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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

pyam: Python Implementation of YaM

pyam is a software development framework with tools for facilitating the rapid development of software in a concurrent software development environment. pyam provides solutions for development challenges associated with software reuse, managing multiple software configurations, developing software product lines, and multiple platform development and build management. pyam uses release-early, release-often development cycles to allow developers to integrate their changes incrementally into the system on a continual basis. It facilitates the creation and merging of branches to support the isolated development of immature software to avoid impacting the stability of the development effort. It uses modules and packages to organize and share software across multiple software products, and uses the concepts of link and work modules to reduce sandbox setup times even when the code-base is large. One sidebenefit is the enforcement of a strong module-level encapsulation of a module s functionality and interface. This increases design transparency, system stability, and software reuse. pyam is written in Python and is organized as a set of utilities on top of the open source SVN software version control package. All development software is organized into a collection of modules. pyam packages are defined as sub-collections of the available modules. Developers can set up private sandboxes for module/package development. All module/package development takes place on private SVN branches. High-level pyam commands support the setup, update, and release of modules and packages. Released and pre-built versions of modules are available to developers. Developers can tailor the source/link module mix for their sandboxes so that new sandboxes (even large ones) can be built up easily and quickly by pointing to pre-existing module releases. All inter-module interfaces are publicly exported via links. A minimal, but uniform, convention is used for building modules.

Myint, Steven↗
DOE OSTI2024

Open-cycle thermochemical energy storage for building space heating: Practical system configurations and effective energy density

Salt-hydrate thermochemical materials (TCM) are promising candidates for energy storage systems for building space heating due to their high theoretical energy density and the need for low regeneration temperature. However, water vapor is required to drive the hydration process of the TCM reactor, which poses a challenge during winter when water vapor is typically scarce. Using indoor air directly lowers the building's humidity to an unconformable level in practice, while the cold outdoor air contains limited moisture. Here we consider different integration strategies for open-cycle TCM reactors in buildings and develop a model to simulate their thermal performance across diverse buildings and climates, specifically for building space heating. The potential energy densities and the levelized cost of storage of the TCM reactor are evaluated in practical scenarios to demonstrate the load-shifting potential of TCM systems for heating applications. We use a strontium chloride (SrCl 2 )-based composite as the baseline and explore the impact of various reactor and material changes to the energy density and levelized cost of storage.

25 ENERGY STORAGE↗
DOE OSTI2022

Smart, Connected Manufactured Housing Solutions through High-Performance Design. Final CRADA report

This report focuses on HVAC, domestic hot water, and miscellaneous electric loads via voluntary opportunities that may arise from partnerships with utilities, as well as future US Environmental Protection Agency ENERGY STAR and DOE Zero Energy Ready Manufactured Home programs. Phase I of this project has begun the technical dialogue toward developing an implementation plan among DOE’s Oak Ridge National Laboratory, Clayton Manufactured Homes, and US Department of Housing and Urban Development Code manufactured housing stakeholders. These activities have focused on delivering high-performance design through integration of technology. Project tasks include the following: Identifying baseline energy analysis resources opportunities from a variety of DOE and utility stakeholders; Developing a smart home and business solution by leveraging existing utility programs working with Smart Homes Partners resources such as ACE IoT Solutions, Google Nest, and Ecobee; Developing improved smarter ventilation systems with industry ventilation partners such as the Madison Group; Developing improved building science QA/QC testing equipment with manufacturers such as The Energy Conservatory, and supporting other feasible concepts vetted under DOE’s Advanced Buildings Collaborative with Slipstream, reinventing HVAC in manufactured housing; and, Developing smart home short- and long-term viable technical solutions in coordination with Clayton Manufactured Homes in new and/or revitalized community scales for future Phase II prototype demonstrations, which may include design (and perhaps construction) of single-section homes targeting rental property developers and multi-section homes targeting low- to middle-income affordable housing community developers Given the ongoing US Department of Energy (DOE) rulemaking activities, baseline energy analysis assessments of envelope prescriptive and Uo (i.e., the overall thermal energy efficiency of the home in British thermal units per square foot of exterior heat loss/gain surfaces) measures were removed from the scope of Phase I of this project.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
NASA NTRS2006

YAM- A Framework for Rapid Software Development

YAM is a software development framework with tools for facilitating the rapid development and integration of software in a concurrent software development environment. YAM provides solutions for thorny development challenges associated with software reuse, managing multiple software configurations, the development of software product-lines, multiple platform development and build management. YAM uses release-early, release-often development cycles to allow developers to incrementally integrate their changes into the system on a continual basis. YAM facilitates the creation and merging of branches to support the isolated development of immature software to avoid impacting the stability of the development effort. YAM uses modules and packages to organize and share software across multiple software products. It uses the concepts of link and work modules to reduce sandbox setup times even when the code-base is large. One side-benefit is the enforcement of a strong module-level encapsulation of a module s functionality and interface. This increases design transparency, system stability as well as software reuse. YAM is in use by several mid-size software development teams including ones developing mission-critical software.

simulations↗
DOE OSTI2023

Small Business Voucher Program: Scaling-Up of Bio-Based C5 Building Block Production: Cooperative Research and Development Final Report, CRADA Number CRD-16-00611

Visolis, Inc. is an early stage industrial biotechnology company developing next generation of processes for producing building blocks for bulk polymers and fuels. The company is developing low-cost routes to the chemicals of the future in support of DOE, EERE and BETO goals to grow the U.S. bioeconomy. NREL has capabilities in scale-up of fermentation processes from bench top through pilot scales and also has expertise and technologies related to production of lignocellulosic sugars from cellulosic feedstocks. NREL's Integrated Biorefinery Research Facility (IBRF) houses multiple fermentation vessels/systems ranging in size from 0.5 to 9,000 L along with ancillary capabilities in compositional analysis, separations, and purification. NREL's role will be to scale-up the Visolis process to produce an intermediate product, mevalonic acid, from both dextrose and biomass derived sugars. The goals of the project are to: 1) transfer and reproduce one of Visolis's proprietary fermentation processes at bench top and pilot scale at NREL's IBRF using dextrose as the feedstock, 2) carry out bench-scale fermentations using Visolis's organism and cellulosic sugars, and 3) produce mevalonic acid from the bench top and pilot scale runs for catalyst lifetime testing and conversion to isoprene.

09 BIOMASS FUELS↗
DOE OSTI2021

U.S.-China Clean Energy Research Center Building Energy Efficiency (CERC-BEE) Open-Source Retrofit Targeting Tool (CRADA FP00007338 Final Report)

To increase the cost-saving energy and carbon dioxide (CO 2 ) emissions reductions in buildings and portfolios at the scale and speed necessary to limit climate change, researchers at LBNL and Johnson Controls (JCI) developed the Building Efficiency Targeting Tool for Energy Retrofits (BETTER). BETTER is a software tool that consists of three components: (1) the BETTER analytical engine source code (which was developed with intellectual property provided by JCI under CRADA FP00007338); (2) the BETTER web application, developed by LBNL and McQuillen Interactive Pty. Ltd; and (3) the BETTER application programming interface (API), also developed by LBNL and McQuillen Interactive Pty. Ltd. BETTER enables building and portfolio owners, managers, and service providers worldwide to quickly, easily identify cost-saving energy efficiency retrofits in existing buildings and portfolios without expensive site visits or complex modeling. With minimal data input, the tool benchmarks a building’s electric and fossil energy usage against peers; quantifies energy, cost and greenhouse gas (GHG) emission reduction potentials at the building and portfolio levels; and recommends energy efficiency measures to decarbonize and electrify buildings and portfolios, targeting specific energy savings levels. No other tool so comprehensively analyzes buildings and portfolios with such ease. If fully implemented, it is estimated that BETTER could help reduce emissions equivalent to planting 1.3 billion trees globally by 2030. Moreover, an additional 50-75% of embodied GHG emissions could be avoided in each case where BETTER results in a building being retrofitted instead of demolished and replaced, providing substantial additional decarbonization benefits for the buildings sector. BETTER has garnered multiple awards and avid interest from investors. In 2020, it earned a R&D 100 Award for innovation and a LBNL Director’s Award for Technology Transfer. In 2021, BETTER was named an EarthX E-Capital Summit Climate Tech Prize semi-finalist

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

Supervisory Control of Loads and Energy Storage in Next-Generation Zero Energy Buildings

A zero energy building (ZEB)—also known as a net zero energy or zero net energy building—is a building that exports as much renewable energy as the total energy it imports from other sources on an annual basis (DOE 2015). Large-scale and commercially viable ZEBs are now in the marketplace, and they are expected to become a larger share of the commercial building footprint as government and private sector policies continue to promote the development of buildings that produce more on-site energy than they use. However, the load profiles of ZEBs are currently perceived by electric utilities to be unfavorable and unpredictable. As shown in Figure ES-1, ZEB load profiles can have abrupt changes in magnitude, at times switching rapidly between exporting and importing electricity. This is a challenge for utilities, which are responsible for constantly balancing electricity supply and demand across the grid. Addressing these concerns will require new strategies and tools.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2021

Towards standardized nuclear reactors: Seismic isolation and the cost impact of the earthquake load case

We report nuclear energy has a key role to play in global decarbonization. Impediments to the widespread deployment of reactors are their projected high capital cost and levelized cost of energy, and time required to analyze, design, license, construct, and commission them. The earthquake load case is a key cost driver for a new build nuclear plant, because near-surface soils and seismic hazard are different at each site, requiring site-specific analysis, design, engineering, qualification, licensing, and regulatory review, essentially making every design First-of-a-Kind (FoaK). To enable deployment at the scale needed for deep decarbonization, the cost and time impact of the seismic load case must be significantly mitigated, and plants must be standardized. Seismic base isolation has been proven to considerably reduce the earthquake response of structures and equipment but has yet to be applied to a nuclear power plant in the United States, in part because the financial impacts, positive or negative, are not known. Because there are no recent non-proprietary data to characterize the influence of the seismic load case on capital cost, it is difficult to confidently quantify the financial benefits of seismic isolation. Scheme-level designs of two fundamentally different advanced reactor buildings were developed to assemble cost data on the influence of the seismic load case. Both buildings were equipped with three bespoke pieces of safety-related equipment and analyzed for incremented levels of earthquake shaking to quantify the seismic penalty on equipment, in terms of vessel weights and horizontal accelerations. Using analysis results, a questionnaire was developed and transmitted to nuclear utilities, reactor developers, engineers, and equipment suppliers to collect cost data on engineering and fabrication costs for these unique pieces of safety-class equipment. Synthesis of the cost data showed that the seismic load case significantly affects the capital cost (sum of engineering and fabrication cost) of safety-class equipment, with engineering costs being comparable to fabrication costs. Standardization of safety-class equipment is made possible by seismic isolation, that is, equipment designed for minimal seismic robustness can resist earthquake shaking at a site of much higher seismic hazard. The average reduction in the capital cost of the safety-related equipment, enabled by seismic isolation, is a factor of two for FoaK equipment and a factor of five for standardized equipment.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2023

Developing energy flexibility in clusters of buildings: A critical analysis of barriers from planning to operation

This paper examines building energy flexibility at an aggregated level and addresses the main barriers and research gaps for the development of this resource across three design and development phases: market and policy, early planning and design, and operation. We review methodologies and tools and discuss barriers, challenges, and opportunities, incorporating policy, economic, technical, professional, and social perspectives. Although various legal and regulatory frameworks exist to foster the development of energy flexibility for small buildings, financing mechanisms are limited with a significant number of perceived risks undermining private investment. For the early planning and design phase, planners and designers lack appropriate tools and face interoperability challenges, which often results in insufficient consideration of demand response programs. The review of the operational phase highlighted the socio-technical challenges related to both the complexity of deployment and communication, as well as privacy and acceptability issues. Finally, the paper proposes a number of targeted research directions to address challenges and promote greater energy flexibility deployments, including capturing building demand side dynamics, improving baseline estimations and developing seamless connectivity between buildings and districts.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2023

Multifamily Building Stock Modeling: Cooperative Research and Development Final Report, CRADA Number CRD-17-00701

U.S. multifamily buildings house 35 million households, consuming 4 quads of source energy and spending $48 billion on utility bills every year. Almost all of these households live in urban areas, where cities are taking the lead on setting aggressive energy goals. Cities currently do not have the data and tools necessary to identify and target opportunities to save energy in their building stock. Building on the open-source, OpenStudio-based ResStock platform, this project will extend the publicly-available ResStock modeling capabilities to the multifamily sector, enabling Radiant Labs, and others, to partner with cities to market and strategically deploy cost-effective, energy efficiency (EE) upgrades directly to high-priority households. Radiant Labs has been successful in using ResStock's single-family capabilities to provide value to the City of Boulder, Colorado. However, lack of multifamily capabilities in ResStock is a roadblock for Radiant Labs working with New York City, San Francisco, Washington, D.C., and other cities that have expressed significant interest in working with them. In addition, other cities, companies, and utilities can use these open-source capabilities to grow their EE portfolios, thereby multiplying the impact of this project. This work also enables national-scale analysis of EE potential in multifamily buildings, which is of strong interest to a variety of stakeholders, including the U.S. Department of Energy (DOE) Office of Energy Policy and Systems Analysis (EPSA), DOE Weatherization Assistance Program (WAP), U.S. Department of Housing and Urban Development (HUD), and the Bonneville Power Administration (BPA).

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

Building Tune-Up Accelerator Program (Final Technical Report)

In 2016, the City of Seattle passed a mandatory Building Tune-Up requirement for all commercial buildings 50,000 square feet (SF) and larger as part of its Climate Action strategy. The requirement is phased in by size with large buildings (greater than 200,000 SF) required first. This allowed Seattle’s Office of Sustainability & Environment (OSE) to offer the Building Tune-Up Accelerator (TUA) Program to the “mid-size” building market (less than 100,000 SF) to meet the requirements early. With funding from the US DOE, a package of technical and financial support was developed for building owners and energy service providers to encourage this hard-to-reach market to participate in the tune-up—and even go beyond requirements for greater energy savings. Seattle City Light, the municipal electric utility, offered participants a simple per square foot financial incentive. Partners at the University of Washington Integrated Design Lab, Smart Buildings Center and Pacific Northwest National Lab (PNNL) offered service provider trainings, analytical tools and technical support. This final technical report summarizes the program, projected energy and emissions savings and lessons learned from program development to implementation to final evaluation for the 102 buildings that participated.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2022

User Friendly Web-Based Tool to Assess the Energy Efficiency and Durability of Residential Wall Retrofits

According to the U.S. Department of Energy Windows and Building Envelope Research and Development Roadmap for Emerging Technologies, building envelope wall energy loss in the United States accounts for about 5.9 x 1010 kWh or 2 quads of energy annually, costing homeowners and occupants billions of dollars. Enclosure retrofits targeting these losses can save significant energy, reduce greenhouse gas emissions, and save occupants millions of dollars over time. Older homes, built before 1992 when DOE’s Building Energy Codes Program was established, represent approximately 68 percent of the residential building stock in the country, often having significant air leakage and inadequate insulation. Homes with little to no air sealing or insulation have heating and cooling losses that can represent a substantial portion of utility bills.High-performance building envelope retrofit systems are rarely selected for retrofit applications. Current solutions are expensive and/or unfamiliar to many designers, builders, contractors, and code officials and therefore are perceived as risky. The dominant perceived risk is durability specifically related to condensation and moisture accumulation in the building envelope component.The Building Science Advisor (BSA) is a rule-based expert system web-based tool that was originally developed to assist building professionals in designing energy efficient and durable wall systems for new construction. With the present focus being placed on upgrading the existing building stock, a retrofit module has been developed that, based on the location, existing construction, and planned retrofit strategy, provides recommendations on how to address the retrofit in a manner that will perform in accordance with IECC 2018 building code and not create a durability problem. This paper will describe the development of this tool and demonstrate its features and capabilities.

Desjarlais, Andre Omer↗
DOE OSTI2020

Innovations in Sensors and Controls for Building Energy Management: Research and Development Opportunities Report for Emerging Technologies

Sensors, actuators, and controllers, which collectively serve as the backbone of cyberphysical systems for building energy management, are one of the core technical areas of investment for achieving the U.S. Department of Energy (DOE) Building Technologies Office's (BTO's) goals for energy affordability in the national building stock - both commercial and residential. In fact, an aggregated annual energy savings of 29% is estimated in the commercial sector alone through the implementation of efficiency measures using current state-of-the-art sensors and controls to retune buildings by optimizing programmable settings based on occupant schedules and comfort requirements, as well as detecting and diagnosing equipment operation and installation problems (Fernandez et al. 2017). Monitoring and control of building conditions and operations has advanced significantly, from the invention of the modern thermostat just before the start of the 20th century to the midcentury incorporation of direct digital control into devices, the introduction of open protocols and network communications at the end of the century, and finally the invention of cloud-based computing and additional advancements that have enabled remote operation and a proliferation of connected and intelligent devices in building automation. Despite this potential, however, two main challenges hinder widespread adoption of sensors and controls in building operations that can ensure savings for high-efficiency components and equipment (e.g., heat pumps, windows, and lighting devices), as well as additional savings from more sophisticated control architectures and algorithms. energy savings of 29% is estimated in the commercial sector alone through the implementation of efficiency measures using current state-of-the-art sensors and controls to retune buildings by optimizing programmable settings based on occupant schedules and comfort requirements, as well as detecting and diagnosing equipment operation and installation problems (Fernandez et al. 2017). Monitoring and control of building conditions and operations has advanced significantly, from the invention of the modern thermostat just before the start of the 20th century to the midcentury incorporation of direct digital control into devices, the introduction of open protocols and network communications at the end of the century, and finally the invention of cloud-based computing and additional advancements that have enabled remote operation and a proliferation of connected and intelligent devices in building automation. Despite this potential, however, two main challenges hinder widespread adoption of sensors and controls in building operations that can ensure savings for high-efficiency components and equipment (e.g., heat pumps, windows, and lighting devices), as well as additional savings from more sophisticated control architectures and algorithms.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2020

2019 ASHRAE Handbook: HVAC Applications - Chapter 37 - Energy Use and Management

Handbook is a highly-regarded engineers reference book for heating, ventilating, air conditioning, and energy engineers. Building energy and water use metrics were developed for 53 commercial and residential building types. Supporting narrative was drafted and provided along with multiple tables of building performance metrics for publication in this ASHRAE handbook. ORNL (T. Sharp) developed the building performance metrics in Tables 2, 3, and 4 and authored the narrative about them. T. Sharp also authored the section on "Benchmarking Water Use" and developed building water use metrics published in Table 5.

Sharp, Terry↗
DOE OSTI2022

Prototype College Building Energy Model: Building Characteristics and Energy Simulation Results

The US Department of Energy supports the development of commercial building energy codes and standards. To support commercial building energy research activities and the development of commercial building energy codes and standards, continuous efforts have been made to convert 16 prototype building models, which cover 80% of US commercial building floor space, to OpenStudio prototype buildings. Additionally, the suite of prototype building models was expanded to include the addition of new building prototype models (e.g., courthouse, college building). Multiple sources, including databases, documented projects, and personal communications, were used to define the prototype college building, and a 4-story with 69,063 ft 2 building was considered as the prototype college building to represent an average-sized college building in the United States. To represent realistic occupancy schedules and increase the granularity of information, actual class reservation schedules were collected and used. This report documents the building and system characteristics of the prototype college building model combined with climate-specific and construction vintage–specific requirements for the building envelope and systems from ASHRAE Standard 90.1. The energy simulation results are presented for 4 construction vintages (2004, 2007, 2010, and 2013) and 15 ASHRAE climate zones. The site energy use intensity of the college building was compared with 2012 Commercial Building Energy Consumption Survey (CBECS) and ENERGY STAR data to verify the simulation results. The site energy use intensity of the college building ranged from 60 to 202.4 kBtu/ft 2 , and compared with the energy use intensities of Commercial Building Energy Consumption Survey (122.9 kBtu/ft 2 ) and ENERGY STAR (84.3 kBtu/ft 2 ) data, the prototype college building results are in a reasonable range.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2022

GEN3D Experimental and Numerical Development of GEN3 Durability Models

Understanding of the high temperature durability of particles and the materials that contain them is critical to next generation of concentrating solar power (CSP) technology. Here we studied the durability of particles and their containment materials under extreme UV cycling, thermal cycling, and in low-speed high temperature mechanical wear situations. The optical stability of seven candidate particles has been determined following exposure to the high temperature conditions present in a generation 3 particle-based CSP technology. Particle solar weighted absorptance and emittance measured periodically during 10,000 high solar irradiance exposure cycles and up to 400 hours of isothermal aging has been documented. The particle aging due to repeated exposure to concentrated solar flux represented the 30-year lifetime of a power plant. Models were fit to the absorptivity and emissivity data following the isothermal aging provides the projected optical degradation of the particles as a function of temperature. Mechanical wear was studied through the use of custom developed wear testing facilities for measuring high temperature impact wear, abrasion wear, and particle attrition. Additionally, a novel technique for measuring the high temperature mechanical properties of single particles was developed. Through these tests it was observed that high nickel alloys generally showed lower wear than comparable iron based steels, particularly at elevated temperatures of 800°C. Mechanical wear at these temperatures is a highly complex phenomenon combining both mechanical wear and oxidation. Additionally, the containment materials wear rates are influenced by the particles (both hardness and roundness), making the wear mechanisms complex. The initial wear test conducted in the abrasion test rig revealed a substantial amount of oxide materials in the particle bed after testing (in relative to later tests), and substantially more wear, likely indicating a need for concern in startup operation of particle facilities to not incur high wear from the presence of oxides. Particle attrition experiments have only been conducted for a single material but increase size distribution, reduction in circularity, and particle diameter is observed. Efforts to develop predictive models was limited due to a testing campaign that prioritized testing materials for particle pathway developers over building a comprehensive design of experiments. The results discussed in this report inform future CSP developers and researchers further de risking the technology and assisting in its future development. ParticleBased CSP development provides a path to dispatchable solar power generation with storage at a price competitive in the current energy market. Lowering the cost of CSP technology provides a carbon free power generation solution that can assist in the transition from fossil fuels to renewable sources of electricity.

14 SOLAR ENERGY↗
NASA NTRS2015

Simplified Methodology to Estimate the Maximum Liquid Helium (LHe) Cryostat Pressure from a Vacuum Jacket Failure

The aircraft-based Stratospheric Observatory for Infrared Astronomy (SOFIA) is a platform for multiple infrared astronomical observation experiments. These experiments carry sensors cooled to liquid helium temperatures. The liquid helium supply is contained in large (i.e., 10 liters or more) vacuum-insulated dewars. Should the dewar vacuum insulation fail, the inrushing air will condense and freeze on the dewar wall, resulting in a large heat flux on the dewar's contents. The heat flux results in a rise in pressure and the actuation of the dewar pressure relief system. A previous NASA Engineering and Safety Center (NESC) assessment provided recommendations for the wall heat flux that would be expected from a loss of vacuum and detailed an appropriate method to use in calculating the maximum pressure that would occur in a loss of vacuum event. This method involved building a detailed supercritical helium compressible flow thermal/fluid model of the vent stack and exercising the model over the appropriate range of parameters. The experimenters designing science instruments for SOFIA are not experts in compressible supercritical flows and do not generally have access to the thermal/fluid modeling packages that are required to build detailed models of the vent stacks. Therefore, the SOFIA Program engaged the NESC to develop a simplified methodology to estimate the maximum pressure in a liquid helium dewar after the loss of vacuum insulation. The method would allow the university-based science instrument development teams to conservatively determine the cryostat's vent neck sizing during preliminary design of new SOFIA Science Instruments. This report details the development of the simplified method, the method itself, and the limits of its applicability. The simplified methodology provides an estimate of the dewar pressure after a loss of vacuum insulation that can be used for the initial design of the liquid helium dewar vent stacks. However, since it is not an exact tool, final verification of the dewar pressure vessel design requires a complete, detailed real fluid compressible flow model of the vent stack. The wall heat flux resulting from a loss of vacuum insulation increases the dewar pressure, which actuates the pressure relief mechanism and results in high-speed flow through the dewar vent stack. At high pressures, the flow can be choked at the vent stack inlet, at the exit, or at an intermediate transition or restriction. During previous SOFIA analyses, it was observed that there was generally a readily identifiable section of the vent stack that would limit the flow – e.g., a small diameter entrance or an orifice. It was also found that when the supercritical helium was approximated as an ideal gas at the dewar condition, the calculated mass flow rate based on choking at the limiting entrance or transition was less than the mass flow rate calculated using the detailed real fluid model2. Using this lower mass flow rate would yield a conservative prediction of the dewar’s wall heat flux capability. The simplified method of the current work was developed by building on this observation.

Ungar, Eugene K.↗
DOE OSTI2025

Capability Building Progression of an Insider Threat Mitigation Program at an International Nuclear Power Plant (Rev. 1)

With threats to nuclear facilities continuously evolving, the development and implementation of insider threat mitigation programs (ITMPs) are increasingly important. The Office of International Nuclear Security (INS) within the U.S. Department of Energy’s National Nuclear Security Administration (DOE/NNSA’s) developed Capability Building Progression of an Insider Threat Mitigation Program at an International Nuclear Power Plant to assist newcomers and existing nuclear power plant (NPP) operators in addressing insider threats and establishing effective response measures for insider activities.

98 NUCLEAR DISARMAMENT, SAFEGUARDS, AND PHYSICAL P↗