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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↗

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↗

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↗

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↗

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↗

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↗

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↗

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↗

2018 Workshop 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↗

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↗

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↗

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↗

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↗

The Operation of the Tevatron Vacuum System

Outline: Tevatron Overview and Some History; Vacuum Upgrades; Cryogenic Upgrades; Maintenance and Records; Vacuum Diagnostics; Failures; Lessons Learned

43 PARTICLE ACCELERATORS↗

Envision Charlotte Project Final Report

The Envision Charlotte Project (EC Project), supported by partners at the Center for Climate and Energy Solutions, the University of North Carolina at Charlotte’s Center for Sustainably Integrated Buildings and Sites and the City of Charlotte, has successfully demonstrated that existing buildings can benefit from operations improvements and low-cost efficiency upgrades, and that behavioral change campaigns can be effectively designed for measurability, longevity and impact. Support from this grant gave Envision Charlotte and its partners the resources and flexibility to demonstrate a variety of approaches to improve coordination with stakeholders in the implementation of programs to reduce the consumption of energy, water and waste. The project team also gained insights into the motivations and abilities that influence stakeholder engagement in sustainability initiatives at multiple levels. Importantly, as this report describes, strong partnerships between nonprofits, industry partners and research institutions can produce tangible impacts and replicable results in building efficiency. Further, building operators working alongside student researchers can form productive relationships that can advance building energy management goals. Key Findings of the EC Project This project focused on advancing solutions to energy efficiency in U.S. commercial buildings. The Building Re-Tuning™ Training (BRT) developed by the U.S. DOE’s Pacific Northwest National Lab (PNNL), designed to detect energy savings opportunities and implement improvements with resources and online tools, provided the starting point for the curriculum developed by stakeholders in the EC Project. Although the project partners encountered some issues with data consistency, the overall project outcomes fell short of the energy savings stated in the original proposal, and the total participating building targets were lower than anticipated, important findings, outcomes and lessons learned were achieved. EC Project grantees observed that the PNNL BRT, as currently written, was not compatible with the skills of average frontline mechanical personnel in the Charlotte region where the grant program was performed. Frontline staff are not, typically, energy managers, engineers or building commissioning agents, but they can play a key role in building performance. As detailed in this report, the grantees therefore focused on changes to the BRT that improved the level of training and competency of the frontline workers in this region. Among the technical observations related to improving the BRT that were observed in the EC Project: centralized facilities management often has an impact on building performance; operators can be overly reliant on service contracts; individual behaviors matter, and technology cannot be viewed as a crutch; current Building Automation Systems (BAS) are often too complex to support building efficiency optimization, but BAS coupled with appropriate training can support better outcomes; the “perfectly optimized” building is not a near-term possibility, but better education, especially of executives and managers, on the role of behavioral intervention is a promising direction the building science community can and should pursue; a lack of standards and protocols, and competition between proprietary software from service contracts, remain challenges for this industry. These technical observations, in turn, informed the EC Project’s overall findings, which were: Accomplishing building efficiency is a process of education for all involved in the building design, construction and operation supply chain. Building operators, as a professional class, have an opportunity for further training and education that will lead to better on-the-job performance. An updated Building Re-Tuning™ Training curriculum, based on the findings of this report, could be an avenue for these operators’ professional development.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

GM Light Duty Fuel Cell Electric Vehicle Validation Data

General Motors LLC (GM) completed a multi-phase project with the Department of Energy to validate light-duty fuel cell electric vehicle (FCEV) performance and durability using dynamometer fuel cell system and real-world vehicle performance data. This project began with GM’s Gen 0 Fuel Cell Fleet vehicles with Technology Insertion operating strategies and materials, and extended to GM’s Gen 1 and early Gen 2 commercial-design intent Fuel Cell stacks and Fuel Cell Systems. The intent of this project was to understand how fuel cell materials, system architectures, and operating strategies impact fuel cell stack durability under fully dynamic operating conditions such as those seen in a light duty vehicle application. More than 87,000 hours of system run time were accumulated under this project simulating several vehicle lifetimes under aggressive driver usage conditions. Lessons learned from this demonstration project have helped expedite the development of a commercially viable, zero-petroleum, zero-emission, Fuel Cell propulsion system. Durability test results have enabled a substantial reduction in the precious metal content in the Fuel Cell Stack with each successive generation of stack design. Stack lifetimes between the first and current design iterations have increased nearly tenfold, while the overall precious metal content has been reduced by approximately 85%. The Gen 2 system power density (kW/gPt) is over five times that of the Gen 0 system. In addition, run time voltage degradation as a function of total platinum was reduced by more than an order of magnitude between the first and last phase of this project. GM is proceeding with a low volume production program aided by the results of the durability testing performed under this cooperative agreement.

08 HYDROGEN↗

Production Facility Prototype Blower 1000 Hour Test Results III

Long duration operations tests of the Aerzen GM 12.4 roots style blower in a closed loop configuration provides valuable data and lessons learned for long-term operation at the Mo-99 production facility. The blower was operated in a closed loop configuration with the flow conditions anticipated in plant operation with a Mo-100 target inline. The additional thermal energy generated from beam heating of the Mo-100 disks was not included in these tests. Eight long duration 500 and 1000 hour tests have been completed since the first test was performed in January of 2016. All eight long duration tests have proven successful in exposing preventable issues related to oil and helium leaks.

47 OTHER INSTRUMENTATION↗

Conceptual Design of an Improved Sodium Plugging Loop

Based upon lessons learned in operating the initial sodium portion of the Sodium Plugging Phenomena Loop that itself became plugged and could not be unplugged, a set of improved design features have been identified for a new sodium loop that is less prone to inadvertent plugging. The new design features include a new sodium vessel that combines the functionalities of an expansion tank and a cold trap, increasing the loop tubing diameter/size, improving the thermal designs of the pump and flow meter, improved heater zoning, and an improved temperature distribution strategy along the loop. A new plugging loop conceptual design implementing these features has been developed.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗