Los Alamos National Laboratory Actinide Research Quarterly · 2020. 9. 12. · Actinide Research...

In This Issue

■ Basic Research andPublic Policy Alternatives

■ WIPP: Three Years inOperation, Decades inDevelopment

■ Filling the WIPPPipeline with Actinides

■ New Initiatives in theLaboratory’s Handling ofLegacy TransuranicWaste

■ WITS is Central to aCradle-To-Grave WasteManagement System

■ SynchrotronRadiation Studies AidEnvironmental Cleanup

N u c l e a r M a t e r i a l s R e s e a r c h a n d T e c h n o l o g y

Quarterly Actinide Research

To Mars and BeyondLos Alamos expertise in plutonium-238 heat-source productionwill play an important role in a new NASA initiative

1st quarter 2002

Los Alamos National Laboratory

Actinide Research Quarterly

ii Nuclear Materials Technology/Los Alamos National Laboratory

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Actinide Research Quarterly highlights recent achievements and ongoingprograms of the Nuclear Materials Technology (NMT) Division. We welcome yoursuggestions and contributions. ARQ can be read on the World Wide Web at: http://www.lanl.gov/orgs/nmt/nmtdo/AQarchive/AQhome/AQhome.html.

A hot-pressed fuel pelletof plutonium oxideglows red before thesurface has cooled.Fuel pellets like this aremade at TA-55 out ofpurified scrap fromdisassembled heatsources. The pellets,about 27.5 millimetersin diameter and 27.5millimeters in length, willbe encapsulated to formfueled clads to be usedin radioisotopic thermo-electric generators forNASA missions. Theimage running acrossthe bottom of the covershows the microstruc-ture of a conformingweld of a nonimpactedfueled clad. To study asample with metallogra-phy, researchers polisha sample to a mirrorfinish, treat the surfaceto reveal the grains ormicrostructure, and thenexamine the structureunder the microscope. Ifthe weld is nonconform-ing, it is analyzedfurther and the informa-tion used to adjustwelding parameters.The complete story ison pages 1-4.

In This Issue

1 To Mars and Beyond

5 Basic Research and Public Policy Alternatives

8 WIPP: Three Years in Operation,Decades in Development

10 Filling the WIPP Pipeline with Actinides

14 New Initiatives in the Laboratory’sHandling of Legacy Transuranic Wastes

16 WITS is Central to a Cradle-to-GraveWaste Management System

18 Synchrotron Radiation StudiesAid Environmental Cleanup

About theCover

Actinide ResearchQuarterly is producedby Los AlamosNational Laboratory

LALP-02-061

1st quarter 2002

Nuclear Materials Technology/Los Alamos National Laboratory 1

NASA has announced a new research program that will propeldeep-space exploration through the coming decades.Plutonium-238 and Los Alamos will play an important rolein the initiative, which will rely on radioisotope heat sources fabricatedat Los Alamos to supply power and heat for missions to Mars and beyond.

NASA said the initiative will enable sophisticated mobile laboratoriesto travel over the surface of Mars, drilling deep underground at promis-ing sites where signs of life can be sought, and conduct a large variety ofother experiments day and night, around the clock.

Radioisotope Thermoelectric Generators (RTGs) fueled by plutonium-238 have been used to provide electrical power for spacecraft since 1961.In addition, low-power Light Weight Radioisotope Heater Units(LWRHUs) have been used to maintain spacecraft equipment withintheir normal operating temperatures. These RTGs and LWRHUs are intwo dozen spacecraft, including Pioneer, Voyager, Galileo, Cassini, andMars Pathfinder. (For more information on the historical perspective onplutonium-238 heat sources, see ARQ, 1st Quarter, 2001.)

Los Alamos has the only plutonium-238 scrap recovery, fuel process-ing, and analysis capabilities in the United States. Until the late 1980s,plutonium-238 was produced and purified in reactors at SavannahRiver. Those reactors have been shut down, so the aqueous scrap recov-ery process of heat-source materials is now performed at Los Alamos’Plutonium Facility at TA-55. For the next two decades, it is estimatedthat Los Alamos will produce two to eight kilograms of plutonium-238fuel per year to meet the needs of NASA’s space applications.

Currently, the aqueous scrap recovery process is being done in abench-scale operation. A full-scale aqueous scrap recovery glove-boxline is expected to become operational later this year. The Plutonium-238Science and Engineering Group (NMT-9) oversees the plutonium-238recovery and heat-source fabrication operation.

To make a general-purpose heat source (GPHS) unit or LWRHU,researchers at TA-55 recover plutonium-238 fuel from old, disassembledheat sources. The scrap is purified to remove decay products (mainlyuranium-234) and other impurities from the plutonium dioxide. Theresulting purified oxides are formed into fuel pellets and encapsulatedto form fueled clads.

Before these fueled clads can be used in GPHSs or LWRHUs, a set ofchemical and physical parameters must be met during purification andfabrication steps. Los Alamos has full capabilities to determine theseparameters for heat-source production and provide analysis for safetyimpact testing. These capabilities include chemical analyses, neutronemission-rate measurements, particle size determination, calorimetricmeasurements, helium leak tests, metallography and ceramography,ultrasonic weld examinations, and radiography.

This article wascontributed by AmyWong, MaryAnnReimus, Paul Moniz,and Gary Rinehartof Plutonium-238Science andEngineering (NMT-9).

To Mars and BeyondLos Alamos expertise in plutonium-238 heat-source productionwill play an important role in a new NASA initiative


Nuclear Materials Technology/Los Alamos National Laboratory2

To Marsand Beyond

The full-scale aqueous scrap recovery operation will also includegamma-based measurement equipment (a plutonium process monitor-ing—or PPM—system) and a solution in-line alpha counter (SILAC).These technologies will be used to monitor the ion-exchange processand alpha concentration of solutions inside the glove-box line.

Chemical analysis capabilitiesResearchers need chemical data on plutonium-238 samples (feed

oxides, purified oxides, granular plutonium-238, and process solutions)to establish the necessary baseline parameters and measurements forprocess control, material control and accountability, waste disposal,and product certification. To acquire the data, members of the ActinideAnalytical Chemistry Group (C-AAC) perform chemical analyses atlaboratories located in the Chemistry Materials and Research(CMR) Building.

The chemical analysis begins by dissolving plutonium material inconcentrated hydrochloric and hydrofluoric acids using the sealed-reflux procedure. The sealed-reflux dissolution method allowsresearchers to dissolve high-fired fuel at a temperature of 150 to200 degrees Celsius and a pressure of 50 to 115 pounds per squareinch. Spectroscopy is used to determine the purity of the resultingplutonium oxide. If the expected plutonium content is low (one micro-gram per gram or less), gross alpha counting is used to calculate theplutonium-238 content.

Analyses of actinide impurities, including uranium-234,americium-241, neptunium-237, and plutonium-236, are performedby radiochemical methods (gross alpha and gamma counting, gammaand alpha spectroscopy, and radionuclide separations). The plutoniumisotopic composition is determined by thermoionization mass spec-trometry. Direct-current arc and inductively coupled plasma massspectrometry techniques are used to determine nonactinide cationicand anionic impurities.

Because of material-at-risk issues at the CMR Building, Los Alamoshas begun consolidating plutonium-238 operations. The majority of theplutonium-238 chemical analysis capabilities will be moved into theTA-55 Plutonium Facility within the next several years.

Physical measurement capabilitiesSpontaneous fission of plutonium-238 produces approximately 2,220

neutrons per second per gram. Energetic alpha particles react withlight isotopes, producing even higher neutron emission rates. To re-duce the neutron emission rate, researchers treat the purified oxidewith oxygen-16 exchange to reduce oxygen-17 and -18 in the products.Researchers then measure the neutron emission rate of the oxide usinga thermal neutron counter.

1st quarter 2002


After a fuel pellet is hot-pressed, it is encapsu-lated in an iridium alloycontainer and subjectedto ultrasonic immersiontesting to examine theintegrity of the weld.These images show thetest results of conform-ing (top) and noncon-forming (middle) weldsof fueled clads. Thegreen area in thenonconforming weld’sdata indicates apossible defect. Thebottom table shows themagnitude of the signalreflected in the test. Theblack line is the trace ofthe magnitude illustratedby color in the middleimage, and the blue lineis the trace of themagnitude in the topimage. If a fueled cladhas ultrasonic reflectorsin excess of a set level,it is inspected withradiography to deter-mine whether the heatsource is acceptable forflight use. Rejected heatsources are recycled,and the plutonium oxiderecovered from them isused to fabricate newfuel pellets.

Calorimetry is used to determine the power output of heat-producingmaterials. Plutonium-238 has a half-life of 87.74 years and a power out-put of 0.567 watts per gram. Several types of calorimeters are used atTA-55 to measure low-wattage (up to five watts) and high-wattage (upto 200 watts) fuel. A typical GPHS fueled clad contains approximately150 grams of pluto-nium-238 oxide andhas 61 to 62 wattsof power.

An LWRHU con-tains 2.67 grams ofplutonium-238 oxideand has a nominalheat output of onewatt. Calorimetricmeasurements arealso used to performmaterial accountabil-ity measurements ofplutonium-238.

A plutonium-238GPHS fuel pellet ishot-pressed and en-capsulated in an iri-dium alloy containerwith a weld shield.Each iridium cladcontains a sintered iridium powder frit vent designed to release thehelium generated by the alpha particle decay of the fuel. Ultrasonicimmersion testing is performed to examine the weld integrity of theplutonium-fueled clad. If a fueled clad has ultrasonic reflectors in excessof the reject specification level, it is inspected with radiography. Thisadditional engineering data determines whether the heat source isaccepted or rejected for flight use.

Heat sources must be designed and constructed to survive impact.NMT-9 can determine the particle-size distribution of fines—small par-ticles that are broken off from the fuel pellet during the impact test—recovered from impact tests that are less than 100 microns in diameter.Impact tests on plutonium-238 and simulant fueled clads are conductedto determine the response to probable launch accident scenarios of barefueled clads and of GPHS modules with up to four clads each.

Particle-size analysis is also used to verify the particle size of milledoxides before dissolution. NMT-9 has equipment that can measureparticles ranging in size from 0.5 to 600 microns.

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To Marsand Beyond

Researchers use metallographic andceramographic examinations on componentsrecovered from impact tests. The microstruc-ture of the clad material, girth welds, andsamples of fuel pellets are also examined. Ametallograph with a magnification range up to500 times actual size is interfaced to the glove-box line through a unique hood extension.

In-line processmonitoring capabilities

In the full-scale plutonium-238 aqueousrecovery operation, a PPM system will beused to monitor americium, uranium, andplutonium gamma rays during the ion-ex-change process. This PPM system will providereal-time elution profiles of actinide impuritiesthat will help in reducing solution waste vol-ume and will providea monitoring toolduring washingand elution steps.

In addition, a SILACwill be used for moni-toring the alpha activ-ity in hydroxidefiltrate in the full-scaleresidue polishing op-erations. By knowingthe approximate alphaconcentration, an op-erator can adjust theoperating parametersof the ultrafiltrationprocess to maximizethe removal of pluto-nium and uranium

These images showthe microstructure ofconforming (top) andnonconforming(bottom) welds of cladmaterial. Metallo-graphic examinationsare performed on testcomponents todetermine possiblefailure mechanisms.The black spots in thenonconforming weldare bubbles or voids inthe weld itself. Theseare sometimes formedduring the weldingprocess when themetal is molten. Voidsadversely affect theintegrity of the weld,and here they makethe weld nonconform-ing, or unacceptable.The nonconformingweld was identified byultrasonic testing, andverified by radiographyand metallography.The ultrasonic andradiographic examina-tions indicated thelocation of the flaw inthe nonconformingweld, allowing re-searchers to preciselysection the sample atthat location to revealthe microstructure ofthe nonconformingarea. Researchers atTA-55 use a LECO300 metallographwith a magnificationrange up to 500 timesactual size.

from the residue solutions before dischargingthem into the Laboratory’s Liquid Waste Treat-ment Facility.

To help meet its goals, NASA is dependingon Los Alamos and the Plutonium Facility’sunique capabilities to process and fabricateplutonium-238 into heat sources. Several Marsand deep-space exploration programs that re-quire plutonium-238 heat sources are currentlyongoing or under development. For example,the twin Mars Exploration Rovers that are be-ing prepared for launch in the summer of 2003are expected to carry several plutonium-238LWRHUs on board.

Support for the Laboratory’s heat sourcework is provided by DOE’s Office of Spaceand Defense Power Systems. ■

1st quarter 2002


GuestEditorial

The opinions in this editorial arethe author’s. They do not neces-sarily represent the opinions ofLos Alamos National Laboratory,the University of California, theDepartment of Energy, or theU.S. government.

This editorial wascontributed byRodney C. Ewingof the Universityof Michigan,departments ofNuclear Engineeringand RadiologicalSciences, MaterialsScience andEngineering,and GeologicalSciences.

Basic Research and Public Policy Alternatives“We should not expect that the same level of understanding that caused theproblem will be sufficient to solve the problem.” Albert Einstein

During the last few months therehave been a number of importantpolicy decisions made that will havea direct impact on research programs related tothe fate of plutonium and other actinides.

This past November, President George W.Bush proposed to reduce the number of deployedU.S. warheads from 6,000 to between 1,700 and2,200 by 2012. Russian President VladimirPutin responded with a pledge to reduce theRussian nuclear arsenal to 1,500 warheads.

The Department of Energy (DOE) subse-quently announced that it will move forwardwith a plan to convert approximately 34 metrictons of “excess” weapons plutonium into amixed oxide (MOX) fuel to be “burned” incommercial reactors.

An earlier, parallel program to immobilizea part of this plutonium—the so-called “scrapplutonium”—into a durable solid for storageand direct disposal has been abandoned. Theparallel strategies were based on the conceptof the “spent fuel standard” that envisionedthe fissile material as being protected by highlyradioactive fission products.

President Bush has recommended the YuccaMountain site in Nevada for the geologic dis-posal of used nuclear fuel from nuclear powerplants and high-level waste from defense pro-grams. The MOX fuel, after a once-throughcycle of burn-up, is destined for disposal in theYucca Mountain repository.

Each of these policy decisions is controver-sial, and each is linked to the other through acomplex chain of legal, regulatory, and politicaldecisions. The failure of any single part of thepolicy chain will have a profound effect on thesuccess or failure of the other policy decisions.

Issues affecting policy formationAs an individual researcher, I have become

increasingly concerned at the minimal role sci-ence plays in arriving at these decisions, andeven more concerned that these decisions re-main disconnected from one another. In this

short piece, I cannot argue the mer-its or deficiencies of the indi-vidual policy decisions ordescribe their connections.I can, however, raise somesimple issues that shouldbe addressed in the formu-lation of these policies.

“Burning” the weap-ons-grade plutonium willnot reduce, to any majorextent, the inventory ofplutonium. U.S. vulner-ability to terrorist attackusing diverted materialsis not much reduced bythe new policy. Althoughthe isotopic vector of the plutonium will havebeen modified, the spent MOX fuel is still apotential source of weapons-usable material.

Protecting fissile material, either in the spentnuclear fuel or in a high-level nuclear wasteglass, is only a short-term solution, as thisstrategy essentially protects a fissile nuclidewith a half-life of 24,100 years with the highactivity of fission products whose half-livesare on the order of 30 years.

Finally, MOX fuel, mainly UO2, is not stableunder the oxidizing conditions that will pre-vail at Yucca Mountain. In presence of mois-ture and air, one can expect rapid alterationof the spent fuel and the formation of mobileUO2

2+ complexes. This spent MOX fuel in-creases the overall inventory of long-livedfissile material, and this may have an impacton the long-term safety of the repository.

Science vs politicsAs researchers, should we be concerned

with these policy decisions? We could, per-haps, leave such considerations to higher-levelgovernment officials, but as Thomas Jeffersonsaid, “Science is my passion; politics my duty.”

Because of changes in policy, researchprograms will begin and end abruptly.

Rodney C. Ewing



New programs will be focused on support-ing the present policy decision. Effort andexpertise are lost with each change. Costs es-calate as programs are redirected. Less timethan money is usually available to developsupporting data, models, and a scientificrationale for a new policy.

I understand that change is necessary, asevery new policy has specific scien-tific and technical needs, but thesechanges drive the science—ratherthan having science inform the policy.

I want to argue that, while abruptchanges may be the fate of appliedresearch programs, this should not bethe fate of basic research. A policy de-cision does not settle the fundamentalscientific issues.

In fact, in my experience, there islittle evidence that the fundamentallimitations outlined by science areused to constrain the conceptualframework of the policy. Cost, sched-ule, and politics are more likely to bethe drivers of policy than the underly-ing science. With faith and funding,every technical problem is presumedto have a solution.

However, most policy decisions inthe nuclear domain have proven to be highrisk, the cost is high, and failure propagatesthroughout the system. The high cost and ex-tended delays in the construction and opera-tion of the Defense Waste Processing Facility atSavannah River have impacted the efforts tobuild a similar vitrification facility at Hanford.

A recent directive from the Assistant Secre-tary for Environmental Management now pro-motes a goal of eliminating the need to vitrifyat least 75 percent of the waste presently des-tined for vitrification.

In studies of the radiation-resistance of composi-tions in the Gd2 (ZrXTi1-x )2O7 binary, we discoveredthat ion beam irradiations could be used to create aburied layer of disordered fluorite-type structure in amatrix of pyrochlore. The disordered structure formsat the peak of the damage profile and has an ionicconductivity of two to three orders of magnitudegreater than the surrounding insulating matrix.Thus, research on a potential plutonium-bearingwaste form has also created a new avenue for thedesign and fabrication of nanoscale mixed ionic-electronic conductors in the pyrochlore oxides. Thishas important applications in the development ofsolid oxide fuel cells and sensors. (Physical ReviewLetters, 87, 2001).

GuestEditorial

The original decision to vitrify waste at Sa-vannah River coincided with the decision toeliminate basic research on alternative wasteforms. The decision to look at alternatives tovitrification at Hanford will now require con-siderable effort and research on alternativewaste forms. With each swing of the pendu-lum, the cost increases.

1st quarter 2002


Basic research should providealternatives to policy

Every policy decision should anticipatefailure and explicitly develop alternatives.As a small example, I cite our own work onradiation effects in phases that can incor-porate actinides.

Until recently, the U.S. strategy included thedevelopment of a titanate pyrochlore for the im-mobilization of the “scrap” plutonium (to besurrounded by a high-level waste glass in a canis-ter, the “can-in-can” concept).

Although durable, the titanate pyrochlore ishighly susceptible to alpha-decay damage, be-coming fully amorphous in hundreds of years.However, through a basic research programfunded by Basic Energy Sciences, our researchgroup discovered that the closely relatedzirconate pyrochlore is resistant to radiationdamage, remaining crystalline for millionsof years.

From a scientific perspective, this phenom-enon is of fundamental interest and is the sub-ject of exciting research at Los Alamos andPacific Northwest National Laboratory inWashington, as well as in France, England, andRussia. From a policy perspective, the discov-ery is irrelevant, as immobilization of pluto-nium in ceramics is not the present strategy.

Still, this discovery provides an alternative tothe present policy.

The discovery of a new class of radiation-resistant solids opens the door to research ona new class of materials that may have manyapplications to the materials problemsthroughout the DOE complex. As is often thecase, there have already been importantspinoffs from studies of the radiation damageeffects in these materials because the ionicconductivity of Gd2(Zr, Ti)2O7 can be greatlyincreased by disordering the structure to asimpler fluorite structure. Ion-beam irradia-tions have been used to manipulate the con-ductivity of these solids at the nanoscale.

The structure of funding within DOE oftenplaces a high priority on research and engi-neering programs that support present poli-cies. However, the risk of failure could belowered if there were a conscious effort tofund basic research programs that providefuture alternatives to today’s policy. ■



Three years ago the Waste Isolation Pilot Plant (WIPP) in south-eastern New Mexico accepted its first shipment of low-leveltransuranic waste. Since then, almost 18,000 drums of wastehave been delivered to the site, and a milestone was reached in Januarywhen the site accepted its 500th shipment. During the next 35 years,about 37,000 shipments are expected to be delivered to the site.

WIPP is the nation’s first permanent, deep geological disposal facilityfor low-level waste generated by the nuclear weapons program. Regu-lations do not allow WIPP to accept commercial or high-level radioac-tive waste. President George W. Bush has endorsed a high-level wasterepository at Yucca Mountain in Nevada. Congress is expected to takeup that debate later this year.

WIPP required years of scientific research, regulatory struggles, andinput from the public before it began opera-tions in March 1999. The idea for a WIPP datesback to the 1950s, when the National Academyof Sciences launched a search for a geologicalformation stable enough to contain wastes forthousands of years. In 1955, after extensivestudy, salt deposits were recommended as apromising medium for the disposal of radioac-tive waste.

Salt is a good candidate for nuclear wastedisposal for several reasons. Most salt depositsare found in stable geological areas wherethere is very little earthquake activity. Saltdeposits are found in areas where there is noflowing fresh water—if water were present, itwould have dissolved the salt beds. Salt also isrelatively easy to mine. And, because rock saltheals its own fractures, the salt formations willslowly move in to fill mined areas and seal thewaste from the environment. The salt rock alsoprovides shielding from radioactivity similar tothat of concrete.

The Atomic Energy Commission (AEC),the forerunner to the Department of Energy(DOE), originally selected a salt mine nearLyons, Kansas, for WIPP, but it turned out tobe unacceptable. Several years later, a site nearCarlsbad, N.M., was chosen. Congress autho-rized WIPP in 1979, and the DOE constructedthe facility during the 1980s.

WIPP: Three Years in Operation,Decades in Development

Information andphotos for thisarticle wereprovided by theDOE CarlsbadField Office.

Wipp Update

The Waste Isolation Pilot Plant (WIPP), the world’sfirst permanent underground repository for transu-ranic (TRU) waste, is located in a remote desertarea in southeastern New Mexico. Above: Thisschematic shows the aboveground facilities and thesurrounding countryside, as well as the repositoryareas (the gray rectangles) excavated almost one-half mile underground. Above right: Drums of wastefill an underground disposal room. Right: Thesecutaways show the contents of drums of TRUwaste. Most of the waste that is coming to WIPPconsists of rags, clothing, tools, debris, and otherdisposable items contaminated with radioactiveelements, mostly plutonium. Far right: Morethan seven miles of tunnels make up theWIPP underground.

1st quarter 2002


The salt formations at WIPP were formed about 225 million years agoduring the evaporation of an ancient ocean. These geologic formationsat WIPP are about 2,000 feet thick, beginning 850 feet below the surface.

Waste destined for WIPP consists mainly of equipment, clothing, andother debris that has been contaminated with small amounts of pluto-nium and other transuranics. The waste, which has been accumulatingsince the Manhattan Project, is currently stored at almost two dozensites around the United States.

Ninety-seven percent of the waste comes from just five sites: LosAlamos, Rocky Flats Environmental Technology Site in Colorado, IdahoNational Engineering and Environmental Laboratory, Hanford Site inWashington, and Savannah River Site in South Carolina.

Federal and State regulations require that waste be characterized be-fore it is shipped to WIPP. Characterization requires knowing the physi-cal, chemical, and radiological properties of the waste to make sure itcontains only materials allowed to be shipped to and accepted by WIPP.Once received at WIPP, and before they are buried, the wastes must beconfirmed to contain only those materials allowed to be disposed atthe site.

Safely disposing and storing the accumulated waste from almost 60years of nuclear research is a daunting task. WIPP is a critical part ofthe DOE’s effort to clean up this legacy waste and protect the publicand the environment. In the articles that follow, we take a look at sev-eral issues of nuclear waste, including technologies Los Alamos is usingto safely store and track waste, how Los Alamos researchers are assist-ing the cleanup effort at Rocky Flats, and a guest editorial on WIPP’sfirst three years of operation. ■



In May 1999, I was appointed managerof the Department of Energy (DOE)Carlsbad Field Office, which is respon-sible for the DOE’s Waste Isolation Pilot Plant(WIPP) and the National Transuranic WasteManagement Program. WIPP is a deep geo-logic repository located near Carlsbad, N.M.,for the disposal of defense-generated transu-ranic (TRU) waste. The National TransuranicWaste Management Program coordinates thecharacterization of this waste at DOE sitesacross the country and the transportation ofthe waste to WIPP for disposal.

Upon arriving in Carlsbad, I immediatelyrealized the need to accelerate TRU wasteshipments to WIPP. At the time, WIPP was re-ceiving one to two shipments of TRU wasteper week. At that rate, it would take the facil-ity 255 years to complete its mission! Clearly,something had to be done, so I challengedWIPP employees and organizations to “fill thepipeline” to achieve and sustain 17 shipmentsper week.

I am proud to say that three years later,WIPP is receiving 17 shipments per week andis now ramping up to receive 25 per week. Letme tell you how our team achieved this goal.

Filling the pipeline required a culture changeas much as anything else. For years, WIPP fo-cused on preparing the facility for opening.This meant passing literally hundreds of auditsby regulators, oversight groups, and internalreview teams. After the facility finally openedfor TRU waste disposal operations on March26, 1999, most WIPP employees and organiza-tions continued to focus their attention “insidethe fence”—to improving the WIPP waste han-dling process and facility operations.

Our challenge was to get these employeesand organizations to shift some of their focusto “outside the fence”—improving TRUwaste characterization and transportation.Changing a culture can take years, but we didnot have that kind of time. So, we launched afull-scale communication blitz to effect achange in their focus.

But, communication is not enough to effect aculture change—you must hold organizationsand employees accountable. WIPP became oneof the first DOE facilities to use a new methodof contractor accountability: the performance-based incentive. Through a number of perfor-mance-based incentives, we made sure that thecontractor had incentives to accelerate wasteshipments to WIPP. Not only was the contrac-tor held accountable, my own DOE employeeswere as well.

Filling the WIPP Pipeline with Actinides

This article wascontributed by InésTriay, manager ofthe CarlsbadField Office.

Inés Triay

Wipp Update

A truck carries three Transuranic PackageTransporter Model II—or TRUPACT-II—containersto the WIPP site. The stainless steel containersare approximately eight feet in diameter, ten feethigh, and can hold up to fourteen fifty-five-gallonwaste drums.

1st quarter 2002


In addition to changing the culture at WIPP,many technical initiatives were also necessaryto aid in filling the pipeline. Researchers at LosAlamos National Laboratory had previouslydesigned and produced a TRU waste mobileloading unit, and we accelerated its deploy-ment and use at the Savannah River Site inSouth Carolina. The mobile loading unit con-tains a suite of equipment capable of loading55-gallon TRU waste containers intoTRUPACT-IIs (the shipping casks we use fortransport to WIPP).

The Central Characterization Project isanother accomplishment of the past year. Thisproject is a mobile waste characterization sys-tem consisting of four parts. Nondestructiveassay instrumentation is used to characterizethe radiological content of each drum, whilenondestructive evaluation equipment (real-time-radiography) is used to examine thephysical contents of each drum.

The characterization system also includes avisual examination capability (in a glove box)for confirming a statistical subset of the real-time radiography examinations, andheadspace gas sampling and analysis equip-ment to draw and composite air in theheadspace of each container for analysis for abroad spectrum of volatile organic com-pounds. The mobile/modular units currentlydo not have the capability to core and analyzehomogeneous solids, such as cemented drums.

The mobile waste characterization system isaccompanied by a mobile loading unit. Theseunits give sites the ability to characterize andstage transuranic waste destined for shipmentto WIPP in accordance with all necessaryrequirements and to meet WIPP’s disposalrequirements. Currently, the EnvironmentalProtection Agency and the New Mexico Envi-ronment Department have approved theproject for use on a specific waste streamlocated at the Savannah River Site. Photos courtesy of the

DOE Carlsbad FieldOffice

Members of the WIPPCentral Characteriza-tion Project mobileloading crew deploy themobile loading unit atthe Savannah RiverSite. This was the firstshipment of transuranic(TRU) waste certified,characterized, loadedinto TRUPACT-IIcontainers, and shippedfor disposal at WIPPunder the CentralCharacterizationProject. The shipmentarrived at WIPP on theevening of April 6,2002.



To date, these efforts have resulted in sev-eral critical accomplishments during the pastthree years. WIPP has ramped up from receiv-ing one to two waste shipments per week to 17shipments per week, for a total of just over 700shipments received. The site also has sur-passed one million employee-hours withouta lost-time accident and has achieved morethan one and a half million safe transportationshipment-miles.

To put this in perspective, in our first threeyears of operation we have safely emplacedalmost ten percent (1,250 kilograms) of theweapons-grade plutonium in the baseline in-ventory projected for disposal. Interestingly,we have received almost the same number ofcuries of americium-241, since we acceptedshipments early on of some of the reprocessingsludge from the Idaho National Engineeringand Environmental Laboratory. The more than67 kilocuries of americium-241 in WIPP todayare roughly equivalent to that in a commonsmoke detector for each person on the planet.

Another surprising fact deals with theamount of hazardous volatile organic com-pounds that has been shipped to WIPP in thefirst three years of operation. With all the em-phasis on organic hazardous materials in TRUwaste destined for WIPP, the total amount ofvolatile organic compounds that WIPP is re-quired to track as stipulated in our ResourceConservation and Recovery Act permit withthe State of New Mexico is less than 28 litersof gas. No, that’s not a typo.

There are nine specific “contaminants ofconcern” in the volatile organic compoundmonitoring requirements of the WIPP permit.If all of the approximately 18,000 drums ofTRU waste in WIPP today had been treatedto extract these volatile organic compoundsfrom the headspace gas, they would resultin a total of 28 liters at standard temperatureand pressure.

Wipp Update

Waste handlers performa swipe test to check forradioactive contami-nants before unloading55-gallon drums from aTRUPACT-II container.

1st quarter 2002


Recently, a new proposal has been made toconstruct an Actinide Chemistry and Reposi-tory Science Laboratory (ACRSL) adjacent tothe Carlsbad Environmental Monitoring andResearch Center (CEMRC), which is a part ofNew Mexico State University. In conjunctionwith DOE’s Office of Science and Technology(EM-50) and Los Alamos, we transferred theContaminant Analysis Automation trailer fromLos Alamos to CEMRC last year. The Contami-nant Analysis Automation technology will be-come a significant part of the ACRSL, whichwill be operated by CEMRC.

The Los Alamos Carlsbad Office will per-form radiochemistry experiments needed toaddress issues related to nuclear waste charac-terization and repository performance in thesenew facilities. Sandia National Laboratorieswill also conduct actinide chemistry experi-ments here. These studies will help addressspecific scientific and technical issues relatedto waste characterization, repository perfor-mance, and enhanced operations of the repository.

Several experiments are planned. Research-ers will study the effects of WIPP-relevant ma-terials—such as reductants—and potentialradiolysis byproducts—for example, hy-pochlorite and peroxide—on the oxidationstates and speciation of plutonium, americium,uranium, thorium, and neptunium. They alsohope to study the effects of organic ligands onthe mobility of plutonium and other actinideelements in WIPP-relevant brines, the demobi-lization of actinides by borehole fill materials,and the efficacy of oxidation state analogs forpredicting the behavior of the actinides.

Space is too limited here to describe all theother initiatives the WIPP project is pursuingto fill the disposal pipeline with waste ac-tinides. We are exploring many streamlined

Miners use a Marietta drum miner to cut passagesand rooms in the ancient, stable salt deposits. Theequipment can mine up to 875 tons per shift.

ways of characterization, and there are numer-ous transportation enhancement opportunities,including a rail option. We plan a subsequentcontribution to “Actinide Research Quarterly”next year with an update on how the WIPPproject is solving the nation’s TRU wastedisposal problem.

It has been a challenging three years. By ac-celerating waste shipments to WIPP, we aremaking a positive contribution to our nationalsafety and security, as well as paving the pathforward for the nuclear industry. ■



Anyone in the Laboratory who workswith actinides potentially generatestransuranic (TRU) waste destinedfor the Waste Isolation Pilot Plant (WIPP) inCarlsbad, N.M. Because a high volume oflegacy TRU waste also exists in storage here,reducing waste volume and efficiently manag-ing legacy waste are topics that should be ofconcern to us all.

The Lab’s new programs for handlinglegacy waste date back to 1994–95 when theState of New Mexico intervened to request thatnearly 17,000 drums of solid mixed and TRUwaste be placed in an inspectable and retriev-able configuration. So began the transuranicwaste inspectable storage project (TWISP).

The drums had been stored for nearly 20years at TA-54 on above-grade asphalt pads indense-pack arrays under plywood, plastic, andsoil. Facility and Waste Operations (FWO)

New Initiatives in the Laboratory’sHandling of Legacy Transuranic Waste

Division ultimately retrieved the drums fromthree such pads, and after washing andventing them, transferred them into six domesat TA-54. Here, they are inspected weekly, atminimum, and daily on any day when aLaboratory staff member enters a given dome.

And happily for both taxpayers and Labadministrators, TWISP was completed twoyears ahead of schedule and $18 millionunder budget.

Another concern in the arena of TRU wastemanagement has been the profusion of whatare known as “RFP crates”—Fiberglas™-rein-forced boxes containing a diversity of equip-ment ranging from glove boxes tohigh-efficiency particulate air (HEPA) filtrationsystems contaminated with both TRU andother types of waste, such as beryllium andlow-level waste (LLW).

Often these crates are very large, and almostalways, the items inside were packaged with-out much attention to space efficiency. Thiswaste issue has spawned the DecontaminationVolume Reduction System (DVRS) Project, aninitiative to process RFP crates by characteriz-ing their waste, reducing its volume, and en-closing it in crates for shipment to WIPP ifTRU, or storage at Los Alamos if LLW. A rela-tive of a good old-fashioned “Escort-Eldoradoequalizer” proved invaluable in this project.

The basic methodology involves unsheath-ing each crate, segregating its waste (if rel-evant) into TRU and LLW, and if feasible,decontaminating each component by suchtechniques as paint-stripping, surface abrasion,and the use of chemical cleaners and surfac-tants. Each component is then reduced in vol-ume by “Big Blue,” a massive compactor, kin tothose that compress both luxury and subcom-pact vehicles into the rectangular jumbles ofmetal that we often see being transported torecycling sites.

The resulting secondary waste must thenbe repackaged to meet WIPP-approved

This aerial view of the transuranic wasteinspectable storage project (TWISP) shows the sixstorage domes at TA-54. Since the mid-1990s,thousands of drums of solid mixed and transuranicwaste have been retrieved from dense-pack arraysand transferred into the domes, where they areinspected at least weekly, and daily on any daywhen a staff member enters a given dome.

LegacyWaste

1st quarter 2002


procedures if TRU, and Los Alamos wasteacceptance criteria if LLW. And because safetyis always first priority, the DVRS facility has adouble firewall, each wall rated for a two-hourfire protection delay.

Along the way, other techniques haveproved useful during this process of waste cat-egorization and reduction. For example, gassampling of the crate interiors allows the de-tection of explosive or acid gases, mercury va-por, and loose radiological contamination.

And during the FWO Division’s explorationof options for noninvasive crate-content iden-tification, an ingenious gamma-radiographyadaptation was proposed. Because manycrates are larger than the size limits of mostradiography machines, a solution was discov-ered in the form of the machines used by Bor-der Patrol agents to scan tractor-trailer rigs fordrugs and/or illegal immigrants—machineslarge enough to handle most or all RFP crates.

Unfortunately, the events of Sept. 11 neces-sitated a temporary withdrawal of the offer ofradiography personnel participation in thescreening project, but it is hoped that this as-pect of the operation will soon become reality.

There are also technologi-cal improvements in the off-ing in the waste-reductionarena. For example, a carbondioxide decontaminationblaster has shown promise inremoving surface layers ofactinide-contaminated items.The blaster produces a resi-due from which carbon diox-ide evaporates, leaving agreatly reduced volume ofTRU and an actinide-decon-taminated remainder that canbe disposed of as LLW. Otherchemical-decontamination

methods are also being researched.“If we can get the money to do this stuff, we

will,” said Ray Hahn of Solid Waste Opera-tions (FWO-SWO). One possible source of in-come may be the FRPs from other laboratoriesin the DOE complex. If an acceptable means oftransport to Los Alamos can be found for theirFRPs, Lawrence Livermore and other laborato-ries may ship them here for decontaminationand reduction on a fee basis.

—Vin LoPresti

Los Alamosimplemented thetransuranic wasteinspectable storageproject—or TWISP—as a way to makethousands of drumsof legacy waste moreinspectable andretrievable. BeforeTWISP, drums ofwaste were buried onpads in dense-packarrays underplywood, plastic, andsoil. Here, workersuncover drums froman array beforewashing, venting,and moving them todomes at TA-54.Waste drums fromthree such pads havebeen retrieved.

This massive compactor—known as “Big Blue”—has proved invalu-able to the Decontamination Volume Reduction System (DVRS)Project, which is aimed at decreasing the profusion of space-wasting“RFP crates.” Contaminated waste, ranging from glove boxes to airfiltration systems, that was originally stored in large reinforcedplywood crates is sorted, decontaminated, and fed to Big Blue, whichreduces the waste into the black jumbles of metal at the bottom of thephoto. The compressed waste will be repackaged either for shipmentto WIPP or storage at Los Alamos.



Researchers in the Waste Managementand Environmental ComplianceGroup (NMT-7) have developedan innovative system for tracking theNuclear Materials and Technology (NMT)Division’s radioactive and contaminatedwaste. It will store this retrievable informationin a central database accessible to otherLaboratory organizations.

The Waste Inventory Tracking System(WITS) is central to NMT’s “cradle-to-grave”approach to waste management because itprovides one source for information gatheringand archiving.

WITS also minimizes the possibility of hu-man error by automating the characterizationprocess through the use of bar codes and ahand-held personal digital assistant (PDA) totrack waste shipments. This information isalso vital to staff at the TA-54 Waste DisposalSite, where the waste is received and staged ordisposed, depending upon its classification.

WITS was designed in collaboration withBeta Corporation International and IntelligentProgramming, LLC, over a two-and-a-half-year period beginning in 1998. The PDA isused to read the bar code on each container ofwaste. This bar code, which is created at thewaste source, identifies the contents of eachcontainer; exactly what’s in it and how muchof it there is by weight. This information goesdirectly into a database that prints out a com-plete inventory of each container and main-tains a searchable archive that is available toall authorized employees.

WITS is Central to a Cradle-To-GraveWaste Management SystemInnovative Tracking System Improves Accountability,Eliminates Paper Trail, Reduces Inventory Time

The system eliminates the paper trail and allthe shortcomings associated with cumbersomefiles and human error.

Besides streamlining the information-building process, WITS also drastically reducesthe time it takes to create the inventory.Bernadette Martinez, the technical lead for in-formation management in NMT-7, says that itused to take about three hours to characterizeone dumpster shipment of 90 low-level radio-active waste boxes and fill out the per-dumpster waste acceptance forms.

This process now takes about 20 minutesand includes an electronic-signature feature.The waste acceptance form is still used, but aprintout of the waste contents as well as pho-tographs to document the shipment now ac-companies it. The increased accuracy andoverall cost-saving benefits are substantial.

WITS also reduces the time and effort toprocess the waste data at TA-54. Before WITS,NMT-7 personnel completed a Chemical WasteDisposal Request (CWDR) for each wastepackage. The information on the CWDRwas entered by hand into the computerizedChemical/Low-Level System at TA-54. Toensure accuracy, the data was entered a secondtime and compared. The paper copy of theCWDR was filed and maintained as a wastemanagement record.

WITS

1st quarter 2002


WITS eliminated the need for double dataentry and the management of the paperCWDR. Martinez says, however, that the “keything about WITS is its ability to integrate in-formation among divisions.” This across-the-Laboratory integration is important for severalreasons: It creates a database that is accessibleto anyone who needs it; it increases theLaboratory’s accountability; and it decreasesthe time and effort involved in delivering,maintaining, and retrieving paper-onlyrecords.

Currently, WITS is used for compactablewaste such as low-level radioactive room trashand noncompactable waste containing metaland wood. However, the incorporation ofchemical and hazardous waste into WITS re-quires additional refinements in the system.

WITS may have many applications outsideof waste management. Martinez has been con-tacted by other national laboratories, severalBritish companies, and Toyota Motor Manu-facturing North America, Incorporated, forinformation about WITS and its possible appli-cations to general inventory management.

One notable, nonwaste use of WITS wasmade last year when a contamination incidentat TA-55 resulted in workers having to checkevery compression fitting in the productionbuilding. WITS’ functionality was used to

document the checking of approximately25,000 fittings with a “fitting tracker” softwaremodule. After the fittings were documented astight, check/leak verifications were per-formed. The estimated 50,000 total checks per-formed over a three-month period resulted ina quick resumption of operations. Members ofNMT Division won a Los Alamos Achieve-ment Award for their effort.

This innovative system may have otheruses at the Lab, says Martinez. Because WITSrequires only a two-hour operator training touse the system, it could be used as a cost-effective tracking system in any number ofwork situations, including a basic inventory ofeverything from computers to lock-out/tag-out accounting. ■

—Ed Lorusso

Egan McCormick of the Waste Management andEnvironmental Compliance Group (NMT-7)performs a field inventory of low-level waste boxesusing a hand-held personal digital assistant—orPDA. The PDA has a built-in bar code reader thatscans a bar code on the container and uploads theinformation to a database. This bar code, which iscreated at the waste source, identifies the contentsof each container; exactly what’s in it and howmuch of it there is by weight. The technology is partof the Waste Inventory Tracking System (WITS)developed by NMT-7 to track radioactive andcontaminated waste.



The Rocky Flats EnvironmentalTechnology Site (RFETS) is an environ-mental cleanup site located about 15miles northwest of downtown Denver. For-merly known as the Rocky Flats Plant, this sitemade components for nuclear weapons usingvarious radioactive and hazardous materialsuntil December 1989, when plant operationswere shut down.

Nearly 40 years of nuclear weapons produc-tion left behind a legacy of contaminated facili-ties, soils, and surface water. Two decades ofroutine monitoring have shown that the envi-ronment around RFETS is contaminated withactinide elements (uranium, plutonium, andamericium) from site operations.

More than 2.5 million people live within a50-mile radius of the site; 300,000 of those livein the Rocky Flats watershed. The Environ-mental Protection Agency designated the site aSuperfund cleanup site and a massive acceler-ated cleanup effort began in 1995.

The key priority of site management andsurrounding community leaders is the safe,accelerated closure of Rocky Flats. Kaiser-Hill,the company in charge of the cleanup, and theDepartment of Energy (DOE), in close coordi-nation with Rocky Flats stakeholders, areworking aggressively to substantially com-plete the cleanup and closure of Rocky Flatsby 2006. The price tag for the closure is esti-mated to be between $6 billion and $8 billion.

This article wascontributed byDavid L. Clark(NMT-DO); StevenD. Conradson(MST-8); Mary P.Neu, D. WebsterKeogh, PamelaL. Gordon, andC. Drew Tait(C-SIC); WolfgangRunde and MavisLin (C-INC); andCraig Van Pelt(NMT-9).

Synchrotron Radiation Studies AidEnvironmental CleanupLos Alamos Study Offers the First Spectroscopic Confirmationof the Speciation of Plutonium in Soils at Rocky Flats

The Rocky Flats plant was a top-secret productionsite 15 miles northwest of downtown Denver. From1952 to 1989, the primary mission was to manufac-ture parts for the U.S. nuclear weapons stockpile.These operations involved fabricating componentsout of plutonium, uranium, and beryllium. Nearly 40years of nuclear weapons production left a legacyof nuclear waste at the site, including contaminatedfacilities, process waste lines, and buried wastes.Major dispersal of plutonium contamination into theimmediate environment resulted from fires inproduction buildings and leakage of contaminatedwaste oil stored outdoors.

In 1992, the Rocky Flats mission changed toclosure and cleanup. Today, Rocky Flats is in theprocess of deactivating, decontaminating, decom-missioning, and demolishing the weapons produc-tion facilities and buildings in the industrial area.The purpose of the final closure phase isremediation of the environmental legacy of nuclearweapons production and transition to long-termstewardship as a wildlife refuge.

SynchrotronStudies

1st quarter 2002


Chemical speciation studiesResearchers at Los Alamos are assisting the

cleanup effort by studying contaminated soilsfrom the site using x-ray absorption spectros-copy at Stanford Synchrotron Radiation Labo-ratory. Earlier studies of the site have shownthat plutonium is present in surface soils andthat there is a clear west-east trend in contami-nation away from an old drum storage siteknown as the 903 Pad. More than 90 percent ofthe plutonium is contained within the upper10 to 12 centimeters of soils downwind of the903 Pad.

The Los Alamos team has been studying theapplication of synchrotron radiation tech-niques to plutonium environmental behavior,and their most recent study has resulted in thefirst spectroscopic confirmation of the chemi-cal speciation of plutonium in soils at RFETS.The speciation of contaminants (i.e., the el-emental identities of the contaminants, theirphysical states, oxidation states, host-phaseidentities, molecular structures, and composi-tions) controls their toxicity, bioavailability,transport, and fate in the environment.

The data acquired from the Los Alamosstudy (combined with other site-specific stud-ies) are key to choosing proper remediationstrategies, the correct model for assessing pub-lic health risks, and aiding decisions for futureland configuration and management.

The probability of the release of plutoniumfrom RFETS soils to the surrounding environ-ment depends on the solubility of its compoundsin groundwater and surface waters, the ten-dency of plutonium compounds to be adsorbedonto mineral phases in soil particles, and by theprobability that the colloidal forms of pluto-nium will be filtered out by the soil or rockmatrices, or adsorb or settle out during transport.

The 903 Pad was used in the 1950s and 1960s for storage, on bare ground,of approximately 4,000 drums of plutonium-contaminated solvents and oils.A major release of plutonium to the environment occurred when plutonium-contaminated waste oil leaked from these drums. The drums were removedin 1967 and 1968 after radioactive contamination was detected.

Plutonium-contaminated soil was dispersed by the wind during remediationactivities, and an asphalt pad was installed in 1969 to control the spread ofplutonium contamination. The area around the 903 Pad continues to be oneof the major sources of plutonium contamination at the Site.

Los Alamos researchers used synchrotron x-ray absorption spectroscopy onplutonium-contaminated soils from the 903 Pad to identify the chemical form(or speciation) of plutonium in these soils to assess its environmentalbehavior and to assist the site in assessing cleanup strategies.



L-edges

K-edgeAb

sorp

tio

n C

oef

fici

ent

Incident Photon Energy, Electron Volts (eV)

L3 L2L1

Using XANES Spectroscopyto Determine Oxidation States

When a beam of x-rays passes through matter, it loses intensity via interac-tion with the matter. A plot of the x-ray absorption as a function of energy (thegraphic on the top) shows a decrease in absorption with increasing energy,the presence of a sharp rise at certain energies called edges, and a series ofoscillatory wiggles (or fine structure) at energies above these edges. It isthese characteristic energy regions where x-rays are strongly absorbed(referred to as absorption edges) that are used in x-ray absorption spectroscopy.

The x-ray absorption near edgestructure (XANES) can be used todetermine the oxidation state of thetarget (x-ray absorbing) element insolution or in the solid state. Theenergy at which an absorptionedge appears depends on theionization potential of the ion.This ionization potential increaseswith the ion’s valence, so ingeneral, the absorption shifts tohigher energy with increasingoxidation state.

Los Alamos researchers used thiseffect to determine the oxidationstate of plutonium in contaminatedsoils and concrete samples fromthe Rocky Flats EnvironmentalTechnology Site. In XANES spectraof plutonium (the graphic on thebottom), there are distinct differ-ences in the energy of the risingabsorption edge, the intensity ofthe peak (sometimes referred toas the “white line”), and thestructure in the absorption featuresat the higher energies beyond theabsorption peak.

All of these features change with thechanging oxidation state of pluto-nium. These differences in theXANES spectra are used to identifythe oxidation state of plutonium inRFETS samples.

22270

0.5

1.0

1.5

Pu(III)

Pu(IV), soil, concrete

Pu(V)Pu(VI)

E-ray Absorption atPlutonium L2 Edge

22290

Energy (eV)

No

rmal

ized

Ab

sorb

ance

22310

These factors are largely governed by thechemical oxidation state and its associatedchemistry. Plutonium in lower oxidation statestends to form complexes with extremely lowsolubilities and stronger sorption to mineralsurfaces under most environmental conditions.Plutonium in the higher oxidation states tendsto form complexes with relatively higher solu-bilities and weak sorption to mineral surfaces.

Scientific techniques that provide informa-tion on the nature of plutonium oxidationstates in the environment are therefore ofgreat interest.

Synchrotron-based methods are extremelypowerful for the study of speciation in theenvironment because they can be usedunder environmentally relevant conditions,namely, in the presence of water at ambientpressures and temperatures, and at dilutemetal ion concentrations.

The chemical oxidation state and electronicproperties can be determined from the X-rayAbsorption Near Edge Structure (XANES).X-ray Absorption Fine Structure (XAFS) spec-troscopy probes the local chemical environmentof a material, providing information on the iden-tity of atoms in the first coordination sphere ofthe central metal ion, the number of neighboringatoms, and their interatomic distances.

Because the samples do not need to be crys-talline, XAFS is ideally suited to the study ofhighly disordered solids and amorphous mate-rials that are likely to be found as a result ofaccidental environmental contamination.

SynchrotronStudies

1st quarter 2002


The Los Alamos team examined x-rayabsorption spectroscopy of a series of well-characterized standard compounds followedby samples of contaminated RFETS soils andconcrete collected from the site. These studiesused Stanford Synchrotron RadiationLaboratory’s new Molecular EnvironmentalScience Beam Line.

The XANES measurements on RFETS soilfrom the 903 Pad and concrete from a contami-nated building clearly show that the oxidationstate of plutonium is Pu(IV), and the XANESspectral signatures are very similar to that ofsolid plutonium dioxide (PuO2) in both soiland concrete samples. One of the soil sampleswas concentrated enough that XAFS data couldbe studied. XAFS data analysis revealed localstructure features nearly identical to that of thesolid PuO2 standard.

Los Alamos x-ray absorption studies there-fore show unambiguously that plutonium inRFETS soils taken from the 903 Pad is in oxida-tion state (IV) and in the chemical form of in-soluble PuO2. For decades it had beenpresumed that plutonium in RFETS soils ex-isted as PuO2, but this hypothesis had neverbeen proven.

Using XAFS Spectroscopyto Determine Local Atomic Structure

X-ray Absorption Fine Structure (XAFS) spectroscopy reveals information onthe solid-state structure of a sample, even if the sample is amorphous,noncrystalline, or dissolved in solution. XAFS provides information about thenumber of atoms and their interatomic distance from a central target atom.

In the case of plutonium dioxide (PuO2 ), the crystalline structure has cubicsymmetry and is shown here from the perspective of a central plutoniumatom (dark green). If we probe the x-ray absorption of plutonium in thissample, we will extract the local structural environment around a plutoniumatom in the sample.For PuO2 , there areeight near-neighboroxygen atoms (shownin red) that all sit at a2.33 angstromdistance from thecentral plutoniumatom in the structure.In the cubic PuO2structure, there arealso 12 neighboringplutonium atoms(light green) at aninteratomic distanceof 3.81 angstromsfrom the centralplutonium atom.Finally, in thisexample, there isanother “shell”containing 24 distantoxygen atoms (shownin pink) at an inter-atomic distance of4.66 angstroms.

It is this combination of the number of near-neighbor atoms, their elementalidentities, and their interatomic distances that uniquely define the chemicalstructure using XAFS spectroscopy.



The Los Alamos study is the first spectroscopic confirmation of thespeciation of plutonium in soils at RFETS. This finding is consistentwith the observed insolubility of plutonium in site-specific waters andsupports a growing body of evidence that physical (particulate) trans-port is the dominant mechanism for plutonium migration at RFETS.

This recognition not only identified the need for the site to developa soil-erosion model, but also significantly helped in gaining publictrust that an erosion model was the correct model for the site andthat soluble transport models are inappropriate for plutonium inRFETS soils.

Plutonium XAS measurements have developed into a decision-making tool for Kaiser-Hill LLC, saved the company millions of dollarsby focusing site-directed efforts in the correct areas, and will aid theDOE in its effort to clean up and close the RFETS by 2006. ■

SynchrotronStudies

1st quarter 2002


Third Plutonium Futures ConferenceSet for July 2003 in Albuquerque

The next Plutonium Futures Conference is scheduled for the summerof 2003 in Albuquerque at the Marriott Hotel. The conference, the thirdin a series, is sponsored by Los Alamos National Laboratory, in coop-eration with the American Nuclear Society.

In 2000, the Plutonium Futures Conference hosted more than 400visitors from 15 countries. The conferences, held every three years, pro-vide an international forum for presentation and discussion of currentresearch on physicaland chemical proper-ties and environmen-tal interactions ofplutonium and otheractinide elements.

A number of issuessurrounding plutoniumand other actinidesdeserve and receive significant national and international attention, in-cluding the safe storage and long-term management of surplus weap-ons materials and the management of large inventories of actinides fromcivilian nuclear-power generation. The technical basis for addressingthese issues requires intensive and increasing understanding of the un-derlying plutonium and actinide science and technology.

Scientists, engineers, and university students throughout the world,as well as the national laboratories and the Department of Energy’snuclear complex, are expected and encouraged to participate and maketechnical contributions.

A second announcement and call for papers will be issued this sum-mer. To sign up to receive more information, visit the website atwww.lanl.gov/Pu2003, or contact Kathy DeLucas at [email protected],(505) 665-3618.

PaProtactinium

231.0359

91+4+5

◊20◊9◊2

UUranium238.029

92-3-4-5-6

◊21◊9◊2

NpNeptunium237.0482

93-3-4-5-5

◊22◊9◊2

PuPlutonium

(145)

94+3+4+5+6

◊23◊8◊2

AmAmericium

(145)

95+3+4+5+6

◊23◊8◊2

CmCurium(247)

96+3+2

◊25◊9◊2

BkBerkelium

(247)

97+3+4

◊27◊8◊2

PuPlutonium

(145)

+3+4+5+6

◊23◊8◊2 3



Publicationsand Invited

Talks

Authors: Have youpublished a paper,book or bookchapter, or givenan invited talk?Please e-mail thespecifics to:[email protected].

Alferink, S., J.E. Farnham, and M.M. Fowler, “Solu-tion In-Line Alpha Counter (SILAC) InstructionManual, Version 4.00,” Los Alamos National Labo-ratory report LA-13828-M (June 2001).

Bailey, J.A., F.L.Tomson, S.L. Mecklenburg, G.M.MacDonald, A. Katsonouri, A. Puustinen, R.B.Gennis, W.H. Woodruff, and R.B. Dyer, “Time-Re-solved Step-Scan Fourier Transform Infrared Spec-troscopy of the CO Adducts of Bovine Cytochrome cOxidase and of Cytochrome bo3 from EscherichiaColi,” Biochemistry 41 (8), 2675-2683 (2002).

Berg, J.M., K.C. Rau, D.K. Veirs, L.A. Worl, J.T.McFarlan, and D.D. Hill, “Performance of Fiber-Optic Raman Probes for Analysis of Gas Mixtures inEnclosures,” Appl. Spectrosc. 56 (1), 83-90 (2002).

Bolton, F.N., and J.F. Kleinsteuber, “A Perspective onthe Effectiveness of Risk Assessment by First-LineWorkers and Supervisors in a Safety ManagementSystem,” Human and Ecological Risk Assessment 7 (7),1777-1786 (2001).

Danis, J.A., W.H. Runde, B. Scott, J. Fettinger, and B.Eichhorn, “Hydrothermal Synthesis of the First Or-ganically Templated Open-Framework UraniumPhosphate,” Chemical Communications (22), 2378-2379 (2001).

Duval, P.B., C.J. Burns, W.E. Buschmann, D.L. Clark,D.E. Morris, and B.L. Scott, “Reaction of theUranyl(VI) Ion (UO2

2+) with a TriamidoamineLigand: Preparation and Structural Characterizationof a Mixed-Valent Uranium(V/VI) Oxo-ImidoDimer,” Inorg.Chem. 40 (22), 5491-5496 (2001).

Duval, P.B., C.J. Burns, D.L. Clark, D.E. Morris, B.L.Scott, J.D. Thompson, E.L. Werkema, L. Jia, and R.A.Andersen, “Synthesis and Structural Characteriza-tion of the First Uranium Cluster Containing anIsopolyoxometalate Core,” Angewandte Chemie–In-ternational Edition 40 (18), 3358-3361 (2001).

Gordon, J.C., G.R. Giesbrecht, J.T. Brady, D.L. Clark,D.W. Keogh, B.L. Scott, and J.G. Watkin, “Observa-tion of a Significantly Reduced 1JC-H Coupling Con-stant in an Agostic f-Element Complex: X-rayCrystal Structure of (ArO)Sm[(µ-OAr)(µ-Me)AlMe2]2(Ar=2,6-i-Pr2C6H3),” Organometallics 21 (1), 127-131 (2002).

Gutierrez, R.L., “Development of the Low-PressureHydride/Dehydride Process,” Los Alamos NationalLaboratory report LA-13806-MS (April 2001).

Jordan, H., K.D. Bennett, and D.C. Keller, “AirborneRelease Fractions of Beryllium Metal in a Fire-Lit-erature Review and Recommendation,” Los AlamosNational Laboratory report LA-13843-MS (Septem-ber 2001).

Jordan, H., D.J. Gordon, J.J. Whicker, and D.L.Wannigman, “Predicting Worker Exposure from aGlovebox Leak,” Los Alamos National Laboratoryreport LA-13833-MS (May 2001).

Sampson, T.E., T.L. Cremers, and D.G. Tuggle,“ARIES Nondestructive Assay (NDA) System,” LosAlamos National Laboratory report LA-13847-MS(August 2001).

Sheldon, R.I., “An Estimate of the HighTemperature, Metal Rich Phase Boundary ofPlutonium Sesquioxide,” J. Nucl. Mater. 297 (3), 358-360 (2001).

Sheldon, R.I., and A.C. Larson, “DiffractionGeometry for the LANSCE Single CrystalDiffractomerr–SCD,” Los Alamos NationalLaboratory report LA-13877-MS (February 2002).

Silver, G.L., “Proportional Equations in PlutoniumChemistry,” Journal of Radioanalytical and NuclearChemistry 245, 229-232 (2000).

Silver, G.L., “The Auto-Reduction of HexavalentPlutonium-239 in Acid Solution,” Journal ofRadioanalytical and Nuclear Chemistry 246, 429-430,(2000).

Silver, G.L., “Plutonium Polymer Formation,”Journal of Radioanalytical and Nuclear Chemistry 247,561-562 (2001).

Silver, G.L., “Plutonium Oxidation States inSeawater,” Applied Radiation and Isotopes 55, 589-594(2001).

Silver, G.L., “The Four-Point DiamondConfiguration,” Applied Mathematical Modelling 25,629-634 (2001).

Taylor, T.N., G.K. Lewis, D.M. Wayne, J.C. Fonseca,and P.G. Dickerson, “The Role of Impurities inBubble Formation During Directed Light Processingof Tantalum,” Applied Surface Science 180 (1-2), 14-26(2001).

1st quarter 2002


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ARQ wins publication award

Three issues of the “Actinide Research Quarterly” have won anAward of Merit from the Kachina Chapter of the Society for TechnicalCommunication’s 2001 Technical Publications Competition. The is-sues submitted were 4th Quarter 2000, 1st Quarter 2001, and 2nd

Quarter 2001. The award was presented to K.C. Kim, chief scientistof Nuclear Materials Technology (NMT) Division, former editor AnnMauzy, editor Meredith Coonley, and designer Susan Carlson.Mauzy, Coonley, and Carlson are with Communication Arts andServices (IM-1).

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