quarterly - los alamos national laboratory...figure 3. the 5d–5f resonant photo-emission spectrum...

1Nuclear Materials Research and Technology/ Los Alamos National Laboratory

Los Alamos National LaboratoryThe Actinide Research

a U.S. Department of Energy LaboratoryQuarterly

In This Issue

1 Photoemission Studies at the

Advanced LightSource Shed Light on

Plutonium PhaseCharacteristics

4O2F in FOOF Holds

Promise for PuDecontamination

6 Nuclear Materials

Including “Orphans”Require a Comprehen-

sive ManagementStrategy

8Wing 9 Hot Cells

Support WorkInvolving Highly

Radioactive Materials

11Publications and

Invited Talks

12NewsMakers

1st quarter 1999

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

XBD9811-03028.tif photo courtesyof University of California, Berkeley

continued on page 2

The physical characteristics of any given material are largelyderived from the behavior of its valence electrons. Valenceelectrons are the lowest-energy electrons in a material andare responsible for the formation of chemical bonds. Typi-cally, in a metal, electrons are either localized around a particu-lar atom or are delocalized (i.e., shared by all the atoms in the crystal)throughout the entire metal. The actinide series is interesting because asthe atomic number increases across the series, the electrons in theactinide metals transit from delocalized 5f electrons(Ac–Pu) to localized 5f electrons (Pu–No). Plutonium(element 94) is located right at this transition.This placement in the series leads to pluto-nium metal being one of the most com-plex materials known. Metallicplutonium displays six allotropicphases (α, β, γ, δ, δ′, and ε) at stan-dard pressure. A 20% volumeexpansion occurs during thechange from the α phase to theδ phase. These physical propertieshave been attributed to the 5f valenceelectrons changing from delocalized states tolocalized states as the crystal structure changes fromthe α to the δ phase.

Soft x-ray techniques (photon energy in the range of10–1000 eV) such as photoelectron; x-ray emission; and near-edgex-ray absorption spectroscopies have been used to determine theelectronic structure of many (in fact most) materials. However, thesetechniques have not been fully utilized on the actinides. The safety is-sues involved in handling the actinides make it necessary to minimizethe amount of radioactive materials used in the measurements. To ourknowledge, the only synchrotron radiation source in the world wheresoft x-ray measurements have been performed on plutonium is theSpectromicroscopy Facility at Beam Line 7.0.1 at the Advanced LightSource (ALS). The ALS is the premier synchrotron radiation facil-ity in the world for the study of the electronic structure of materi-als using soft x-ray photons. The Spectromicroscopy Facility was firstused for resonant photoemission measurements on plutonium oxidein 1993. Our first measurements on plutonium were conducted in thefall of 1998.

Photoemission Studies at the AdvancedLight Source Shed Light on PlutoniumPhase Characteristics

resonant p

hotoemission sp

ectrum

2 Nuclear Materials Research and Technology/ Los Alamos National Laboratory

Actinide Research Quarterly

Photoemission Studies at the Advanced Light SourceShed Light on Plutonium Phase Characteristics(continued)

The Spectromicroscopy Facility is de-signed so that measurements can be made onsmall quantities of hazardous material. Thisfacility has a photon flux of 1013 photon/sec ata photon energy of 100 eV with 0.01 eV resolu-tion. The high photon flux allows one to focusthe beam down to a size of 50 microns and stillhave enough light intensity at the sample formeasurements to be conducted in a reasonabletime frame, 1–10 minutes per spectrum. There-fore, the sample size can be on the order of 100microns in diameter. This greatly minimizesthe amount of plutonium on site during theexperiment. The microfocussing capabilityalso allowed us to focus onto a single δ-plutonium microcrystallite grown by JasonLashley (MST Division).

We performed core-level photoemission,valence band photoemission, and near-edgex-ray absorption spectroscopy on both poly-crystalline α-plutonium and δ-plutoniummicrocrystals. Only the photoemissionexperiments will be described here. Photo-electron spectroscopy is predicated upon thephotoelectric effect first described by Einsteinin 1905. The experimental photoemission

setup at theSpectromicroscopyFacility is shown inFigure 1. An incidentphoton is absorbedby an atom in thesolid, and an electronis ejected. An electronenergy analyzer isused to measure thedirection and kineticenergy of the emittedelectron. The kineticenergy of the photo-electron is directlyrelated to its bindingenergy in the solid.

Figure 2 shows the Pu 4f core-level photo-emission spectra from the α- and δ-plutoniumsamples. The spectrum arising from core-levelphotoemission is sensitive to energy differ-ences in the initial state (no core hole) and thefinal state (core hole and free photoelectron).The two core-level spectra in Figure 2 are simi-lar in that they both show two features, a sharpfeature at low binding energy and a broadfeature at higher binding energy. The low-binding-energy feature can be ascribed to ametallic initial state with a delocalized finalstate. As the 5f electrons are more delocalizedin the α- than in the δ-plutonium, the greaternumber of delocalized electrons in the α-plutonium leads to greater intensity in thispeak than the δ-plutonium.

Presently, the higher-binding-energy fea-ture is not completely understood. It is likelythat this feature has two states contributing toit. We believe that, in simplistic forms, onepossible component contributing to the featureis made up of emission to an electronic finalstate with localized 5f electrons. If this is thecase, it suggests that both localized and delo-calized 5f electrons are present in the α- andδ-plutonium phases. The second possible com-ponent of this feature is from an initial statethat has been oxidized.

Valence band spectra show that a smallamount of oxygen remains on the surface afterthe sample preparation. The binding energy ofPuOx is higher than that of the metal andwould be expected to be seen around the posi-tion of the unknown high-binding-energy fea-ture. A final determination of the exact natureof this high-binding-energy feature will shedlight on the poorly understood valence elec-tronic structure of plutonium, as well as on thepresence of localized and delocalized 5f elec-trons in the different plutonium phases.

Our initial goal of the valence electronicstructure measurements was to determine thedensity-of-state of the 5f valence electrons inα- and δ-plutonium. This experiment can bedirectly compared with electronic structurecalculations performed by theoreticians. Fig-ures 3(a and b) show the resonant photoemis-sion spectra of the valence band from δ- and

This article wascontributed byJeff Terry andRoland Schulze(both NMT-11).Others contributingto the researchwere JasonLashley (MSTDivision), TomZocco (NMT-11),J. Doug Farr(NMT-11), EliRotenberg, KeithHeinzelman, andDavid Shuh(LawrenceBerkeleyLaboratory), andMike Blau andJim Tobin(LawrenceLivermore NationalLaboratory).

Figure 1. The photoemission setup at theSpectromicroscopy Facility at ALS. The position of theanalyzer is fixed with respect to the incoming photons.Angle-resolved photoemission is performed by rotating thesample.


1st quarter 1999

α-plutonium, respec-tively. In a resonantphotoemission experi-ment, valence bandphotoemission spectraare collected as the pho-ton energy is scannedthrough a core-levelabsorption edge. Thiscan result in an en-hancement of the emis-sion from specificvalence levels. In thecase of plutonium,scanning the photon energy through the 5dabsorption edge results in a resonant enhance-ment of the 5f valence emission. The 5d–5fresonant photoemission measurements in plu-tonium are a measurement of the 5f contribu-tion to the valence density of states.

Two types of information are obtained inthe resonant photoemission measurementsthat can greatly enhance the understanding ofplutonium metal. Two-dimensional data slicescan be taken in either the constant-photon-energy direction or the constant-binding-energy direction. Slices taken with a constantphoton energy are the equivalent to standardphotoemission spectra with the exception thatspecific valence states are emphasized. Differ-ent states turn on or become enhanced at dif-ferent photon energies.

The data in Figures 3(a and b) show cleardifferences in the resonant photoemissionspectra from the α- and δ-plutonium. This ismost evident in the state at binding energy0 eV. If this peak is followed as the photonenergy is varied, one notices that in the δ-plutonium (Figure 3a), after 100 eV, the peaksmoothly increased to a maximum and thensmoothly decreased after the maximum wasreached. In direct contrast, the α-plutonium(Figure 3b) showed oscillatory behavior afterthe initial maximum was reached. Theoreticalcalculations of the resonant photoemission arecurrently ongoing to try to understand thesedifferences.

A large theoreticaleffort has been under-taken to understandthe plutonium datathat we have collected.The next phase of thevalence-band, elec-tronic structure mea-

Figure 2. Core-level photoemissionspectra from a large crystallite δ-plutonium sample and a polycrystallineα-plutonium sample are shown. Thesespectra were collected with a photonenergy of 850 eV and an analyzer passenergy of 6 eV. Note that two largecomponents are visible in each spec-trum, a sharp feature at low bindingenergy and a broad feature at higherbinding energy.

Figure 3. The 5d–5f resonant photo-emission spectrum with analyzerpass energy of 1 eV showing the 5fdensity of states in the valence bandfrom (a) a large crystallite δ-plutoniumsample, and (b) a polycrystalline α-plutonium sample.

2.0

Broad Manifold of States

SharpMetallicState

1.5

1.0

0.5

0-450 -440 -430

Binding Energy (eV)

Inte

nsity

-420 -410

Pu 4f Core Levelhν = 850 eVPass Energy 6 eV

AlphaDelta

surements will involve measuring the electrondispersion relation (band structure) of the va-lence electrons in δ-plutonium, and thedata will be compared with theoreti-cal calculations. The band struc-ture can only be measured ona single crystal of a material,and it is imperative to haveexcellent crystals for themeasurement. Future investi-gations will be based upon spin-resolving and photon-dichroicphotoelectron spectroscopy. Thephoton-dichroic measurements include thevariant magnetic x-ray linear dichroism.

The unique 5f valence electronic prop-erties of plutonium metal cannot beexplained by the typical one-electron calculations used todescribe prototypical met-als. Calculations on pluto-nium metal incorporatethese properties into calcula-tions in an ad hoc manner. We canmeasure these effects directly to fur-ther our understanding of one of the mostcomplex materials known.

(a)

(b)Photon Energy (eV)

Photon Energy (eV)

Binding Energy (eV)

Binding Energy (eV)



RN97377002.eps

This article wascontributed byKyu C. Kim,NMT ChiefScientist.

The traditional method of recovering ura-nium and plutonium from process streams isto dissolve actinide-containing residues andwastes in strong acidic media and put themthrough a series of separation processes suchas precipitation, filtration, and ion exchange.Over the half century of nuclear materials pro-cessing activities, this method has producedvoluminous nuclear wastes stored at variousnuclear sites. The search for safe disposalmethods continues to this day. From a pro-cessing efficiency standpoint, a better way ofseparating actinides from their major constitu-ents is to act upon only the minor componentswithout dissolving the entire matrices. Itwould be ideal if a gaseous reactant could beflowed through the residue matrices, and onlythe volatile actinides recovered as gaseousproducts, leaving behind the actinide-depletedresidues. This article describes identificationand analysis of an exotic chemical that holdsa great promise in actinide recovery, decon-tamination of process equipment, and wastereduction in actinide processing.

In the early 1980s the Los Alamos laserisotope separation program for plutonium hadcompleted the scientific concept demonstra-tion and moved toward a small-scale processdemonstration. This program was calledmolecular laser isotope separation (MLIS) andcode-named Lippizan. Before this we had anuranium isotope separation program code-named Jumper. Our sister laboratory atLivermore had two similar programs; theirprocess was called atomic vapor laser isotopeseparation.

An MLIS process uses stable moleculesthat bear the isotope of interest in their mo-lecular structures. Both uranium and pluto-nium form stable gaseous molecules calledhexafluorides. Six fluorine atoms occupy thesix apexes in an octahedral geometry with auranium or plutonium atom in the center.This particular soccer-ball-like geometry ac-counts for the chemical stability as a gaseousmolecule. Most of the world’s supply of sepa-rated uranium isotope 235U comes largely froma gaseous diffusion process employing ura-nium hexafluoride as the working medium.

Plutonium hexafluoride is the only knownstable gaseous molecule at room temperature,so it is not surprising that several isotope sepa-ration schemes were devised in the early yearsusing this molecule.

Once produced, plutonium hexafluoride isfairly stable under process conditions such ascirculation, compression, and expansion, in-side the process pipes. However, it is not soeasy to make plutonium hexafluoride undermild chemical conditions. This problem is fur-ther complicated when the MLIS end productis solid particles, and plutonium hexafluoridealso decomposes slowly to a solid product thatcoats the inside wall of the process pipes as theprocess continues. So we needed a way orways to recover the solid product from theprocess line. The only way to accomplish thisrecovery was then to turn the solid productback to gaseous product in situ. We weresearching for chemicals to accomplish theproduct recovery and cleanup of theprocess line.

By the early to mid 1980s we had identi-fied a few chemicals that could be used for thepurpose. Krypton difluoride (KrF2), dioxygendifluoride (FOOF), and the fluorine atom werethe most promising among all we investigated.Krypton and oxygen in these molecules aremerely carriers of F atoms. In the case of FOOFwe discovered subsequently that the activespecies involved in the actual fluorination re-action was a radical species—O2F—derivablefrom FOOF. This story is about the discoveryof O2F and characterization of some of itsproperties. A radical has unpaired electronsunlike a stable molecular electronic configura-tion so that it is usually very reactive withneighboring species, and it does not hangaround long (less than several seconds atmost) for us to detect readily in its isolatedstate.

The structure of FOOF had been studiedpreviously by microwave spectroscopy byother researchers. This compound is also veryunstable. It can be stored indefinitely only atvery low temperature, such as that of liquidnitrogen. The infrared spectrum of solid (fro-zen) FOOF at 77 K had been recorded, and all

O2F in FOOF Holds Promise for Pu Decontamination


1st quarter 1999

C40-1.eps

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0.15

0.50

0.85

1.20

2425 1788

Wave numbers (cm-1)

Abs

orba

nce

1363 938 513

0.29

0.21

0.14

0.07

01560 1528 1496 1464 1432

Wave number (cm-1)

Ab

sorb

ance

O2F

FOOF

continued on page 11

fundamental vibrations assigned also. But thespectral quality was very poor because thesemeasurements had been made on a minutequantity of impure samples. A serious obstacleto the study of FOOF in the gas phase hadbeen the difficulty in obtaining sufficientamounts of the pure compound and preserv-ing it for a sufficient length of time for spectro-scopic investigation.

In late 1984 we recorded for the first time acomplete infrared spectrum of gaseous FOOFobtained under well-defined conditions usinga special spectrometer that we had developedat Los Alamos. For the first time we were ableto make accurate vibrational frequency assign-ments and determine their intensities.

Immediately after recording the first com-plete spectrum of FOOF, we noticed an unex-plainable spectral feature centered at 1490 cm-1

(See Figure 1.) This spectral feature did notvary in its relative intensity with the rest of thepeaks. Furthermore, it is the only feature in theentire fundamental infrared region apart fromthose of FOOF. The molecular vibrationaltheory tells us that whatever species is respon-sible for this feature must be a compound sim-pler than FOOF or a heteronuclear, diatomicmolecule. We did not consider the idea of aradical because of the attributes of radicals dis-cussed above. The half-life of a radical speciesis typically so short that one cannot record itsspectrum over many minutes as required for aspectral scan. And yet this unexplained featurepersisted in all samples of FOOF. We alsoeliminated early on the possibility that it mightbe the diatomic radical OF because moleculessuch as FOOF do not break apart at theirstronger O-O bonds spontaneously underthese experimental conditions.

Within the first week of successfully re-cording the FOOF spectrum, we had to specu-late that we might have an unusual radicalspecies—O2F—coexisting with FOOF in oursample. How then could we prove our hy-pothesis that a reactive radical species like O2Fcoexists with another unstable molecule—FOOF? To answer this question unambigu-ously we devised an experiment to produce

O2F directly andrecord its spectrumin the absence ofFOOF. Now, thisexperimental designis based on theassumption that thehalf-life of O2F is suf-ficiently long (for ex-ample, seconds) sothat we could probecontinually while weproduced this short-lived species in anexperimental design, described below.

The experimental design thus conceived islaser flash photolysis combined with coaxialprobing. A strong laser beam produces F at-oms along its beam path, the F atoms reactwith an oxygen molecule to form the transientradical O2F, and its presence is detected simul-taneously by probing the sample volumewithin the laser beam path. Although easilydescribed, this arrangement requires that thelaser beam and the probe beam should bemade co-linear, and the probe beam should beinside the laser beam volume for maximumsensitivity. We would make a mixture of twobasic ingredients, fluorine and oxygen, whichwe considered as the starting materials. Anintense ultraviolet laser beam at 248 nm wasinjected into the sample chamber that con-tained the mixture. The laser beam was pulsedat less than 10 Hz. The probe infrared beamfrom the spectrometer was combined using adichroic mirror and made co-linear along theentire beam path. Our hope was that as thelaser beam produced the expected radicalspecies at some low-frequency interval, asteady-state concentration of O2F would beestablished between the production and disap-pearance, and the probe infrared beam wouldbe monitoring this steady-state concentrationcontinually. (A dichroic optical materialreflects and transmits different wavelengthlights so that two beams of different wave-lengths can be combined coaxially and propa-gated together along the same beam path.)

Figure 1. The firstcomplete infraredspectrum ofgaseous FOOF.The laser pro-duced O2F spec-trum is shown inthe inset.



“Nuclear materials” is a generic termmeaning materials of interest to the nuclearindustry, sometimes synonymous with“source” and “special materials,” as listed inthe Atomic Energy Commission Manual. A vastknowledge base has been generated over thepast six decades to safely manage all nuclearmaterials to maximize their benefits and mini-mize their hazards. However, it should be rec-ognized that the knowledge base was notalways adequate nor effectively used in thepreservation and use of these materials. As aresult, many environments have been im-pacted by nuclear materials, and the potentialfor impacting more still exists. Therefore, it isimportant to develop a comprehensive strategyto better manage these valuable resources forthe future.

A recent estimate by the Brookings Institu-tion points out that the United States spentover $5.5 trillion during the past five decadesto build and maintain nuclear defense capabili-ties, almost $1 trillion of this in nuclear materi-als production and related activities. Under aseries of Congressional initiatives, the DOE hasthe major responsibilities for long-term man-agement of all nuclear materials from the de-fense sector and a major portion of thoseoriginating from the civilian sector. Currently,numerous programs address the long-termmanagement of materials for national security(including those re-sulting from weaponsdismantlement,nuclear wastes, spentnuclear fuels, andcontaminated sitesand facilities). Theseprograms are at vari-ous stages of develop-ment, demonstration,and implementation.

Nuclear Materials Including “Orphans” Requirea Comprehensive Management Strategy

Our ability to achieve the goals of our excessfissile material disposition programs is depen-dent on complex international agreements andis likely to take many decades.

A large inventory of nuclear materialsoriginating within and outside of national se-curity programs exists in addition to thosenecessary for national security or declared ex-cess. These may be properly described as “or-phan nuclear materials.” The disposition oforphan nuclear materials is still awaiting rec-ognition and resource allocations. A prelimi-nary but incomplete estimate made last yearidentified over 30,000 records of 72 millioncuries of miscellaneous radioactive materials.The actual numbers may be many times thoseidentified last year.

A unique example of orphan nuclear ma-terials is the man-made neutron sources thatare used extensively in defense projects, in-dustries, universities, and research organiza-tions. Most of these neutron sources consist ofhomogeneous mixtures of an alpha- orgamma-emitting radionuclide and a low-atomic-number element or its compound. It isestimated that there are several hundred thou-sand such sources now in use within the U.S.,and about 3,000 are being produced and dis-tributed annually (Figure 1) . A 1985 Congres-sional mandate makes the DOE responsiblefor receiving abandoned, damaged, and re-

K. K. S. Pillay is the ProjectLeader for WasteManagement,NMT-DO.

Figure 1. ScottAllen and GeorgePowell (BUS-4)may be calledupon to recoverand transportneutron sourceswidely used inoil and gas welllogging. Nuclearmaterial "or-phans" such asthese sourcespose a problemfor the manageddisposal of excessnuclear materials.

Editorial


1st quarter 1999

turned neutron sources and disposing of themin an environmentally benign fashion. Inap-propriate disposition of these sources has thepotential to cause extreme hazard to humanbeings and irreparable harm to the environ-ment (Figure 2). Los Alamos National Labora-tory spent many years to develop a simple,elegant method (chemical separation flowsheet) to separate the two components of theneutron sources. This technology was success-fully demonstrated in dismantling over athousand neutron sources and making theminnocuous and environmentally benign.Unfortunately, the implementation of thiselegant technology to address large-scale dis-position of neutron sources is now in doubt.

Present challenges to nuclear materialsmanagement are too numerous for extensivediscussion here. There is, however, a tacit rec-ognition that a common strategic frameworkis necessary to avoid the environmental blun-ders of the past. During the past decade, a se-ries of studies and assessments have beenperformed to identify and quantify the needsof nuclear materials management.

On January 20, 1998, the DOE Office of theDeputy Assistant Secretary for Nuclear Mate-rial and Facility Stabilization initiated theNuclear Material Integration (NMI) Project.The goals of the NMI were to inventory andanalyze the nuclear materials in the DOEComplex. The scope of this project includednot only materials owned by the Office of En-vironmental Management (EM) but also thoseowned by other programs and stored in EMfacilities. The ultimate goal of this effort wasto develop a comprehensive nuclear materialmanagement plan for the nation.

Three material management teams wereresponsible for the different groups of materi-als in the DOE Complex: the TransuranicTeam, responsible for most transuranic ele-ments; the Uranium/Thorium Team, respon-sible for most uranium and thorium materials;and the Nonactinide Isotope and SealedSources Team, responsible for all radioactiveisotopes with an atomic number less than 90,and all sealed sources, irrespective of atomicnumber. About 250 people from across the

country participated in developing data andstrategies for the management of all the“excess” nuclear materials within the DOEcomplex and those that are likely to becomeDOE’s responsibility in the future. The threeteams prepared a total of twelve independentreports (nuclear material management plans)and submitted them to DOE/EM in 1998.Separate materials management plans wereprepared for depleted uranium, high-enricheduranium, low-enriched uranium, natural ura-nium, nonactinide isotopes, 241Am, 237NP and238Pu, 239Pu, 242Pu, thorium, transuranic heavyelements, and 233U. These reports are presentlyconsidered “predecisional draft documents”and are not yet available for generaldistribution.

While many such studies have developedvaluable data, heretofore, follow-up actionshave been disappointing. Missing in previousfollow-up actions is the desire to address theproblem as a national or societal issue. Insteadit is always addressed as the issue relevant toa particular agency of the government or asubordinate bureaucracy interested only insimplistic solutions. It is this approach thatought to change to achieve the goals of acomprehensive strategy to manage all nuclearmaterials for the benefit of mankind and toinstill public confidence in associated tech-nologies and institutions.

In the best traditions of U.S. science, anobjective evaluation of the recommendationsmade by the NMI teams has been requested byan independent organization, the NationalAcademy of Sciences. DOE/EM is champion-ing the cause for an Academy study to reviewthe 12 reports. However, this study is stillwaiting because of limited DOE resources.It is to be hoped that the Academy will evalu-ate the reports, and that their recommenda-tions will include comprehensive managementand preservation of nuclear materials, includ-ing neutron sources and other “orphans,” thatare generated by both the defense and civiliansectors. It is also to be hoped that such recom-mendations will be implemented in a timelymanner.

The opinionsin this editorialare mine; theydo not neces-sarily representthe opinionsof Los AlamosNationalLaboratory,the Universityof California,the Departmentof Energy, orthe U.S.Government.

Figure 2. A dam-aged americium-beryllium neutronsource recoveredfrom a privatecompany by LosAlamos.



Wing 9 Hot Cells Support Work InvolvingHighly Radioactive Materials

The Wing 9 hot cells in the CMR Facilitywere designed and constructed in 1960 to pro-vide shielding and remote handling capabili-ties for work on highly radioactive materials.Commissioned in 1961 by President John F.Kennedy, the hot cells supported the RoverProject and the postmortem of irradiated fuelsfor breeder reactors. Even as the hot cells be-gan decommissioning for closure in the late1980s, they were used successfully to demon-strate the characterization and packaging of

resident, remote-handled transuranic waste foreventual shipment to the Waste Isolation PilotPlant (WIPP). This expertise continues to be aWing 9 capability available to the industry andthe DOE complex. Since 1989, a variety ofprojects have been identified that have ex-tended the life of the facility and are discussedlater in this article.

Each of the 16 6’x6’x11’ hot cells and thecorridor that connects them are designed toprovide adequate shielding to the worker froma 100,000 Ci source of 1-MeV gamma radiation(Figure 1). Also contained in the hot cells arein-cell remote machining and handling capa-bilities that allow operations on highly irradi-ated components. The inner-cell door designalso provides a means of connecting two hotcells for installation of large pieces of equip-ment. The facility can handle all types of radio-active materials that are alpha, beta, gamma,and neutron emitters. An array of 364 heavilyshielded storage wells and a crane capacity upto 25 tons support the hot cell capability.

The current authorization basis allows a totalinventory in the16 hot cells of up to 77 kg of239Pu equivalent.

Technical and programmatic objectivesrequire the Hot Cell Team in Group NMT-11to work on programs that encompass state-of-the-art remote handling of highly irradiatedmaterials, components, and systems. A keycomponent of this program includes effectivefacility management practices to maintain re-mote handling operations that are compliantwith DOE regulations. The Wing 9 staff exper-tise is the key to success with capabilities suchas design engineering, process analysis,project management, welding, fabrication,robotic operations, and handing and shippingof high-activity components. Additionally, thestaff has experience with the fabrication ofparts made from special nuclear materials anddisassembly and analysis of highly irradiatedcomponents and materials. Currently, theWing 9 team is providing expertise to otherlaboratories and universities for a varietyof special remote handling problems.Following are descriptions of somecurrent Wing 9 projects.

The Molybdenum-99 ProjectIn response to the U.S. medical

community’s concern that the nation must relyon a single, limited, foreign source for the ra-dioisotope molybdenum-99 (99Mo), Congresshas tasked the DOE to develop a domesticsource of 99Mo, which is essential for conduct-ing thousands of life-saving medical diagnos-tic procedures each day. The 99Mo programinvolves five primary activities: (1) target fab-rication, (2) target irradiation, (3) extractionand purification, (4) transportation, and(5) waste management. The Isotope Produc-tion and Distribution branch of the DOEconducted assessments that identified the best99Mo production option currently available:the fabrication of uranium targets at LosAlamos National Laboratory and target irra-diation, and extraction and purification pro-cessing at Sandia National Laboratories.

A target fabrication demonstrationprogram has successfully been completed inWing 9. A target is a 304 stainless steel tube

Figure 1. The hotcells in Wing 9 ofthe CMR Buildingcan remotelyhandle andprocess all typesof radioactivematerials that arealpha, beta, orneutron emitters.Capabilities in-clude character-ization and pack-aging of WIPPwaste as well astasks that mayrequire a room-sized, heavilyshielded remote-handling facilityfor highly radioac-tive materials.


1st quarter 1999

Figure 2. TheWing 9 fabricationline producesuranium targetsthat will be usedfor productionof 99Mo.

C377-4

Figure 3. Molddesign test cast-ing using depleteduranium. Eventu-ally a clad 237Npsphere will beused for criticalitymeasurements.

continued on page 10

approximately 18 inches long and 1.25 inchesin outer diameter. Inside the tubing, 235U iselectroplated onto the steel surface to providea very thin layer of uranium to interact withneutrons. The process takes 36 to 48 hours todeposit approximately 20 grams of uraniumcoating per target. The target tubes have capswelded at each end and are qualified as“reactor-ready” before transfer to Sandia forirradiation. The fabrication and electroplatingprocess is shown in the glovebox enclosuresin Figure 2.

Neptunium ProjectThe NMT-11 staff of Wing 9 has been

asked to fabricate a clad, solid ~7 kg 237Npmetal sphere for criticality measurements atTA-18. The 237Np first-daughter product, 233Pa,is highly radioactive so the entire process mustbe performed within a shielded hot cell.

The necessary equipment to melt and castthe 237Np metal remotely will be installed in ahot cell “alpha box” to process the alpha-emitting materials and to contain potentiallyhigh levels of contamination. The alpha boxwill be purged with nitrogen gas, which pro-vides a low-oxygen-concentration atmosphereto allow work with the neptunium metal, apyrophoric material.

The 237Np sphere will be cast in a vacuumwithin a graphite mold designed by MST-6 toeliminate voids in the sphere volume. Themold design (shown in Figure 3) has been suc-cessfully tested by MST-6 using depleted ura-nium to cast a sphere to within about 0.010" onthe diameter and very near theoretical density.MST-7 personnel encapsulate the 237Np spherefirst within tungsten hemispheres and thenwithin two pure, welded Ni spheres forcladding. This project provides a tool to theLos Alamos Critical Experiments Facility stafffor experiments for fundamental research.

Sanitization ProjectPlans are being formulated to initiate a

sanitization project at Los Alamos to removeclassified aspects from actinide-contaminated,nonnuclear weapon components generatedfrom disassembly of nuclear weapons and

other weapons-related activities. The systemdesigned for accomplishing this activity con-sists of an induction furnace for melting me-tallic components and a jaw crusher forpulverizing brittle, nonmetallic items. Thissystem is tentatively planned for installationin Wing 9 of the CMR Building and consists ofseveral glove boxes containing the processingequipment and a HEPA-filtered environmen-tal housing surrounding the glove box system.Discussions with DOE sponsors are currentlyunderway to establish the funding and scopeof the operation.

ULISSES ProgramTo achieve the next generation of uranium

processing technology, Los Alamos has devel-oped the Uranium Line for Special SeparationScience (ULISSES), a modular test-bed forchemical process optimization. This new pro-cessing line will include state-of-the-art disso-lution chemistry and separation science,on-line sensors coupled to automated instru-mentation, and recycling with waste minimi-zation based on environmentally benignchemicals. This technology base will be usedto develop, design, and demonstrate advancedchemical processing technology that mini-mizes hazardous wastes.



Figure 4. Drum-loading, canister-handling systemfor loading, weld-ing, packaging,and transportationof waste destinedfor WIPP.

Wing 9 Hot Cells Support Work InvolvingHighly Radioactive Materials (continued)

Remote-Handled Transuranic Waste(RH-TRU)

The RH-TRU Program involved character-izing and packaging remote-handled TRUwaste for ultimate WIPP disposal. Becausemany of the waste cans packaged thus farhave typical radiation readings between 400and 1000 R/hr at contact, a unique drum-loading and canister-handling system wasdesigned and constructed for loading, weld-ing, packaging, and transportation of theRH-TRU Waste (see Figure 4). To date, sixteenWIPP-approved canisters have been character-ized, packaged, and placed into retrievableunderground storage at Los Alamos (Area G)awaiting shipment to WIPP. This capability inthe hot cell facility is operational to supportthe eventual disposition of RH-TRU waste atWIPP. The technology will also serve to re-solve RH-TRU packaging problems at othersites within the DOE complex.

Magnetic Isotope Separation (MIS)Program

The MIS process is designed to separateisotopes for medical applications and thestockpile stewardship program. The process isperformed in a separator system with the po-tential to process many different elements. Theisotopes being separated are radioactive and

have an activity of up to approximately 20 Ci.Radioisotopes of interest to be separated are82Sr/85Sr, 32P/33P, 184Re/186Re, 168Tm, 170Tm/171Tm, 173Lu/174mLu/174gLu, 88Zr/93Zr/95Zr, 190Ir/192Ir, and possibly others. These radioisotopesare limited to nonactinide materials.

Accelerator Production of Tritium(APT) Program

This Wing 9 capability has been developedto support the APT Program by evaluating andtesting candidate materials that have beenirradiated (Alloy 718, 316L and 304L stainlesssteel, modified Fe9Cr1Mo(T91), Al6061-T6,Al5052-0) for use in the APT target andblanket. The specimens have been irradiatedfor fewer than 3,600 hours to a maximumproton fluence of 4 x 1021 p/cm2 in the center ofthe proton beam. Specimens are then carefullyremoved from the packages in the hot cells inWing 9 to begin mechanical testing, whichincludes tensile, bend and compact tensiontests, metallographic examination, andtransmission electron microscopy. Specimenswill yield data on the effects of protonirradiation under a number of test conditions.

Actinide Source-Term Waste TestProgram (STTP)

The Actinide STTP is designed to measuretime-dependent concentrations of actinide ele-ments from actual, contact-handled TRU wasteimmersed in brines that are chemically similarto those typically found in the undergroundformations of WIPP. The STTP will determinethe effect of TRU waste matrices and brinechemistry on the concentrations and behaviorof actinides under WIPP bounding conditions.

Several actual TRU waste types typical ofDOE waste inventories have been character-ized and loaded into specially designed testcontainers filled with brine containing addi-tives to enhance the action of each influencingvariable. The test containers are then placed inenvironmental chambers in Wing 9 to simulatein-situ conditions found at WIPP. Analysis isthen performed on the brine leachate andheadspace gas in the test containers.

This article wascontributed byStanBodenstein,SuzanneHelfinstine,Robert Romero,and JimLedbetter,all of NMT-11.


1st quarter 1999

Publications and Invited Talks(December 1998–February 1999)

Editor’s note: We get information from the library whenpapers have received LA numbers. However, it may bemany months before the papers are published. Since ARQlists only those papers that are published or have beenaccepted for publication, we have no way to track themfrom the time they first receive numbers. We must relyon authors to tell us when their papers are accepted forpublication in journals or proceedings. So when yourpaper is accepted, we’ll tell your colleagues: please let usknow! Ann Mauzy, 667-5387, [email protected].

Invited TalksE. A. Blum, “Inorganic Membranes for Metal IonSeparations: Surface Effects on Cation Transportacross Porous Alumina Membranes,” IE&CDivision, American Chemical Society, Anaheim, CA,March 21–25, 1999.

A. C. Lawson, B. Cort, J. A. Roberts, andB. I. Bennett, “Neutron Diffraction and thePhysical Properties of the Light Actinides,”American Nuclear Society, Washington, D.C.,November 16, 1998.

PublicationsD. K. Dennison, D. Gallant, D. C. Nelson,L. A. Stovall, and D. E. Wedman, “AutomatedNuclear Material Recovery and Decontaminationof Large Steel Dynamic Experiment Containers,”in “Proceedings of the 8th International TopicalMeeting on Robotics and Remote Systems,”American Nuclear Society (ANS), ANS PittsburghSection, Monroeville, PA, in press.

P. A. Leonard, E. A. Strietelmeier, M. E. Pansoy-Hjelvik, and R. T. Villarreal,“Microbial Characterization for the Source-Term Waste Test Program (STTP) atLos Alamos,” in WM ’99 Proceedings, HLW, LLW, Mixed Waste andEnvironmental Restoration - Working Towards a Cleaner Environment,WM Symposia, Inc., Tucson, AZ, in press.

R. Marshall, A. S. Wong, and D. Thronas, “Lawrence Livermore NationalLaboratory Working Reference Material Production Plan,” Los AlamosNational Laboratory report LA-13552-MS (December 1998).

H. Nakotte, L. Laughlin, H. Kawanaka, Dimitri N. Argyriou, R. I. Sheldon, andY. Nishihara, “Magnetic Properties of Single-Crystalline Mott Insulator YV03,”Applied Physics, in press.

L. L. Romero, J. M. Hoffman, E. May Foltyn, and T. E. Buhl, “OperationalComparison of Bubble (Super Heated Drop) Dosimetry with Routine AlbedoTLD for a Selected Group of Pu-238 Workers,” accepted for publication inOperational Radiation Safety supplement to Health Physics Journal, in press.

S. B. Schreiber, S. L. Yarbro, E. M. Ortiz, F. Coriz, and S. Balkey, “Disposition ofMixed Waste Organics at the Los Alamos Plutonium Facility,” Los AlamosNational Laboratory report LA-13558-MS (January 1999).

S. M. Wander, I. R. Triay, P. S. Z. Rogers, S. T. Kosiewicz, D. R. Yeamans,A. R. Barr, J. D. Farr, J. Foxx, A. J. Montoya, M. A. Gavett, D. P. Taggart, S. E.Betts, G. R. Allen, H. D. Poths, D. R. Janecky , C. P. Leibman, G. I. Vigil, and J. J.Vigil, “Preparation of the First Shipment of Transuranic Waste by the LosAlamos National Laboratory. A Rest Stop on the Road to WIPP,” inProceedings of the Waste Management ’99 Symposium, Laser Options, Inc.,Tucson, AZ, in press.

Success was immediate. The spectrum ofO2F was recorded without the interference ofFOOF and analyzed. With this discovery wewere able to study the properties of O2F andits chemical relationship with FOOF, anotherLos Alamos first in laser photochemistry.It was one of the most wonderful detectivestories of an exotic chemical species and it

helped to meet some of the important isotopeseparation program goals. The discovery ofO2F in FOOF found other applications in lateryears for recovery of plutonium from pluto-nium-containing residues and waste. In thefuture it may be a preferable alternative toacid dissolution of radioactive waste and canbe used to recover plutonium from glove boxsystems and process lines in reactor vessels.

This article was basedon the author’s workand papers published inthe mid 1980’s.

O2F in FOOF Holds Promise for Pu Decontamination(continued)



LosN A T I O N A L L A B O R A T O R Y

Alamos

The Actinide Research Quarterly is published quarterly to highlight recent achievements and ongoingprograms of the Nuclear Materials Technology Division. We welcome your suggestions and contributions.If you have any comments, suggestions, or contributions, you may contact us by phone, by mail, or on e-mail([email protected]). ARQ is now on the Web also. See this issue as well as back issues on-line (http://www.lanl.gov/Internal/divisions/NMT/nmtdo/AQarchive/AQhome/AQhome.html).

Nuclear Materials Technology DivisionMail Stop E500Los Alamos National LaboratoryLos Alamos, New Mexico 87545505/667-2556 FAX 505/667-7966

LALP-99-74Director of NMT: Bruce MatthewsDeputy Directors: Dana C. Christensen and David S. PostChief Scientist: Kyu C. KimWriter/Editor: Ann MauzyDesign and Production: Susan L. CarlsonPrinting Coordination: Lupe Archuleta

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Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by the University of California for the U.S. Department of Energy under contract W-7405-ENG-36.All company names, logos, and products mentioned herein are trademarks of their respective companies. Reference to any specific company or product is not to be construed as an endorsementof said company or product by the Regents of the University of California, the United States Government, the U.S. Department of Energy, nor any of their employees. Los Alamos NationalLaboratory strongly supports academic freedom and a researcher’s right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee itstechnical correctness.

NewsMakers ■ LBL Director Eulogizes Nobel Laureate Glen Seaborg, Who Died February 25, 1999.Following are excerpts from Lawrence Berkeley LaboratoryCharles V. Shank’s memo to LBL employees:

Dr. Seaborg was a true giant of the 20th Century, a legend in theannals of scientific discovery. His daily commitment to matters ofthe laboratory, even in retirement as associatedirector-at-large and as an active researcher,was an inspiration to us all…For his service toscience, to education, and to our nation, we honorDr. Seaborg’s distinguished lifetime and willforever treasure his contributions to our institu-tions and to our lives. We who have been touchedby his wisdom, his energy, and his tirelessdevotion to our profession will miss him… Iencourage you to reflect on Dr. Seaborg’s extraor-dinary life, much of it chronicled by him on anInternet Website accessible through our homepage. Our thoughts and prayers are with theSeaborg family…

Dr. Seaborg’s Life and Contributions are on-line at<http://www.lbl.gov/seaborg/> . Photographs are on-line at <http://www.lbl.gov/Science-Articles/Archive/seaborg-photo-gallery.html> . The 1951 Nobel Prize for Chemistry, presenta-tion and acceptance speeches, are on-line at <http://www-library.lbl.gov/library/text/nobel/sea_mcmillan.html> .

■ Division AwardsGordon Jarvinen has garnered the Division’s 1999 R. D. Baker Award in Science andTechnology; Diedra Yearwood will receive the 1999 William J. Maraman Award for Excellencein Facility Operations at an award ceremony to be held Thursday, May 13, during the DivisionReview.

quarterly - los alamos national laboratory...figure 3. the 5d–5f resonant photo-emission spectrum...

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