A Theory of Decontamination of Fallout from Nuclear Detonations; Part II Methods for Estimating the Composition of Contaminated Systems (Deleted)

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investigations, a rei?Llistic zsnge of felhut ma&s 4aepamis u neaded to design experbmts in which eperarti~ tare&l date em be cibtaiw in this caseit is nece&S&ry t&t the tB3smm& faznoutbe m slmllar to real ft3uout as gassib~. Ifklawm of filuout fzoqpsitfort ie a380 necessary to understend tad cttavelate de&M109 data front pmt associated with the f&lout lp~sb ad zsdbactim elemnts is seeded to for estwting the cqsitia of fia3aut ad no E+tammq of the aaable d&a has been pretiously made. weapon, heigkt or tkp&h of

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The idealizedscalingfunctionsare presentedfirstto Introduce mannerby use of availabledata. %he modeldetonationwillbe a emfacelanddetonationin whichall of the radionuclidesproduce#are retainedby the total mass (claysoil)renmredfrcmthe crater. !Be fslloutthusproducedwillthen depositoveran idealsmoth plana. A mathematicalderivationof the contourratioscslingAractionsfti the 3.2 DEXUUITIONOF THE MASS CONTOURRA!L'IO At any point inthe idlout area,the 131~~8scontourratio5s dnifned in whicha is the mass of

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of Eq. 2 requirescontourmaps of m and I(t) for the whole falloutarea. Inthe.ideel case,Mg wouldbe essentiellyequal to the mass of material removedfrom the crater. -. The fractionof the deticecontourratio at any point in $he fallout area is definedby .I.. in which a is the radioactivity(or measureof it) per unit area and 8~ is the total radioactivity(or measureof it) producedby the device. The ratio, a/&T is the fractionof the deviceper unit area end can be definedandmeasuredinmanywsys. One fairly componunit of measure of the activityis in terms of the number of fissionsfor the radioactivityfrom the fissionprocess. The advantagesofusingthisunit are that its value is independentof tims and that it is also used in determiningweaponyields. The disadvantageof usingtk unit is that it is qtite of'tenrelatedto a singlefissionproducttracernuclide and its fissionyield, and is not a reliablemeasureof the true number of fissionsin a given sampleof falloutwhen the radionuclidesare Exceptingfor fractionationor alterationof the radionuclidecompositionat variouspoints in the falloutarea fromthat producedby the device,the fractionof the device contourratio for an extended plane surfaceshouldbe a grend averagefunction. Even vith the occurrence of fractionation,the point variation.of this contourratio will not be large for areas where the patternof fractionationis the stx~. Other paranretersthat effectthe value of this contourare discussed in sane of the followingsections. For the idealizedmodel function,it will be assumedthat, in the

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as fissionproducts.The izmiucedproductshave no effecton the vslue of.8or m in termsof fissionsbut do effectthe valueof I(t)in both integrationsperunittime. For a givencazpositionof radiomclides is in fissionsper sq ft then e has the unitsr/hr/(fiss/sqftd;in the latterunitsthe parsmetera doesnot dependon t. Valuesof C&,(t) for the fissionproductsfrom severalk398 f fissionhavebeen calculated as a functionof time afterfission.9 j and puced activities(captureproducts)Keep- the fissionproducts sionprodu is the valueof the (r/hr)/(fission/sqf't)for the fislideper is the nuuiberof neturoncapturesto form the Jth radionucproducedby the deviceis in whichW is the totalnuclearyieldof the device,b is the ratioof

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value, 1.45 x 1023 fissions/KC,wilJ.be used for K. Co&ination of in which FD*(t) is-the idealized plane value of the fraction of device this f'unc~ionhrrnbeen given previously in a reports whicyldiscussed the CASTLE Shot Bravo f8llou-tpattern and fallout pattea sum8tions radionuclides produced, with eU. the mass of soil remwed from the crater, MO, is 0 n an idealplane, each fission/sq ft would give hence the mass contourratio wouldbe givenby The variationof M. with soils msy be estimatedfrom yield for surfacedetonationon clay-type fork inmgend WinKT. 6 Substitutingfor Mo, *l and cb,(t) in Eq. 9 For falloutin which the radionuclidesere fusedwithin or tied uniformlythratghoutall the particlesand in which the fkactionation However,if the specificactivityof the falloutand the flxctionation m of the radionuclideschangesfkom point-to-point,I+(t) becomesa point

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EquationL5 suggeststhat, for the stated assumptions,s(t) should vary inverselywith distance. For small particleswhere the falling tour ratio for those particlesis givenby For these assumedconditions,I&(t) decreases s usre root of the distance. For the secondcase,the averagespecificactivityis gitinby in which k4 is'a constant. For this case where the specificactivityis tance and Is givenby AlthoughEq. I.8does not comtaina distanceterm and inthst sense is not a point function,the region of its appliceihilityis, of course, restrictedto the area within'whichthe particleswith a constantspeciIn additionto the distance,x, 4s. 15 and 16 euggest that the (t) dependson the wind velocityand the hei@t from which the psrtic es fall. l%e latterdependson weapon yield. If the bottom m s of the cloudsis used as a referencepoint with respectto the masure

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of h, use of the empirical.functionsfrom reference This rather simpletreatmnt of how the value of Mr(t) msy depend and on the mode of falloutparticleformationindicatesat leastthe scope of the informationrequiredin the develomnt of a reliable There are two methodsfor determiningthe msss contourratio; each requiresa radiationmeasurenrentand a falloutsample. The most direct method is to collectsamplesand weigh them (withappropriateanalyses for correctionto a scalablemass). The secondm&hod is to obtain sufficientpure falloutto determinethe specificactivityof the fallout and to determine,by soil samplingin the falloutarea,the activity per unit srea. The fractionof device contourratio can be determined from the same samplesof falloutand radiationsmasurements;radiochemical analysesof the samplessre required.

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Real differencesbetweenobservedvalues of the contourratios and those predictedfkomthe idealizedcontourratio functionsare expected to occur. The major causesof miation in the functions,including those that cause variancefrom the idealizedfunction,are: 1. Weapontype and yield 3. Effect of terrainroughnesson falloutdepositionpatternsand on the radiationsdeliveredat a point from a given radiation 4. Instrusmntresponseto the radiations .: 5. Depth or heightof detonation Y 6. Activityand mass particlesize relations 7. ryPe of environmentalmaterialat shot point 8. Degree of mixing of cratermaterialwith the radioactivenuclides In the measuremnt of the observedvalues,there will be discrepenties due to samplingbias, recoverylosses,analyticalerror, and in- !Cheweapontype will mainly influencethe valuesof the fraction of fissionyield,b, and the values of the neutroncaptureratios,Cj; it may indirectlyinfluenceother factorssuch as fractionation.The idealizedmass contourratio functionssuggestthat the yield itself shouldnot influencethe value of the mass contourratio as much as The absenceof the more volatileradionuclidesin falloutparticles resultsin fractionation.When certainof the fissionproducttracer nuclideor nuclidesare used in determiningthe value for the numberof fissions,and other rsdionuclidesare not present in the proper smount, the true vslues of i and icp sre lower than given in the idealized he unfractionatedfissionproductsand the observed value of the contourratioswill be larger. If the reduction radionuclide,then the grossreductionin the value of ia msy similarlybe definedby the gross fissionpoduct "R" value,q&t), from gross ionization-ratemeasurementsor from knowledgeof the r values of all the importantradiol?uclides.Since "R" values for a g ven radio-1 nuclidemay vary with particlesize, r%(t) may vary with distance(i.e. be a point fkxtion). The contourratio scalingparametersensitiveto fractionationis 60 (t); in terms of r@(t) and rj, it is givenby

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rti(x,t)with the lattertwo given as explicitArnctionsof tie distance. ally till tend to give lower valuesof ifp(t)and ij(t) then those calculatedfor en infiniteauioothplane surface, !l?hese factorswi3l also influencethe velue of k(t) to give largerobservedvaluesof the contour ratio. As with fractionation,these factorswould be easiestto tion of the dependenceof the factorson the photon enezgies and Noton abundancesmy be requiredto obtainthe mltiplier. The terms to be inwhich D is the relativeresponseofthe instrumentand qis the "terrainfactor". The data treated in Section4 consistsof radiation measuremnts taken at 3 f+t above extendedplsne sources(or corrected to such a geometry). In addition,all radiationmeasurementswere taken with or convertedto the AN/PDR=3g(TlB)surveyinstrument. The value of D i for each individualnuclidefor this instrumentsre gLven in The size of the cratera& the amountof earth or debristhrown upwardby a detonationof a givenyield decreaseswith the height of the zero point. For subsurfaceexplosions,the cratersize increases as the depth of the zero point increasesup to a given depth. Deyord this given depth,the emountof cratermaterialthrownup decreases until such depth of detonationwhere no cratermaterielis ejected. In the model explosionwhere all the radioactivityproduc& is Wxed with all the cratermaterial,the variationof q(t) with depth of burst can be expressedas

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in which s(t) is the value of the mass contourratio for a surface detonation,s is the ratio Ao/Ah where A. is the cratermass scaling coefficientfor surfacedetonations(see Eq. 10) and Ah is the crater mass correctionfactorto a surfacedetonation;for air bursts,ah has values that are greaterthan 1.00; az~3,for undergroundbursts,ochhas valuesthat sre less thsn 1.00. -I Possibleeffectsof the particlesize aad specificactivityon the ined, is concernedonly with the total activityper unit area’and the total pacticlemass per unit area at a given location. The& can be estimatedby use of falloutmodel cwtations if both the activityand msss distributionsare known as a mction of particlesize. z The psrticlesthat carrythe radioactivematerialback to earth are composedessentiallyof the environmentalmaterialsat the shot point. For nesr-surfacebursts,the types of materia3.sof most interest tures of the two for harbordetonations. If’ the mass of the original materialis scalablewith weaponyield, then the equivslentmass of the originallPaterialmust be used in the contourscalingfunctions. For ally of seawaterwhich, as drops or ice particles,will changein size duringtheir fall time due to evaporationor condensationof the water. If they dry completely,the final residualmass would be about 3 $Jof the originalseawatermass.' In this case the originalcompositionmsy be determinedon the basis of the seawatermass's& if the contour ratios are point functions,the vslue of the ratio at a locationwill dependon how the evaporationtakes place in space ti time. DOE/lW Meteorologicalfactorsare of major wrtance in the distribution of the falloutfYm the timz that it is formd. Althougbthe scaling functionsdiscussedin this report are only concernedwith the contsminated systemafterthe fallouthas been deposited,the discussionin Section3.3 showedthat the wird speedwas Involvedwhen the activity was taken as varyingwith the squareof the particlediameter. Thus the factorsthat influencethe distributionof the falloutmay indirectly influencethe value of the contourratios if the latterare point ftmcThe effectof the inclusionof nonscalableor extraneousdebris in fallouton the mass contourratio, as previouslynrentioned,would result in high apparentobservedvalues of the mass contourratio.

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tion~parameters,knowledgeof its effecton the contourratio and its frequencyand conditionsof occurrenceis necessaryin considering whetheror not it is sufficientlyimportantto warrantseparatetreatment and inclusionfor considerationin decontaminationinvestigations Of the severalmeasurementerrors,the one least amenableto treatmentor reductionby cerefulanalyticaltechniquesis that due to semplingbias. It will depend on type of saapler,samplinglocation, sampleSize, and many other factors. The parametersmos+ seriously affectedby this bias are m Etnda; the value of - the amunt of felloutcollectedwith respectto the localterrain (average)will be low. However,this generalizationis not valid for f the i&la& collectingstationsat OperationCAE!!FMwhere the collectors were at grade level and were not recoveredfor severaldays after shot. In the meantime,both inert coral and fellat particlesdriftedinto the collectorsby actionof the wind. Cosibiningthe variouscorrectionfactorstiich, if known,would providea more reliablescalingfunctionfor each of the contourratios than those for the idealizedfalloutmodel gives For the idealized model function,K(X,W) is equal to 1.23 x 10-10 ,-0.038 The only ~~I-IIISin Xq. 25 that depend on distance

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Althoughthe quantityof debrismy not be scalablewith otherdetonation parameters,knowledgeof its effect on the contourratio and its _ - frequencyand conditionsof occurrenceis necessaryin considering whetheror not it is sufficientlyimportantto warrantseparatetreatment and inclusionfor considerationin decontaminationinvestigations Of the severalmeasurementerrors,the one least appenableto treatmentor reductionby carefulanaQM.caJ.techniquesis that due to samplingbias. It will depend on type of sampler,smsplinglocation, sample-size,and lllanyother factors. The parametersmost eeriously affectedby this bias are m and a; the value of "p1 very sensitive. For most collectingdevicesand 8 ling locations, the amountof falloutcollectedwith respectto the localterrain (average)will be low. However,this generalizationis not valid for were at grade level and were not recoveredfor severaldays after shot. In the meantime,both inert coral and f&lout particlesdriftedinto the collectorsby actionof the wind. Cosibiningthe variouscorrectionfactorswhich, if known,would providea rare reliablescalingfunctionfor each of the contourratios than those for the idealizedfalloutmodel gives For the idealizedmodel function,K(X,W) is equal to 1.23 x 10-lO,-O.o38 for sU.vslues ofx. The only term in Eq. 25 that depemion distance

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tion), the specificactitityof the falloutand curtitityper unit area for severaltest detonation6ere given in Table 1 along with the distance where X is the 1 MT scaleddistanceand x is the measureddi&mce. falloutpatternor (~11averagedistanceon the grated along the path of the particlesfar those 8rrivingat a given locationunder 6m meteorologicalcormiitlons.Correction6in x for these factorswere not tradein the data of Able 1. (JANGLE"U" Shot) and the detonation (REDWINGNavajo)being the largest ti the above resultsfYom calculationof the first 4(l) value from the gross 66mple wei@t Includingthe desert sand blown into the collectorby the blast . the falloutparticleswere separatedfranthe gross sampleby a mamet. *

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btwy of Observed Velcs of the Me.66 ContourRatio, Actitity per Unit Area, armiSp6clfic Activity of FaSLcut Station Distance I(l), obs

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I Dataf'rcmreferences12, 13, aad 17 wereused to derivethe rth . indicate dlsfances so that

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(N!FS soil) and the Tewa curvewith Zunicurve(coral)indicatesalso that the grossfractionationdecreaseswithyield. No comparisoncan be madebetweenthe coraland NTS soilfrom these curvesbecauseof the largediffsrencesin yieldand distances. to the fuelactuallyused)is givenin Tahle8 far samre distanceis shown-forsll the redionuclidesin the Zuniand Tewaf&lout. In ShotFlatheedonly the radionuclideswithrare gas precursors correlationsof the "R" valuesof Table8 with distanceand of References19 and 20 with particlesize (withaid of Eq. made if a fractionationparameter,z, is definedas Althoughthe dataof Table8 are somewhatscatteredwithrespectto a continuouschangein rj or 23, they all can be adjusted,withinabout 30 withthe semevalueof k, for a the dataof Reference2G givesan evenbetterfit for a constantks. If zfp is definedas the sum of all the zj of fissionpoduct mix-

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TIME AFTER BURST (HRI Fig. 2 Ratio of Decay Curves: FalloutSazugle/CloudSampleBased on M099 Analysis

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It may be noted that z ie defined88 the ratio nuclidecontainedin the particlesto thst not of the fractionof the containedin the particle (i.e. lost from the perticle)assumingrj for the referencenuclide nificanceexceptfar the caseswhere all rj are either1 or 0 or where Bp is taken to be ~oportional to the averagevalue of z,(j)for the With the latterof the two views of z" , the data of Table 1 and Fig. 1 were used to, obtainvaluesof ks for% for Shots Shasta,Tew8 and for appliction et Shot Tewa w&s detonatedin 2 feet of water, the values.of for only the Zuni and CoulcmbC Bats were used for obtaining for 80 assumeddependenceof k, on weaponyield ti the z" valuesfor Shasta (Diablo)and Zuni were used for a scalingfunctionfPor2%. Ihe two in which the respectivevaluesapply only to determiningrfp at H + lhr can approachunity as the distanceincreases. Equation32 indicatest t rfp ep~oeches unity et shorterdistancesas the yield yield increases. !l!heee treads in fractionationcorrespondto the observeddate. The constantssre adjustedto r The values of 2 k, for the felloutfrcm mm of the test shots of yield 5 XC andlargeris assumedTV be unfractionated.

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iw For rare gasesonlywhich cmtributevery ing 2/3 of i(1)is takento be unfractionated at ell distances. The ratioof the cratervolum or cratermass for a surfacedetonationto that for detonationsat otherscaleddepthsis plottedas a functionof the nuclearscaleddepthin Fig. 3 as taken fromReference6. The nuclearscaleddepthis definedas the chargedepthdividedby the cuberoot of the nuclearyieldin lbs of TNT. There is a differencein the veluesof the scaleddepthin Fig. 3 f'romthose givenin Reference6. Inthat report, the equivalent blast yield(inl!NTunit;e)ofnucleer sives;conversionwes madethereforein Fig. 3 to accouutfor this de-

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If the curveof Fig. 3 is applied to the idealizedmass contour ratioscalingfunctions,wherethe totalcratermass is mixed with EU t 1 the radlonuclides,the valueof the contourratio would decreaseas the scaledheightincreasesand would increaseas the scaleddepthIncreases ’ ‘the confined vaporsat lsger valuesof the scsleddepthcouldresult in condensationmd pmticle formation~processesthatdiffermarkedly from surfaceand above-surfacedetonations,resultingin siepiflcant deviationsfromthe idealizedmodel.'Itmaybe notedthatthe curveof ** Fig. 3 has no inflectionat zeroctige depthsnd that it is very steep near zerochargedepth. Ihereforeif Eq. 23 is validin:termsof the 9 givenin Fig. 3, the valueof $(t) is extreppelysen&tlveto the Shots were averaged.For the ‘S’ Shot, the averagevalueof for the 'S" Shotwith a A of -0.02is 1.45;this correction nmtal and computationalerrorsInvolvedin obtainingthe averagevalues. ThusFig. 3 canbe used as a guidein adjustingtheq(l)values for detonationswithA valuesbetueen-0.02and 0.13. When the data from OperationTE9WQTESS Shotard othersare reduced,it may be possibleto derivea betterscslingfunctionfor 5 thsnthat givenin Fig. 3. tiveto the heigbtor depthof burstunlessthe fractionationof the radioactivecomponentschsngeswithtbe heightor depthofburst. In enrichedwithrespectto the otherfissionproducts.21No conclusions canbe made at the presenttime re g the relativedegreeof fractionationin the two JAN= Shots. 8 effect was not considered inthetreatmentofthe data inthis report. for sapr?test shotsare swmmrisedin

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The coH@atiOn of q was cerried out …