LA-8189+RProgressReport

ONW1/Sub/7g/E511-01100-10

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Oklo—Natural Fission Reactor Program

July I—September 30, 1979

For Reference

Not to be taken fromthis room

LOSALAMOSSCIENTIFICLABORATORYPost Office Box 1663 LosAlamos. New Mexico 87545

~ AffiimmtivsActk@quslOpportunityEmploya

Previousreportsinthisseries,unclassified,areLA-7658-PR,LA-7816-PR,andLA-8054-PR.

ThisreportwasnoteditedbytheTechnicalInformationstaff.

ThisreportwaspreparedbytheLosAlamosScientificLaboratoryoftheUniversityofCaliforniaunderSubcontractES11-01100withBattelleMemorialInstitute,ProjectManagementDivision,underContractEY-76-C4)61830withtheUSDepartmentofEnergy.ThesubcontractwasadministeredbytheOfficeofNuclearWasteIsolation.

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l’his taa.rt wai prr$..rrd u an account of work sponsoredby the United SW.. Go.rmmcnt. Neither the United Statesn.mthe United S-16 Department of En. rv. nor -v of theiremplcwees.nor any of that contwctors. subeomr.etocs, mIhci, cmPIoY-a. nmkrs *nY WM1811tY..zD,.= oc iMP1id. 0<usumci any leml liab81iW or remonstbtlttv for the acc. racY.emnpletrneia. pr usd.lness of anv Inronnstion. amaratus.product. or processdlxclosed.or rePrese.u th.t titsuse wouldriot infcincePrivate!, owmd richtc.

uNITED STATESOCPARTM ENT OF ENERGYCONTRACT W-740 S-ENG. S6

LA-8189-PRProgressReportONW1/Sub/79/E51 1-01100-10

UC-11Issued: January 1980

Oklo—Natural Fission Reactor Program

July 1—September 30, 1979

~z~ A. E. Norrispp~

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DISTRIBUTION.

ABSTRACT. . .

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PROGRAMOBJECTIVE

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PROGRESSDURINGTHE CURRENTQUARTER

A. AdditionalOklo Samples. . . .

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B. LeadMigrationStudiesat Key Lake

c. Techniquesfor IsotopicAnalysesof

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Ruthenium

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D. JointProposalforMigrationStudiesin Australia

E. Conclusions. . . . . . . . . . . . . . . . . . .

F. Communications. . . . . . . . . . . . . . . . .

PROBLEMS. . . . . . . . . . . . . . . . . . . . . . .

ACTIVITIESPLANNEDFOR NEXT QUARTER . . . . . . . . .

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Departmentof EnergyMr. C. R. CooleyBid.CodeGTNMS B107Washington,D. C. 20545

Departmentof EnergyDr. JohnA. PattersonBid.CodeFEDRA-224,MS-6521Washington,D.C. 20461

Dr. WayneA. Carbiener(6)BattelleOfficeof NuclearWasteIsolation505 KingAvenueColumbus,OH 43201

Mr. R. Y. LowreyWeaponsProductionDivisionAlbuquerqueOperationsOfficeP. O. Box 5400Albuquerque,NM 87115

Prof.PaulKrugerDepartmentof CivilEngineeringStanfordUniversityStanford,California943o5

Prof.DouglasG. BrookinsDepartmentof GeologyUniversityof New MexicoAlbuquerque,New Mexico 87131

Mr. W. J. MaeckExxonNuclearIdahoCompany,Inc.RadiochemistrySubsectionPostOfficeBox 2800IdahoFalls,Idaho 83401

Dr. J. E. DelmoreExxonNuclearIdahoCompany,Inc.RadiochemistrySubsectionPostOfficeBox 2800IdahoFalls,Idaho 83401P

Los AlamosScientificLaboratoryG. A. Cowan,ADCEL,MS-102D. C. Hoffman,CNC-DO,MS-760J. E. Sattizahn,CNC-11E. A. Bryant,CNC-11D. B. Curtis,CNC-11C. J. Duffy,CNC-11A. J. Gancarz,CNC-11A. E. Norris,CNC-11R. J. Vidale,CNC-11

v

OKLO-NATURALFISSIC}NREACTORPROGRAN

July 1— September30, 1979

by

A. E. Norris

ABSTRACT

Nearly 200 sampleswere collectedat the Oklo mine inGabon this quarter for shipmentto the United States tocontinuestudiesof lead, ruthenium,and technetiummigra-tionaroundnaturalfissionreactors. The firstanalysesofsamples collectednear a rich uraniumore body in Canadashow thepresenceof radiogeniclead in pyriteand sandstonematerials. Analysesof additionalsamplesare underwaytopermitthe interpretationof the data in termsof transportpaths. A techniquewas developedthisquarterto eliminatethe interferenceof organicmaterialsduringthe mass spec-trometricanalysesof rutheniumin Oklo sampleswith highasphalticcontents. A proposalwas draftedfor a studyofnaturallyoccurringradionuclidemigrationat rich uraniumore bodiesin Australiato be performedjointlyby theU. S.Departmentof Energyand the AustralianAtomicEnergyCom-mission.

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I. PERSONNEL

This reportcoverssomeof the activitiesof the followingindividuals.

Los AlamosScientificLaboratory

E. A. BryantG. A. CowanD. B. CurtisA. J. GancarzA. E. Norris

IdahoNationalEngineeringLaboratory

J. E. DelmoreF. A. DuceW. J. MaeckR. A. Nielson

Universityof New Mexico

D. G. Brookins

II. PROGRAMOBJECTIVE

The goalof thisprogramis the determinationof ratesof reactorproduct

migrationand themechanismsof transportin geologicmediathat includenatural

fissionreactorsor richuraniumore bodies.

III.PROGRESSREPORTEDPREVIOUSLY

Fundingfor thisprogram,whichincludesthe UnitedStates’participation

in the internationalinvestigationof theOklo naturalfissionreactorphenome-

non, commencedin fiscalyear 1975. The firstformalreportof progressin

thisprogramwas the annualreportof fiscalyear 1976,issuedin November,

1976. The Oklophenomenonrefersto the occurrenceof self-sustainingfission

chainreactionsin a seriesof very richuraniumore pockets~

tensivePrecambrianpitchblendedepositin Gabon,West Africa

formedcriticalmassesabout2 x 109yearsago. The duration

was severalhundredthousandyears. Duringthis time,approx:J’

ocatedin an ex-

The uranium

of criticality

mately6 tonsof

uraniumwere fissioned.Studiesof the Oklophenomenonhave shownthatmany

) fissionproductswere retainedat the siteswheretheywere generated. Principal9objectivesof our currentstudiesof the Oklophenomenonare identificationof

the migrationpathsof someof the mobilefissionproductsand reconstruction

of the paleohydrologyand transporthistoryof the Oklo site.

Leadwas chosenas the firstelementto be investigatedfor tracingtrans-

port paths. Lead is not a fissionproduct,but it is formedfromthe radioactive

decayof uranium. Previouswork has shownthat-70% of the radiogeniclead is

missingfromthe Oklo reactorsite. The Oklo settingappearsto be favorable

for tracingleadtransport,becausethe commonleadbackgroundis low and the rquantityof radiogenicleadthatwas producedcan be calculated.However,when

thisworkwas begun,we did not knowwhetherwe wouldbe able to obtainrequi- Csitesamplesfromthe Oklo location. Therefore,we undertookthe measurement

of radiogenicleadtransportin the vicinityof a richuraniumore body in Canada.

This undertakingis providingvaluable,becausethe geologicsettingdiffers

fromthe Okloprovenanceand shouldprovideusefulinformationconcerninglead

transportin a high grademetamorphicrock.

The resultsof analysesof the Oklo samplesthatwere shippedto us for

leadtransportstudieshavebeen givenin a previousquarterlyreport. Analyses

of the data indicatedthata majortransportpath and repositoryinvolvedthe

conglomeratematerialunderlyingthe Oklonaturalreactorzones. The data could

not be used to inferthe methodof leadtransportfromthe uraninitegrainsto

thebasalconglomerate,but diffusionappearedto be the mechanismby which

leadwas removedfromthe uraninitegrains,whereit was formed. Waterflow,

we presume,was the meansof transport.

Rutheniumwas chosenas the secondelementto be investigatedfor tracing

transportpaths. Measurementsof rutheniumisotopeabundancesin conjunction

with uraniumanalysespermitthe determinationof the gainor lossof fissio-99genierutheniumrelativeto uranium. Furthermore,because Ru is formedby

the decayof 2.13x 105year 99Tc, it is possibleto determinefrom‘9Ru99measurementsthe gainor lossof Tc relativeto uraniumand rutheniumduring

the timewhen the-99Tc was decaying. Lastquarterwe reportedthe detection

of isotopicanomaliesat distancesas far as 10 metersfroma naturalfission

reactor. Theseanomaliesindicatedthe redistributionof fissiogenicruthenium.and technetiumrelativeto eachotherand to uranium. This observationis a

significantstep towarddeterminingelementtransportpathsand migrationrates

in a naturalenvironment.Additionalwork in theserutheniummigrationstudies fhas involveddevelopmentof a uranium-rutheniumage datingtechniqueand iso-

topicanalysesof rutheniumin nanogramquantities.

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IV. PROGRESSDURINGTHE CURRENTQUARTER

A. AdditionalOklo Samples

Dr. A. J. Gancarztravelledto theClklomine in Gabon,Africa,thisquarter

to collectsamplesfor additionalstudiesof elementmigrationin the vicinity

of the naturalfissionreactors. The collectedsamples,approximately200 in

number,can be categorizedas follows:

1. Samplesfromreactorzone9. The sampleswere collectedfromtraver-

ses spacedat 3 to 5 meters. The intervalsbetweensamplesranged

down to 10 cm.

2. Core librarysamplesof rockfroma stratigraphicunit containing

the naturalfissionreactors. Thesesamplescontainpyrite. They

were collectedat distancesrangingto NI km fromthe reactorzones.

3. Samplescollectedin an undergroundmine. Thesesamplesare from

locationsphysicallylowerthanthe naturalfissionreactors,but

fromthe stratigraphicunit thatcontainsthe reactorzones.

4. Samplescontaininggalenaand pyritefromfaultand fracturezones

in the Oklomine.

5. Samplesof powderedore. Each sampleis an aliquotof a batchof

ore thatweighed40 to 60 tons.

When thesesamplesare receivedat the Los AlamosScientificLaboratory,

an extensiveanalyticalprogramwillbeginfor the purposeof determiningthe

distancesto which radiogenicleadand fissiogenicrutheniumand technetium

were transportedfromthe Oklonaturalfissionreactorzones.

B. LeadMigrationStudiesat Key Lake

Work is underwayto measureuraniumand leadconcentrationsand leadiso-

topicabundancesin samplesselectedfromthe 402 thatwere collectedat the

Key Lake,Canada,uraniumore deposit. The purposeof thiswork is to measure

the rateof radiogeniclead transportin a geologicregimedistinctlydifferent

fromthatat the Oklo location. To date,uraniumconcen~rationshavebeen

measuredin 21 samples. Lead concentrationsand isotopicabundanceshavebeen

measuredin ten of these21 samples. The data indicatethatsamplesfromthe

Athabascasandstoneand a pyriterich rockfromthe contactbetweenthe sand-

stoneand the crystallinebasementare enrichedin radiogenicleadrelativeto

uranium. A pyriterichsampleof basemen~rockunderlyingthe uraniumore is

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relativelydeficientin radiogeniclead. Additionalwork is necessarybefore

statementscan be made aboutlikelytransportpathsfor this radiogeniclead,

particularlyin regardto its transportin the metamorphicbasementrock. Our

analyticalwork on the suiteof 402 samplesis continuing.

c. Techniquesfor IsotopicAnalysesof Ruthenium

The chemicalproceduredevelopedformass spectrometricanalysesof nano-

gram amountsof rutheniumin uraniumore gavepoor resultswhen certainOklo

sampleswere analyzed. The asphalticcontentof theseoreswas sufficiently

highthat organicmaterialcarriedthroughnot onlyone RU04 distillation,but

even througha seconddistillation.It was not possibleto oxidizethe organic

materialto effecta separationfromruthenium,becauseany oxidationstep

vigorousenoughto oxidizethe organicmaterialwouldoxidizerutheniumto RU04>

whichwoulddistill,too.

A successfulsolutionto thisproblemwas foundby modifyingthe procedure

to includea precipitationthatcarriesmost of the ruthenium,whileleaving

the organicmaterialbehind. In thismodification,rutheniumis distilledfrom

the solutionof ore, thenferricironis addedin sufficientquantityto permit

its good recoveryas the hydroxide. Sodiumhydroxideis addedto the solution

to precipitateFe(OH)3,which carriesthe ruthenium.The solidphaseis separ-

ated,dissolved,and redistilled.Rutheniumyieldsas high as 98% havebeen

obtainedwith ths procedure. Furthermore,the resultsof mass spectrometric

analysesare freefromorganicinterferences,evenwhen rutheniumis separated

fromoreswith high asphalticcontent.

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D. JointProposalfor MigrationStudiesin Australia

Mr. PhillipJ. Shirvingtonof the AustralianAtomicEnergyCommission

visitedthe Los AlamosScientificLaboratoryfromJuly 16 throughJuly 18 to

discussa possiblecollaborationbetweentheU.S.A.and Australiato measure

themigrationof naturallyoccurringradionuclidesat selectedAustralian

uraniumore bodies. A three-yearcollaborativeefforthas been proposedto

measurethe migrationdistancesand transportratesof 234U 230Th and 226Ra w> 9

at the JabilukaTwo uraniumore body; to compareradionuclidemigrationbehavior ?in zoneswhereuraniumis in the 6+ oxidationstate VepSUS migrationin zones

whereuraniumis in the 4+ valencestate;and to comparemeasurementsof uranium

sorptionand desorptionin laboratoryexperimentswith informationobtained

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aboutsorptionand resorptionwhen uraniumhas been in contactwith the sorbant

materialin naturefor timesof the orderof 105years. The 234Uand 238U

analysesrequiredfor thisworkwouldbe performedwithmass spectrometrictech-

niquesat the Los AlamosScientificLaboratory,whilethe 230Th and 226Ra

analyseswouldbe doneby the AustralianAtomicEnergyCommissionresearch

establishment.The sorption-desorptionexperimentswouldbe donejointly.

The proposalfor thiscollaborationwas completedat the end of this

quarter. It is beingsubmittedfor approvaland authorizationto the appropri-

ate Australianand United

E. Conclusions

The tripto the Oklo

Statesagencies.

mine in Gabonwas successfulin its goalof collecting

additionalsamplesfor our studiesof elementmigrationin the vicinityof

naturalfissionreactors. Whilethe samplesare in transit,we are analyzing

the Key Lakeore samplesto studyradiogenicleadmigrationin a high grade,

metamorphosedrockenvironment.Finally,a chemicalproblemthathindered

measurementsof rutheniumisotopicabundancesin someOklo ore sampleswith

highasphalticcontentappearsto be solved.

F. Communications

The

program.

included

disseminationof the resultsof thiswork is a continuingpart of our

This quarterthe followingtalksgivenby Prof.D. G. Brookins

aspectsof thiswork.

July 12, 1979,LawrenceLivermoreLaboratory,“ArgillaceousRocksas Radio-activeWasteRepositories:EvidencefromOklo.”

July 31, 1979,Institutefor BehaviorResearch,Universityof New Mexico,“TheEnds of the NuclearFuel Cycle: UraniumResourcesand the DisposalofRadioactiveWaste.”

August22, 1979,EastMesa CivitanClub,Albuquerque,New Mexico,“GeologicalAspectsof RadioactiveWasteDisposal: Oklo,WIPP,and otherExamples.”

September20, 1979,LawrenceBerkeleyLaboratory,“Okloand RadioactiveWaste.”

v. PROBLEMS

No problemsare hinderingthe progressof thiswork withinits

fundingand manpowerlevels.

VI. ACTIVITIESPLMIN_EDFOR NliXTQUARTER

The activitiesplannedfor next quarterincludecontinuationof the analy-

ticalwork on theKey Lake samplesto measureradiogenicleadmigrationand.99presentationof a paperentitled Tc, Pb, and Ru MigrationAroundthe Oklo

NaturalFissionReactors”at the InternationalSymposiumon the ScientificBasis

for NuclearWasteManagement,to be held in BostonNovember26 through29.

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