Neutron Science In the News – 2011
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Programmed cell death, or apoptosis, is a naturally occurring and necessary biological process. In apoptosis, the 192 amino acid BAX protein inserts itself into mitochondrial membranes, causing their contents to leak out and their eventual demise.
This is our fate as mammals. In a typical human, some 50 to 70 million cells die daily as a result of apoptosis. Old cells complete their life cycle and die. New cells are born.
In utero, apoptosis has a creative role, responsible for the separation of the fingers of the growing fetus. However, a defective apoptosis function (i.e., too little or too much) has been implicated in a variety of diseases, including atrophy of limbs and organs and some cancers.
The collaboration is led by Cécile Fradin, a biophysicist from McMaster University, which is located in Hamilton, Ontario, from the Canadian Neutron Beam Center at Chalk River (Ontario, Canada). The team also includes other researchers from McMaster and from ORNL's Neutron Sciences Directorate.
In hopes of getting a better understanding of how the BAX protein interacts with membranes, the researchers combined long-known fluorescence techniques with neutron scattering at the General-Purpose SANS instrument at the ORNL High Flux Isotope Reactor. The cell mimics were vesicles (hollow spheres) made of bilayers with a lipid composition similar to mitochondrial membranes. These so-called liposomes are also used in medicine, where, filled with drugs, they can be functionalized to target and treat cancer and other diseases.
DOE Pulse 12/1
Whether climbing mountains in Peru or using the neutron scattering beam line at HFIR, Andy Christianson sees both as an “expression of wanderlust.” Perhaps its Christianson’s attitude toward science that led him down a path of exploration, which led to the International Union of Pure and Applied Physics Young Scientist Prize (Structure and Dynamics of Condensed Matter).
At 38, Christianson’s main interest lies in understanding fundamental physical properties of materials. Assuming scientists can understand a material, they can start thinking about creating materials with new and potentially more useful properties.
Most of what Christianson works with he finds interesting, but he admits that studying iron-based superconductors was an especially fun and unique experience. “It was the first time I was involved in a field where the competition was so stiff that you had to keep pounding and pounding, otherwise, someone else was going to do the same thing,” he said.
Christianson finds both magnetism and superconductivity appealing, and since iron-based superconductors have both properties, he says they satisfy his intellectual curiosity. Armed with a scientific admiration for what neutrons can tell us, Christianson studies materials using the neutron scattering beam lines at SNS and HFIR.
Wind Powered Engineering and Development 12/1
Increasing demand and a shrinking supply of rare-earth elements for magnets creates an opportunity for a research team at Oak Ridge National Laboratory and the University of Minnesota. The goal is to create a recipe for a replacement that doesn’t use scarce ingredients. The prospect of not having enough rare earth elements such as neodymium and dysprosium for magnets looms large for industries that need them. Researchers Allard, Edgar Lara-Curzio and Mike Brady of ORNL, and Jian-Ping Wang at the University of Minnesota are focused on developing magnets made from abundant and inexpensive materials. Of specific interest is an iron-nitride compound with a specific phase that potentially exhibits the highest saturation magnetization ever reported for a material.
“This is a critical parameter related to the highest degree to which a material can be magnetized,” said Allard, who said this particular iteration of the iron-nitrogen compound has values up to 18% higher than the best commercial alloy, iron cobalt. The problem is that this material is metastable and exhibits relatively low coercivity, which means it demagnetizes easily. The best permanent magnets, such as those made of neodymium-iron-boride, score high in such areas.
The team will devise a method of producing this pure phase, iron-nitride compound and use specialized modeling methods to better understand the role of alloying additions that might stabilize the material so it retains its magnetic properties. The researchers hope to better understand the magnetic behavior of the “alpha double prime” phase by correlating microstructure at the atomic level to processing and magnetic behavior.
Once researchers characterize the elusive phase, their goal will be to make bulk quantities of the material and move toward their ultimate goal of replacing neodymium-iron-boride magnets for wind, automotive, and other energy technologies. This work with the University of Minnesota builds on previous work with Wang in which ORNL researchers were able to characterize iron nitride films with demonstrated potential. Allard noted that the Spallation Neutron Source made it possible to perform polarized neutron reflectometry, a test performed by Valeria Lauter to determine magnetic property.
Materials that don't expand under heat aren't just an oddity. They're useful in a variety of applications—in mechanical machines such as clocks, for example, that have to be extremely precise. Materials that contract could counteract the expansion of more conventional ones, helping devices remain stable even when the heat is on.
"When you heat a solid, most of the heat goes into the vibrations of the atoms," explains Brent Fultz, professor of materials science and applied physics and a coauthor of the paper. In normal materials, this vibration causes atoms to move apart and the material to expand. A few of the known shrinking materials, however, have unique crystal structures that cause them to contract when heated, a property called negative thermal expansion. But because these crystal structures are complicated, scientists have not been able to clearly see how heat—in the form of atomic vibrations—could lead to contraction.
But in 2010 researchers discovered negative thermal expansion in ScF3, a powdery substance with a relatively simple crystal structure. To figure out how its atoms vibrated under heat, Li, Fultz, and their colleagues used a computer to simulate each atom's quantum behavior. The team also probed the material's properties by blasting it with neutrons at the Spallation Neutron Source at Oak Ridge National Laboratory in Tennessee; by measuring the angles and speeds with which the neutrons scattered off the atoms in the crystal lattice, the team could study the atoms' vibrations. The more the material is heated the more it contracts, so by doing this scattering experiment at increasing temperatures, the team learned how the vibrations changed as the material shrank.
Theoretically, during the doping of a chaotic magnetic insulator material with nonmagnetic material’s atoms, the magnetic interferences between the material’s magnetic ions will be lessened. However, according to Neutron Scattering Science Division’s Matthew Stone and his partners from Stanford University, during the doping of the antiferromagnetic insulator barium manganate, where the manganese is replaced by the nonmagnetic vanadium atoms, the magnetic excitations or magnons of the barium manganate retained their energy and strength.
The research findings will provide the basic knowledge of magnetic interferences in insulator materials. The findings can also be used to enhance applications of magnets in devices, said Stone.
For the first time, neutron images in 3 dimensions have been taken of rare archaeological artifacts here at ORNL. Bronze and brass artifacts excavated at the ancient city of Petra, in Jordan were recently imaged in 3 dimensions using neutrons at HFIR's CG-1D Neutron Imaging instrument.
The data that is now being analyzed will for the first time give eager archeologists and ancient historians significant, otherwise wholly inaccessible insight into the manufacturing and lives of cultures that once occupied settlements within the Roman Empire, Middle East, and Colonial-period New England.
Science Daily 9/30
Molecular motion in proteins comes in three distinct classes, according to a collaboration by researchers at the Department of Energy's Oak Ridge National Laboratory and the University of Tennessee, in research reported in Physical Review Letters.
The research team, directed by ORNL-UT Governor's Chairs Jeremy Smith and Alexei Sokolov, combined high-performance computer simulation with neutron scattering experiments to understand atomic-level motions that underpin the operations of proteins.
The research was primarily conducted by ORNL's Liang Hong, with the support of Benjamin Lindner and Nikolai Smolin from ORNL. They performed neutron scattering experiments at ORNL's Spallation Neutron Source on the BASIS instrument and at the National Institute of Standards and Technology Center for Neutron Research.
R&D Magazine 9/28
Researchers at the Bio-SANS instrument at the High Flux Isotope Reactor are getting a leg up in their research from a "low tech" lighting tool that can be fixed to their samples and then pushed directly into the neutron beam, to illuminate the response of layers of cyanobacteria to changes in light.
"It's really low tech," says Volker Urban, lead instrument scientist on the Bio-SANS, with a grin. "You can buy the parts anywhere." The lighting tool is the work of graduate student Brad O'Dell, a visiting intern from Cambridge University. The device combines light-emitting diodes (LEDs) with the electronics that drive the illumination.
Industrial users are starting to eye the potential of neutron science for solving problems that can't be solved in any other way. At the same time, the Spallation Neutron Source and High Flux Isotope Reactor neutron science facilities at Oak Ridge National Laboratory are exploring ways to woo such users and to make a match of it, to the benefit of both.
Knoxville News Sentinel 9/20
The CORELLI instrument (Elastic Diffuse Scattering Spectrometer) is not scheduled to be commissioned until 2014, but part of the new research instrument at the Spallation Neutron Source is already being installed. According to information provided by ORNL, workers installed the detector tank earlier this week on SNS Beam Line No. 9. The big assembly, which consists of 25 tons of stainless steel, was lifted into its position by an overhead crane, the lab said.
ORNL spokesman Bill Cabage, in an email message, wrote: "Now that the tank is in place, banks of neutron detectors will be installed around the interior, a process that will take about six months. When the instrument is complete, it will be encased in several tons of high-density concrete shielding. Ranor, Inc., fabricated the detector tank, and Haselwood Services and Manufacturing carried out the installation."
The lab said the CORELLI instrument is designed to "probe complex disorder in crystalline materials through scattering of single-crystal samples."
Knoxville News Sentinel 9/19
The budget climate is affecting lots of things, including the planned expansion and power upgrades at the Spallation Neutron Source.
"It'll take a little longer," Oak Ridge National Laboratory Director Thom Mason said last week during an interview regarding budget planning.
Mason lauded the effort at the SNS to date, noting that he was fortunate to lead the project during the construction phase and up until the point where the first neutrons were made. "I felt like it was an exciting time," he said.
Over the past four years since SNS startup, Mason said there had been a notable ramp up and progress, with much of the heavy lifting done under Ian Anderson's leadership. The SNS research program now has in excess of 750 users, can operate at a megawatt of power and has a good stable of research instruments, he said.
Experiments at the Spallation Neutron Source (SNS) and High Flux Isotope Reactor (HFIR), both located at the Department of Energy's Oak Ridge National Laboratory, indicate novel behaviors in the antiferromagnetic material cobalt aluminum oxide, -- CoAl2O4, or cobalt aluminate -- which researcher Gregory MacDougall of ORNL's Neutron Scattering Sciences Division describes as a "highly frustrated magnetic system."
"Frustrated" in this context refers to a condition where competing interactions between the magnetic spins within the atomic structure prevent the establishment of a long-range ordered state.
"Frustration is often associated with exotic behavior in materials, including piezoelectricity, multiferrocity, and high-temperature superconductivity, each of which is potentially important for future energy-efficient technologies," MacDougall said.
R&D Magazine 9/2
Solar cells that convert sunlight into electricity could be a widely used renewable energy source. Getting to that point, though, requires breakthroughs in their cost and their efficiency at turning sunbeams into electric current. Neutron scattering experiments conducted at Oak Ridge National Laboratory are helping solar cell makers obtain the hard data they need to refine their materials and manufacturing processes.
One of the most promising options for lowering costs is to make solar cells from thin films made up of combinations of plastics called polymers. These devices are easy to produce in large numbers because they use conventional industrial processing methods, which are relatively cheap and energy efficient compared to the processes used to make the silicon solar cells that are most widely used now. Also, panels made from organic solar cells are lighter and less expensive to install than the bulky solar panels made from silicon cells.
Researchers at Department of Energy facilities like the Oak Ridge National Laboratory are accelerating research concerning the behavior of confined greenhouse gases at "supercritical" levels.
In a supercritical stage of a fluid, the density of liquid and vapor becomes identical. This same situation can be applied in the problem of getting rid of greenhouse gases. Specifically, greenhouse gas can be sequestered for a long time in coal seams deep underground, where conditions become supercritical for carbon dioxide.
Research is now focused on the behavior of confined fluid, or how the confinement in small pores affects their phase behavior. Scientists are working to answer questions like how much carbon dioxide coal can take up and whether it will get physically or chemically transformed with time.
For now, research has shown that there are indeed pores inaccessible to carbon dioxide and methane. Several scientific findings have also been released with the help of the General-Purpose Small-Angle Neutron Scattering Diffractometer at Oak Ridge's High Flux Isotope Reactor.
Five of the world's most advanced instruments for neutron scattering research are serving the neutron science community following the completion of the $68.5 million SING project at Oak Ridge National Laboratory's Spallation Neutron Source (SNS). The project to design, build and install the five instruments for neutron scattering analysis at the SNS, funded by the Department of Energy's Office of Science, was recently finished ahead of schedule and under budget.
Knoxville News Sentinel 8/11
Oak Ridge National Laboratory announced the completion of a long-running, $68.5 million project that added five neutron-scattering research instruments to the Spallation Neutron Source. The project, known as SING (SNS Instruments -- Next Generation), was approved last week by Harriet Kung, the director of the Department of Energy's Office of Basic Energy Sciences, according to information released by ORNL.
The five instruments were identified as Spallation Neutrons and Pressure Diffractometer (SNAP); the Fine-Resolution Fermi Chopper Spectrometer (SEQUOIA); the Single-Crystal Diffractometer (TOPAZ), which is shown in photograph here; the Nanoscale-Ordered Materials Diffractometer (NOMAD); and the Hybrid Spectrometer (HYSPEC).
ORNL said the concepts for the instruments were developed via a series of workshops and conferences and the help of dedicated review committees. The lab said DOE awarded funds for the work, beginning in late 2003.
Knoxville News Sentinel 8/1
Workers are wrapping up a maintenance period at the Spallation Neutron Source, with the restart of the accelerator to get under way Tuesday, according to Ian Anderson, Oak Ridge National Laboratory's associate lab director for neutron sciences. Anderson said the plan is to restart at 850 kW and stay at that power level through December, when it's time for another change of the target. Then, the accelerator will be ramped up to 1 MW, he said. I asked Anderson about preparations for potential funding shortfalls at SNS, given the current climate in Washington, and whether there were any contingency funds stashed away for emergency use.
"We don't have any contingency funds hidden away, but we are making very strategic decisions on what we will do and what we can put off until later," he responded. "The focus will be on getting the science out of the presently operating instruments." Because of the fiscal situation, I also wondered if there were still plans for a second Target Facility (expected to cost in the range of $1B or maybe more).
"The second target station facility is still very much on the table with potentially an expanded role to accomplish fusion materials testing," Anderson said. "This capability, with the appropriate ratio of materials damage and He production, can only be carried out at sources like SNS and is very important for ITER (International Thermonuclear Experimental Reactor) and follow-on projects."
DOE News Blog 7/5
It’s said that a friend in need is a friend indeed. But what do you do when your friend needs a supercomputer... or something even harder to find, like a Spallation Neutron Source or a High Flux Isotope Reactor?
If you’re a researcher in the Energy Department’s Office of Science, it’s pretty simple: you offer them time on one of yours. And that’s exactly what researchers at several Office of Science facilities are doing for their counterparts in Japan.
On March 11th, the Tohoku Earthquake and subsequent tsunami struck Japan’s main island of Honshu with shattering force. Tens of millions are still adjusting to the aftermath of those disasters, not only those living in quake-ravaged areas, but all around the country.
Many scientists are among them. For instance, the Japan Proton Accelerator Research Complex (J-PARC) has been shut down due to earthquake damage. Researchers using electricity-hungry supercomputers at other facilities had their work put on hold due to the power shortages still afflicting the country.
That’s where researchers in the Energy Department’s Office of Science have come in. Scientists at Oak Ridge National Laboratory have given their Japanese counterparts time on the Spallation Neutron Source (SNS) and High Flux Isotope Reactor, both of which are similar to the experimental equipment at J-PARC. The team at SNS has accepted two-dozen research proposals from J-PARC scientists, who expect to complete their work before December. Scientists at Oak Ridge even joined with citizens from the city to make a $20,000 donation to their sister city of Naka, Japan, which will be used to repair a local school damaged by the earthquake.
Knoxville News Sentinel 6/24
The Graphite Reactor, the world's first continuously operated nuclear reactor and a National Historic Landmark, is looking better than ever -- or at least better than recently. The reactor museum at Oak Ridge National Laboratory was recently refurbished in time for the summer season of public tours sponsored by the U.S. Department of Energy. The Graphite Reactor is one of the main stops on the three-hour bus tours, which take place daily Monday through Friday.
The Oak Ridge reactor was a pilot facility for production of plutonium during the World War II Manhattan Project and then became a pioneering facility for production of radioisotopes and site of early neutron-scattering experiments.
ORNL is the world's leading center for neutron sciences. About 10,000 people visit the reactor, which was shut down in the 1960s, each year. That number is down considerably from the pre-9/11 days when security wasn't so tight and visitors could come and go at their leisure.
According to ORNL, the refurbishment was the first "major makeover" to the museum areas since 1982, when the Graphite Reactor got special attention via the World's Fair staged in Knoxville.
"In many ways, the most reasonable universe would be one in which there is no matter," says the University of Tennessee's Geoff Greene. "But that is manifestly not the universe we see. So something is wrong with the simple picture, and it is not understood why the universe actually has matter, instead of no matter, which makes more sense." This question, and others like it, are at the heart of the science that will be addressed at the Fundamental Physics Beam Line now being commissioned at SNS.
Beam line 13 is a cooperative venture between Basic Energy Sciences at DOE, which granted a beam line to nuclear physics, and the Nuclear Physics Program Office, which supported the construction of the FNPB and supports operation of the experiments.
Beam line 13 has an atypical user program. As with other beam lines, selection of approved experiments is made by a proposal-driven process, with the key criterion being scientific merit as determined by peer review. But at FNPB, a single experiment doesn't necessarily run for a few days, as most do at SNS and HFIR. Instead, it may run continuously for several years.
Knoxville News Sentinel 6/22
It's probably not too thrilling to some of the local hoteliers, but Oak Ridge National Laboratory's new $8.85 million on-site Guest House is about ready to open. Construction of the new 47-room mini-hotel (a mix of single and double units) was completed May 31, and first occupancy is expected in August, ORNL spokesman Ron Walli said. The Guest House will be managed by Paragon Hotel Co., out of Anderson, S.C., which also manages the Comfort Inn in Oak Ridge, Walli said. The facility, which is located on Chestnut Ridge near the Spallation Neutron Source, is designed to house visiting scientists who want to be near their experiments at SNS, Center for Nanophase Materials Sciences and other lab research facilities.
Science Daily 6/6
Neutron analysis of the atomic dynamics behind thermal conductivity is helping scientists at the Department of Energy's Oak Ridge National Laboratory gain a deeper understanding of how thermoelectric materials work. The analysis could spur the development of a broader range of products with the capability to transform heat to electricity.
Researchers performed experiments at both of ORNL's neutron facilities -- the Spallation Neutron Source and the High Flux Isotope Reactor -- to learn why the material lead telluride, which has a similar molecular structure to common table salt, has very low thermal conductivity, or heat loss -- a property that makes lead telluride a compelling thermoelectric material. "The microscopic origin of the low thermal conductivity is not well understood. Once we do understand it better we can design materials that perform better at converting heat to electricity," said Olivier Delaire, a researcher and Clifford Shull Fellow in ORNL's Neutron Sciences Directorate.
Knoxville News Sentinel 5/18
The High Flux Isotope Reactor at Oak Ridge National Laboratory, which was constructed in the mid-1960s, is pretty doggone ancient when it comes to nuclear reactors. However, the folks at ORNL think there's decades of life still left in the old research reactor, and they've apparently been pretty successful in refurbishing, upgrading and maintaining the systems needed to make that strategy work.
The HFIR was restarted earlier this month following a 45-day outage, one of two big maintenance periods scheduled annually - one in the spring and one in the fall - to replace parts, check systems and do all sorts of preventive maintenance. According to Ron Crone, the research reactors chief at ORNL, nearly 150 individual projects or activities were completed during the latest reactor outage. Crone said work was done on the reactor's electrical, instrumentation and experimental systems, as well as a number of activities on the cold source - which slows down the streams of neutrons that emanate from the reactor core to make them more useful for studies of biological samples and experiments with other types of materials.
Scientists travel to Oak Ridge from around the world to do neutron-scattering experiments at the reactor, and ORNL is the only U.S. source for some of the radioisotopes produced at the High Flux Isotope Reactor.
R&D Magazine 5/19
An ORNL-University of Tennessee Graduate School of Medicine collaboration has for the first time successfully characterized the earliest structural formation of the disease type of the protein "huntingtin" that creates such havoc in Huntington's Disease.
Researchers originally thought the deposits, which appear under the microscope as "clumps," were the cause of the devastation that ensues in the brain. More recently they think the clumping may actually be a kind of biological housecleaning, an attempt by the brain cells to clean out these toxic proteins from places where they are destructive. So what are the toxic species? When and where do they occur? To answer this question, Christopher Stanley, a Shull Fellow in the Neutron Scattering Science Division at ORNL, began to work with Valerie Berthelier, a UT Graduate School of Medicine researcher who studies protein folding and misfolding in HD. The pair wanted to explore the structures of the earliest aggregate species believed to be the most toxic.
Knoxville News Sentinel 5/2
The University of Kentucky's Patterson School of Diplomacy and International Commerce is establishing relationships at both the Y-12 National Security Complex and Oak Ridge National Laboratory, and that could prove to be an example for others to follow. The Kentucky school is directed by Ambassador Carey Cavanaugh, and for the second year in a row he brought students to visit Y-12 and get an up-close look at nuclear weapons facilities (at least as much as possible on an unclassified visit). The group also toured ORNL facilities, including a visit to the High Flux Isotope Reactor, and got a briefing from Ned Sauthoff, director of the U.S. team working on the International Thermonuclear Experimental Reactor.
Thermoelectric materials are a hot new technology that is now being studied intensively by researchers funded by the U.S. Department of Energy's Energy Frontier Research Centers. Oliver Delaire, a Shull fellow at ORNL, is part of such a collaboration, this one led by an EFRC at the Massachusetts Institute of Technology. Delaire uses neutron scattering and computer simulation to investigate the microscopic structure and dynamics of thermoelectric materials so that researchers can make them more efficient for new, energy-saving applications.
At ORNL, Delaire and his collaborators are using the Time of Flight spectrometers at SNS-ARCS and CNCS-and the HB-3 Triple-Axis Spectrometer at the High Flux Isotope Reactor. "The SNS instruments offer more power," Delaire said. "They can sample the whole parameter space very efficiently. They offer a unique opportunity in a single experiment to sample all the types of atomic vibrations, all the phonons inside the solid. And once we have this information, we can reconstruct the microscopic thermoconductivity, which is really the property we are trying to understand."
Researchers from Washington University in St. Louis and the Department of Energy's Oak Ridge National Laboratory used small-angle neutron scattering to analyze the structure of chlorosomes in green photosynthetic bacteria. Chlorosomes are efficient at collecting sunlight for conversion to energy, even in low-light and extreme environments.
"It's one of the most efficient light harvesting antenna complexes found in nature," said co-author and research scientist Volker Urban of ORNL's Center for Structural Molecular Biology, or CSMB.
Neutron analysis performed at the CSMB's Bio-SANS instrument at the High Flux Isotope Reactor allowed the team to examine chlorosome structure under a range of thermal and ionic conditions.
"We found that their structure changed very little under all these conditions, which shows them to be very stable," Urban said. "This is important for potential biohybrid applications – if you wanted to use them to harvest light in synthetic materials like a hybrid solar cell, for example."
Lab Manager Magazine 3/29
Stress, fatigue and heavy loads aren't always negative elements of work - in fact, they are what attracted Jennifer Forrester to the Spallation Neutron Source at Oak Ridge National Laboratory. Forrester, a research scientist working in the research group of professor Jacob Jones at the University of Florida, came seeking stress at SNS as part of her work on piezoelectric ceramics. Applying stress to piezoelectric crystals produces an electric field, whereas applying an electric field to the same material causes a shape change.
These unique properties make piezoelectrics valuable for diverse applications in such consumer products as cell-phone touch screens, fuel injection, airbag deployment sensors, fire igniters and guitar pickups.
"What we're trying to do is improve them -- put a higher electric field on them and have more shape change. Or the other way around -- put a higher load on them so that they put out a corresponding electric field. The more shape change you can get out of them, the more potential applications you have," Forrester said.
Knoxville News Sentinel 3/19
In a place dubbed the Atomic City, where anything nuclear is of interest, the evolving nuclear emergency in Japan had everyone's attention over the past week.
It was, literally, the talk of the town.
Much discussion focused on the Fukushima Dai-ichi nuclear power plant, where multiple reactor units suffered damage from the March 11 earthquake and tsunami. Experts based at Oak Ridge National Laboratory and other Oak Ridge facilities were tracking events but frustrated by the lack of detailed information - and sometimes conflicting reports - coming out of Japan.
Tim Powers, a division director at ORNL, said the High Flux Isotope Reactor - a 45-year-old research reactor at the lab - is designed to withstand an earthquake in the range of 6.0-7.0 on the Richter scale. The 85-megawatt reactor is much smaller than power reactors in Japan, he said, noting that the fuel core of a power reactor is about a thousand times heavier than the one at HFIR.
The ORNL reactor operates at 155 degrees Fahrenheit, compared with about 500 degrees for one of the Japanese reactors, and there are systems to provide cooling at the research reactor even if power is lost, Powers said.
John Sorensen, an ORNL researcher and one of the nation's top experts in emergency preparedness, closely watched the early days of the developing nuclear threat in Japan and was pretty impressed with the efforts to evacuate an area around the nuclear plant - especially considering the problems with roads and other infrastructure damaged by the massive earthquake and tsunami.
"In these cases, there was sufficient time to evacuate people before any release of radiation occurred," said Sorensen, who along with his wife, Barbara Vogt, gained fame for a 2001 study touting the use of duct tape and plastic to create a safe room against chemical terrorism.
Knoxville News Sentinel 3/14
In light of the nuclear emergency in Japan, everyone is asking questions about the reactors in the United States and whether events taking place in Japan could happen in the U.S. I asked the folks at Oak Ridge National Laboratory about the High Flux Isotope Reactor, the lab's research reactor that uses highly enriched uranium fuel to produce isotopes and provide neutrons for research experiments with materials, and how it differs from the reactors of concern in Japan.
Tim Powers, who heads the lab's nonreactor nuclear facilities division, was fielding questions today because some of the reactor folks were gone, and he said the High Flux Isotope Reactor is a lot different than the nuclear power reactors in Japan.
"We're much smaller than the reactors in Japan," he said, noting that the fuel core of a power reactor is about a thousand times heavier than the one at HFIR. The operating power level at HFIR is 85 megawatts, compared to about 1,380 megwatts at the Japanese reactors, and the ORNL reactor operates at 155 degrees Fahrenheit, compared to about 500 degrees F for a one of the Japanese reactors, he said.
Nature News 3/8
Scientists on three continents are scrambling to understand a potentially serious problem with superconducting cables destined for ITER, the world's largest fusion experiment. Nature has learned that preliminary tests of cable for ITER's powerful central magnet show that it degrades too quickly to be used. If unresolved, the problem threatens to further delay a project that has already suffered many years of technical and budgetary setbacks. "I'm concerned, but we have a plan in place to solve the problem," says Ned Sauthoff, the head of the United States' contribution to ITER.
Neutron studies of the failed cable are also under way at the Spallation Neutron Source at Oak Ridge National Laboratory in Tennessee, along with X-ray tomography experiments at Lawrence Livermore National Laboratory in California, according to Sauthoff. In addition, other types of Nb3Sn cables are being tested to see if they are more resilient. "We're going to test until we get a success," he says. Sauthoff hopes that the situation can be resolved by June. If a fix for the cable takes longer, then additional facilities could be tasked with manufacturing coils for the central solenoid to speed up production, but this would add extra expense to the project.
Popular Mechanics 3/2
Oak Ridge was established in 1943 with the secret mission of producing uranium and plutonium for a nuclear bomb. The lab's main complex today more resembles a college campus, with sleek glassy buildings, green lawns and zigzagging walkways. Although public access is restricted for most of the year, during the Secret City Festival in the third weekend of June, bus tours depart daily from the American Museum of Science and Energy in downtown Oak Ridge and visit some of the lab's most famous sites: Y-12, where uranium for the first bomb was enriched; the Graphite Reactor, the world's second oldest nuclear reactor; and the $1.4 billion Spallation Neutron Source, the world's most powerful neutron source.
E! Science News 2/22
A theoretical technique developed at the Department of Energy's Oak Ridge National Laboratory is bringing supercomputer simulations and experimental results closer together by identifying common "fingerprints." ORNL's Jeremy Smith collaborated on devising a method -- dynamical fingerprints -- that reconciles the different signals between experiments and computer simulations to strengthen analyses of molecules in motion. The research will be published in the Proceedings of the National Academy of Sciences.
"When we started the research, we had hoped to find a way to use computer simulation to tell us which molecular motions the experiment actually sees," Smith said. "When we were finished we got much more -- a method that could also tell us which other experiments should be done to see all the other motions present in the simulation. This method should allow major facilities like the ORNL's Spallation Neutron Source to be used more efficiently."
Researchers at the Department of Energy's Oak Ridge National Laboratory and the University of Tennessee, using the Spallation Neutron Source's ARCS Wide Angular Range Chopper Spectrometer, performed spin-wave studies of magnetically ordered iron chalcogenides. They based their conclusions on comparisons with previous spin-wave data on magnetically ordered pnictides, another class of iron-based superconductors.
"As we analyze the spectra, we find that even though the nearest neighbor exchange couplings between chalcogenide and pnictide atoms are different, the next nearest neighbor exchange couplings are closely similar," said Pengcheng Dai, who has a joint appointment with ORNL's Neutron Sciences Directorate and the University of Tennessee.
New Energy And Fuel 2/7
Oak Ridge National Laboratory researchers have developed a biohybrid photo conversion system – based on the interaction of photosynthetic plant proteins with synthetic polymers – that can convert visible light into hydrogen fuel. This is another part of the first step to making solar panels for directly producing fuel.
The research team’s work seeks to mimic photosynthesis, the natural process carried out by plants, algae and some bacterial species that converts sunlight energy into chemical energy and sustains much of the life on earth.
ORNL researcher Hugh O’Neill, of the lab’s Center for Structural Molecular Biology, said, “Making a, self-repairing synthetic photo conversion system is a pretty tall order. The ability to control structure and order in these materials for self-repair is of interest because, as the system degrades, it loses its effectiveness. This is the first example of a protein altering the phase behavior of a synthetic polymer that we have found in the literature. This finding could be exploited for the introduction of self-repair mechanisms in future solar conversion systems.” If the team is proven right, the lifespan of a unit would be greatly expanded improving the economics.
The research team comes from various laboratory organizations including its Chemical Sciences Division, Neutron Scattering Sciences Division, the Center for Structural Molecular Biology and the Center for Nanophase Materials Sciences. The team members are O’Neill, William T. Heller, and Kunlun Hong, all of ORNL; Dimitry Smolensky of the University of Tennessee; and Mateus Cardoso, a former postdoctoral researcher at ORNL now of the Laboratio Nacional de Luz Sincrotron in Brazil.
Photosynthesis, the natural process carried out by plants, algae and some bacterial species, converts sunlight energy into chemical energy and sustains much of the life on earth. Researchers have long sought inspiration from photosynthesis to develop new materials to harness the sun's energy for electricity and fuel production.
In a step toward synthetic solar conversion systems, the ORNL researchers have demonstrated and confirmed with small-angle neutron scattering analysis that light harvesting complex II (LHC-II) proteins can self-assemble with polymers into a synthetic membrane structure and produce hydrogen.The researchers envision energy-producing photoconversion systems similar to photovoltaic cells that generate hydrogen fuel, comparable to the way plants and other photosynthetic organisms convert light to energy.
"Making a, self-repairing synthetic photoconversion system is a pretty tall order. The ability to control structure and order in these materials for self-repair is of interest because, as the system degrades, it loses its effectiveness," ORNL researcher Hugh O'Neill, of the lab's Center for Structural Molecular Biology, said.
"This is the first example of a protein altering the phase behavior of a synthetic polymer that we have found in the literature. This finding could be exploited for the introduction of self-repair mechanisms in future solar conversion systems," he said. Small angle neutron scattering analysis performed at ORNL's High Flux Isotope Reactor (HFIR) showed that the LHC-II, when introduced into a liquid environment that contained polymers, interacted with polymers to form lamellar sheets similar to those found in natural photosynthetic membranes.
Oak Ridge National Lab and North Carolina State University scientists are helping to develop medicines that will block the spread of viruses. Using the Bio-SANS instrument at ORNL’s High Flux Isotope Reactor, these researchers are studying how viruses change their structure as they move between different host species. Through small angle neutron scattering they were able to compare the structural details of viruses from mammalian and insect cells.
The differences? Mammalian-grown viruses have larger diameters, higher levels of cholesterol and a different distribution of genetic material.
ORNL researcher Flora Meilleur explains, “These results suggest that structural changes are likely to be important in transmission between hosts. The chemical environment of the host cell appears to affect how the virus assembles itself.”
A year and a half ago, nuclear medicine physicians were hit with a double whammy. On 9 May 2009, the High Flux Reactor in Petten, the Netherlands, was shut down to fix corroded pipes. Ten days later, a heavy-water leak forced a shutdown at the National Research Universal reactor in Chalk River, Canada.
The twin problems created a temporary shortage of technetium-99, a radioisotope used in more than 30 million procedures a year worldwide for imaging everything from blood flow through the heart to bone cancer. Physicians were forced to use less Tc-99 for many procedures, ration what scant supplies remained, and find less desirable substitutes.
Producing Mo-99 by absorbing neutrons eliminates the need for U-235. The separation process also generates far less radioactive waste than traditional methods do. It does require extremely powerful neutron sources, however, such as the High Flux Isotope Reactor at Oak Ridge National Laboratory in Tennessee. Those sources are already in heavy demand for neutron scattering work and other scientific techniques. So GE Hitachi is also exploring the possibility of carrying out its neutron capture work at commercial nuclear power reactors.
The field of an electron spin that is not canceled in an unfilled shell makes some elements magnetic -- iron, nickel, chromium, vanadium, and the rare earths. In the ARCS experiment at SNS, the novel material being probed with neutrons is a crystalline powder of a strontium-chromium-oxygen (SrCr2O4) compound, an antiferromagnetic material made at the Institute for Quantum Matter.
"We are studying materials with strongly correlated electrons, where each electron coordinates its motion with the immediate surroundings beyond a response to the average," Collin Broholm, professor of physics at Johns Hopkins University, explained. "As a social analog, consider a crowd milling around in an airport. If each individual is not affected by the details of how people look and behave but just senses an anonymous crowd, we call this response mean field behavior, which is not so exciting.
"Instead, we are interested in electron spins that form dynamic clusters in response to interactions with other electrons. The social analog could be the spontaneous formation of groups of individuals chatting with each other after a frustrating flight delay is announced. To understand electron correlations we use neutrons, because their magnetic moment makes them exquisitely sensitive to electron spins.
Scientists and engineers at the Spallation Neutron Source at Oak Ridge National Laboratory are working with the U.S. ITER Project Office at ORNL, the Japanese Atomic Energy Agency and the ITER Organization to resolve issues with a critical component of the experimental fusion energy facility ITER. The VULCAN Engineering Diffractometer at SNS is being used to examine superconducting cables for ITER's central solenoid magnet, which induces the electrical current needed to confine and shape the plasma inside the reactor.
Hassina Bilheux, a physicist and a neutron imaging scientist at ORNL, uses beam line CG-1D at the High Flux Isotope Reactor (HFIR) to image automobile engine system components, two-phase fluid components in commercial cooling systems, and electrodes used for lithium batteries.
Michael Cameron of DuPont, former chair of the SNS and HFIR Users Group, has cited applications in the auto industry and in transportation generally as highly promising for such partnerships.
Neutron imaging is just taking off at ORNL; there is currently no instrument at the laboratory devoted exclusively to it. Bilheux, the lead for developing ORNL's neutron imaging capabilities, works on industrial imaging projects with colleagues at ORNL and in industry.