Source: ORNL | Release | January 8, 2019
Nuclear—Deep space travel
By automating the production of neptunium oxide-aluminum pellets, Oak Ridge National Laboratory scientists have eliminated a key bottleneck when producing plutonium-238 used by NASA to fuel deep space exploration. Pu-238 provides a constant heat source through radioactive decay, a process that has powered spacecraft such as Cassini and the Mars Rover. “Automating part of the Pu-238 production process is helping push annual production from 50 grams to 400 grams, moving closer to NASA’s goal of 1.5 kilograms per year by 2025,” said ORNL’s Bob Wham. “The automation replaces a function our team did by hand and is expected to increase the output of pressed pellets from 80 to 275 per week.” Once the pellets are pressed and enclosed in aluminum tubing, they are irradiated at ORNL’s High Flux Isotope Reactor and chemically processed into Pu-238 at the Radiochemical Engineering Development Center. In 2012, NASA reached an agreement with the Department of Energy to restart production of Pu-238, and ORNL was selected to lead the project.
Caption: Oak Ridge National Laboratory scientists have automated part of the process of producing plutonium-238, which is used by NASA to fuel deep space exploration. Resolving this key bottleneck will help boost annual production of the radioisotope towards NASA’s goal of 1.5 kilograms of Pu-238 per year by 2025. Credit: Genevieve Martin and Jenny Woodbery/Oak Ridge National Laboratory, U.S. Dept. of Energy
Scientists at Oak Ridge National Laboratory and Hypres, a digital superconductor company, have tested a novel cryogenic, or low-temperature, memory cell circuit design that may boost memory storage while using less energy in future exascale and quantum computing applications. The team used Josephson junctions made from niobium and aluminum-based materials, fabricated at Hypres, for the single-bit memory design on a chip and demonstrated write, read and reset memory operations occurring on the same circuit. “The test showed the viability of memory processing functions to operate faster and more efficiently,” ORNL’s Yehuda Braiman said. “This could lead to substantially decreased access energies and access times and allow for more circuits to occupy less space.” Building on the initial design, ORNL’s Braiman, Niketh Nair and Neena Imam continue working on multi-valued memory cell circuits and large arrays of memory cells. Their first step was a ternary memory cell circuit design, which was published in Superconductor Science and Technology.
Caption: Oak Ridge National Laboratory and digital superconductor company Hypres designed a layout of four memory cells with different parameters. Their study of cryogenic memory cell circuit designs may boost storage while using less energy in future exascale and quantum computing applications. Credit: Dr. Amir Jafair-Salim/Hypres
Caption: A fabricated single-bit memory design on a chip developed by Oak Ridge National Laboratory and Hypres demonstrated write, read and reset memory operations occurring on the same circuit. Credit: Dr. Amir Jafair-Salim/Hypres
Buildings—On-the-go HVAC check
Technicians can access a free tool developed by Oak Ridge National Laboratory to support the installation and repair of heating, ventilation and air conditioning systems, particularly when using new refrigerants. Researchers at ORNL have launched a mobile app called fProps to quickly check fluid properties such as refrigerant, coolant and air while installing or repairing HVAC equipment in commercial and residential buildings. Users specify inputs for each property and a wizard then guides through the module within the tool. “With fProps, technicians have at their fingertips a way to evaluate air, coolant, refrigerants and capacity calculation functions,” said ORNL’s Bo Shen. “This tool also provides additional support for professionals using new low global warming potential refrigerants in HVAC systems.” The fProps app is a pilot program, and additional modules can be added in the future based on interest.
Caption: ORNL’s fProps is a mobile phone app that allows HVAC technicians to quickly check fluid properties before equipment installation or repair. Credit: Oak Ridge National Laboratory, U.S. Dept. of Energy
Vehicles—Fuel cell power up
Oak Ridge National Laboratory scientists studying fuel cells as a potential alternative to internal combustion engines used sophisticated electron microscopy to investigate the benefits of replacing high-cost platinum with a lower cost, carbon-nitrogen-manganese-based catalyst. “We used electron microscopy to demonstrate that atomically dispersed manganese can act as an oxygen reduction reaction catalyst while also increasing durability,” said ORNL’s David Cullen. Fuel cell technologies hold promise for use in vehicles because of their high-power density, low operating temperature and carbon-free emissions. Yet, the high cost associated with platinum-based catalysts and insufficient durability of alternative platinum-free catalysts remains a market barrier. “Our team’s finding could open up the potential for widespread use in transportation and other energy conversion applications,” said Cullen. ORNL researchers were part of a team that produced the results published in Nature Catalysis.
Caption: ORNL researchers used high-resolution electron microscopy to show that nitrogen-doped carbon with atomically dispersed manganese can enhance the performance and durability of low-cost platinum-free polymer electrolyte fuel cells, an important step towards use of such fuel cells in transportation applications. Credit: Oak Ridge National Laboratory, U.S. Dept. of Energy
Neutrons—Quest for QSLs
Researchers used neutron scattering at Oak Ridge National Laboratory’s Spallation Neutron Source to investigate bizarre magnetic behavior, believed to be a possible quantum spin liquid rarely found in a three-dimensional material. QSLs are exotic states of matter where magnetism continues to fluctuate at low temperatures instead of “freezing” into aligned north and south poles as with traditional magnets. “If you could shrink down to see what individual electrons are doing, it would seem as though nothing special was going on,” said Kemp Plumb of Brown University. “But, when you zoom out, a beautiful collective pattern emerges signifying a new phase of matter that hasn’t been seen before.” Observations of the material’s quantum behavior are consistent with the theoretical models. This indicates the material has the right ingredients for fractionalized magnetic excitations that could be harnessed for future quantum information technologies. The research was published in Nature Physics.
Caption: Neutrons reveal a striking pattern of connected “bow ties” that is characteristic of the emergent electron motion in the quantum spin liquid state, observed in a three-dimensional material belonging to a class of minerals used in a wide range of technological applications. Credit: Kemp Plumb/Brown University and Genevieve Martin/Oak Ridge National Laboratory, U.S. Dept. of Energy