4th quarter 2001 TheLos Actinide Alamos National Research Laboratory N u c l e a r M Quarterlya 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 a U.S. Department of Energy Laboratory

Researchers Use Transmission Electron Microscopy to Observe Helium Bubbles in Plutonium Los Alamos, Livermore, and Aldermaston In This Issue Collaborate on Plutonium-Aging Study Mark Wall of Lawrence Livermore National The ability to directly image self-irradiation damage accumulation Laboratory uses in plutonium is critical to understanding aging. Scientists know that Livermore’s powerful helium is building up in plutonium metal during self-irradiation. transmission electron What they don’t know is what is happening to that helium over time, microscope to image and how it ultimately affects the behavior of plutonium over long periods. a sample. Los Alamos Researchers from Los Alamos and Lawrence Livermore national researchers are collaborating with laboratories and the Atomic Weapons Establishment at Aldermaston Livermore and the 4 in the United Kingdom are col- Shock-Wave Research Atomic Weapons laborating on a study to observe Establishment at on Plutonium Yields the microstructural effects New Information Aldermaston, United caused by the formation of Kingdom, to study the Concerning Dynamic helium atoms and vacancies microstructural effects Material Properties during self-irradiation. of the buildup of Recent studies using helium in aging 6 Livermore’s state-of-the-art plutonium. Recent A Personal Perspective Transmission Electron Microscopy research has revealed on Issues in Science (TEM) facility have revealed the the existence of minute and Technology in existence of minute—approxi- bubbles too tiny to be seen with conventional NMT Division mately 1 nanometer TEM instruments. in diameter—spheri- Photo courtesy of Lawrence 9 cally shaped Livermore National Laboratory Publications and bubbles, which are Invited Talks too tiny to be seen with conventional TEM instruments. Scientists pre- sume the tiny bubbles formed from the mi- gration and 10 coalescence Newsmakers of many helium-filled vacancy clusters, which occur as pluto- nium ages. continued on page 2

Nuclear Materials Technology/Los Alamos National Laboratory 1 Actinide Research Quarterly

Helium Bubbles

Contributors to this The existence of bubbles in plutonium has third law: For every article are: Thomas been seen before in heated samples. The fact action there is an Zocco (NMT-6); that researchers saw bubbles in materials un- equal and opposite Mark Wall, Adam der approximately room-temperature storage reaction. This move- Schwartz and Bill conditions is somewhat surprising, according ment may cause sig- Wolfer (Lawrence to Los Alamos researcher Tom Zocco of nificant damage to the Livermore National Manufacturing Systems (NMT-6). surrounding atomic Laboratory); and “It implies that helium and helium vacancy arrangement. This two-dimensional Paul Roussel clusters are mobile at room temperature and Imagine a three- representation shows the crystalline lattice (Atomic Weapons can cluster, forming the bubbles,” said Zocco. dimensional, periodic and two types of Establishment, “The formation of bubbles can have a variety atomic arrangement— damage caused by the Aldermaston, United of effects on the mechanical and physical a lattice—of pluto- radioactive decay Kingdom). properties of plutonium metals and alloys, nium atoms in a process. Each red dot Also contributing to which can possibly affect the long-term aging crystalline structure. represents an atom. this project are: Mary of our stockpile.” When any atom radio- In the figure on the left, Esther Lucero and Zocco was one of the first researchers to actively decays, the an interstitial atom (the Michael Ramos successfully use TEM for the microstructural resulting uranium black dot) is displaced (NMT-16). analysis of plutonium metal and alloys. As atom and helium and squeezed between part of this collaboration, he has developed a nucleus fly apart, hit- other atoms. In the Figures: L. Kim Nguyen Gunderson sample matrix and supplied prepared and ting other atoms as figure on the right, a (IM-1) vacancy is created by aged plutonium materials for examination. they travel through the alpha release and the lattice. Both the uranium-235 recoil. uranium and helium atoms generate sub- stantial damage within the atomic arrange- ment of the crystalline structure, which results in defects or discontinuities in this normally periodic arrangement. The defects are prima- rily of two forms: vacancies or missing atoms in the lattice, or interstitial atoms, which are atoms squeezed between other regularly spaced atoms. The amount of damage produced is directly related to the mass and energy of each moving This schematic Livermore is finishing the sample preparation, particle. The uranium atom is large and does illustrates the performing the TEM operations, and provid- not travel far and deposits its kinetic energy radioactive decay ing image simulations. Researchers from over a short distance. This causes significant process of a Aldermaston also are providing material damage to the lattice and creates thousands of plutonium-239 atom. and expertise. displaced plutonium atoms. The alpha particle Radioactive materials are made up of atoms The alpha particle (or helium ion), on the releases and the that are inherently unstable and decay over uranium-235 atom other hand, is very energetic and travels recoils. varying periods of time to form more stable farther through the lattice. But because the atomic elements. For example, the unstable alpha particle is relatively small, it creates a plutonium-239 isotope decays by the process lower number of lattice defects and less over- of alpha emission. When the alpha particle is all damage. emitted, the loss of protons and neutrons from Because of the high local stresses created the plutonium-239 atom transmutes it to a from squeezing the atoms into abnormal uranium-235 ion. This uranium ion rapidly re- positions, most of them quickly return to coils during the alpha release, as in Newton’s the vacancies created when they were

2 Nuclear Materials Technology/Los Alamos National Laboratory 4th quarter 2001

displaced from their The technique for imaging these original positions in small voids is called the defocus or the lattice. This “Fresnel fringe” imaging technique. “self-healing” Depending on the amount and process returns most direction of defocus, the small of the atoms to their voids or bubbles will visually original, uniformly appear as small white or black spots spaced positions. with surrounding black or white However, the defects that do not self-heal fringes, respectively. The diameter ultimately result in the buildup of excess dam- of these circular fringes will vary age in the material. It is this lattice damage and with defocus, and is not easily its long-term accumulation that is of interest to related to the true diameter of the researchers investigating the aging or self- voids or bubbles. irradiation damage phenomena in radioactive For example, when measuring materials. (For more details on the aging ef- small (less than 1 nanometer) voids fects in plutonium, see The Actinide Research or bubbles, the diameter of the cen- Quarterly, 4th Quarter 1999.) tral bright or dark spots may be in After the alpha particle comes to rest in the error as much as 50 percent from the lattice, it rapidly attracts free electrons from its true diameter. Therefore, it is neces- surroundings to become a helium atom. This sary to perform image simulations process occurs at a pace that creates approxi- to correctly interpret the actual size. mately 29 helium atoms per year for every After the under- or over-focused 1 million atoms of plutonium. This may not images are collected, they can be seem like a significant amount, but over a processed and analyzed. Through period of years the accumulation of helium careful control of the processing becomes substantial and potentially can bring parameters, image-processing soft- about significant changes in macroscopic ware quickly identifies and mea- physical properties. sures the bubbles in a variety of The remaining defects (vacancies and ways, such as bubble density, mean diameter, At the top is a raw interstitials) that survive the self-healing pro- area, aspect ratio, and roundness. By measur- (as-captured) digital cess coexist with the helium atoms, forming ing or estimating the thickness of the TEM Transmission Electron complex interactive relationships. Helium at- specimen and counting the number of bubbles Microscopy (TEM) oms may readily combine with nearby vacan- in each image, researchers can calculate the image. The image on the bottom has been cies to form helium-filled vacancies, which true bubble density. processed and shows diffuse randomly until they meet and bind Through the use of complex image identified and measured with other similar species, creating a bubble simulation techniques, Livermore researchers bubbles. The existence nucleus. The bubble nucleus grows as it cap- are determining how Fresnel contrast images of bubbles in plutonium tures additional helium-filled vacancies of bubbles appear and change as a function of has been seen before in moving through the lattice. defocus and bubble position in the TEM heated samples. The Larger voids or bubbles, and/or those sample. This may require correction factors for fact that bubbles were having associated strain fields, are readily bubble size, to account for distortions pro- seen in materials under observable in conventional TEM. However, the duced from the many imaging effects. approximately room- imaging and observation of very small voids The researchers also are modeling helium temperature storage (less than 2 nanometers in diameter) or small bubble nucleation and growth. By coupling conditions is somewhat surprising, according to bubbles that are in equilibrium (no strain) experiments and modeling, they hope to researchers. with the surrounding lattice are difficult and develop a good correlation between bubble require the use of a TEM with a highly formation and age. ■ coherent source of electrons and relatively high resolving ability.

Nuclear Materials Technology/Los Alamos National Laboratory 3 Actinide Research Quarterly

Shock-Wave Research Shock-Wave Research on Plutonium Yields New Information Concerning Dynamic Material Properties Los Alamos Researchers Obtain the First Dynamic Data on a Particular Plutonium Alloy

Contributors to this In a nuclear weapon, many materials are The work so far has focused on a particular article are: Robert subjected to impulsive loading—high- delta phase plutonium alloy. Researchers Hixson and John intensity, short-duration forces—caused by have obtained a considerable amount of Vorthman (DX-1), detonating high explosives. To understand shock Hugoniot data that will allow the and Benjamin Lopez how materials respond to such conditions, moderate- to low-pressure equation-of-state (NMT-16). scientists must study the dynamic properties to be defined. In addition, new data on the of plutonium metal and other materials over a phase diagram for delta plutonium have been wide variety of pressures and time scales. obtained, including the location of solid-solid Scientists can duplicate these extreme phase changes and dynamic melting. Infor- Researchers are using conditions of elevated temperature and pres- mation concerning the rate, or kinetics, of the gas gun contained in sure by creating shock waves and allowing these transitions also has been obtained. this glove box in PF-4 to them to propagate through materials. The size, Probably the largest amount of research duplicate the extreme speed, and shape of the shock wave is deter- has focused on the dynamic strength of delta conditions of elevated mined by the dynamic material behavior of plutonium in tension: spall. Careful research temperature and the sample being studied, so careful measure- has been done on the effect of impurities and pressure created by the ments of the shock wave can be used to deter- peak stress on tensile strength. The research high explosives in a mine material properties. has resulted in the first dynamic data ever obtained on this plutonium alloy. The data are of very high quality, according to the researchers, and currently is being used by theorists to develop new physics models for the dynamic response of this alloy. The Launcher, housed in Building PF-4 at TA-55, can be used with either a gas breech or a propellant breech to provide the projectile acceleration. It can launch projectiles at speeds ranging from about 0.1 kilometer per second to almost 2 kilometers per second, or from 200 miles per hour to more than 4,000 miles per hour. The gun works by firing a projectile at a small plutonium sample, or target. When the projectile impacts the sample, shock waves are generated in both the projectile and the sample. In the target, material ahead of the shock wave is stationary until the shock wave nuclear weapon. Nuclear Materials Science (NMT-16) passes; after the shock wave passes, the mate- Research on a delta operates a Kolsky-bar apparatus to gather rial is moving. A shock wave also moves back phase plutonium alloy dynamic data on plutonium at low pressures into the projectile, slowing down the has resulted in the first and a relatively long time scale, and a gas gun projectile’s initial velocity. High pressures are dynamic data for the alloy. The gun can to gather dynamic data at much higher pres- generated in the region between these two launch projectiles at sures and shorter time scales. One of the sim- shock waves. speeds ranging from plest, most-controlled, and most-accurate tools Higher projectile velocities lead to higher about 200 miles per used to create shock waves is a smoothbore pressures and faster shock velocities. Shock hour to more than 4,000 gun. Researchers in Detonation Science and waves may be viewed as wave disturbances miles per hour. Technology (DX-1) and NMT-16 are conduct- that abruptly change the pressure, tempera- Photo by Paul Moniz ing experiments on such a gun—the 40mm ture, density, and internal energy of a sub- Launcher, so named because of its bore size. stance from an initial value to a final state.

4 Nuclear Materials Technology/Los Alamos National Laboratory 4th quarter 2001

Impactor Target Sample

Electrical Pin

Light from Laser The final state generated is at a higher describes the locus of Doppler shifted light sent to pressure, temperature, internal energy, and end states that may Velocity Interferometer (VISAR) density than the initial unshocked material. be achieved in a ma- In other words, a shock wave compresses terial through shock- a material. wave compression Because NMT-16’s gas gun is used to study and is different for different materials. The This simple diagram of a plutonium, it is contained in a glove box. most basic understanding of how a material target assembly shows This greatly increases operational difficulties responds to shock compression is contained in the electrical pins, one compared with guns used outside of TA-55, the shock Hugoniot. on each side of the and special techniques had to be developed Data obtained from these kinds of target, from which researchers obtain the to perform well-controlled experiments. experiments provide a wealth of additional time at which impact The Launcher’s projectile is a cylinder of information. Materials with limited strength occurred. The velocity plastic or metal. High-pressure gas in the typically have two distinct waves created in interferometer (VISAR) breech is used to push the projectile down the an experiment. The first wave propagates at detects the velocity barrel. The material inserted into the nose of the longitudinal wave speed and takes the history of the back of the the projectile, called the impactor, varies de- material to the point where it plastically target. This surface pending on the data researchers are trying to yields. A second wave, which moves more moves when a shock collect. Some materials are stiffer than others, slowly than the first and in which plastic de- wave emerges from the and so produce higher pressures in the target formation occurs, follows the first wave. The sample, and the velocity for a given projectile velocity. velocity interferometer will clearly show this interferometer senses Two electrical pins, one placed on each kind of wave structure. this motion and sends back information about side of the target, record the exact time of Shock-wave experiments can produce infor- wave(s) generated by impact. Another diagnostic tool, a velocity mation on how a material changes phase un- the impact. interferometer, or VISAR, measures the veloc- der increased pressure and temperature. This ity history of the back of the target. This sur- process must be well understood for scientists face moves when a shock wave emerges from to develop physics models that correctly the sample. The velocity interferometer continued on page 11 senses the motion and sends back informa- tion about wave(s) generated by impact. Other pin arrival times are used to mea- sure the angle at which the impactor hits the target plate; also known as impact tilt. This is important for researchers to know because large amounts of tilt can cause data quality to suffer. In addition, by combining impact time with the time-resolved velocity information, researchers can determine the velocity of the wave(s) moving through the target material. VISAR data also may be used to obtain the size and shape of the wave(s) moving through the target, as well as the speed of the material just behind the shock wave—called the particle velocity. In general, faster projec- This delta plutonium sample has been tested in a dynamic tension, or tiles generate higher pressures, higher shock “spall,” experiment. The sample was shock-compressed to a peak velocities, and higher particle velocities. stress state of about 25 kilobar, released, and then recovered. Dynamic A graph of shock velocity vs. particle wave interactions have caused the sample to be split almost in half in a velocity defines a curve called the shock well-controlled manner. This sample has been sectioned and analysis of the tensile damage is under way. “Hugoniot” of a material. The Hugoniot Photo by Mick Greenbank

Nuclear Materials Technology/Los Alamos National Laboratory 5 Actinide Research Quarterly

Editorial A Personal Perspective on Issues in Science and Technology in NMT Division

This article was Since it was first organized in 1989, the strength, while others do not. Interestingly contributed by scope and mission of the Nuclear Materials enough, one can frequently find almost as Kyu C. Kim, Technology (NMT) Division have expanded many proponents as opponents for these be- chief scientist significantly. The division has grown in size— liefs. The first step in addressing the science of NMT Division. the regular employee population of about 700 and technology issue is to understand the na- represents close to 10 percent of the Laboratory ture of these beliefs and to dispel aspects of population—and its annual budget represents the undesirable beliefs. a significantly greater part of the Lab’s budget. NMT Division also operates two of the Belief No. 1: “Because we are working on Laboratory’s major facilities: the Chemistry project deliverables, we do not have the time and Metallurgy Research (CMR) Building and to do science and technology.” the TA-55 Plutonium Facility. I think this belief is shared largely among You’d think that a division like NMT, whose the people who are engaged in programmatic “job” is to conduct scientific and technical re- tasks such as manufacturing weapon compo- search and experimentation, would be expert nents and plutonium heat sources for space in promoting science and technology. But are missions and processing nuclear materials. we doing the best we can in these areas? Or are The term “science and technology” should not there significant obstacles to our doing good be so alien a concept because these people are science? Perhaps the most useful suggestions I actually the practitioners of science and tech- can make are those that can help diagnose the nology in their particular fields of expertise. nature of the problems, if any, that may lie in And yet it’s a contrarian view of what they do the way of promoting science and technology. every day. Just like medical students following a training program in which they may use a Belief No. 2: “Facility and infrastructure decision-making tree to correctly diagnose operation are in competition or in conflict a patient’s illness based on the symptoms, with science and technology activities.” patients’ descriptions, and laboratory test re- This is a unique problem, or a blessing, sults, my goal is to take a closer look at some of depending on your view of the organization. the issues raised by many in relation to NMT’s NMT runs two major nuclear facilities and science and technology. My analysis will be also is the major user of the facilities. No sepa- based mainly on symptoms and descriptions rate funds exist for the facility operation and rather than on hard data and test results. the programmatic work; therefore the word From this analysis, we may be able to come up “competition” creeps in here. In a nuclear fa- with ways to enhance the division’s science cility like ours, facility operation and program- and technology. matic work go hand in hand. The debate is For those of you who may want a more similar to “Which came first: the chicken or the complete picture of NMT’s science and tech- egg?” We must recognize that both operational nology, read NMT Division’s Organizational elements are indivisible parts of the same or- Self-Assessment, which is published annually ganization. in preparation for the annual Science and Technology Assessment (also known as the Belief No. 3: “NMT Division’s mission is Division Review). You can get a copy from the geared toward production, so it has no future division office. in science and technology.” The opinions in this editorial are Many common beliefs develop over time in This statement resonates with the first one, the author’s. They do not neces- sarily represent the opinions of an organization like ours. When enough and it couldn’t be further from the truth. The Los Alamos National Laboratory, people share these beliefs long enough, they existence of our nuclear facilities as national the University of California, the Department of Energy, or the become part of the organizational culture. assets and the continuing maintenance of the U.S. government. Some beliefs contribute to the organization’s knowledge base founded on sound science

6 Nuclear Materials Technology/Los Alamos National Laboratory 4th quarter 2001

and technology serve as the cornerstone for their time doing what they do best. The the national security. NMT members possess division’s main task is to conduct its science unique skills that must be maintained and technology work. Managers are here to and nurtured. ensure that we have skilled people to conduct While the weapons component production the tasks, resources are properly allocated, programs may end some day, maintaining the work gets done on schedule and budget, we knowledge and capability to produce the meet all regulatory requirements, we interact components will always be a mission of this with our sponsors and customers, etc. The sci- Laboratory and this division. Manufacturing entists and technologists should not have to plutonium pits is clearly an important spend their time doing these things; they are component of NMT’s long-term goal and here to do the actual science. We need to mission, but the scope of our work in general clearly separate the responsibilities of the sci- is significantly broader than the manu- entific staff and the management staff, yet cre- facturing program. ate an atmosphere where the two halves can As painfully demonstrated in recent communicate and work in tandem to achieve disastrous events worldwide, Los Alamos the whole. National Laboratory and NMT Division must be at the forefront of science and technology to While it’s easy to list the problems, it’s meet the present and future challenges in every- harder to come up with solutions. The ques- thing nuclear — including nuclear weapons. tion remains: How do we enhance the division’s science and technology? Belief No. 4: “We are making sufficient I think the answer is threefold: a skilled progress and our mission is so compelling that workforce, enhanced productivity, and the business-as-usual approach will ensure strong leadership. our survival and future prosperity.” A scientific organization is only as good as Programmatic dollars have been easier to its people. Without knowledgeable and skilled obtain than scarce research dollars, but com- people, there can be no productivity or excel- placency is the antithesis to scientific prosper- lence. Division leadership and management ity. We should never forget that the nation can, and should, employ effective recruiting relies on Los Alamos because of the scientific and hiring plans to ensure that there are foundation laid by the scientists and technolo- people in all work areas with the proper skills gists who worked here in the past. and talents. We are the direct beneficiaries of the previ- NMT’s core technical capabilities include ous generation’s great scientific minds, and plutonium metallurgy, actinide process chem- our generation should in turn pass on some- istry, actinide ceramics, manufacturing nuclear thing to future generations. Science and tech- parts, and nuclear facility operation. Our ef- nology never stand still. One either advances forts should be directed toward enhancing or risks being surprised by new discoveries by these core capabilities for present as well as friends and adversaries alike. future missions. Not all of our projects or tasks have the same priority. The leadership and Belief No. 5: “Division leaders and manag- management must set the priority and allocate ers know best and understand all the issues; the resources accordingly. therefore, they are likely to make the best deci- The recent realignment of the Laboratory sions for the division’s employees, the divi- program offices into line organizations should sion, and the Laboratory.” help all technical divisions run more effec- Science and technology is not a spectator tively. Under the realignment, our division of- sport; we all should be engaged in it, but we fice will have greater responsibility in making should make sure that people are spending sure that the right amount of resources is

Nuclear Materials Technology/Los Alamos National Laboratory 7 Actinide Research Quarterly

Editorial

allocated to various tasks and that our goals scientific and technological initiatives with and deliverables are met. Also, our division Laboratory-wide implications and visibility. office will have to see that NMT maintains and These include the establishment of the Glenn T. fosters the right mix of capabilities for our Seaborg Institute for Transactinium Science; present and future missions. hosting two international Plutonium Futures– Next to the work itself, the most important The Science conferences; publication for the part of our business is documenting the work. past seven years of The Actinide Research NMT Division’s productivity as measured in Quarterly; and the annual Science and Tech- terms of published reports and scientific ar- nology Assessment. All of these endeavors ticles lags behind other technical divisions. have been highly successful, and NMT One of the problems we have identified is Division members collectively should be that our people are not documenting what proud of these accomplishments. they do in their technical work. By document- Some of our scientists and technologists are ing, I mean recording the experimental steps, engaged in nonscientific work for some por- the processes followed, the observations made, tion of their time. None of us spends all of our the data obtained, etc. From this documenta- time doing science and technology; we all have tion, researchers can write reports, publish a variety of other responsibilities and tasks. technical papers, or present the findings at And some of us may not feel so compelled to scientific meetings. do original scientific work outside our pro- Experimental results should be recorded so grammatic tasks. Whether one does scientific that other researchers can repoduce the same work or programmatic work, the burden is on results. Without documenting the scientific us to convince our sponsors of the importance work or theory in laboratory notebooks, any- and relevance of our work to the sponsors’, thing a researcher might write could be consid- and in our case, national need. It would be ered fiction. You have no proof. foolhardy to expect that all of our scientific Documentation can be done in a variety of ideas will be considered worth pursuing. ways. Reports are the most common in techni- In summary, we have been doing many cal work. Just as any engineered product things very well and some others not too well. comes with a manual, all of our work and It is time to review all of our activities in light products should be accompanied by reports. of our present objective of enhancing NMT When the products, inventions, or results of a Division’s science and technology. While we researcher’s investigation are deemed suffi- are asking our members to excel in their work ciently original, innovative, and new, the and make changes as necessary, the leadership results should be published in scientific and management also should lead and show a journals for public dissemination. Some may willingness to change their mode of operation even be patented. when necessary. We need to become expert at In NMT, we have voluminous documenta- “self-critiquing” to keep up with the tion of how we do certain tasks, but not every- changing times. one keep records of what they actually do, and The work of science and technology is based not enough documents are produced to keep on creativity and imagination, and the people track of what’s been accomplished. In record- in NMT Division excel at both. In light of our ing one’s own work, it is important to record present objective of enhancing the division’s both successes and failures, because failure, as science and technology, let’s take the time to well as success, adds to the scientific knowl- review all of our activities. edge base. Together, we can build upon the legacy of a In addition to NMT’s continued scientific scientific institution that the nation has come to productivity and meeting its programmatic rely on and respect. ■ goals, the division has had a number of

8 Nuclear Materials Technology/Los Alamos National Laboratory 4th quarter 2001

Publications And Invited Talks

Publications: E. W. Moody, M. E. Barr, and G. D. Jarvinen, Attention, authors: 2- M. E. Barr, L. D. Schulte, G. D. Jarvinen, J. Espinoza, “QSAR of Distribution Coefficients for Pu (NO3)6 Have you published a T. E. Ricketts, Y. Valdez, K. D. Abney, and R. A. Complexes Using Molecular Mechanics,” J. paper, book, or book Bartsch, “Americium Separations from Nitric Acid Radioanal. Nucl. Chem. 248 (2), 431–437 (2001). chapter, or given an Process Effluent Streams,” J. Radioanal. Nucl. Chem. 248 (2), 457–465 (2001). R. I. Sheldon, “An Estimate of the High invited talk? Please Temperature, Metal Rich Phase Boundary of send the particulars E. Glagovski , B. Zakharkin, Y. Kolotilov, Y. Plutonium Sesquioxide,” J. Nucl. Mater. 297, 358– to [email protected] and Glagolenko, A. Skobtsov, S. Zygmunt , C. Mason, 360 (2001). we’ll publish your W. Hahn, R. Durrer, S. Thomas, B. Sicard, citation in a future is- P. Brossard, N. Herlet, G. Fraize, and A. Villa, T. N. Taylor, G. K. Lewis, D. M. Wayne, “Conversion of Russian Weapon-Grade Plutonium J. C. Fonseca, and P. G. Dickerson, “The Role of sue of ARQ. into Oxide for Mixed Oxide (MOX) Fuel Impurities in Bubble Formation During Directed Fabrication,” Los Alamos National Laboratory Light Processing of Tantalum,” Appl. Surf. Sci. 180, document LA-UR-01-2668 (submitted to Global 2001, 14–16 (2001). Paris, September 9–13, 2001). D. M. Wayne, W. Hang, D. K. McDaniel, S. Hecker and C. Mason, Eds., “Nuclear Physical R. E. Fields, E. Rios, and V. Majidi, “A Linear Time- Methods in Radioecological Investigations of of-Flight Mass Analyzer for Thermal Ionization Nuclear Test Sites,” in “Proceedings of the NATO Cavity Mass Spectrometry,” Spectrochim. Acta, Part Advanced Research Workshop,” Los Alamos B, 56 (7), 1175–1194 (2001). National Laboratory document LA-UR-00-1774 (August 2000). S. Zygmunt, C. Mason, and W. Hahn, “The U.S. Plutonium Materials Conversion Program in N. Lu and C. F. V. Mason, “Sorption-Desorption Russia,” in “Proceedings of Atalante 2000” Behavior of Strontium-85 onto Montmorillonite and (Avignon, France, October 24–26, 2000), Los Alamos Silica Colloids,” Appl. Geochem. 16 (14), 1653–1662 National Laboratory document LA-UR-00-3442. (2001).

T. P. Martinez and M. E. Cournoyer, “Lead Invited Talks: Substitution and Elimination Study, Part II,” in M. E. Cournoyer, “Software Tools for Hazardous Journal of the American Society of Mechanical Engineers Material Management Excellence,” Chemistry (Waste Management 2001, Tucson, Arizona). Department Seminar Series, University of Texas at El Paso, El Paso, Texas, April 23, 2001. T. P. Martinez and M. E. Cournoyer, “Lead Substitution and Elimination Study,” J. Radioanal. M. E. Cournoyer, “Software Tools for Hazardous Nucl. Chem. 249, (2), 397-402 (2001). Material Management Excellence,” Environmental, Health, and Safety Division Seminar, Brookhaven National Laboratory, Brookhaven, New York, June 22, 2001.

A Four-Day Topical Conference on Plutonium and Actinides PLUTONIUM FUTURES— July 6Ð10, 2003 THE SCIENCE 2003

For more information, visit the Plutonium

Albuquerque, New Mexico, USA Futures—The Science homepage at www.lanl.gov/pu2003.

Nuclear Materials Technology/Los Alamos National Laboratory 9 Actinide Research Quarterly

Newsmakers Patent Issued for Hafnium-Recovery Method

Wayne Taylor of Actinide Chemistry Traditionally, recovering hafnium isotopes Research and Development (NMT-11) and from irradiated tantalum involved separation David Jarminska of Isotope and Nuclear techniques using organic solvents that now are Chemistry (C-INC) have received a patent for considered hazardous. The solvent extraction their process to recover hafnium from irradi- techniques generated a mixed-waste stream ated tantalum. The radioisotope hafnium is containing radioactive and hazardous compo- formed in accelerators by irradiating tantalum nents that cannot easily be treated for disposal. targets with protons. The recovered hafnium isotopes have Taylor and Jarminska’s method involves several industrial applications, including use in precipitation and ion-exchange methods to medical diagnosis and treatment, and for recover high-purity hafnium isotopes in a nuclear physics studies. ■ more environmentally friendly manner.

NMT-15’s Zygmunt Cited for Work on U.S./Russian Project

Stan Zygmunt has been awarded a Nuclear Materials Technology (NMT) Division certificate of merit for his work on the U.S./Russian Federation Plutonium Conversion project. Los Alamos is the lead national laboratory for Russian collaborations on technologies to convert plutonium metal extracted from disas- sembled nuclear weapons into an oxide form suitable for use as mixed-oxide fuel (MOX). Zygmunt is the Los Alamos project leader for the program. Zygmunt’s award was based in part on a commendation from John Baker and Sam Thomas of the Office of Fissile Materials Disposition, National Nuclear Security Administration (NNSA). In a memo to Pit Disassembly/Surveillance Technologies (NMT-15) Group Leader Tim Nelson, Thomas said Zygmunt was responsible for progress being made on the project because of his “crucial contributions and effective relationships with the Russian Federation experts.... Stan’s technical Stan Zygmunt has received a certificate of merit for expertise and his ability to manage and negotiate [have] served this his work on the U.S./Russian Federation Plutonium program with excellent results.” Conversion project. Under an agreement signed with the Russian Federation in 2000, the Photo by Mick Greenbank United States and the Russian Federation each will convert 34 tons of weapons-grade plutonium into a form not easily transformed into weapons. As part of the project, NMT-15 is assisting the Russian Federation with the design, licensing, construction, and commissioning of facilities in Russia for plutonium conversion. France entered into a similar agreement with the Russian Federation in 1992, and it is hoped that the two programs one day will be merged into one. ■

10 Nuclear Materials Technology/Los Alamos National Laboratory 4th quarter 2001

Kniss Receives DOE Award

Laboratory engineer Brett Kniss has received the Department of Energy’s (DOE) Distinguished Associates Award, the highest award given by the DOE to a nonfederal employee. Kniss served as project leader and also chief engineer for the Lab Pit Production Project in Weapons Component Technology (NMT-5). He received the award for his many years of work establishing Los Alamos’ capability to produce small numbers of plutonium pits, the cores of nuclear weapons. “Brett Kniss provided the knowledge, management, and energy to bring together the technical and practical requirements to help put Los Alamos on track to produce a plutonium pit that can be certified for the stockpile,” said Gen. John Gordon, chief administrator of DOE’s National Nuclear Security Administration (NNSA). “Re-establishing pit Brett Kniss receives congratulations on his production is a major mission requirement for DOE, and Brett has been Distinguished Associates Award from Gen. John instrumental in helping NNSA make significant steps in achieving Gordon via a video teleconference. that goal.” ■ Photo by LeRoy N. Sanchez

Shock-Wave Shock-Wave Research on Plutonium... Research continued from page 5 describe the dynamic response of phase changing materials. Shock-wave experiments also can be used to produce data about the dynamic strength of materials in tension. More complicated shock-wave techniques than those described above allow the tensile, or spall, strength of materials to be studied on very short time scales. While the Launcher itself is owned and operated by NMT-16, the shock-wave experi- ments involve several divisions. Researchers in DX-1, with input from others in Applied Physics (X) Division, design the experiments. Ben Jacquez of Structure/Property Relations (MST-8), left, and Johnny Montoya Members of Weapons Component Technol- of Nuclear Materials Technology (NMT-16) make adjustments to the target of ogy (NMT-5) prepare many of the samples. the 40mm Launcher during its shakedown period in November 1995, before the The data are collected and analyzed by DX-1 windows and gloves were installed in the glove box. Researchers performed and sent to X and Theoretical (T) divisions several experiments on inert samples this way to test the system before going for further analysis, physics model develop- hot. Part of the gun barrel is shown on the left; the round aluminum plate with ments, and eventual inclusion in computer the plastic cylinders is the target. codes. The multidivisional research effort has Photo by Tom Baros resulted in a significant amount of new data on plutonium over the past few years. ■

Nuclear Materials Technology/Los Alamos National Laboratory 11 Actinide Research Quarterly

Newsmakers Circle of Life Blanket Presented to NMT Division and the Laboratory

Stacey Talachy, Nuclear Materials Science (NMT-16), top left; NMT Division Leader Tim George, top right; Vera Aguino, Weapons Component Technology (NMT-6), lower left; and Patrick Trujillo, NMT chief of staff, display a blanket recently

presented to the Photo by LeRoy N. Sanchez Laboratory by the American Indian Science and Engineering Society (AISES). The limited-edition “Circle of Life” commemorative Pendleton blanket was presented at the 23rd Annual AISES national conference. NMT Division and the Lab were among the sponsors of the conference, which was held in No- vember in Albuquerque. The inscription with the blanket states: “In honor of all tribal elders, the wisdom keepers who are charged with handing down teachings and spiritual direction so the children better understand their responsibility to the universe and the Creator.” ■

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12 Nuclear Materials Technology/Los Alamos National Laboratory