By Neal Singer
A carbon nanotube of micrometer dimensions offers the same conceptual challenge as does a jumbo shrimp: How can something so small become large, yet remain in its category?
A relatively huge, lightweight carbon tube with good strength and electrical properties is desirable, all right, because it can be manipulated in the far more accessible micrometer regime.
But is it still a nanotube?
Jianyu Huang (1132) at the Sandia/Los Alamos Center for Integrated Nanotechnologies (CINT), and colleagues elsewhere, got around this problem by naming their new creation “colossal carbon tubes” in a paper published in an October issue of Physical Review Letters.
“The structures are remarkable because they are very light, possess good electrical conductivity, and have mechanical properties similar to carbon fibers,” Jianyu says.
Among possible uses are so-called textile electronics and body armor.
Because of their strange, surprising sponginess — walls of graphite-like carbon kept apart by hollow, rectangular compartments — the colossal fibrous tubes have a density of 0.1 gram, compared with 2 grams for the comparable amount of carbon fibers.
The colossal tubes are about the same length as carbon fibers — in the centimeter range. And they appear to be slightly stronger — a very desirable, and until now unheard of, property in large carbon tubes.
MIT carbon technology specialist Mildred Dresselhaus was quoted in an online news column of the journal Nature: “This is a new form of carbon that was unexpected to me.”
Jianyu, who did the microstructure analysis that confirmed that the walls of such tubes consist of graphitic structure, describes the new creation as “a porous, giant, carbon fiber-like tubular structure” of diameters ranging from 40 to 100 micrometers. Conventional carbon nanotubes are about 10 nanometers in diameter.
The material was made at Los Alamos National Laboratory. Researchers there led by Yuntian Zhu and Huisheng Peng found that heating ethylene and paraffin oil produced a carbon vapor that condensed into tubes of pure carbon tens of micrometers wide and up to several centimeters long. -- Neal Singer
A smaller scale, exportable, lifelong proliferation-resistant “right-sized reactor” may be coming soon to a town or military base near you thanks to the efforts of a Sandia research team led by Tom Sanders (6063).
Tom has been collaborating with numerous Sandians on advancing the small reactor concept to an integrated design that incorporates intrinsic safeguards, security, and safety. This opens the way for possible exportation of the reactor to developing countries that do not have the infrastructure to support large power sources. The smaller reactor design decreases the potential of the countries to develop an advanced nuclear regulatory framework.
Incorporated into the design, says team member Gary Rochau (6771), is what is referred to as “nuke-star,” an integrated monitoring system that provides the exporters of such technologies a means of assuring the safe, secure, and legitimate use of nuclear technology.
“This small reactor would produce somewhere in the range of 100 to 300 megawatts of thermal power and could supply energy to remote areas and developing countries at lower costs and with a manufacturing turnaround period of two years as opposed to seven for its larger relatives,” Tom says. “It could also be a more practical means to implement nuclear base load capacity comparable to natural gas-fired generating stations and with more manageable financial demands than a conventional power plant.”
About the size of half of Bldg. 823, where much of Sandia’s energy and water research is conducted, a right-sized reactor facility will be considerably smaller than conventional nuclear power plants in the US that typically have a footprint as large as the Labs’ Tech Area 1 and produce 3,000 megawatts of power.
With approximately 85 percent of the design efforts completed for the reactor core, Tom and his team are seeking an industry partner through a cooperative research and development agreement (CRADA). The CRADA team will be able to complete the reactor design and enhance the plant side, which is responsible for turning the steam into electricity.
Team member Steve Wright (6771) is doing research using Laboratory Directed Research and Development (LDRD) program funding that is expected to allow the reactor system to operate at efficiencies greater than any current designs, ultimately giving the reactor the greatest return on investment.
“In the past, concerns over nuclear proliferation and waste stymied and eventually brought to a halt nuclear energy R&D in the United States and caused constraints on US supply industries that eventually forced them offshore,” Tom says. “Today the prospects of nuclear proliferation, terrorism, global warming, and environmental degradation have resulted in growing recognition that a US-led nuclear power enterprise can prevent proliferation while providing a green source of energy to a developing country.”
Tom says developing countries around the world have notified the International Atomic Energy Agency (IAEA) of their intent to enter the nuclear playing field. This technology will provide a large, ready market for properly scaled, affordable power systems. The right-sized nuclear power system is poised to have the right combination of features to meet export requirements, cost considerations, and waste concerns.
The reactor system is built around a small uranium core, submerged in a tank of liquid sodium. The liquid sodium from the tank is piped through the core to carry the heat away to a heat exchanger also submerged in the tank of sodium. In the Sandia system, the reactor heat is transferred to a very efficient supercritical CO2 turbine to produce electricity.
These smaller reactors would be factory built and mass-assembled, with the potential of producing 50 a year. They would all have the exact same design, allowing for quick licensing and deployment. Mass production will keep the costs down, possibly to as low as $250 million per unit. Just as Henry Ford revolutionized the automobile industry with mass production of automobiles via an assembly line, the team’s concept would revolutionize the current nuclear industry, Tom says.
Because the right-sized reactors are breeder reactors — meaning they generate their own fuel as they operate — they are designed to have an extended operational life and only need to be refueled once every couple of decades, which helps alleviate proliferation concerns. The reactor core is replaced as a unit and “in effect is a cartridge core for which any intrusion attempt is easily monitored and detected,” Tom says. The reactor system has no need for fuel handling. Conventional nuclear power plants in the US have their reactors refueled once every 18 months.
Tom says much of the reactor technology needed for the smaller fission machines has been demonstrated through 50 years of operating experimental breeder reactors in Idaho. In addition, he says, Sandia is one of a handful of research facilities that has the capability to put together a project of this magnitude. The project would tap into the Labs’ expertise in complex systems engineering involving high performance computing systems for advanced modeling and simulations, advanced manufacturing and robotics, and sensors, as well as its experience in moving from research to development to deployment.
“Sandia operates one of three nuclear reactors and the only fuel-critical test facility remaining in the DOE complex,” Tom says. “It is the nation’s lead laboratory for the development of all radiation-hardened semiconductor components as well as the lead lab for testing these components in extreme radiation environments.”
The goal of the right-sized reactors is for them to produce electricity at less than five cents per kilowatt hour, making them economically comparable to gas turbine systems.
Tom says the smaller reactors will probably be built initially to provide power to military bases, both in the US and outside the country. — Chris Burroughs
By Mike Janes
Sandia is seeking commercial partners to license or contribute to the continued development of a new lab-on-a-chip platform for high-throughput manipulation and interrogation of individual cells, one that enables quantitative analysis of cellular behaviors with unprecedented speed, resolution, sensitivity, and multiplexing.
The Microscale Immune and Cell Analysis (MICA) platform is a tool designed to facilitate study of a wide variety of cellular processes. It has consistently demonstrated its value in initial applications at Sandia, which have focused on elucidation of immune cell responses to potentially deadly microbial pathogens.
MICA integrates cell culture and handling, cell stimulation (e.g., introduction of a pathogenic challenge), fluorescence-activated cell sorting (FACS), flow cytometry, high-resolution imaging, and antibody-based proteomic analysis. All experimental manipulations are carried out at the microscale and are fully automated, providing precise control over each cell and its environment. The closed-system format lends itself well to applications in which containment is desirable (e.g., work with dangerous pathogens).
Moreover, because microscale experiments consume vanishingly small amounts of cells and reagents, MICA can be used to investigate cellular processes that have proven impossible or impractical to study at conventional scale.
MICA, its developer say, offers a broad array of benefits over alternative approaches:
“The promise of MICA is immense,” says Glenn Kubiak (8600). Many of the lab tools used today to study cellular behavior, he says, fall short in speed, throughput, ease, and selectivity.
Full development of MICA, Glenn says, should enable advances in a number of fields of interest:
The fully developed MICA platform, Glenn predicts, will provide unparalleled access to realms of biological research that are only now beginning to be explored, particularly with respect to systems-level analysis of the behavior of individual cells.
Sandia’s business development team is currently soliciting commercial partners. Additional information on MICA, including fact sheets, technical papers, and information on partnering with Sandia, can be found at www.ca.sandia.gov/mica/. — Mike Janes