Engineering topics
Roberts, Tom
Publications and source records attributed to Roberts, Tom.
Mu*STAR ADSR Fuel Conversion Facility Evaluation and Cost Analysis
The purpose of the reported effort is the development of a conceptual process for conversion of used nuclear fuel (UNF) from light water reactors (LWRs) to a fluoride salt form to facilitate its use for power generation in a Mu*STAR Accelerator-driven Subcritical Reactor (ADSR). This document evaluates potential processes for converting UNF into a fluoride salt, evaluates the costs/benefits of using enriched lithium in the carrier salt, and analyzes comparable costs of similar facilities to make a rough order of magnitude estimate for the cost to design, construct, and commission a Mu*STAR ADSR fuel conversion facility. This document also makes a high-level comparison of the Mu*STAR ADSR fuel cycle with other important fuel cycles. The results of the cost analysis show that the Mu*STAR ADSR fuel conversion facility will cost more than $100M, possibly up to around $1B, to design and construct. The cost will depend on the size of the hot cell required, which will depend on the processing options chosen for converting the UNF to a molten salt. Operations and maintenance of the facility will be on the order of $10M per year. The design, fabrication, and installation of the remote process equipment to support the fuel conversion will be an additional cost of more than $50M. Cost surveys of Department of Energy hot cell designs and previous Department of Energy hot cell construction suggest that the cost variance may be large, and the risk of escalating costs may be high in the regulation-mandated atmosphere of nuclear facility design and construction. The molten salt for the Mu*STAR ADSR contains all of the nonvolatile isotopes in the UNF, and there is never a separation of the plutonium from the fission products. This makes this conversion process much more proliferation resistant than the reprocessing options used for other closed fuel cycles. When normalized to the amount of electricity produced, the Mu*STAR ADSR fuel cycle’s expected cost might be less than any reprocessing fuel cycle and possibly less than the once-through cycle now used. Simulations show that once the conversion to fluoride is made, that up to seven times as much energy can be extracted from the UNF than was produced by the LWR while making it [Bowman, 2010]. Using once-only, on-site conversion to fluoride means no mining, no enrichment, no manufacturing of fuel rods, and no transportation costs. Typically, the UNF was produced over a 40-year period in an LWR; it can potentially be used for 280 years in Mu*STAR, producing the same power as the LWR did, ultimately requiring disposal of approximately the same volume of material as the LWR generated. Mu*STAR burns most of the higher actinides, which could reduce both the cost of disposal and significantly reduce the longevity of its radiotoxicity. Mu*STAR ADSR’s ability to demonstrate unique and valuable peripheral benefits are additional arguments for this technology, including (1) turning UNF into a valuable commodity (thus, its disposal will not be such an immediate problem, so continued operation of existing LWRs will be more acceptable); (2) burning fissile or fertile fuel including excess weapons-grade plutonium in subcritical mode; and (3) providing high-temperature process heat to convert natural gas to synthetic diesel fuel, water to hydrogen, or for other process-heat applications.
Two-Dimensional Planetary Surface Landers
We proposed to develop a new landing approach that significantly reduces development time and obviates the most complicated, most expensive, and highest-risk phase of a landing mission. The concept is a blanket- or carpet-like two-dimensional (2D) lander (~1-m × 1-m surface area and <1-cm thick) with a low mass/drag ratio, which allows the lander to efficiently shed its approach velocity and provide a more robust structure for landing integrity. The form factor of these landers allows dozens to be stacked on a single spacecraft for transport and distributed en masse to the surface. Lander surfaces will be populated on both sides by surface-mount, low-profile sensors and instruments, surface-mount telecom, solar cells, batteries, processors, and memory. Landers will also incorporate thin flexible electronics, made possible in part by printable electronics technology. The mass and size of these highly capable technologies further reduces the required stiffness and mass of the lander structures to the point that compliant, lightweight, robust landers capable of passive landings are possible. This capability avoids the costly, complex use of rockets, radar, and associated structure and control systems. This approach is expected to provide an unprecedented science payload mass to spacecraft mass ratio of approximately 80% (estimated based on current knowledge). This compared to ~1% for Pathfinder, ~17% for MER, and 22% for MSL rovers. Clearly, one difference is rovers vs. a lower capability lander. An outcome of the Phase I study is a clear roadmap for near-term demonstration and long-term technology development.
A Day in the Life of the Laser Communications Relay Demonstration (LCRD) Project.
This presentation provides an overview of the planned concept of operations for the Laser Communications Relay Demonstration Project (LCRD), a joint project among NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MITLL). LCRD will provide at least two years of bi-directional optical communications at user data rates of up to 1.244 Gbps in an operational environment. The project lays the ground work for establishing communications architecture and protocols, and developing the communications hardware and support infrastructure, concluding in a demonstration of optical communications potential to meet NASAs growing need for higher data rates for future science and exploration missions. A pair of flight optical communications terminals will reside on a single commercial communications satellite in geostationary orbit; the two ground optical communications terminals will be located in Southern California and Hawaii. This paper summarizes the current LCRD architecture and key systems for the demonstration, focusing on what it will take to operate an optical communications relay that can support space-to-space, space-to-air, and space-to-ground optical links.
A Day in the Life of the Laser Communications Relay Demonstration Project
This paper provides an overview of the planned concept of operations for the Laser Communications Relay Demonstration Project (LCRD), a joint project among NASA's Goddard Space Flight Center (GSFC), the Jet Propulsion Laboratory, California Institute of Technology (JPL), and the Massachusetts Institute of Technology Lincoln Laboratory (MIT/LL). LCRD will provide at least two years of bi-directional optical communications at user data rates of up to 1.244 Gbps in an operational environment. The project lays the groundwork for establishing communications architecture and protocols, and developing the communications hardware and support infrastructure, concluding in a demonstration of optical communications' potential to meet NASA's growing need for higher data rates for future science and exploration missions. A pair of flight optical communications terminals will reside on a single commercial communications satellite in geostationary orbit; the two ground optical communications terminals will be located in Southern California and Hawaii. This paper summarizes the current LCRD architecture and key systems for the demonstration, focusing on what it will take to operate an optical communications relay that can support space-to-space, space-to-air, and space-to-ground optical links.
Advances in LADAR Components and Subsystems at Raytheon
Raytheon is developing NIR sensor chip assemblies (SCAs) for scanning and staring 3D LADAR systems. High sensitivity is obtained by integrating high performance detectors with gain, i.e., APDs with very low noise Readout Integrated Circuits (ROICs). Unique aspects of these designs include: independent acquisition (non-gated) of pulse returns, multiple pulse returns with both time and intensity reported to enable full 3D reconstruction of the image. Recent breakthrough in device design has resulted in HgCdTe APDs operating at 300K with essentially no excess noise to gains in excess of 100, low NEP <1nW and GHz bandwidths and have demonstrated linear mode photon counting. SCAs utilizing these high performance APDs have been integrated and demonstrated excellent spatial and range resolution enabling detailed 3D imagery both at short range and long ranges. In the following we will review progress in real-time 3D LADAR imaging receiver products in three areas: (1) scanning 256 x 4 configuration for the Multi-Mode Sensor Seeker (MMSS) program and (2) staring 256 x 256 configuration for the Autonomous Landing and Hazard Avoidance Technology (ALHAT) lunar landing mission and (3) Photon-Counting SCAs which have demonstrated a dramatic reduction in dark count rate due to improved design, operation and processing.
The Mars laser communication demonstration
This paper provides the status of the Mars Laser Communication Demonstration Project, a joint project between NASA's Goddard Space Flight Center (GSFC), the California Institute of Technology Jet Propulsion Laboratory (JPL), and the Massachusetts Institute of Tecnology Lincoln Laboratory (MIT/LL). It reviews the current ideas/designs for the flight and ground segments, the critical technologies required, adn the concept of operations. The laser communication (lasercom) flight terminal will be flown on the Mars Telecom Orbiter (MTO) to be launched by NASA in 2009, and will demonstrate a technology which has the potential of vastly improving NASA's ability to communicate throughout the solar system.