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Hydrogen refueling stations (HRS) operating at high pressures pose a higher risk of leakage than conventional gas stations. Therefore, in this study, a quantitative risk assessment (QRA) was conducted using DNV-GL SAFETI v.8.9. The impact of the shutoff valve was quantitatively assessed, and step-by-step mitigation was applied to propose the minimum installation requirements for the valve necessary to achieve broadly acceptable risk levels. The QRA includes sequence analysis (CA), individual risk (IR), and societal risk (SR), with accident scenarios consisting of catastrophic ruptures and three leak scenarios. The research results indicate that the application of a dual shutoff valve system resulted in an IR of 7.48 × 10−5, effectively controlling the risk below the as low as reasonably practicable (ALARP) criteria of the Health and Safety Executive (HSE). The SR was analyzed based on the ALARP criteria in the Netherlands, and the application of the dual shutoff valve system effectively controlled the risk below the ALARP criteria. Consequently, this study suggests that applying a dual shutoff valve system with a mitigation value exceeding 1.21 × 10−2 can successfully mitigate the risk of urban hydrogen refueling stations to broadly acceptable levels. [ABSTRACT FROM AUTHOR]

The average temperature of the Earth has risen due to the accumulation of greenhouse gases emitted from the usage of fossil fuels. The consequential climate changes have caused various problems, fueling the growing demand for environmentally friendly energy sources that can replace fossil fuels. Batteries and hydrogen have thus been utilized as substitute energy sources for automobiles to reduce fossil fuel consumption. Consequently, the number of hydrogen refueling stations is increasing due to an increase in the number of hydrogen-powered vehicles. However, several incidents have been reported in the United States of America and Japan where hydrogen refueling stations have been operating for a long time. A risk assessment of hydrogen refueling stations operating in urban areas was performed in this study by calculating the risk effect range using a process hazard analysis tool (PHAST) v8.7 from DNV-GL and a hydrogen risk assessment model (HyRAM) from Sandia National Laboratories (SNL). The societal risk was assessed through a probit model based on the calculation results. The assessment results showed that the risk caused by jet fire and overpressure in an incident is lower than the 'as low as reasonably practicable' (ALARP) level. [ABSTRACT FROM AUTHOR]

After the Paris Agreement was signed in 2015, many countries worldwide focused on the hydrogen economy, aiming for eco-friendly and renewable energy by moving away from the existing carbon economy, which has been the primary source of global warming. Hydrogen is the most common element on Earth. As a light substance, hydrogen can diffuse quickly; however, it also has a small risk of explosion. Representative explosion accidents have included the Muskingum River Power Plant Vapor Cloud Explosion accident in 2007 and the Silver Eagle Refinery Vapor Cloud Explosion accident in 2009. In addition, there was an explosion in a hydrogen tank in Gangneung, Korea, in May 2019, and a hydrogen refueling station (HRS) in Norway exploded in 2018. Despite this risk, Korea is promoting the establishment of HRSs in major urban centers, including downtown areas and public buildings, by using the Regulatory Sandbox to install HRSs. This paper employed the Hydrogen Risk Assessment Model (HyRAM) of Sandia National Laboratories (SNL), a quantitative risk assessment (QRA) program specialized in hydrogen energy for HRSs installed in major urban hubs. A feasibility evaluation of the site conditions of an HRS was conducted using the French land use planning method based on the results obtained through evaluation using the HyRAM and the overpressure results of PHAST 8.0. After a risk assessment, we confirmed that an HRS would be considered safe, even if it was installed in the city center within a radius of influence of jet fires and overpressure. [ABSTRACT FROM AUTHOR]

In the semiconductor industry, hydrogen is used with many other hazardous and dangerous substances with flammable, toxic, and corrosive properties. In order to safely handle them, convenient-to-use gas cabinets are often required. As known well, hydrogen is highly flammable and explosive, and risk analysis needs to safely use the gas in the cabinets. In this study, overpressure and impact according to various gas cabinet conditions were measured when hydrogen leaks in the gas cabinet, and the effect of overpressure on the protective wall was simulated. For the research, a demonstration experiment was conducted by custom manufacturing a gas cylinder cabinet identical to the standard used in the field, and the protection performance analysis was performed by reverse-engineering it through 3D scanning. As a result of the demonstration experiment, the maximum pressure at the time of hydrogen gas explosion in the gas cylinder cabinet was measured at 0.3 bar. After calculating the detonation pressure propagation profile using the TNT equivalence method, the protective performance of the protective wall was confirmed using AUTODYN. The maximum stress of the concrete and the maximum stress of the reinforcing bar due to the explosion in the gas cylinder cabinet were calculated to be 30.211 MPa and 112.88 MPa, respectively, which do not exceed the tensile strength of concrete and the yield strength of the reinforcing bar. This result is expected to be of great help to the development of the semiconductor industry by suggesting the rationale for mitigating the firewall when changing the semiconductor layout. [ABSTRACT FROM AUTHOR]

Due to numerous hazardous chemicals to handle, the process plant industry has a higher risk of fire, explosion, and toxic release than other industries. Reviewing the accidents at process plants in the past, it is clear that fire accidents occur with the highest frequency, leading this study to consider accidental fire scenarios at process plants. For the scenario of an incident, a jet fire involving a massive amount of hydrogen gas to be processed or delivered at the process plant has been selected. The analysis of incident outcome resulting from the hydrogen jet fire has been implemented through the computational fluid dynamics simulation methodology Kameleon FireEx. Based on the outcome of this simulation, the consequences of a jet fire with high temperature and heat radiation are analyzed and evaluated. In addition, the results from Phast ver. 7.11 simulation for the same scenario are presented for comparison and further validation. [ABSTRACT FROM AUTHOR]

The primary purpose of a flare model is to provide a reasonably accurate prediction of radiant heat flux at any point of interest around the flame in order to be able to define safe release locations. In order to do this, a flare model needs to provide a good prediction of the following critical flame parameters: flame length, flame tilt, and radiant heat fraction, including the impact of wind and release orientation on these parameters. In addition, the model needs to distribute the radiant heat along the flame in a reasonably realistic way and to allow for the transmissivity of the ambient air. Industry standard models for vertical flares include Chamberlain [Chamberlain, Chem Eng Res Des 65 (1987)], API 521 [API STANDARD 521, Pressure-Relieving and Depressuring Systems, 6th Edition, American Petroleum Institute, Washington DC, 2014], and Brzustowski & Sommer [API STANDARD 521, Pressure-Relieving and Depressuring Systems, 6th Edition, American Petroleum Institute, Washington DC, 2014]. These models were originally developed primarily based on hydrocarbon data. Several commercially available consequence models allow the use of these models for all flammable materials. Due to the lack of other options, these commercially available consequence software models are often applied to hydrogen, syngas (hydrogen/carbon monoxide mixtures), and other materials that are well outside the intended scope of the models. A review has been performed to evaluate applicability of the Chamberlain, API 521, and Brzustowski & Sommer models to hydrogen and syngas, including comparison with limited published data. As a result of this review, a number of significant concerns have been identified. This has led to initiation of a new test program to collect data specifically for hydrogen and syngas and the subsequent development of new models. © 2014 American Institute of Chemical Engineers Process Saf Prog 34: 141-146, 2015 [ABSTRACT FROM AUTHOR]

Hydrogen is a critical component in the production of cleaner fuels. Underground pipelines provide a safe, reliable supply of hydrogen to refineries and the petroleum industry. Proper assessment of the risks associated with underground hydrogen pipelines requires an accurate model of the jet fire consequence. This article will describe experimental and modeling work undertaken in order to define the appropriate methodology for utilizing DNV's PHAST software tool to represent the hydrogen jet fire from the rupture of underground hydrogen pipelines. Two experiments were conducted to measure the flow and radiation from an intentionally ignited rupture of a 6 in. diameter, 60 barg hydrogen pipeline buried 1 m underground. Adjustments to PHAST modeling parameters were required in order to obtain agreement between the measured and predicted radiation and flame length values. The modeling assumptions and parameter adjustments include: Velocity modification to account for interaction of the flow out of the two ends of the ruptured pipe and to model the subsequent discharge from the crater., Specification of the fraction of heat radiated., Specification of the angle of the release., © 2013 American Institute of Chemical Engineers Process Saf Prog, 2013 [ABSTRACT FROM AUTHOR]

There has been an increase in environmental degradation associated with the use of fossil fuels in an attempt to meet the ever-increasing demand for electricity. Therefore, alterative renewable energy sources have garnered the attention of many researchers globally; hydrogen is an important example due to its eco-friendly nature. For hydrogen to be used as an energy source, it has to first be compressed. The explosion of high-pressure hydrogen vessels has been the driver of most accidents associated with its use. To prevent explosions, thermally activated pressure relief devices (TPRDs) are used to release hydrogen. The TPRD release orientations in a tunnel, which is a confined space, were investigated in this study based on a high-pressure release of hydrogen. In addition, we also propose an evacuation and safety protocol in the event of such an accident. In addition, the dynamics associated with the release of hydrogen were analyzed based on vehicle type. We found that in passenger cars and buses, hydrogen is released from the bottom and top, respectively. The dispersion range in this study was simulated based on a hydrogen concentration of 4%, in which air currents, including those from jet fans in the tunnel, are considered. The results confirm that passenger cars are barely affected by the jet fan airflow, and backward release facilitates evacuation and secures a safety zone more effectively compared with vertical emission. Meanwhile, upward releases were significantly affected by the jet fan. Overall, release in the airflow direction, regardless of the tunnel location, was confirmed to be effective in the context of evacuation and securing safety zones for buses. • Consequence analysis for Thermally-activated Pressure Relief Devices of HFCVs. • Thorough CFD simulations to help the decision-making for emergency responders. • Open space and confined space hazards comparison for different vehicle types. • Open space and confined space hazards comparison for different TPRD release angles. [ABSTRACT FROM AUTHOR]