practice D 3648.9.2 Perform sufficient gamma isotopic analyses of the liq-uid, gaseous, and suspe
24、nded fractions of the sample to ensurethat at least 95 % of the coolant activity due to gamma emittingisotopes has been quantified. Samples should be analyzed atapproximately 2 h, 24 h, and 7 days following samplecollection. Multiple sample analyses are required to ensureaccurate quantification of t
25、he longer-lived isotopes because ofmasking caused by the high initial activity of the sample. Ifinterferences continue to be a concern with the results of theanalysis conducted on Day 7, it may be necessary to conductadditional gamma isotopic analyses of the sample at approxi-mately 30 days after co
26、llection.9.3 Perform sufficient isotopic analyses of the liquid, gas-eous, and suspended fractions of the sample to ensure that atleast 95 % of the coolant activity due to nongamma emittingisotopes has been quantified.9.4 Tabulate the concentrations, uniformly measured inCi/cc (37kBq/cc) or Ci/g (37
27、kBq/g), of all applicable gammaand nongamma emitting radioisotopes identified in the sample.Some examples of the radioisotopes or types of radioisotopesfound in a typical sample are the radioactive noble gases, purebeta emiter such as tritium, carbon-14, strontium-89 and 90,and yttrium-90, beta/gamm
28、a emitters such as cobalt-60, elec-tron capture isotopes such as iron-55, and reactor coolantsuspended and particulate material (commonly referred to ascrud).10. Calculation10.1 Calculate the average energy per disintegration, E,inMeV according to the following equation:E5(i 5 1nAi* Ei!(i 5 1nAi(1)w
29、here:E= average energy per disintegration, MeV/disintegration,Ai= activity of the ith radionuclide uniformly measured,Ci/cc or Ci/g, andEi= isotopic energy emission for the ith radionuclide,MeV/disintegration.10.2 The values for Aiare simply the measured activitylevels, uniformly measured in Ci/cc (
30、37 kBq/cc) or Ci/g (37kBq/g), for each appropriate radionuclide identified in thesample (for example, Co-60, Sr-90, Xe-133, etc.).10.3 The values for Eiare constant for each radionuclideand depend upon the decay scheme for that radioisotope. Eiiscalculated from the following equation:Ei5 Eibeta!1EiC
31、E! 1 EiA! 1 Eigamma!1EiX! (2)where:Ei(beta) = the average, abundance weighted, beta en-ergy per disintegration, MeV/disintegration,Ei(CE) = the average, abundance weighted, conversionelectron energy per disintegration, MeV/disintegration,Ei(A) = the average, abundance weighted, Augerelectron energy
32、per disintegration, MeV/disintegration,Ei(gamma) = the average, abundance weighted, gammaenergy per disintegration, MeV/disintegration, andEi(X) = the average, abundance weighted, X-ray en-ergy per disintegration, MeV/disintegration.10.4 An example for the calculation of Eifor the disinte-gration of
33、 xenon-133 (EXe-133) follows.10.4.1 The decay scheme for Xe-133 (3) is given in Fig. 1.10.4.2 First, calculate EXe-133(beta).10.4.2.1 To determine each Ei(beta), multiply the averageenergy per disintegration for each beta emitted by its abun-dance and sum the products. The average beta energies for
34、eachisotope may be found in the literature (4-6). Or, it may beD5411052approximated by multiplying the maximum beta particle en-ergy per transformation by a factor of one-third. Only one-thirdof the maximum beta energy is included in the calculationbecause the remaining two-thirds of the energy is d
35、issipated byneutrino emission (7). Neutrinos are very unreactive andrelinquish their energy very slowly. Therefore, their contribu-tion is ignored when considering the total energy available forabsorption at the site boundary.10.4.2.2 The average energies and abundances of the majorbeta emissions fo
36、r the decay of Xe-133 are (6):beta # Average Energy Abundance2 0.0751 MeV 0.69 %3 0.101 MeV 99.3 %10.4.2.3 Therefore, EXe-133(beta) is:EXe-133(beta) = (beta #2 average energy) * (beta 2 abundance)+ (beta #3 average energy) * (beta 3 abundance)EXe-133(beta) = 0.0751 * 0.0069 + 0.101 * 0.993,EXe-133(b
37、eta) = 0.101 MeV/disintegration.10.4.3 Next, calculate Ei(CE).10.4.3.1 Unlike beta particle emissions, conversion elec-trons are monoenergetic emissions and are not accompanied byneutrino emission. Therefore, their contributions to Ei(beta) isincluded at their full emission energy minus the binding
38、energyof the emitted electron. Here again the abundance for eachtransformation is an included factor.10.4.3.2 The energies and abundances of the major conver-sion electron emissions for the decay of Xe-133 are (6):CE # Energy AbundanceK-2 0.0450 MeV 53.3 %L-2 0.0753 MeV 8.14 %10.4.3.3 Therefore, EXe
39、-133(CE) is:EXe-133(CE) = (K-2 energy) * (K-2 abundance)+ (L-2 energy) * (L-2 abundance)EXe-133(CE) = 0.0450 * 0.533 + 0.0753 * 0.0814,EXe-133(CE) = 0.0301 MeV/disintegration.10.4.4 Next, calculate EXe-133(A).10.4.4.1 Similar to conversion electron emissions, Augerelectrons are monoenergetic emissio
40、ns and are not accompa-nied by neutrino emission. Therefore, their contribution to Eiisalso included at their full emission energy minus the bindingenergy of the emitted electron. Here again the abundance foreach transformation is an included factor.10.4.4.2 The energies and abundances of the major
41、Augerelectron emissions for the decay of Xe-133 are (6):Auger Electron Energy AbundanceL 0.00355 MeV 49.7 %K 0.0255 MeV 5.6 %10.4.4.3 Therefore, EXe-133(A) is:EXe-133(A) = (L energy) * (L abundance)+ (K energy) * (K abundance)EXe-133(A) = 0.00355 * 0.497 + 0.0255 * 0.056,EXe-133(A) = 0.00319 MeV/dis
42、integration.10.4.5 Next, calculate EXe-133(gamma). The energies andabundances of the major gamma emissions for the decay ofXe-133 are (6):gamma # Energy Abundance5 0.0796 MeV 0.217 %6 0.0810 MeV 37.6 %10.4.5.1 Therefore, EXe-133(gamma) is:EXe-133(gamma) = (gamma #5 energy) * (gamma #5 abundance)+ (g
43、amma #6 energy) * (gamma #6 abundance)EXe-133(gamma) = 0.0796 * 0.00217 + 0.081 * 0.376,EXe-133(gamma) = 0.0306 MeV/disintegration.10.4.6 Next, calculate EXe-133(X). The energies and abun-dances of the major X-rays emissions for the decay of Xe-133are (6):X-ray # Energy AbundanceKalpha20.0306 MeV 13
44、.3 %Kalpha10.0310 MeV 24.6 %10.4.6.1 Therefore, EXe-133(X) is:EXe-133(X) = (Kalpha2energy) * (Kalpha2abundance)+(Kalpha1energy) * (Kalpha1abundance)EXe-133(X) = 0.0306 * 0.133 + 0.0310 * 0.246,EXe-133(X) = 0.0116 MeV/disintegration.10.4.7 The final step in the calculation of EXe-133is:EXe-133=EXe-13
45、3(beta) + EXe-133(CE)+EXe-133(A) + EXe-133(gamma) +EXe-133(X)EXe-133= 0.106 MeV/dis + 0.0301 MeV/dis + 0.00319 MeV/dis + 0.0306MeV/dis + 0.0116 MeV/disEXe-133= 0.181 MeV/disintegration.10.5 To calculate the value of Efor the entire sample then,an Eivalue for each radionuclide is calculated. The prod
46、uct Eiand Aiare determined for each isotope and summed. This sumis then divided by the total activity of the sample to give E.10.6 The decay energies for several nuclides, typicallyfound in reactor coolants, are given in Appendix X1 (4). Thetable is condensed to show the measured, total average ener
47、gyfor all emitted electrons (the sum of the abundance weightedaverage energy for the beta, conversion electron, and Augerelectron energies = Ei(beta) + Ei(CE) + Ei(A) and the totalaverage photon energy (the sum of the abundance weightedgamma and X-ray energies = Ei(gamma) + Ei(X), rather thaneach in
48、dividual contributor. It is important to note that the tableuses the measured, average beta energy per disintegrationrather than the approximated13 maximum beta energy. Valuescalculated by nuclear operators may differ from those ofAppendix X1 due to rounding and variations found in theliterature for
49、 the energies of each emanation.11. Keywords11.1 average energy per disintegration; disintegration; Ebar; MeV per disintegration; nuclear reactor; radioactivity;reactor coolant; technical specificationsFIG. 1 Decay Scheme for Xe-133D5411053APPENDIX(Nonmandatory Information)X1. See Table X1.1 below.TABLE X1.1 Average Fission Product Decay Energies for Different Radiation Types (4)IsotopeAverage Total Electron Energy Emitted Average Total Photon Energy EmittedHalf-LifeMev/decay Mev/decayBr-84 1.2492 1.7874 31.8 minKr-85 0.2505 0.0022 10.72 yearsKr-85m 0.2
