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DOE OSTI2018

Merging symmetry projection methods with coupled cluster theory: Lessons from the Lipkin model Hamiltonian

Coupled cluster and symmetry projected Hartree-Fock are two central paradigms in electronic structure theory. However, they are very different. Single reference coupled cluster is highly successful for treating weakly correlated systems, but fails under strong correlation unless one sacrifices good quantum numbers and works with broken-symmetry wave functions, which is unphysical for finite systems. Symmetry projection is effective for the treatment of strong correlation at the mean-field level through multireference non-orthogonal configuration interaction wavefunctions, but unlike coupled cluster, it is neither size extensive nor ideal for treating dynamic correlation. We here examine different scenarios for merging these two dissimilar theories. We carry out this exercise over the integrable Lipkin model Hamiltonian, which despite its simplicity, encompasses non-trivial physics for degenerate systems and can be solved via diagonalization for a very large number of particles. We show how symmetry projection and coupled cluster doubles individually fail in different correlation limits, whereas models that merge these two theories are highly successful over the entire phase diagram. Despite the simplicity of the Lipkin Hamiltonian, the lessons learned in this work will be useful for building an ab initio symmetry projected coupled cluster theory that we expect to be accurate in the weakly and strongly correlated limits, as well as the recoupling regime.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

TRU Corp Board Slides

This report presents LANL news, TRU waste certification, Plans to reduce inventory, and Lessons learned.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

DOE OSTI2018

Final Technical Report

In September 2010, RTI and the DOE/NETL signed a cooperative agreement (DE-FE000489) to design, build, and operate a pre-commercial syngas cleaning system that would capture up to 90% of the CO 2 in the syngas slipstream, and demonstrate the ability to reduce syngas contaminants to meet DOE’s specifications for chemical production application. This pre-commercial syngas cleaning system is operated at Tampa Electric Company’s (TEC) 250-MWe integrated gasification combined cycle (IGCC) plant at Polk Power Station (PPS), located near Tampa, Florida. The syngas cleaning system consists of the following units: Warm Gas Desulfurization Process (WDP) - this unit processes a syngas flow equivalent of 50 MWe of power (50 MWe equivalent corresponds to about 2.0 MM scfh of syngas on dry basis) to produce a desulfurized syngas with a total sulfur (H 2 S+COS) concentration ~ 10 ppmv. Water Gas Shift (WGS) Reactor - this unit converts sufficient CO into CO 2 to enable 90% capture of the CO 2 in the syngas slipstream. This reactor uses conventional commercial shift catalyst technologies. Low Temperature Gas Cooling (LTGC) - this unit cools the syngas for the low temperature activated MDEA process and separates any condensed water. Activated MDEA Process (aMDEA) - this unit employs a non-selective separation for the CO 2 and H 2 S present in the raw syngas stream. Because of the selective sulfur removal by the upstream WDP unit, the CO 2 capture target of 90% CO 2 can be achieved with the added benefit that total sulfur concentration in the CO 2 product is < 100 ppmv. An additional advantage of the activated MDEA process is that the non-selective sulfur removal from the treated syngas reduces sulfur in the treated gas to very low sub-ppmv concentrations, which are required for chemical production applications. Testing to date of this pre-commercial syngas cleaning system has shown that the technology has great potential to provide clean syngas from coal and petcoke-based gasification at increased efficiency and at significantly lower capital and operating costs than conventional syngas cleanup technologies. However, before the technology can be deemed ready for scale-up to a full commercial-scale demonstration, additional R&D testing is needed at the site to address the following critical technical risks: WDP sorbent stability and performance; Impact of WDP on downstream cleanup and conversion steps; Metallurgy and refractory; Syngas cleanup performance and controllability; Carbon capture performance and additional syngas cleanup The proposed plan to acquire this additional R&D data involves: Operation of the units to achieve an additional 3,000 hours of operation of the system within the performance period, with a target of achieving 1,000 hours of those hours via continuous operation of the entire integrated pre-commercial demonstration system; Rapid turnaround of repairs and/or modifications required as necessary to return any specific unit to operating status with documentation and lessons learned to support technology maturation, and; Proactive performance of maintenance activities during any unplanned outages and if possible while operating.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2018

California-Specific Power-to-Hydrogen and Power-to-Gas Business Case Evaluation

Flexible operation of electrolysis systems represents an opportunity to reduce the cost of hydrogen for a variety of end-uses while also supporting grid operations and thereby enabling greater renewable penetration. California is an ideal location to realize that value on account of growing renewable capacity and markets for hydrogen as a fuel cell electric vehicle (FCEV) fuel, refineries, and other end-uses. Shifting the production of hydrogen to avoid high cost electricity and participation in utility and system operator markets along with installing renewable generation to avoid utility charges and increase revenue from the Low Carbon Fuel Standard (LCFS) program can result in around $2.5/kg (21%) reduction in the production and delivery cost of hydrogen from electrolysis. This reduction can be achieved without impacting the consumers of hydrogen. Additionally, future strategies for reducing hydrogen cost were explored and include lower cost of capital, participation in the Renewable Fuel Standard program, capital cost reduction, and increased LCFS value. Each must be achieved independently and could each contribute to further reductions. Using the assumptions in this study found a 29% reduction in cost if all future strategies are realized. Flexible hydrogen production can simultaneously improve the performance and decarbonize multiple energy sectors. The lessons learned from this study should be used to understand near-term cost drivers and to support longer-term research activities to further improve cost effectiveness of grid integrated electrolysis systems.

30 DIRECT ENERGY CONVERSION↗

DOE OSTI2018

Power Take-off System for Marine Renewable Devices

The Power Take-off (PTO) System for Marine Renewable Devices (Project) envisioned the design, manufacture and testing of a generator that would ultimately be suitable for fully flooded seawater operation. This would require a generator design and bearing system capable of operating in the presence of seawater without corrosion. The original generator concept design focused on a switched reluctance electromagnetic design for the generator with the understanding that the switched reluctance design would be more robust and tolerant of a seawater medium. A trade study was conducted to prove that hypothesis, but the results of the study indicated that there was no benefit to adopting a switched reluctance design over a more conventional synchronous permanent magnet design. In addition, the novelty of the switched reluctance design added more technical risk to the Project than was warranted. ORPC’s cost of energy analyses pointed to reliability as being the most critical factor for achieving Project systems performance advancement (SPA) metrics. Consequently, the choice of a permanent magnet (PM) machine design over a potentially less reliable switched reluctance design was necessary to achieve the Project results. As a result, ORPC determined that a PM design was a more appropriate design to achieve the Project goals and ORPC selected a highly qualified PM generator firm for the design, manufacture and factory testing of the generator. The factory acceptance test (FAT) of the generator took place on March 20-22, 2017 and all tests were successfully passed. Developing a design for a driveline as part of the PTO system required a full understanding of the loads and operating conditions expected. Detailed analyses for developing turbine loads and subsequent definition of bearing specifications were performed using various analytical methods. Two candidate bearing designs were proposed as part of the Project. After initial design work had been completed, ORPC designed a representative full-scale driveline to validate the detailed design of the advanced driveline components. Full-scale components were manufactured, instrumented and tested, simulating actual system parameters. This full-scale bearing test was conducted at the University of Maine Advanced Structures and Composites Laboratory. The purpose of this test was to characterize the frictional losses associated with bearings and test the suitability and functionality of some commercially available shaft couplings and expansion bushings in cross-flow turbine drivelines. In parallel with component testing and dynamometer testing of the PTO system, ORPC performed design work to demonstrate how the advanced PTO system will be integrated with all ORPC turbine generator units (TGUs). The work would focus primarily on the TidGen® TGU and assess how the advanced PTO would be integrated into TidGen® 001 or other units, then field-deployed and tested in an open water environment under actual operational conditions. In addition to the benefits provided to the MHK industry in general, and ORPC in particular, the Project provided benefits to the general public, including the following: • Increased general awareness of the potential for generation of electricity from ocean energy resources • Demonstrated continuing advancements in the commercialization of MHK technologies, making them more likely to contribute to the electricity generation supply in America in the coming years • Continued awareness of the local economic benefits from the MHK industry through job creation and local spending • Confirmation of a path to improvements in availability, power-to-weight ratio (PWR) and reduction in levelized cost of energy (LCOE). All Project tasks were completed, and the Project objectives were accomplished. All project milestones and deliverables were met. The designs, methodologies, practices, testing, data, analysis and lessons learned from the Project are a step forward in the development of the U.S. MHK industry and provide a sound basis for ultimate commercialization of ORPC’s power systems. Based on the what was learned and demonstrated during the Project, ORPC has determined that the ORPC power systems have the potential of accelerating the commercialization of tidal and ocean current MHK power systems.

16 TIDAL AND WAVE POWER↗

DOE OSTI2018

American Recovery and Reinvestment Act of 2009: Final Report on Customer Acceptance, Retention, and Response to Time-Based Rates from Consumer Behavior Studies

Time-based rate programs, enabled by utility investments in advanced metering infrastructure (AMI), are increasingly being considered by utilities as tools to reduce peak demand and enable customers to better manage consumption and costs. Under the Smart Grid Investment Grant Program (SGIG), the U.S. Department of Energy (DOE) partnered with several electric utilities to conduct consumer behavior studies (CBS). The goals involved applying randomized and controlled experimental designs for estimating customer responses more precisely and credibly to advance understanding of time-based rates and customer systems, and provide new information for improving program designs, implementation strategies, and evaluations. The intent was to produce more robust and credible analysis of impacts, costs, benefits, and lessons learned and assist utility and regulatory decision makers in evaluating investment opportunities involving time-based rates.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2018

Reducing Energy Burden with Solar: Colorado's Strategy and Roadmap for States

The Colorado Energy Office (CEO) recently implemented a multi-pronged strategy to reduce energy burden for low-income (LI) Colorado residents through the deployment of solar electricity generation. Due to these efforts, approximately 20 MW of photovoltaic (PV) solar may be deployed in Colorado by the end of 2019 specifically for low-income households. Relying on interviews with ten subject-matter experts and other research, this report outlines the details of the CEO strategy including why the agency pursued this strategy, how it was carried out, and lessons learned from implementation. Though CEO's strategy is unique and tailored to the needs of Colorado, it is possible that other states might learn from CEO's experiences when designing their own LI strategies. As a result, the report concludes by outlining six primary steps for designing a comprehensive low-income solar strategy.

14 SOLAR ENERGY↗

DOE OSTI2018

Low-Income Community Solar: Utility Return Considerations for Electric Cooperatives

The objective of this short report is to identify project structures that make low-income community solar projects more cost-effective, replicable, and scalable, for electric cooperative and municipal utilities. This report explores the tradeoffs between providing energy bill savings for low-income subscribers and utility project returns, as well as some of the key lessons learned from existing successful low-income community solar pilot projects.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2018

Next-Generation Performance-Based Regulation. Volume 1: Introduction - Global Lessons for Success; Volume 2: Primer - Essential Elements of Design and Implementation; Volume 3: Innovative Examples from Around the World

Performance-based regulations (PBRs) provide a regulatory framework to connect goals, targets, and measures to utility performance or executive compensation. Well-designed PBRs provide incentives for utility performance, benefiting consumers and utility owners alike. This report considers the role of both PBRs and more discrete performance incentive mechanisms (PIMs) in 21st century power sector transformation. Innovative technologies are transforming the way electricity is generated, delivered, and consumed. PBRs have the potential to realign utility, investor, and consumer incentives and mitigate emerging challenges to the utility business model, renewable integration, and even cyber security.The goals of PBRs in the form of multi-year rate plans are in many respects the same in terms of providing reasonably priced and reliable service to customers. However, today's technologies have changed, and there is more emphasis on clean energy. Thus, the pathways and the potential outcomes are different than they were in the 20th century when centralized generator stations and large infrastructure additions dominated the utility landscape. Given unprecedented changes underway in the electricity sector, PBRs - by specifying expectations of utility performance and outcomes for consumers, while staying agnostic to the exact means of delivery - constitute a form of prescient regulation that harnesses disruption. PBRs are one tool in a broader toolbox in the transition toward flexible regulatory and market structures that rewards utilities that adapt or evolve in reaction to market and technology change. PBRs and PIMs have great value for the electric industry when designed well and can be applied to many different situations. How exactly PBR mechanisms are most effectively enacted will vary based on the utility ownership model, institutional arrangements, and a variety of other local factors. PBRs should be tailored to the needs and goals of each jurisdiction, and perhaps each utility, to most effectively achieve the needs of a 21st century power grid in that jurisdiction. Presented in three volumes, this report highlights the lessons learned from their evolving history, explores essential elements of their design and implementation as well as considerations for how they may be best applied, and examines leading examples of PBRs from the United Kingdom, New York, Denmark, Mexico, and South Africa. The full report, 'Next-Generation Performance Based Regulation - Emphasizing Utility Performance to Unleash Power Sector Innovation,' published in September 2017, can be accessed at https://www.nrel.gov/docs/fy17osti/68512.pdf.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2018

Marine Mammal Behavioral Response to Tidal Turbine Sound

The sound emitted by tidal turbines overlaps with the generalized hearing ranges for marine mammals and may, consequently, affect marine mammal behavior. Because of the strong environmental protections for marine mammals, these effects are of interest to resource agencies and project developers. The primary goal of this project is to improve the understanding of how sound emitted by tidal turbines may affect marine mammal behavior, with the intent that such understanding may allow this environmental risk to be “retired” for initial demonstrations and arrays. A secondary project goal is to evaluate the efficacy of marine mammal observations from a shore-based vantage point as a method to detect change as a consequence of marine energy stressors. Three, two-week trials were conducted across spring, summer and autumn of 2017 during which vantage-point observations of marine mammals were made from land. We refer to these two-week periods as ‘trials’ as they represent different periods of field data collection. These observations consisted of scan samples every 10 minutes with a set of binoculars and a DSLR camera. When pinnipeds were sighted, still images were taken. When harbor porpoise were sighted, focal follows using video were initiated. These data were later analyzed to estimate the location of animals sighted using photogrammetric techniques. For approximately half of each trial period, a boat was moored in the study area from which an underwater projector was used to play back tidal turbine sounds at a broadband source level of 158 dB re µPa @ 1 m. The other half of each trial period had no playbacks and was used as a control period. During the control and playback periods, ancillary data were collected in the study area near the sea floor (ambient noise, tidal velocity, and porpoise clicks) while weather and vessel tracks were recorded near the vantage-point station. Harbor seals did not show a significant response to the simulated turbine noise, nor did harbor porpoise change their closest point of approach or change the direction/deviation of the paths during periods when the playback was occurring. While porpoise sightings and porpoise acoustic detections were significantly reduced during playback periods in the first two trials, the number of detections during the playback periods increased during the third trial. Similarly, the calculated distance from porpoises to the playback location suggests that harbor porpoises avoided an area around the playback location of approximately 300 m during Trial 1, which decreased to approximately 100 m in Trial 2, and disappeared in Trial 3. This could be an indication of habituation or increased tolerance, either to the playback sound or the vessel presence. Our finding of no significant effect of turbine noise on harbor seals contrast with the findings in a previous study by Hastie et al. (2017) conducted in United Kingdom waters. However, due to substantive differences in source levels and propagation loss, seals in our study would need to have been within 10 m of the playback location to experience similar received levels to those in the Hastie et al. study. Consequently, the two studies may actually be in agreement. Our findings of significant effect of turbine noise on harbor porpoise are in line with previous studies suggesting the harbor porpoise are sensitive to noise. However, we note that, due to cost and logistical constraints, the playback vessel was only mooring during the playback periods. Consequently, we cannot definitively ascribe the changes in porpoise behavior to the simulated turbine noise, playback vessel presence, or a combination of both factors. This methodological limitation and other lessons learned are discussed to benefit future studies that explore the effects of acoustic stressors on marine mammals.

16 TIDAL AND WAVE POWER↗

DOE OSTI2017

Considerations for Corridor and Community DC Fast Charging Complex System Design

As auto manufacturers bring vehicles to market with large batteries that provide over 200 miles of driving range, interest in faster charging options for plug-in electric vehicles (PEVs) is intensifying. This report focuses on direct current fast charger (DCFC) systems and how they can be deployed to provide convenient charging for PEV drivers. First, lessons learned from previous DCFC deployment and data collection activities are shared to describe consumer experience with DCFC systems to date. Second, considerations and criteria are established for designing and upgrading DCFC complexes that provide fast-charging opportunities for PEV drivers in urban communities and on rural corridors. Third, cost estimates are shared for hypothetical high-power DCFC complexes that meet simplified design requirements. Finally, results for a business case analysis are presented that shed light on the financial challenges associated with DCFCs.

25 ENERGY STORAGE↗

DOE OSTI2017

2017 Workshop Summary: MHK Environmental Compliance Cost Reduction Strategies Workshop

This three year effort started in FY17 with the objectives of capturing environmental compliance costs and lessons learned from MHK developments that have gone through the permitting and compliance process. The goal is to find ways to improve the efficiency and effectiveness of the permitting and compliance process and reduce costs to encourage investment in MHK projects. The project team is composed of Sandia National Laboratories, Integral Consulting, Kearns & West, and H. T. Harvey & Associates. Step one of the project process, collect data to determine permitting and compliance costs, is currently underway. Step two of the project process, identify cost reduction pathways and step three, develop cost reduction strategies, will follow and are envisioned as an iterative approach to best meet the project goal.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2018

2018 Webinar Summary: MHK Environmental Compliance Cost Reduction Strategies Workshop

This three-year effort started in FY17 with the primary objective of detailing the environmental compliance costs and lessons learned from U.S. based MHK projects that have gone through the permitting and compliance process. The project goal is to find ways to improve the efficiency and effectiveness of the permitting and compliance process that reduce deployment uncertainties and associated risks/costs; ultimately encouraging investment in MHK projects. The project team is composed of Sandia National Laboratories, H. T. Harvey & Associates, Integral Consulting, and Kearns & West. Step one of the project process, collect data to determine permitting and compliance costs, was a focus during 2017, but is an ongoing process to ensure the project team is working with the most recent and accurate data as possible. Currently, the project team is focusing on step two of the project process, identify cost reduction pathways. Step three, develop cost reduction strategies, will follow during Fall 2018 and Winter 2019. Each step is envisioned as an iterative approach working with industry and regulators to best meet the project goal.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2018

2018 Workshop Summary: MHK Environmental Compliance Cost Reduction Strategies Workshop

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2017

Status Report on Activities of the Systems Assessment Task Force, OECD-NEA Expert Group on Accident Tolerant Fuels for LWRs

The Organization for Economic Cooperation and Development /Nuclear Energy Agency (OECD/NEA) Nuclear Science Committee approved the formation of an Expert Group on Accident Tolerant Fuel (ATF) for LWRs (EGATFL) in 2014. Chaired by Kemal Pasamehmetoglu, INL Associate Laboratory Director for Nuclear Science and Technology, the mandate for the EGATFL defines work under three task forces: (1) Systems Assessment, (2) Cladding and Core Materials, and (3) Fuel Concepts. Scope for the Systems Assessment task force (TF1) includes definition of evaluation metrics for ATF, technology readiness level definition, definition of illustrative scenarios for ATF evaluation, and identification of fuel performance and system codes applicable to ATF evaluation. The identification of irradiation facilities around the world that are being used, or are planned to be used, for the irradiation testing of ATF cladding and fuel materials was later added to the TF1 scope (April 2017). The Cladding and Core Materials (TF2) and Fuel Concepts (TF3) task forces have worked to identify gaps and needs for modeling and experimental demonstration; define key properties of interest; identify the data necessary to perform concept evaluation under normal conditions and illustrative scenarios; identify available infrastructure (internationally) to support experimental needs; and make recommendations on priorities. Where possible, considering proprietary and other export restrictions (e.g., International Traffic in Arms Regulations), the Expert Group has facilitated the sharing of data and lessons learned across the international group membership. The Systems Assessment task force is chaired by Shannon Bragg-Sitton (Idaho National Laboratory [INL], U.S.), the Cladding Task Force is chaired by Marie Moatti (Electricite de France [EdF], France), and the Fuels Task Force is chaired by a Masaki Kurata (Japan Atomic Energy Agency [JAEA], Japan). The original Expert Group mandate was established for June 2014 to June 2016. In April 2016 the Expert Group voted to extend the mandate one additional year to June 2017 in order to complete the task force deliverables; this request was subsequently approved by the Nuclear Science Committee. All reports are currently in final draft and will be submitted to NEA for final formatting/editing in October 2017. A final EGATFL meeting will be held at NEA Headquarters in Paris, France on November 2-3, 2017 to resolve any final comments on the task force reports. This report provides brief summary of the Systems Assessment Task Force deliverable report.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗

DOE OSTI2018

Commercial Property Assessed Clean Energy (CPACE) for Tax-Exempt and Public Entities (“CivicPACE”)

This report summarizes the work of the CivicPACE team to open the market for property assessed clean energy financing for the nonprofit, tax exempt sector. Property Assessed Clean Energy (PACE) finances property improvements that are paid back through a line item on the property owner’s tax bill. Most states restrict such improvements to renewable energy and energy efficiency, although they may include water conservation and disaster related improvements such as hurricane or earthquake preparedness. When such projects are developed for commercial properties, it is referred to as commercial PACE or CPACE. When CPACE applies to tax exempt or nonprofit organizations, we refer to it as CivicPACE. CivicPACE also represents the name of this program. The purpose of the CivicPACE project was to help nonprofit tax-exempt organizations such as affordable housing, faith-based institutions, and schools gain greater access to financing for solar energy deployment through PACE. As such, the lessons learned and best practices from the CivicPACE team work is intended for state and municipal program designers, PACE administrators, solar installers, and nonprofit organizations. CPACE is experiencing rapid growth. Cumulative CPACE financing grew from 8.2 million in 2010 to 111 million in 2014 to 588 million in 2017. Renewable energy, mostly solar, represents about a quarter of the financing; the nonprofit sector represents about 10% of total financing. The Project Team was formed in early 2015 when solar financing options were limited for nonprofits (NPOs). Traditional bank financing was difficult for nonprofit organizations to secure since they are often viewed as a credit risk. Despite the growth of CPACE, few tax-exempt organizations were using the financing mechanism at the start of 2015. Nonetheless, CPACE financing appeared to have tremendous potential for solar development for tax-exempt organizations such as schools, churches, and multifamily affordable housing, because it addresses many of the traditional nonprofit financing roadblocks, such as credit risk. Given the benefits and the rapid growth of CPACE, the opportunity to expand CPACE financing for solar development on tax-exempt buildings was timely. The Project team was comprised of The Solar Foundation (TSF), Urban Ingenuity (UI), and Clean Energy Solutions, Inc. (CESI). The Solar Foundation was the Principal Investigator and overall team lead. The Solar Foundation is an independent 501(c)(3) nonprofit organization whose mission is to accelerate adoption of the world’s most abundant energy source. PACE financing specialist Urban Ingenuity was the lead for the team for the pilot projects. Clean Energy Solutions (CESI) was the lead on the market analysis, financial modeling, and HUD regulatory issues for PACE financed solar development on affordable housing. The CivicPACE team focused on four key activities to help open the market for CPACE financing of solar development for nonprofit entities: research, pilot projects, technical assistance, and information dissemination.

14 SOLAR ENERGY↗

DOE OSTI2019

Negative Ion Drift Time Projection Chamber Development for High-Resolution Tracking

Gas Time Projection Chambers (TPCs) are used extensively in High Energy Physics. Modern micro-pattern gaseous detectors (MPGDs) have made it feasible to construct large-volume TPCs with high readout granularity, so that ionization can be imaged with spatial resolution of order 100 μm or better. A challenge with large TPCs is preserving the track geometry over large drift distances. The reduced diffusion offered by negative ion drift (NID) has long been considered a possible means to scaling up TPCs at reduced cost, but NID has up to now required toxic and often flammable multi-component gas mixtures. A number of recent breakthroughs in the field have, however, led to a resurgence of interest in NID gas TPCs: First, it was found that multiple charge carriers in NID can be utilized to measure the absolute position of primary ionization in the drift direction, yielding a powerful new handle on backgrounds, at zero additional cost. Second, work by one of the PIs has revealed SF6 gas to be a non-toxic, non-flammable, NID gas with suitable minority charge carriers present. Third, preliminary work by the PIs suggests that multiple MPGD technologies work well with SF6. This opens the door to a new generation of large, high-resolution, low-background, low-cost gas TPCs. In this work we will investigate MPGD charge multiplication and charge readout in NID TPCs with SF6 gas. The objectives are to quantify the improvement over electron drift TPCs, and to identify the optimal MPGD types, operational parameters, electronics, and vacuum technologies for future low-background experiments. We will measure low-level detector performance parameters such as gain, gain resolution, and spatial resolution, as well as the resulting higher-level performance parameters such nuclear recoil identification efficiency, gamma-ray background rejection, track angle resolution and recoil energy resolution. The proposed work also includes investigation of acrylic vacuum vessels and collaboration on dedicated charge readout chips, both required for next-generation NID MPGD TPCs. MGPD NID TPCs may prove transformative for applications which require both high readout granularity and large detector volumes, such as the reconstruction of nuclear recoils in the context of large-scale directional dark matter searches, measurements of coherent neutrino-nucleus scattering, and directional neutron detection. While the proposed work is focused on nuclear recoils, the lessons learned will be widely applicable to gas TPCs in HEP, and hence have broad impact.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2018

Fracture Effects on Explosive Response (FEER); FY2018 Report

It is known that the violence of explosive response is affected by inertial and mechanical confinement. In a mechanical insult, the impact location creates a contact pressure that can act as confinement surrounding the ignition location, as has been observed in the Skid Test experiment. Under certain conditions — the details of which have not been well characterized — the ignition can produce cracking in the explosive, down which flames are observed to propagate. Cracks serve to simultaneously provide additional surface area for accelerating the reaction, as well as vent paths for quenching the reaction. These are competing behaviors, and the factors which govern the outcome are poorly described. A new experiment was devised to examine the effect of a controlled pre-load pressure on the explosive response. Sixteen experiments were performed on 1-inch thick discs of PBX 9501, with diameters of 1 in ch, 4.25 in ch, and 5 in ch. The explosive was compressed to a known pre-load between two clear windows and ignited at the center of the bottom surface with a focused laser impinging on a graphite inclusion. The ensuing reaction was imaged through the windows used to compress the sample, and from the side. A speckle pattern was applied to some samples for performing DIC (digital image correlation) for the purpose of quantifying the strain field and tracking crack growth. A threshold behavior was observed, in which higher-pressure pre-load resulted in cracks forming, while lower-pressure pre-load vented across the face of the explosive. This report presents the preliminary results, discusses the observations, enumerates hypotheses regarding the observed behavior, identifies lessons learned, and outlines a path forward for the next round of testing. Proof testing was only recently concluded and considerable additional analysis is required. These data will be valuable for the ongoing development of a constitutive mechanical and cracking failure model that will aid in predicting explosive response in mechanical impact scenarios.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗