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NREL researcher Andrey Bernstein discusses asynchronous and distributed tracking of time-varying fixed points as part of the Innovative Optimization and Control Methods for Highly Distributed Autonomous Systems workshop. NREL hosted the workshop to exchange ideas on state-of-the-art control and optimization strategies as well as get feedback on work being done at NREL.
During wound healing, fibroblasts deposit extracellular matrix that guides angiogenesis and supports the migration and proliferation of cells that eventually form the scar. They also promote wound closure via differentiation into α-smooth muscle actin (SMA)-expressing myofibroblasts, which cause wound contraction. Low oxygen tension typical of chronic nonhealing wounds inhibits fibroblast collagen production and differentiation. It has been suggested that hypoxic mesenchymal stromal cells (MSCs) secrete factors that promote wound healing in animal models; however, it is unclear whether these factors are equally effective on the target cells in a hypoxic wound environment. Here we investigated the impact of MSC-derived soluble factors on the function of fibroblasts cultured in hypoxic fibroblast-populated collagen lattices (FPCLs). Hypoxia alone significantly decreased FPCL contraction and α-SMA expression. MSC-conditioned medium restored hypoxic FPCL contraction and α-SMA expression to levels similar to normoxic FPCLs. (SB431542), an inhibitor of transforming growth factor-β{sub 1} (TGF-β{sub 1})-mediated signaling, blocked most of the MSC effect on FPCL contraction, while exogenous TGF-β{sub 1} at levels similar to that secreted by MSCs reproduced the MSC effect. These results suggest that TGF-β{sub 1} is a major paracrine signal secreted by MSCs that can restore fibroblast functions relevant to the wound healing process and that are impaired in hypoxia. - Highlights: • Fibroblasts were cultured in collagen lattices (FPCLs) as model contracting wounds. • Hypoxia decreased FPCL contraction and fibroblast α-smooth muscle actin expression. • Mesenchymal stromal cells (MSCs) restored function of hypoxic fibroblasts. • MSCs regulate fibroblast function mainly via secreted transforming growth factor-β{sub 1}.
We study the detailed structure of galaxies at redshifts z {>=} 2 using cosmological simulations with improved modeling of the interstellar medium and star formation. The simulations follow the formation and dissociation of molecular hydrogen and include star formation only in cold molecular gas. The molecular gas is more concentrated toward the center of galaxies than the atomic gas, and as a consequence, the resulting stellar distribution is very compact. For halos with total mass above 10{sup 11} M{sub Sun }, the median half-mass radius of the stellar disks is 0.8 kpc at z Almost-Equal-To 3. The vertical structure of the molecular disk is much thinner than that of the atomic neutral gas. Relative to the non-radiative run, the inner regions of the dark matter halo change shape from prolate to mildly oblate and align with the stellar disk. However, we do not find evidence for a significant fast-rotating 'dark disk' of dark matter around the stellar disk. The outer halo regions retain the orientation acquired during accretion and mergers and are significantly misaligned with the inner regions. The radial profile of the dark matter halo contracts in response to baryon dissipation, establishing an approximately isothermal profile throughout most of the halo. This effect can be accurately described by a modified model of halo contraction. The angular momentum of a fixed amount of inner dark matter is approximately conserved over time, while in the dissipationless case most of it is transferred outward during mergers. The conservation of the dark matter angular momentum provides supporting evidence for the validity of the halo contraction model in a hierarchical galaxy formation process.
The contractile properties of fast-twitch and slow-twitch skeletal muscles are primarily determined by the myosin isoform content and modulated by a variety of sarcomere proteins. X-ray diffraction studies of regulatory mechanisms in muscle contraction have focused predominately on fast- or mixed-fibre muscle with slow muscle being much less studied. Here, we used time-resolved X-ray diffraction to investigate the dynamic behaviour of the myofilament proteins in relatively pure slow-twitch-fibre rat soleus (SOL) and pure fast-twitch-fibre rat extensor digitorum longus (EDL) muscle during twitch and tetanic contractions at optimal length. During twitch contractions the diffraction signatures indicating a transition in the myosin heads from ordered OFF states, where heads are held close to the thick filament backbone, to disordered ON states, where heads are free to bind to thin filaments, were found in EDL and not in SOL muscle. During tetanic contraction, changes in the disposition of myosin heads as active tension develops is a quasi-stepwise process in EDL muscle whereas in SOL muscle this relationship appears to be linear. The observed reduced extensibility of the thick filaments in SOL muscle as compared to EDL muscles indicates a molecular basis for this behaviour. These data indicate that for the EDL, thick filament activation is a cooperative strain-induced mechano-sensing mechanism, whereas for the SOL, thick filament activation has a more graded response. Further, these different approaches to thick filament regulation in fast- and slow-twitch muscles may be adaptations for short-duration, strong contractions versus sustained, finely controlled contractions, respectively.
The Petroleum Technology Transfer Council (PTTC) is a unique not-for-profit network that focuses on transferring Exploration and Production (E&P) technology to the domestic oil and natural gas producing industry. PTTC connects producers, technology providers and innovators, academia, research and development (R&D) consortiums and governments. Local affordable workshops delivered by Regional Lead Organizations (RLOs), which are typically a university or geological survey, are a primary tool. PTTC also maintains a website network, issues a national newsletter, provides a column in a major trade publication, and exhibits at major industry events. It also encourages industry to ask technology-related questions, striving to find relevant answers that will save questioners significant time. Working since late 1993, the PTTC network has a proven track record of providing industry with technology insights they can apply. Volunteers at the regional and national level provide key guidance regarding where to focus technical effort and help connect PTTC with industry. At historical funding levels, PTTC had been able to hold well more than 100 workshops per year, drawing 6,000+ attendees. As funding decreased in the early 2000s, the level of activity decreased and PTTC sought a merger with the American Association of Petroleum Geologists (AAPG), becoming an AAPG-managed organization at the start of FY08. This relationship with AAPG was terminated by mutual consent in May 2011 and PTTC once again operates independently. Chris Hall, California continued to serve as Chairman of the Board of Directors until December 2013. At the time PTTC reorganized into a RLO led organization with Mary Carr and Jeremy Viscomi as co-Executive Directors. Jerry Anderson became the Chairman of the PTTC Board of Directors and Chris Hall continues to serve on the Board. Workshop activity stabilized at 55-65 workshops per year averaging 3,100 attendees. FY14 represented the fifth year in a multi-year contract with the Department of Energy (DOE) for providing technology transfer services. This report summarizes activity and results during for five years, FY10 through FY14. In FY12 changes occurred in responsibilities of consultants serving HQ, because funding was reduced below the threshold level of $500,000 audits were no longer required and consultant time was reduced on the primary contract. Contracts for Permian Carbon Capture Utilization and Storage (CCUS) training, and providing tech transfer services to the Research Partnership to Secure Energy for America (RPSEA) provided work that enabled HQ to retain services of regular consultants. Both CCUS and RPSEA were five year contracts with PTTC, and providing services for these DOE funded contracts provided synergy for PTTC and the oil and gas industry. With further decreases in DOE funding the regions conducted workshops with no PTTC funding starting in June FY11. Since 2011 the number of workshops has declined from 79 in FY10 and FY11 to 49 in FY12, and risen to 54 in FY13 and 63 in FY14. The attendee's numbers dipped slightly below 3,000 per year in FY 10, FY12, and FY13, but rose to over 3,800 in FY 11 and 3105 in FY14. Quantitative accomplishments: PTTC has maintained its unique structure of a national organization working through Regional Lead Organizations (RLOs) to deliver local, affordable workshops. During the contract period PTTC consolidated from 10 to five regions to increase efficiency, and because no active RLO's would be maintained in the Central and Eastern Gulf Coast regions. RLO's for the regions are located at: Eastern - West Virginia University, (Illinois Geol. Survey., W. Michigan Univ. FY10-12); Midwest created in FY13 - Illinois Geological Survey, W. Michigan University; Midcontinent - University of Kansas, expanded to Houston, TX (2013-14); Rocky Mountain - Colorado School of Mines; Texas/SE New Mexico (FY10-FY11) - Bureau of Economic Geology, Univ. of Texas at Austin; West Coast - Conservation Committee of California O&G Producers.
There is a need for an inspection frequency that demonstrates reasonable assurance that the confinement function of dual-purpose-canisters (DPCs) is maintained as these DPCs are returned to storage service following transportation. The DPCs contain spent fuel from shutdown reactor sites. The currently-proposed 100% DPC inspection frequency is overly conservative and unnecessary to demonstrate reasonable assurance that the confinement function of all DPCs is maintained for return to storage service. Testing all DPCs does not appropriately reflect the very low risk of leakage (i.e., low probability based on design and low consequences based on analysis). Currently, there are 1066 DPCs forecast to be loaded at reactor sites which either are shutdown or plan to cease operations by 2025. These DPCs may be transported by rail in sets of 3 to 5 DPCs per shipment. Assuming each rail consist originates at a single reactor site, an alternative proposal to test one canister/consist/site would result in 356 to 214 canisters, respectively, being tested given the population of 1,066 canisters This Savannah River National Laboratory (SRNL) report outlines statistically-based, random sampling plans that provide guidance on the number of samples of these canisters that are needed to establish bounds on the quality of the outcome of such sampling. The quality of each proposed sampling plan is expressed in the form of a statement that the number of undetected, unacceptable canisters in the population is less than some number, call it D, at a high level of confidence. In addition, evaluations using a similar approach for random sampling at the proposed levels of 214 and 356 canisters are provided. This is a technical report that does not take into account the contractual limitations under the Standard Contract for Disposal of Spent Nuclear Fuel and/or High-Level Radioactive Waste (Standard Contract) (10 CFR Part 961). Under the provisions of the Standard Contract, DOE does not consider spent nuclear fuel in multi-assembly canisters to be an acceptable waste form, absent a mutually agreed upon contract amendment. To the extent discussions or recommendations in this report conflict with the provisions of the Standard Contract, the Standard Contract provisions prevail.
During the years of 2018 through 2023, The Washington State University Energy Program (WSU EP) operated the Northwest Combined Heat and Power Technical Assistance Partnership under contract to the US Department of Energy’s Advanced Manufacturing Office (AMO), a part of DOE’s larger Office of Energy Efficiency and Renewable Energy. This contract provided direction and funding for providing technical outreach, information and technical/economic analysis services in support of expanding development of Combined Heat and Power (CHP) over a four state region in the Pacific Northwest. The states served included Alaska, Idaho, Oregon and Washington. During the duration of this contract, the WSU EP delivered performed specific assigned tasks and provided services of various generally prescribed types, with the overall goal of increasing adoption of CHP as an efficient heat and power supply in the region. Indications – though not formally evaluated to our knowledge – are that this goal was achieved. Over many years, the WSU team has provided support for CHP developments in these states under similar previous Department of Energy contracts, and many such projects have been built. While the early-phase outreach, education and techno-economic assessments that the NW CHP TAP provides rarely immediately result in project construction, there is no doubt that the WSU EP team has had substantial influence in the construction of a number of important CHP projects in the region. Examples of projects implemented directly under the current team’s guidance and services during this contract cycle include an 875 kilowatt biomass fueled CHP system installed at the University of Idaho, and 5 megawatt natural gas fueled CHP system at the University of Montana ( UM Breaks Ground on New Power Facility, Slashes Emissions 30% (umt.edu) ). Many other CHP systems recently installed are also either directly or at least partially the result of information and technical services provided by the team. Finally, though much more difficult to quantify and less glamorous, the team has helped countless organizations to understand CHP and determine whether and how CHP may be a fit for them, before they consider paying for engineering services. Whether the ultimate outcome has been to include CHP or not, the expert skills provided by the NW CHP TAP team have provided real value to these organizations considering this relatively complex technology. Over the duration of the contract our team provided 71 Initial Technical Assessments and 17 Advanced Technical Assessments; 53 End-User Engagements and 33 Stakeholder Engagements of various types; 42 Technical Profiles (Project Profiles, Program Profiles and Policy Profiles), and produced 14 technical articles for the Department of Energy. Unfortunately, these quantities provide no measure of the value that the team has provided. Only our clients can judge that, and we are confident that they are pleased with the benefits we have offered them.
The contract baseline, contract requirements review, contract modifications, contract problem areas and conclusions are addressed. Contract baseline was established 11 June 1987 and updated 1 December 1989. Significant changes were introduced into the 1989 baseline as compared to the original baseline. Contract modifications were made to add requirements as the program matured and as definition of requirements were completed. Problems were solved in real time through the contractor/customer team involvement and relationship to assure a timely and successful mission. The conclusion is that the CGF performed as designed and the experiments performed during the USML-1 Mission supports the conclusion.
This Final Report summarizes the activities performed by Science Applications International Corporation (SAIC) under contract NAS 8-40431 "Cost and Schedule Analytical Techniques Development Contract" (CSATD) during Option Year 3 (December 1, 1997 through November 30, 1998). This Final Report is in compliance with Paragraph 5 of Section F of the contract. This CSATD contract provides technical products and deliverables in the form of parametric models, databases, methodologies, studies, and analyses to the NASA Marshall Space Flight Center's (MSFC) Engineering Cost Office (PP03) and the Program Plans and Requirements Office (PP02) and other user organizations. Detailed Monthly Reports were submitted to MSFC in accordance with the contract's Statement of Work, Section IV "Reporting and Documentation". These reports spelled out each month's specific work performed, deliverables submitted, major meetings conducted, and other pertinent information. Therefore, this Final Report will summarize these activities at a higher level. During this contract Option Year, SAIC expended 25,745 hours in the performance of tasks called out in the Statement of Work. This represents approximately 14 full-time EPs. Included are the Huntsville-based team, plus SAIC specialists in San Diego, Ames Research Center, Tampa, and Colorado Springs performing specific tasks for which they are uniquely qualified.
During parturition, rats exhibit characteristic behavioral expressions of labor. Lordosis contractions, consisting of an elongation of the dams body, are observed beginning several hours prior to neonate births, whereas vertical contractions, repeated rapid lifts of the abdomen, occur immediately preceding the birth of each neonate. We analyzed underlying changes in intrauterine pressure (IUP) using a telemetric sensor that we modified for use in freely-moving rats. This technique enabled us to correlate behavioral expressions of labor contractions with IUP. A small telemetric blood pressure sensor was fitted within a fluid-filled balloon, similar in size to a full term rat fetus. On Gestational day 19 of the rats' 22-day pregnancy, a unit was surgically implanted within the uterus. The dams were simultaneously videotaped, enabling us to directly correlate IUP signals with behavioral expressions of labor contractions. Earlier phases of labor, consisting predominantly of lordosis contractions were characterized by lower pressures relative to later phases during which higher pressures and vertical contractions were frequently observed.
There are only a few reports of the influence of imposed flow on an active lymph pump under conditions of controlled intraluminal pressure. Thus, the mechanisms are not clearly defined. Rat mesenteric lymphatics and thoracic ducts were isolated, cannulated and pressurized. Input and output pressures were adjusted to impose various flows. Lymphatic systolic and diastolic diameters were measured and used to determine contraction frequency and pump flow indices. Imposed flow inhibited the active lymph pump in both mesenteric lymphatics and in the thoracic duct. The active pump of the thoracic duct appeared more sensitive to flow than did the active pump of the mesenteric lymphatics. Imposed flow reduced the frequency and amplitude of the contractions and accordingly the active pump flow. Flow-induced inhibition of the active lymph pump followed two temporal patterns. The first pattern was a rapidly developing inhibition of contraction frequency. Upon imposition of flow, the contraction frequency immediately fell and then partially recovered over time during continued flow. This effect was dependent on the magnitude of imposed flow, but did not depend on the direction of flow. The effect also depended upon the rate of change in the direction of flow. The second pattern was a slowly developing reduction of the amplitude of the lymphatic contractions, which increased over time during continued flow. The inhibition of contraction amplitude was dependent on the direction of the imposed flow, but independent of the magnitude of flow. Nitric oxide was partly but not completely responsible for the influence of flow on the mesenteric lymph pump. Exposure to NO mimicked the effects of flow, and inhibition of the NO synthase by N (G)-monomethyl-L-arginine attenuated but did not completely abolish the effects of flow.
The Kennedy Space Center Level III SBIR/STTR management staff is under the Technology Transfer Office within the Spaceport Engineering and Technology Directorate. The SBIR and STTR programs provide an opportunity for small high technology companies and research institutions to participate in Government-sponsored research and development (R&D) programs in key technology areas. The SBIR program was established by Congress in 1982 to provide increased opportunities for small businesses to participate in R&D programs, increase employment, and improve U.S. competitiveness. The program's specific objectives are to stimulate U.S. technological innovation, use small businesses to meet Federal research and development needs, increase private sector commercialization of innovations, and foster and encourage participation by socially disadvantaged businesses. Legislation enacted in December 2000 reauthorized the program and strengthened emphasis on pursuing commercial applications of SBIR projects. An SBIR Phase I contract is the opportunity to establish the feasibility and technical merit of a proposed innovation. Selected competitively, the Phase I contract lasts for 6 months and is funded up to $70,000. SBIR Phase II contracts continue the most promising Phase I projects based on scientific! technical merit, expected value to NASA, company capability, and commercial potential. Phase II contracts are usually for a period of 24 months and may not exceed $600,000. NASA usually selects approximately 40 percent of Phase I projects to continue to the Phase II level. Phase III is the process of furthering the development of a product to make it commercially available. The STTR program awards contracts to small business concerns for cooperative R&D with a nonprofit research institution. Research institutions include nonprofit research organizations, Federal laboratories, or universities. The goal of the program established by Congress is to facilitate the transfer of technology developed by a research institution through the entrepreneurship of a small business. The STIR program is smaller in funding than the SBIR program. While the proposal is submitted by the small business concern, at least 30 percent of the funding and work must originate with the research institution. STTR Phase I projects receive up to $100K for a one-year effort, and a Phase II contract receives up to $600K for two years.
A high-efficiency radioisotope power system was being developed for long-duration NASA space science missions. The U.S. Department of Energy (DOE) managed a flight contract with Lockheed Martin Space Systems Company to build Advanced Stirling Radioisotope Generators (ASRGs), with support from NASA Glenn Research Center. DOE initiated termination of that contract in late 2013, primarily due to budget constraints. Sunpower, Inc., held two parallel contracts to produce Advanced Stirling Convertors (ASCs), one with Lockheed Martin to produce ASC-F flight units, and one with Glenn for the production of ASC-E3 engineering unit "pathfinders" that are built to the flight design. In support of those contracts, Glenn provided testing, materials expertise, Government-furnished equipment, inspection capabilities, and related data products to Lockheed Martin and Sunpower. The technical support included material evaluations, component tests, convertor characterization, and technology transfer. Material evaluations and component tests were performed on various ASC components in order to assess potential life-limiting mechanisms and provide data for reliability models. Convertor level tests were conducted to characterize performance under operating conditions that are representative of various mission conditions. Despite termination of the ASRG flight development contract, NASA continues to recognize the importance of high-efficiency ASC power conversion for Radioisotope Power Systems (RPS) and continues investment in the technology, including the continuation of the ASC-E3 contract. This paper describes key Government support for the ASRG project and future tests to be used to provide data for ongoing reliability assessments.
Historically, most successful NASA projects have depended on effectively blending project management, systems engineering, and technical expertise among NASA, contractors, and third parties. Underlying these successes are a variety of agreements (e.g., contract, memorandum of understanding, grant, cooperative agreement) between NASA organizations or between NASA and other Government agencies, Government organizations, companies, universities, research laboratories, and so on. To simplify the discussions, the term "contract" is used to encompass these agreements. This section focuses on the NASA systems engineering activities pertinent to awarding a contract, managing contract performance, and completing a contract. In particular, NASA systems engineering interfaces to the procurement process are covered, since the NASA engineering technical team plays a key role in the development and evaluation of contract documentation. Contractors and third parties perform activities that supplement (or substitute for) the NASA project technical team accomplishment of the NASA common systems engineering technical process activities and requirements outlined in this guide. Since contractors might be involved in any part of the systems engineering life cycle, the NASA project technical team needs to know how to prepare for, allocate or perform, and implement surveillance of technical activities that are allocated to contractors.
Stirling Radioisotope Power Systems (RPS) are being developed by NASA's RPS Program in collaboration with the U.S. Department of Energy (DOE). Efforts ranging from 2001 to 2015 enabled development of the Technology Demonstration Convertor (TDC) for use in the 110-watt Stirling Radioisotope Generator (SRG-110) and the Advanced Stirling Convertor (ASC) for use in the Advanced Stirling Radioisotope Generator (ASRG). The DOE selected Lockheed Martin Space Systems Company (LMSSC) as the system integration contractor for both flight development efforts. The SRG-110 housed two TDCs fabricated by Infinia and resulted in the production of 16x demonstration units and 2x engineering units. The project was redirected in 2006 to make use of a more efficient and lower mass ASCs under development by Sunpower Inc. The DOE managed the flight contract with LMSSC and subcontractor Sunpower Inc. from 2007 to 2013 to build the ASRG, with support from NASA Glenn Research Center (GRC). Sunpower Inc. held two parallel contracts to produce ASCs, one with Lockheed Martin to produce ASC-F flight units and one with GRC for the production of ASC-E3 engineering unit pathfinders that were used to refine the flight design and production processes. The DOE initiated termination of the ASRG contract in late 2013. After ASRG had ended, GRC completed characterization testing of the ASRG Engineering Unit #2 (EU2) and the GRC contract with Sunpower was also completed. The NASA RPS Program Office has recently initiated a new Dynamic Power Conversion development effort which includes the potential maturation of Stirling, Brayton, and Rankine power convertors for the next generation of RPS. The effort started with the request for proposal and review of submits. Contracts are anticipated for release in 2017 and will initially focus on a design phase prior to fabrication and testing. This new effort will focus on robustness in addition to high efficiency, specific power, and reliability. Also, some requirements introduced during the ASRG contract have also been included in the new effort, such as constant lateral loading. Due to the focus on robustness and new requirements relative to the older TDC design, the Stirling Cycle Development Project has initiated an assessment of government owned hardware to help inform requirements evolution and evaluation of future designs. While lessons learned from the ASRG flight development project have been taken into consideration, the evaluation of the TDC design had not been completed for some existing environments or relatively new requirements. To further assess the TDC design, a series of tasks were initiated to evaluate degradation for units that have operated unattended for over 105,000 hours, demonstrate robustness to a random vibration environment, characterize and evaluate performance for varying lateral load profiles. The status for each task are described.
Stirling Radioisotope Power Systems (RPS) are being developed by NASAs RPS Program in collaboration with the U.S. Department of Energy (DOE). Efforts ranging from 2001 to 2015 enabled development of the Technology Demonstration Convertor (TDC) for use in the 110-watt Stirling Radioisotope Generator (SRG-110) and the Advanced Stirling Convertor (ASC) for use in the Advanced Stirling Radioisotope Generator (ASRG). The DOE selected Lockheed Martin Space Systems Company (LMSSC) as the system integration contractor for both flight development efforts. The SRG-110 housed two TDCs fabricated by Infinia and resulted in the production of 16x demonstration units and 2x engineering units. The project was redirected in 2006 to make use of a more efficient and lower mass ASCs under development by Sunpower Inc. The DOE managed the flight contract with LMSSC and subcontractor Sunpower Inc. from 2007 to 2013 to build the ASRG, with support from NASA Glenn Research Center (GRC). Sunpower Inc. held two parallel contracts to produce ASCs, one with Lockheed Martin to produce ASC-F flight units and one with GRC for the production of ASC-E3 engineering unit pathfinders that were used to refine the flight design and production processes. The DOE initiated termination of the ASRG contract in late 2013. After ASRG had ended, GRC completed characterization testing of the ASRG Engineering Unit 2 (EU2) and the GRC contract with Sunpower was also completed. The NASA RPS Program Office has recently initiated a new Dynamic Power Conversion development effort which includes the potential maturation of Stirling, Brayton, and Rankine power convertors for the next generation of RPS. The effort started with the request for proposal and review of submits. Contracts are anticipated for release in 2017 and will initially focus on a design phase prior to fabrication and testing. This new effort will focus on robustness in addition to high efficiency, specific power, and reliability. Also, some requirements introduced during the ASRG contract have also been included in the new effort, such as constant lateral loading. Due to the focus on robustness and new requirements relative to the older TDC design, the Stirling Cycle Development Project has initiated an assessment of government owned hardware to help inform requirements evolution and evaluation of future designs. While lessons learned from the ASRG flight development project have been taken into consideration, the evaluation of the TDC design had not been completed for some existing environments or relatively new requirements. To further assess the TDC design, a series of tasks were initiated to evaluate degradation for units that have operated unattended for over 105,000 hours, demonstrate robustness to a random vibration environment, characterize and evaluate performance for varying lateral load profiles. The status for each task are described.
The Thermal Energy Conversion Branch at NASA Glenn Research Center (GRC) is supporting the development of high-efficiency power convertors in support of Radioisotope Power System (RPS) development. Significant progress was made towards such a system that utilized Stirling conversion machines during the 2001 to 2015 timeframe. Flight development of the Advanced Stirling Radioisotope Generator (ASRG) was cancelled in 2013 by the Department of Energy (DOE) and NASA Headquarters primarily due to budget constraints, and the Advanced Stirling Convertor (ASC) technology contract was subsequently concluded in 2015. A new chapter of technology development has recently been initiated by the NASA RPS Program. This new effort is considering all dynamic power convertor options, such as Stirling and Brayton cycles. Four convertor development contracts supporting this effort were awarded in 2017. The awarded contracts include two free-piston Stirling, one thermoacoustic Stirling, and one turbo-Brayton designs. The technology development contracts each consist of up to three phases: Design, Fabricate, and Test. As of May 2018, all contracts have completed the Design Phase, and each underwent a design review with an independent review board. Two of the contracts have been awarded the Phase 2 option for fabrication. Convertors manifesting from these development efforts will then undergo independent validation and verification at NASA facilities, which will consist of convertor performance and RPS viability demonstrations. Example tests include launch vibration simulation, performance mapping over the environmental temperature range, and static acceleration exposure. In parallel with this renewed development effort, NASA GRC is still demonstrating free-piston Stirling convertor technology using assets from previous projects. The Stirling Research Laboratory (SRL) is still operating 10 convertors from previous development projects. Four of which are flexure-bearing based, and the other six are gas-bearing based. One of the flexure-bearing convertors has accumulated over 110,000 hours of operation, and holds the current maintenance-free heat-engine run-time record. Another flexure-bearing convertor was recently manually shutdown after 105,620 hours of operation, then disassembled and inspected. This inspection produced a wealth of information about the effects of this amount of runtime on the technology's components. One of the engineering unit flexure-bearing convertors recently underwent launch simulation vibration test, a static acceleration exposure up to 20 g, and was then placed on extended operation. Amongst the gas-bearing convertors, the longest running unit has accumulated over 70,000 hours of operation. Four high-fidelity gas-bearing convertors from the ASRG project are still operating continuously, for which the longest runtime has reached 26,000 hours.
Most of the spent nuclear fuel (SNF) in dry storage in the United States is safely and securely stored in dual-purpose (i.e., storage and transportation) canisters [1]. However, some of the SNF is stored in storage-only (i.e., non-transportable) packages, or packages that may become nonconforming for continued storage or transportation for a variety of reasons. Currently, the capability to remediate dry storage systems (DSSs) for SNF that are not transportable or that need to be repaired to maintain confinement boundary integrity during storage service does not exist without on-site access to a spent fuel pool. Hence, there is a potential future need for a mobile facility with remediation capabilities that can be used at multiple storage installations. These capabilities would permit needed repairs to an existing DSS to support continued storage or for the dry transfer of fuel to a new conveyance suitable for transport, if necessary. This is a technical paper that does not take into account the contractual limitations under the Standard Contract for Disposal of Spent Nuclear Fuel and/or High-Level Radioactive Waste (Standard Contract) (10 CFR Part 961). Under the provisions of the Standard Contract, DOE does not consider spent nuclear fuel in canisters to be an acceptable waste form, absent a mutually agreed to contract amendment. To the extent discussions or recommendations in this paper conflict with the provisions of the Standard Contract, the Standard Contract provisions prevail. A novel design concept for a Mobile Examination and Remediation Facility (MERF) is proposed with functions and capabilities to remediate a DSS. The proposed MERF would be a multi-purpose facility, remotely operated and computer-controlled with semi-automated equipment to allow trained operators to safely perform remediation activities while keeping worker radiation dose as low as reasonably achievable. It would include a shielded rotating platform with support towers and would use commercial off- the-shelf examination and repair equipment. A slip ring arrangement underneath the rotating platform would allow for the power supply without impeding the continuous rotation and would simplify cable management. The support towers would be mounted on the rotating platform, and each tower would have vertical and horizontal positioning capability for axial and radial tool location. The rotating platform would be attached to the main MERF structure. Capabilities would include visual, surface, and volumetric examinations to fully characterize physical conditions on canister surface before and after a repair; repair techniques, e.g., laser beam welding, friction stir welding, or cold spray, to perform needed remediation activities; and associated equipment for surface preparation such as cutting and grinding equipment. The proposed design would be simple, modular, robust, economically viable, and easily transportable and would have a small footprint. The modular design would present several advantages including compatibility with a variety of different DSSs, on-site assembly, and transportability; it also would be built in interchangeable sections to facilitate decontamination. Further, shielding would be supplemented through interface with the existing transfer cask and storage overpack. Robustness and canister stability would be achieved using pneumatic holders and steel support structures designed with vibration absorbers to reduce impacts and/or a 'pendulum' effect during a seismic event. Thus, the proposed MERF would be designed to: (i) minimize handling of an affected DSS to the extent practicable, (ii) provide radiation shielding and minimize dose to operators and the public during remediation activities, and (iii) enable examination, repair, and repackaging. This paper describes the proposed MERF design concept and capabilities, main components, equipment, different modes of operation, and operating procedures. Structural and safety assessments would need to be performed before final design, licensing, and deployment. The MERF is evaluated with respect to regulatory impact (first of a kind, prior experience), operational impact (safety, security, staffing, ongoing operations, constraints), worker dose (low, medium, high), cost (low, medium, high), schedule (duration, time sequence), and technology readiness level. (authors)