Safety is an essential element for realizing the hydrogen economy safe operation in all of its aspects from hydrogen production through storage, distribution and use; from research, development and demonstration to commercialization. As such, safety is given paramount importance in all facets of the research, development and demonstration of the U.S Department of Energy s (DOE) Hydrogen, Fuel Cells and Infrastructure Technologies (HFCIT) Program Office. The diversity of the DOE project portfolio is self-evident. Projects are performed by large companies, small businesses, DOE National Laboratories, academic institutions and numerous partnerships involving the same. Projects range from research exploring advances in novel hydrogen storage materials to demonstrations of hydrogen refueling stations and vehicles. Recognizing the nature of its program and the importance of safety planning, DOE has undertaken a number of initiatives to encourage and shape safety awareness. The DOE Hydrogen Safety Review Panel was formed to bring a broad cross-section of expertise from the industrial, government and academic sectors to help ensure the success of the program as a whole. The Panel provides guidance on safety-related issues and needs, reviews individual DOE-supported projects and their safety plans and explores ways to bring learnings to broadly benefit the DOE program. This paper explores the approaches used for providing safety planning guidance to contractors in the context of their own (and varied) policies, procedures and practices. The essential elements that should be included in safety plans are described as well as the process for reviewing project safety plans. Discussion of safety planning during the conduct of safety review site visits is also shared. Safety planning-related learnings gathered from project safety reviews and the Panel s experience in reviewing safety plans are discussed.

Burning hydrogen emits thermal radiation in UV, NIR and IR spectral range. Especially, in the case of large cloud explosion, the risk of heat radiation is commonly underestimated due to the non-visible flame of hydrogen-air combustion. In the case of a real explosion accident organic substances or inert dust might be entrained from outer sources to produce soot or heated solids to substantially increase the heat release by continuum radiation. To investigate the corresponding combustion phenomena, different hydrogen-air mixtures were ignited in a closed vessel and the combustion was observed with fast scanning spectrometers using a sampling rate up to 1000 spectra/s. In some experiments, to take into account the influence of organic co-combustion, a spray of a liquid glycol-ester and milk powder was added to the mixture. The spectra evaluation uses the BAM code of ICT to model bands of reaction products and thus to get the temperatures. The code calculates NIR/IR-spectra (1 - 10 m) of non-homogenous gas mixtures of H2O, CO2, CO, NO and HCl taking into consideration also emission of soot particles. It is based on a single line group model and makes also use of tabulated data of H2O and CO2 and a Least Squares Fit of calculated spectra to experimental ones enables the estimation of flame temperatures. During hydrogen combustion OH emits an intense spectrum at 306 nm. This intermediary radical allows monitoring the reaction progress. Intense water band systems between 1.2 and 3 m emit remarkable amounts of heat radiation according to a measured flame temperature of 2000 K. At this temperature broad optically-thick water bands between 4.5 m and 10 m contribute only scarcely to the total heat output. In case of co-combustion of organic materials, additional emission bands of CO and CO2 as well as a continuum radiation of soot and other particles occur and particularly increase the total thermal output drastically.

About 20 years ago Fraunhofer ICT has performed large scale experiments with premixed hydrogen air mixtures [1]. A special feature has been the investigation of the combustion of the mixture within a partial confinement, simulating some sort of a lane , which may exist in reality within a hydrogen production or storage plant for example. Essentially three different types of tests have been performed: combustion of quiescent mixtures, combustion of mixtures with artificially generated turbulence by means of a fan and combustion of mixtures with high speed flame jet ignition. The observed phenomena will be discussed on the basis of measured turbulence levels, flame speeds, and overpressures. Conditions for DDT concerning critical turbulence levels and flame speeds as well as a scaling rule for DDT related to the detonation cell size of the mixture can be derived from the experiments for this special test setup. The relevance of the results with respect to safety aspects of future hydrogen technology is assessed. Combustion phenomena will be highlighted by the presentation of impressive high speed film videos.

No paper available. Presented oral only.

The large eddy simulation (LES) model developed at the University of Ulster has been applied to simulate releases of 5.11 M3 liquefied (LH2) in open atmosphere and gaseous hydrogen (GH2) in 20-m3 closed vessel. The simulations of a spill of liquefied hydrogen confirmed the advantage of LES application to reproduce experimentally observed eddy structure of hydrogen-air cloud.

Numerical simulations are carried out for a highly under-expanded hydrogen jet resulting from an accidental release of high-pressure hydrogen into the atmospheric environment. The predictions are made using two independent CFD codes, namely CFX and KIVA. The KIVA code has been substantially modified by the present authors to enable large eddy simulation (LES). It employs a one-equation sub-grid scale (SGS) turbulence model, which solves the SGS kinetic energy equation to allow for more relaxed equilibrium requirement and to facilitate high fidelity LES calculations with relatively coarser grids. Instead of using the widely accepted pseudo-source approach, the complex shock structures resulting from the high under-expansion is numerically resolved in a small computational domain above the jet exit. The computed results are used as initial conditions for the subsequent hydrogen jet simulation. The predictions provide insight into the shock structure and the subsequent jet development. Such knowledge is valuable for studying the ignition characteristics of high-pressure hydrogen jets in the safety context.

We have investigated hydrogen explosion risk and its mitigation, focusing on compact hydrogen refueling stations in urban areas. In this study, numerical analyses were performed of hydrogen blast propagation and the structural behavior of barrier walls. Parametric numerical simulations of explosions were carried out to discover effective shapes for blast-mitigating barrier walls. The explosive source was a prismatic 5.27 m3 volume that contained 30%2hydrogen and 70%2air. A reinforced concrete wall, 2 m tall by 10 m wide and 0.15 m thick, was set 2 or 4 m away from the front surface of the source. The source was ignited at the bottom center by a spark for the deflagration case and 10 g of C-4 high explosive for two detonation cases. Each of the tests measured overpressures on the surfaces of the wall and on the ground, displacements of the wall and strains of the rebar inside the wall. The blast simulations were carried out with an in-house CFD code based on the compressive Euler equation. The initial energy estimated from the volume of hydrogen was a time-dependent function for the deflagration and was released instantaneously for the detonations. The simulated overpressures were in good agreement with test results for all three test cases. DIANA, a finite element analysis code released by TNO, was used for the structural simulations of the barrier wall. The overpressures obtained by the blast simulations were used as external forces. The analyses simulated the displacements well, but not the rebar strains. The many shrinkage cracks that were observed on the walls, some of which penetrated the wall, could make it difficult to simulate the local behavior of a wall with high accuracy and could cause strain gages to provide low-accuracy data. A parametric study of the blast simulation was conducted with several cross-sectional shapes of barrier wall. A T-shape and a Y-shape were found to be more effective in mitigating the blast.

The method of the numerical solution of a three-dimensional problem of atmospheric release, dispersion and explosion of gaseous admixtures is presented. It can be equally applied for gases of different densities, including hydrogen. The system of simplified Navier-Stocks equations received by truncation of viscous members (Euler equations with source members) is used to obtain a numerical solution. The algorithm is based on explicit finite-difference Godunov scheme of arbitrary parameters breakup disintegration. To verify the developed model and computer system comparisons of numerical calculations with the published experimental data on dispersion of methane and hydrocarbons explosions have been carried out. Computational experiments on evaporation and dispersion of spilled liquid hydrogen and released gaseous hydrogen at different wind speeds have been conducted. The largest mass concentrations of hydrogen between bottom and top limits of flame propagation and cloud borders have been determined. The problem of explosion of hydrogen-air cloud of the complex form generated by large-scale spillage of liquid hydrogen and instant release of gaseous hydrogen has been numerically solved at low wind speed. Shock-wave loadings affecting the buildings located on distance of 52 m from a hydrogen release place have been shown.

The present work proposes a novel safe method for obtaining metallic hydrides. The method is calledSHS (Self-Propagating High temperature synthesis). A novel high pressure gas reactor governed by an electromechanical control device has been designed and built up in order to synthesise metallic hydrides. This system is provided with a control system that allows calculating the amount of gas coming into the reaction vessel at every stage of the process. The main feature of this method is that metallic hydrides can be safely synthesised using low gas reaction pressures. In order to validate the assessing system the main kinetic regularities of SHS in Ti-H2 system were studied. In addition phase analysis (by means of X ray diffraction) as well as chemical analysis have been performed.

A suitably trained emergency response force is an essential component for safe implementation of any type of fuel infrastructure. Because of the relative newness of hydrogen as a fuel, however, appropriate emergency response procedures are not yet well understood by responder workforces across the United States and around the world. A significant near-term training effort is needed to ensure that the future hydrogen infrastructure can be developed and operated with acceptable incident risk. Efforts are presently underway at the HAMMER site in Washington State to develop curricula related to hydrogen properties and behavior, identification of problems (e.g., incorrect equipment installation) and appropriate response, and other relevant information intended for classroom instruction. In addition, a number of hands-on training props are planned for realistic simulation of hydrogen incidents in order to convey proper response procedures in high-pressure, cryogenic, high-leakage or other high-risk accident situations. Surveys of emergency responders, fire marshals, regulatory authorities, manufacturers and others are being undertaken to ensure that the capabilities developed and offered at HAMMER will meet the acknowledged need. This paper describes the training curricula and props anticipated at HAMMER, and is intended to provide useful information to others planning similar training programs.