This report documents analysis to determine whether a hydrogen jet flame impinging on a tunnel ceiling structure could result in permanent damage to the Callahan tunnel in Boston, Massachusetts. This tunnel ceiling structure consists of a passive fire protective board supported by stainless steel hangers anchored to the tunnel ceiling with epoxy. Three types of fire protective boards were considered to determine whether heat from the flame could reach the stainless-steel hangers and the epoxy and cause the ceiling structure to collapse. Heat transfer analyses performed showed that the temperature remains constant where the steel hangers are attached to the passive fire protective board. According to these results, the passive fire protective board should provide adequate protection to the tunnel structure in this release scenario. Tunnel structures with similar suspended fire-resistant liner board materials should protect the integrity of the structure against the extremely low probability of an impinging hydrogen jet flame.
This report documents the development of an arc flash hazard model to calculate the incident energy and zone of influence from high energy arcing faults involving aluminum. The NRC has identified the potential for (HEAFs) involving aluminum to increase the damage zone beyond what is currently postulated in fire probabilistic risk assessment (PRA) methodologies. To estimate the hazard from HEAFs involving aluminum an arc flash model was developed. Differences between the initial model and nuclear power plant (NPP) fire PRA scenarios were identified. Modification of the initial model established from existing literature and test data was used to minimize these differences. The developed model was evaluated against NRC datasets to understand the model prediction and relative uncertainties. Finally, a range of fire PRA zone of influences (ZOI) were developed based on the developed model, target fragility estimates and update HEAF PRA methodology. The results were developed to support an NRC LIC-504 evaluation in tandem with other modeling efforts. The report documents the effort and provides a reference for any future advancements in arc flash modeling.
Hydrogen is an important resource for many different industries throughout the world, including refining, manufacturing, and as a direct energy source. Hydrogen production, through methods such as steam methane reforming, has been developed over several decades. There is a large global demand for hydrogen from these industries and safe production and distribution are paramount for hydrogen systems. Codes and standards have been developed to reduce the risk associated with hydrogen accidents to the public. These codes and standards are similar to those in other industries in which there is inherent risk to the public, such as gasoline and natural gas production and distribution. Although there will always be a risk to the public in these types of fuels, the codes and standards are developed to reduce the likelihood of an accident occurring and reduce the severity of impact, should one occur. This report reviews the current state of hydrogen in the United States and outlines the codes and standards that ensure safe operation of hydrogen systems. The total hydrogen demand and use in different industries is identified. Additionally, the current landscape of hydrogen production and fueling stations in the United States is outlined. The safety of hydrogen systems is discussed through an overview of the purpose, methods, and content included in codes and standards. As outlined in this safety overview, the risk to the public in operation of hydrogen generation facilities and fueling stations is reduced through implementation of appropriate measures. Codes, such as NFPA 2, ensure that the risk associated with a hydrogen system is no greater than the risk presented by gasoline refueling stations.
This report documents an experimental program designed to investigate High Energy Arcing Fault (HEAF) phenomena. The experiments focus on providing data to better characterize the arc to improve the prediction of arc energy emitted during a HEAF event. An open box experiment allow for direct observation of the arc, which allows diagnostic instrumentation to record the phenomenological data needed for better characterization of the arc energy source term. The data collected supports characterization of the arc and arc jet, enclosure breach, material loss, and electrical properties. These results will be used to better characterizing the hazard for improvements in fire probabilistic risk assessment (PRA) realism. The experiments were performed at KEMA Labs located in Chalfont, Pennsylvania. The experimental design, setup, and execution were completed by staff from the NRC, the National Institute of Standards and Technology (NIST), Sandia National Laboratories (SNL) and KEMA Labs. In addition, representatives from the Electric Power Research Institute (EPRI) observed some of the experimental setup and execution. The HEAF experiments were performed between August 22, 2020 and September 18, 2020 on near-identical 51 cm (20 in) cube metal boxes suspended from a Unistrut support structure. The three-phase arcing fault was initiated at the ends of the conductors oriented vertically and located at the center of the box. Either aluminum or copper conductors were used for the conductors. The low-voltage experiments used 1 000 volts AC, while the medium-voltage experiments used 6 900 volts AC consistent with other recently completed experiments. Durations of the experiment ranged from 1 s to 5 s with fault currents ranging from 1 kA to 30 kA. Real-time electrical operating conditions, including voltage, current and frequency, were measured during the experiments. Heat fluxes and incident energies were measured with plate thermometers, radiometers, and slug calorimeters at various locations around the electrical enclosures. The experiments were documented with normal and high-speed videography, infrared imaging and photography.
This report documents an experimental program designed to investigate High Energy Arcing Fault (HEAF) phenomena for low-voltage metal enclosed switchgear containing aluminum conductors. This report covers full-scale laboratory experiments using representative nuclear power plant (NPP) three-phase electrical equipment. Electrical, thermal, and pressure data were recorded for each experiment and documented in this report. This report covers experiments performed on two low-voltage switchgear units with each unit consisting of two vertical sections. The data collected supports characterization of the low-voltage HEAF hazard and these results will be used to support potential improvements in fire probabilistic risk assessment (PRA) methods. The experiments were performed at KEMA Labs located in Chalfont, Pennsylvania. The experimental design, setup, and execution were completed by staff from the NRC, the National Institute of Standards and Technology (NIST), Sandia National Laboratories (SNL) and KEMA. In addition, representatives from the Electric Power Research Institute (EPRI) observed some of the experimental setup and execution. The HEAF experiments were performed between August 26 and Augsut 29, 2019 on nearidentical Westinghouse Type DS low-voltage metal-enclosed indoor switchgear. The threephase arcing fault was initiated on the aluminum main bus or in select cases on the copper bus stabs near the breaker. These experiments used either nominal 480 volts AC or 600 volts AC. Durations of the experiments ranged from approximately 0.4 s to 8.3 s with fault currents ranging from approximately 9.2 kA to 19.3 kA. Real-time electrical operating conditions, including voltage, current and frequency, were measured during the experiments. Heat fluxes and incident energies were measured with plate thermometers, radiometers, and slug calorimeters at various locations around the electrical enclosures. Environmental measurements of breakdown, conductivity and electromagnetics were also taken. The experiments were documented with normal and high-speed videography, infrared imaging and photography. The results, while limited, indicated the difficulty in maintaining and sustaining low-voltage arcs on aluminum components of sufficient duration and at a single point as observed operating experience.
This white paper describes the work performed by Sandia National Laboratories in the New Mexico Small Business Agreement with BayoTech. BayoTech is a hydrogen generation and distribution company that is located in Albuquerque, NM. Their goal is to distribute hydrogen via their hydrogen systems which utilize the core design that was developed by Sandia. However, because the hydrogen economy is in its nascency, the safety and operation of the generating systems require independent validation. Additionally, in their pursuit of permitting at various locations around the nation, they require fire protection engineering support in discussions with local fire marshals and neighboring industrial entities. Sandia National Laboratories has subject matter expertise in hydrogen risk modeling of consequence (overpressure and dispersion) as well as fire protection engineering. Throughout this project, Sandia has worked with BayoTech to provide our expertise in these subject areas to facilitate the market entry of their hydrogen generation project to address the dire need for decarbonization due to climate change. The general approach of the support by Sandia is outlined in the main body, while the location specific evaluation for the Port of Stockton is contained in Appendix A.
This report documents an experimental program designed to investigate High Energy Arcing Fault (HEAF) phenomena for medium voltage electrical switchgear containing aluminum conductors. This report covers full-scale laboratory experiments using representative nuclear power plant (NPP) three-phase electrical equipment. Electrical, thermal, and pressure data were recorded for each experiment and documented in this report. This report covers four of the fourteen planned medium voltage electrical enclosure experiments. Subsequent reports will document the additional experiments performed in the future. The experiments were performed at KEMA Labs located in Chalfont, Pennsylvania. The experimental design, setup, and execution were completed by staff from the United States Nuclear Regulatory Commission (NRC), the National Institute of Standards and Technology (NIST), Sandia National Laboratories (SNL) and KEMA. In addition, representatives from the Electric Power Research Institute (EPRI) observed some of the experimental setups and execution. The HEAF experiments were performed on four near-identical units of General Electric metal-clad medium voltage switchgear. The three-phase arcing fault was initiated on the primary cable connection bus. All four experiments used the same system voltage (6.9 kV) but varied the current and duration. Real-time electrical operating conditions, including voltage, current and frequency, were measured during the experiments. Heat fluxes and incident energies were measured with plate thermometers and slug calorimeters at various locations around the electrical enclosures. Internal enclosure pressures were measured during the experiments. The experiments were documented with normal and high-speed videography, infrared imaging, and photography. Insights from the experimental series included timing information related to enclosure breach, event progression, mass loss measurements for electrodes and steel enclosures, peak pressure rise, particle analysis, along with visual and thermal imaging data to better understand and characterize the hazard. These results will be used in subsequent efforts to advance the state of knowledge related to HEAF.
In order to establish a zone of influence (ZOI) due to a high energy arcing fault (HEAF) environment, the fragility of the targets must be determined. The high heat flux/short duration exposure of a HEAF is considerably different than that of a traditional hydrocarbon fire, which previous research has addressed. The previous failure metrics (e.g., internal jacket temperature of a cable exposed to a fire) were based on low heat flux/long duration exposures. Because of this, evaluation of different physics and failure modes was considered to evaluate the fragility of cables exposed to a HEAF. Tests on cable targets were performed at high heat flux/short duration exposures to gain insight on the relevant physics and failure modes. These tests yielded data on several relevant failure modes, including electrical failure and sustained ignition. Additionally, the results indicated a relationship between the total energy of exposure and the damage state of the cable target. This data can be used to inform the fragility of the targets.
The application of hydrogen as an energy carrier has been expanding into industrial and transportation sectors enabling sustainable energy resources and providing a zero-emission energy infrastructure. The hydrogen supply infrastructure includes processes from production and storage, to transportation and distribution, to end use. Each portion of the hydrogen supply infrastructure is regulated by international, federal, state, and local entities. Regulations are enforced by entities which provide guidance and updates as necessary. While energy sources such as natural gas are currently regulated via the Code of Federal Regulations and United States Code, there might be some ambiguity as to which regulations are applicable to hydrogen and where regulatory gaps may exist. This report contains an overview of the regulations that apply to hydrogen, and those that may indirectly cover hydrogen as an energy carrier participating in a sustainable zero emission global energy system. As part of this effort, the infrastructure of hydrogen systems and regulation enforcement entities are defined, and a visual map and reference table are developed. This regulatory map and table can be used to identify the boundaries of federal oversight for each component of the hydrogen supply value chain which includes production, storage, distribution, and use.
The need to understand the risks and implications of traffic incidents involving hydrogen fuel cell electric vehicles in tunnels is increasing in importance with higher numbers of these vehicles being deployed. A risk analysis was performed to capture potential scenarios that could occur in the event of a crash and provide a quantitative calculation for the probability of each scenario occurring, with a qualitative categorization of possible consequences. The risk analysis was structured using an event sequence diagram with probability distributions on each event in the tree and random sampling was used to estimate resulting probability distributions for each end-state scenario. The most likely consequence of a crash is no additional hazard from the hydrogen fuel (98.1–99.9% probability) beyond the existing hazards in a vehicle crash, although some factors need additional data and study to validate. These scenarios include minor crashes with no release or ignition of hydrogen. When the hydrogen does ignite, it is most likely a jet flame from the pressure relief device release due to a hydrocarbon fire (0.03–1.8% probability). This work represents a detailed assessment of the state-of-knowledge of the likelihood associated with various vehicle crash scenarios. This is used in an event sequence framework with uncertainty propagation to estimate uncertainty around the probability of each scenario occurring.
Many types of vehicles using fuels that differ from typical hydrocarbons such as gasoline and diesel are in use throughout the world. These include vehicles running on the combustion of natural gas and propane as well as electrical drive vehicles utilizing batteries or hydrogen as energy storage. These alternative fuels pose hazards that are different from traditional fuels and the safety of these vehicles are being questioned in areas such as tunnels and other enclosed spaces. Much scientific research and analysis has been conducted on tunnel and garage hazard scenarios; however, the data and conclusions might not seem to be immediately applicable to highway tunnel owners and authorities having jurisdiction over tunnels. This report provides a comprehensive, concise summary of the literature available characterizing the various hazards presented by all alternative fuel vehicles, including light-duty, medium- and heavy-duty, as well as buses. Research characterizing both worst-case and more plausible scenarios and risk-based analysis is also summarized Gaps in the research are identified in order to guide future research efforts to provide a complete analysis of the hazards and recommendations for the use of alternative fuel vehicles in tunnels.
There are numerous vehicles which utilize alternative fuels, or fuels that differ from typical hydrocarbons such as gasoline and diesel, throughout the world. Alternative vehicles include those running on the combustion of natural gas and propane as well as electrical drive vehicles utilizing batteries or hydrogen as energy storage. Because the number of alternative fuels vehicles is expected to increase significantly, it is important to analyze the hazards and risks involved with these new technologies with respect to the regulations related to specific transport infrastructure, such as bridges and tunnels. This report focuses on hazards presented by hydrogen fuel cell electric vehicles that are different from traditional fuels. There are numerous scientific research and analysis publications on hydrogen hazards in tunnel scenarios; however, compiling the data to make conclusions can be a difficult process for tunnel owners and authorities having jurisdiction over tunnels. This report provides a summary of the available literature characterizing hazards presented by hydrogen fuel cell electric vehicles, including light-duty, medium and heavy-duty, as well as buses. Research characterizing both worst-case and credible scenarios, as well as risk-based analysis, is summarized. Gaps in the research are identified to guide future research efforts to provide a complete analysis of the hazards and recommendations for the safe use of hydrogen fuel cell electric vehicles in tunnels.
This report reviews and offers recommendations from Sandia National transportation of hazardous materials in the U.S. The risk criteria should be used with the results of a quantitative risk assessment (QRA) in risk acceptance decision-making. The QRA for transportation is fundamentally the same as a fixed facility. However, there are differences in calculations of both the probabilities of occurrence and location of hazards. Involuntary individual fatality risk is recommended to be acceptable for annual probabilities of less than 3 x 10-7 for any population, including vulnerable populations, and may be considered acceptable at the regulators discretion for non-sensitive/non-vulnerable populations if less than 5 x 10-5 and demonstrated to be as low as reasonably practicable (ALARP). Societal risk is recommended to be acceptable if the annual frequency of events that would result in N or more fatalities is less than 10-5/N events per year and may be considered acceptable at the regulators discretion if less than 10-3/N events per year and demonstrated to be ALARP. These criteria should be applied to the societal risk over the entire transportation route, not normalized per-distance. These values are adapted from the National Fire Protection Association (NFPA) 59A, a U.S. and international standard for liquefied natural gas (LNG) facility siting.
DOE has identified consistent safety, codes, and standards as a critical need for the deployment of hydrogen technologies, with key barriers related to the availability and implementation of technical information in the development of regulations, codes, and standards. Advances in codes and standards have been enabled by risk-informed approaches to create and implement revisions to codes, such as National Fire Protection Association (NFPA) 2, NFPA 55, and International Organization for Standardization (ISO) Technical Specification (TS)-19880-1. This project provides the technical basis for these revisions, enabling the assessment of the safety of hydrogen fuel cell systems and infrastructure using QRA and physics-based models of hydrogen behavior. The risk and behavior tools that are developed in this project are motivated by, shared directly with, and used by the committees revising relevant codes and standards, thus forming the scientific basis to ensure that code requirements are consistent, logical, and defensible.
Additional fueling stations need to be constructed in the U.S. to enable the wide-spread adoption of fuel cell electric vehicles. A wide variety of private and public stakeholders are involved in the development of this hydrogen fueling infrastructure. Each stakeholder has particular needs in the station planning, development, and operation process that may include evaluation of potential sites and requirements, understanding the components in a typical system, and/or improving public acceptance of this technology. Publicly available templates of representative station designs can be used to meet many of these stakeholder needs. These 'Reference Stations' help reduce the cost and speed the deployment of hydrogen stations by providing a common baseline with which to start a design, enabling quick assessment of the suitability of a particular site for a hydrogen station, and identifying contributors to poor economics and research and development areas for certain station designs.
In this investigation a series of small-scale tests were conducted, which were sponsored by the Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research (RES) and performed at Sandia National Laboratories (SNL). These tests were designed to better understand localized particle dispersion phenomena resulting from electrical arcing faults. The purpose of these tests was to better characterize aluminum particle size distribution, rates of production, and morphology (agglomeration) of electrical arc faults. More specifically, this effort characterized ejected particles and high-energy dispersion, where this work characterized HEAF electrical characteristics, particle movement/distributions, and morphology near the arc. The results and measurements techniques from this investigation will be used to inform an energy balance model to predict additional energy from aluminum involvement in the arc fault. The experimental setup was developed based on prior work by KEMA and SNL for phase-to-ground and phase-to-phase electrical circuit faults. The small-scale tests results should not be expected to be scale-able to the hazards associated with full-scale HEAF events. Here, the test voltages will consist of four different levels: 480V, 4160V, 6900V and 10kV, based on those realized in nuclear power plant (NPP) HEAF events.
Sandia National Laboratories conducted a reliability analysis on the Alertus mass notification system to determine if improvements need to be made to the system to increase reliability. The Alertus mass notification system for Building 803 was analyzed with a set number of components. The components, their associated failure modes and failure mode rates were inputted into a fault tree in the SAPHIRE software which calculated the reliability of the system to be 0.998269.
DOE has identified consistent safety, codes, and standards as a critical need for the deployment of hydrogen technologies, with key barriers related to the availability and implementation of technical information in the development of regulations, codes, and standards. Advances in codes and standards have been enabled by risk-informed approaches to create and implement revisions to codes, such as National Fire Protection Association (NFPA) 2, NFPA 55, and International Organization for Standardization (ISO) Technical Specification (TS)-19880-1. This project provides the technical basis for these revisions, enabling the assessment of the safety of hydrogen fuel cell systems and infrastructure using QRA and physics-based models of hydrogen behavior. The risk and behavior tools that are developed in this project are motivated by, shared directly with, and used by the committees revising relevant codes and standards, thus forming the scientific basis to ensure that code requirements are consistent, logical, and defensible.
Safety standards development for maintenance facilities of liquid and compressed natural gas fueled vehicles is required to ensure proper facility design and operating procedures. Standard development organizations are utilizing risk-informed concepts to develop natural gas vehicle (NGV) codes and standards so that maintenance facilities meet acceptable risk levels. The present report summarizes Phase II work for existing NGV repair facility code requirements and highlights inconsistencies that need quantitative analysis into their effectiveness. A Hazardous and Operability study was performed to identify key scenarios of interest using risk ranking. Detailed simulations and modeling were performed to estimate the location and behavior of natural gas releases based on these scenarios. Specific code conflicts were identified, and ineffective code requirements were highlighted and resolutions proposed. These include ventilation rate basis on area or volume, as well as a ceiling offset which seems ineffective at protecting against flammable gas concentrations. ACKNOWLEDGEMENTS The authors gratefully acknowledge Bill Houf (SNL -- Retired) for his assistance with the set-up and post-processing of the numerical simulations. The authors also acknowledge Doug Horne (retired) for his helpful discussions. We would also like to acknowledge the support from the Clean Cities program of DOE's Vehicle Technology Office.
Several jurisdictions with critical tunnel infrastructure have expressed the need to understand the risks and implications of traffic incidents in tunnels involving hydrogen fuel cell vehicles. A risk analysis was performed to estimate what scenarios were most likely to occur in the event of a crash. The results show that the most likely consequence is no additional hazard from the hydrogen, although some factors need additional data and study to validate. This includes minor crashes and scenarios with no release or ignition. When the hydrogen does ignite, it is most likely a jet flame from the pressure relief device release due to a hydrocarbon fire. This scenario was considered in detailed modeling of specific tunnel configurations, as well as discussion of consequence concerns from the Massachusetts Department of Transportation. Localized concrete spalling may result where the jet flame impinges the ceiling, but this is not expected to occur with ventilation. Structural epoxy remains well below the degradation temperature. The total stress on the steel structure was significantly lower than the yield stress of stainless steel at the maximum steel temperature even when the ventilation was not operational. As a result, the steel structure will not be compromised. It is important to note that the study took a conservative approach in several factors, so observed temperatures should be lower than predicted by the models.
This report presents the results of instrumentation cable tests sponsored by the US Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research and performed at Sandia National Laboratories (SNL). The goal of the tests was to assess thermal and electrical response behavior under fire-exposure conditions for instrumentation cables and circuits. The test objective was to assess how severe radiant heating conditions surrounding an instrumentation cable affect current or voltage signals in an instrumentation circuit. A total of thirty-nine small-scale tests were conducted. Ten different instrumentation cables were tested, ranging from one conductor to eight-twisted pairs. Because the focus of the tests was thermoset (TS) cables, only two of the ten cables had thermoplastic (TP) insulation and jacket material and the remaining eight cables were one of three different TS insulation and jacket material. Two instrumentation cables from previous cable fire testing were included, one TS and one TP. Three test circuits were used to simulate instrumentation circuits present in nuclear power plants: a 4–20 mA current loop, a 10–50 mA current loop and a 1–5 VDC voltage loop. A regression analysis was conducted to determine key variables affecting signal leakage time.
The Nuclear Regulatory Commission's (NRC) current fire protection regulatory framework was initiated in response to a cable fire that occurred at the Browns Ferry Nuclear Power Station in 1975. Following the issuance of several guidance documents, in 1981 the Commission codified deterministic requirements to provide reasonable assurance that fire would not jeopardize reactor safety (10 CFR 50.48 "Fire Protection" and Appendix R to 10 CFR 50). Since then, the results of plant operating experience, NRC inspection activities and cable fire testing programs have served to clarify the application of these requirements. In 2004, the NRC amended 10 CFR Part 50.48 to add a new subsection, 10 CFR 50.48(c), that endorses, with exceptions, the National Fire Protection Association's 805, "Performance-Based Standard for Fire Protection for Light Water Reactor Electric Generating Plants — 2001 Edition," as a voluntary alternative for demonstrating compliance with Appendix R. To date, approximately half of all operating plants have transitioned to a risk-informed approach under 10 CFR 50.48(c). Regardless of the selected approach, each operating nuclear power plant should establish a comprehensive fire protection program that includes features needed to minimize the likelihood and consequence of firesl. To achieve this objective, fire protection programs integrate the NRC's long-held safety concept of defense-in-depth (DID) by providing multiple barriers against potentially unacceptable consequences of fire. To minimize the frequency and size of fires, the first lines of defense include controls for fire prevention, such as controlling combustibles and ignition sources and fire mitigation features, such as fire detection and suppression systems. In the unlikely event that a fire should start and continue to grow in spite of these features, appropriate fire protection features, such as fire-rated barriers are provided as necessary to ensure the accomplishment of essential shutdown functions. This handbook was specifically developed for NRC inspectors that may be assigned to perform elements of Inspection Procedure (IP) 71111.05T, "Fire Protection (Triennial)," including, (a) "Protection of Safe Shutdown Capabilities," (e) "Alternative Shutdown Capability," and (f) "Circuit Analyses." Thus, the document concentrates solely on the final element of defense-in-depth— ensuring reactor safety will not be compromised in the event of a serious fire. In addition to describing how the NRC's regulatory framework has evolved since the Browns Ferry Fire, the handbook illustrates the content and scope of various analyses typically referenced in a plant's fire protection licensing basis and includes techniques and insights for assessing the plant's conformance to those criteria.
We review liquid hydrogen (LH2) as a maritime vessel fuel, from descriptions of its fundamental properties to its practical application and safety aspects, in the context of the San Francisco Bay Renewable Energy Electric Vessel with Zero Emissions (SF-BREEZE) high-speed fuel-cell ferry. Since marine regulations have been formulated to cover liquid natural gas (LNG) as a primary propulsion fuel, we frame our examination of LH2as a comparison to LNG, for both maritime use in general, and the SF-BREEZE in particular. Due to weaker attractions between molecules, LH2is colder than LNG, and evaporates more easily. We describe the consequences of these physical differences for the size and duration of spills of the two cryogenic fuels. The classical flammability ranges are reviewed, with a focus on how fuel buoyancy modifies these combustion limits. We examine the conditions for direct fuel explosion (detonation) and contrast them with initiation of normal (laminar) combustion. Direct fuel detonation is not a credible accident scenario for the SF-BREEZE. For both fuels, we review experiments and theory elucidating the deflagration to detonation transition (DDT). LH2fires have a shorter duration than energy-equivalent LNG fires, and produce significantly less thermal radiation. The thermal (infrared) radiation from hydrogen fires is also strongly absorbed by humidity in the air. Hydrogen permeability is not a leak issue for practical hydrogen plumbing. We describe the chemistry of hydrogen and methane at iron surfaces, clarifying their impact on steel-based hydrogen storage and transport materials. These physical, chemical and combustion properties are pulled together in a comparison of how a LH2or LNG pool fire on the Top Deck of the SF-BREEZE might influence the structural integrity of the aluminum deck. Neither pool fire scenario leads to net heating of the aluminum decking. Overall, LH2and LNG are very similar in their physical and combustion properties, thereby posing similar safety risks. For ships utilizing LH2or LNG, precautions are needed to avoid fuel leaks, minimize ignition sources, minimize confined spaces, provide ample ventilation for required confined spaces, and to monitor the enclosed spaces to ensure any fuel accumulation is detected far below the fuel/air mix threshold for any type of combustion.
This paper presents a risk assessment of a Liquefied Natural Gas (LNG)/diesel hybrid locomotive to identify and rank failures that could result in the release of LNG or Gaseous Natural Gas (GNG) to the surrounding environment. The Federal Railroad Administration (FRA) will analyze industry safety assessments of the proposed rail vehicles and the goal of this risk analysis is to identify and prioritize hazard scenarios so the FRA can ensure that they are properly addressed. For operational activities, a Failure Modes and Effects Analysis (FMEA) was performed to identify high risk failure modes. A modified hazard and operability study (HAZOP) methodology was used to analyze hazard scenarios for the maintenance activities for the LNG and Compressed Natural Gas (CNG) dual-fuel locomotives and the LNG tender car. Because refueling operations are highly dependent on human interactions, a human factors assessment was also performed on a sample refueling procedure to identify areas of improvement and identify best practices for analyzing future procedures. The FMEA resulted in the identification of 87 total failure modes for the operational phase, three of which were deemed to have a High risk priority, all involving the cryogenic storage tank. The HAZOP for the LNG tender resulted in the identification of eight credible hazard scenarios and the HAZOP for the locomotive in the maintenance mode identified 27 credible hazard scenarios. The high and medium risk failure modes and hazard scenarios should be prioritized for further analysis.
The objective of this research is to better understand the fire-induced failure modes of instrumentation cables and evaluate the potential effect those failure modes could have on plant instrumentation circuits (i.e., circuit, component, and/or system response). In particular, this research is intended to better quantify the signal leakage that may occur before catastrophic failure in instrumentation circuits.
A fire at a nuclear power plant (NPP) has the potential to damage structures, systems, and components important to safety, if not promptly detected and suppressed. At Browns Ferry Nuclear Power Plant on March 22, 1975, a fire in the reactor building damaged electrical power and control systems. Damage to instrumentation cables impeded the function of both normal and standby reactor coolant systems, and degraded the operators’ plant monitoring capability. This event resulted in additional NRC involvement with utilities to ensure that NPPs are properly protected from fire as intended by the NRC principle design criteria (i.e., general design criteria 3, Fire Protection). Current guidance and methods for both deterministic and performance based approaches typically make conservative (bounding) assumptions regarding the fire-induced failure modes of instrumentation cables and those failure modes effects on component and system response. Numerous fire testing programs have been conducted in the past to evaluate the failure modes and effects of electrical cables exposed to severe thermal conditions. However, that testing has primarily focused on control circuits with only a limited number of tests performed on instrumentation circuits. In 2001, the Nuclear Energy Institute (NEI) and the Electric Power Research Institute (EPRI) conducted a series of cable fire tests designed to address specific aspects of the cable failure and circuit fault issues of concern1. The NRC was invited to observe and participate in that program. The NRC sponsored Sandia National Laboratories to support this participation, whom among other things, added a 4-20 mA instrumentation circuit and instrumentation cabling to six of the tests. Although limited, one insight drawn from those instrumentation circuits tests was that the failure characteristics appeared to depend on the cable insulation material. The results showed that for thermoset insulated cables, the instrument reading tended to drift and fluctuate, while the thermoplastic insulated cables, the instrument reading fell off-scale rapidly. From an operational point of view, the latter failure characteristics would likely be identified as a failure from the effects of fire, while the former may result in inaccurate readings.
The objective of this project was to devolop a plan for modifying the Turbulent Combustion Laboratory (TCL) with the necessary infrastructure to produce a cold (near liquid temperature) hydrogen jet. The necessary infrastructure has been specified and laboratory modifications are currently underway. Once complete, experiments from this platform will be used to develop and validate models that inform codes and standards which specify protection criteria for unintended releases from liquid hydrogen storage, transport, and delivery infrastructure.
A cooperative research and development agreement was made between Linde, LLC and Sandia to develop a plan for modifying the Turbulent Combustion Laboratory (TCL) with the necessary infrastructure to produce a cold (near liquid temperature) hydrogen jet. A three-stage heat exchanger will be used to cool gaseous hydrogen using liquid nitrogen, gaseous helium, and liquid helium. A cryogenic line from the heat exchanger into the lab will allow high-fidelity diagnostics already in place in the lab to be applied to cold hydrogen jets. Data from these experiments will be used to develop and validate models that inform codes and standards which specify protection criteria for unintended releases from liquid hydrogen storage, transport, and delivery infrastructure.
Building a hydrogen infrastructure system is critical to supporting the development of alternate- fuel vehicles. This report provides a methodology for implementing a performance-based design of an outdoor hydrogen refueling station that does not meet specific prescriptive requirements in NFPA 2, The Hydrogen Technologies Code . Performance-based designs are a code-compliant alternative to meeting prescriptive requirements. Compliance is demonstrated by comparing a prescriptive-based fueling station design with a performance-based design approach using Quantitative Risk Assessment (QRA) methods and hydrogen risk assessment tools. This template utilizes the Sandia-developed QRA tool, Hydrogen Risk Analysis Models (HyRAM), which combines reduced-order deterministic models that characterize hydrogen release and flame behavior with probabilistic risk models to quantify risk values. Each project is unique and this template is not intended to account for site-specific characteristics. Instead, example content and a methodology are provided for a representative hydrogen refueling site which can be built upon for new hydrogen applications.
This project addresses the following technical barriers from the Safety, Codes and Standards section of the 2012 Fuel Cell Technologies Office Multi-Year Research, Development and Demonstration Plan (section 3.8): (A) Safety data and information: limited access and availability (F) Enabling national and international markets requires consistent RCS (G) Insufficient technical data to revise standards.
Sandia National Laboratories evaluated published safety assessment methods across a variety of industries including Liquefied Natural Gas (LNG), hydrogen, land and marine transportation, as well as the US Department of Defense (DOD). All the methods were evaluated for their potential applicability for use in the LNG railroad application. After reviewing the documents included in this report, as well as others not included because of repetition, the Department of Energy (DOE) Hydrogen Safety Plan Checklist is most suitable to be adapted to the LNG railroad application. This report was developed to survey industries related to rail transportation for methodologies and tools that can be used by the FRA to review and evaluate safety assessments submitted by the railroad industry as a part of their implementation plans for liquefied or compressed natural gas storage ( on-board or tender) and engine fueling delivery systems. The main sections of this report provide an overview of various methods found during this survey. In most cases, the reference document is quoted directly. The final section provides discussion and a recommendation for the most appropriate methodology that will allow efficient and consistent evaluations to be made. The DOE Hydrogen Safety Plan Checklist was then revised to adapt it as a methodology for the Federal Railroad Administration’s use in evaluating safety plans submitted by the railroad industry.
This report presents the results of a series of cable fire-retardant coating tests sponsored by the US Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research and performed at Sandia National Laboratories in conjunction with the National Institute of Standards and Technology (NIST). The goal of the tests was to assess the effects of three commercially available fire-retardant cable coating materials on cable thermal and electrical response behavior under fire-exposure conditions. The specific test objectives were to assess, under severe radiant heating conditions, how the coating materials impacted (1) cable thermal response and (2) electrical integrity behavior. The tests were not explicitly designed to assess the impact of the coatings on cable flammability, although some insights relative to the burning behavior of the coating materials themselves and cable ignition times were gained. NIST is currently investigating these attributes under the Cable Heat Release, Ignition, and Spread in Tray Installations During Fire (CHRISTIEFIRE) program (NUREG/CR-7010). The cables used in construction of the test articles were all seven-conductor 12AWG (American wire gage) control or power type copper conductor electrical cables. Two cable insulation types were represented, a polyethylene thermoplastic material and a cross-linked polyethylene thermoset material. Both cable types used have been tested extensively in recent NRC-sponsored experimental programs involving both circuit failure modes and effects testing and fire growth testing. The test articles included uncoated cables and cables coated with one of three fire-retardant coating materials: Carboline Intumastic 285, Flamemastic F-77, and Vimasco 3i. Test configurations included single lengths of cables, bundles of seven cables, and bundles of ten cables. The tests show that, under certain conditions, the fire-retardant coatings provide a substantial benefit relative to delays in cable heating, ignition and electrical failure times. However, as has been seen in prior test programs, the performance varied substantially among the coating products. The current tests also show that the benefit gained by the coatings was heavily dependent on the thermal mass of the coated cable system. Low thermal mass systems, such as the single lengths of coated cable, saw essentially no net benefit from application of the coatings. Intermediate mass systems, represented by the seven-cable bundles, saw some benefit from application of the coatings, but the benefit was inconsistent, and some cables in the bundles saw essentially no delay in thermal response or time to failure. For the larger thermal mass systems, represented by the ten-cable bundles, the benefit of the coatings was both more pronounced and more consistent with all coatings providing a measurable benefit.
Automakers and fuel providers have made public commitments to commercialize light duty fuel cell electric vehicles and fueling infrastructure in select US regions beginning in 2014. The development, implementation, and advancement of meaningful codes and standards is critical to enable the effective deployment of clean and efficient fuel cell and hydrogen solutions in the energy technology marketplace. Metrics pertaining to the development and implementation of safety knowledge, codes, and standards are important to communicate progress and inform future R&D investments. This document describes the development and benchmarking of metrics specific to the development of hydrogen specific codes relevant for hydrogen refueling stations. These metrics will be most useful as the hydrogen fuel market transitions from pre-commercial to early-commercial phases. The target regions in California will serve as benchmarking case studies to quantify the success of past investments in research and development supporting safety codes and standards R&D.
Safety standards development for maintenance facilities of liquid and compressed gas fueled large-scale vehicles is required to ensure proper facility design and operation envelopes. Standard development organizations are utilizing risk-informed concepts to develop natural gas vehicle (NGV) codes and standards so that maintenance facilities meet acceptable risk levels. The present report summarizes Phase I work for existing NGV repair facility code requirements and highlights inconsistencies that need quantitative analysis into their effectiveness. A Hazardous and Operability study was performed to identify key scenarios of interest. Finally, scenario analyses were performed using detailed simulations and modeling to estimate the overpressure hazards from HAZOP defined scenarios. The results from Phase I will be used to identify significant risk contributors at NGV maintenance facilities, and are expected to form the basis for follow-on quantitative risk analysis work to address specific code requirements and identify effective accident prevention and mitigation strategies.