France

In the frame of a sustainable development investigations dealing with massive Hydrogen production by means of nuclear heating are carried out at CEA. For nuclear safety thermodynamic efficiency and waste minimization purposes the technological solution privileged is the coupling of a gas cooled Very High Temperature Reactor (VHTR) with a plant producing Hydrogen from an Iodine/Sulfur (I/S) thermochemical cycle. Each of the aforementioned facilities presents different risks resulting from the operation of a nuclear reactor (VHTR) and from a chemical plant including Hydrogen other flammable and/or explosible substances as well as toxic ones. Due to these various risks the safety approach is an important concern. Therefore this paper deals with the preliminary CEA investigations on the safety issues devoted to the whole plant focusing on the safety questions related to the coupling between the nuclear reactor and the Hydrogen production facility. Actually the H2 production process and the energy distribution network between the plants are currently at a preliminary design stage. A general safety approach is proposed based on a Defence In Depth (DID) principle permitting to analyze all the system configurations successively in normal incidental and accidental expected operating conditions. More precisely the dynamic answer of an installation to a perturbation affecting the other one during the previous conditions as well as the potential aggressions of the chemical plant towards the nuclear reactor have to be considered. The methodology presented in this paper is intended to help the designer to take into account the coupling safety constraints and to provide some recommendations on the global architecture of both plants especially on their coupling system. As a result the design of a VHTR combined to a H2 production process will require an iterative process between design and safety requirements.

The paper presents an overview of the main achievements of the internal project InsHyde of the HySafe NoE. The scope of InsHyde was to investigate realistic small-medium indoor hydrogen leaks and provide recommendations for the safe use/storage of indoor hydrogen systems. Additionally InsHyde served to integrate proposals from HySafe work packages and existing external research projects towards a common effort. Following a state of the art review InsHyde activities expanded into experimental and simulation work. Dispersion experiments were performed using hydrogen and helium at the INERIS gallery facility to evaluate short and long term dispersion patterns in garage like settings. A new facility (GARAGE) was built at CEA and dispersion experiments were performed there using helium to evaluate hydrogen dispersion under highly controlled conditions. In parallel combustion experiments were performed by FZK to evaluate the maximum amount of hydrogen that could be safely ignited indoors. The combustion experiments were extended later on by KI at their test site by considering the ignition of larger amounts of hydrogen in obstructed environments outdoors. An evaluation of the performance of commercial hydrogen detectors as well as inter-lab calibration work was jointly performed by JRC INERIS and BAM. Simulation work was as intensive as the experimental work with participation from most of the partners. It included pre-test simulations validation of the available CFD codes against previously performed experiments with significant CFD code inter-comparisons as well as CFD application to investigate specific realistic scenarios. Additionally an evaluation of permeation issues was performed by VOLVO CEA NCSRD and UU by combining theoretical computational and experimental approaches with the results being presented to key automotive regulations and standards groups. Finally the InsHyde project concluded with a public document providing initial guidance on the use of hydrogen in confined spaces.

The paper presents the results of the CFD inter-comparison exercise SBEP-V3 performed within the activity InsHyde internal project of the HYSAFE network of excellence in the framework of evaluating the capability of various CFD tools and modelling approaches in predicting the physical phenomena associated to the short and long term mixing and distribution of hydrogen releases in confined spaces. The experiment simulated was INERIS-TEST-6C performed within the InsHyde project by INERIS consisting of a 1 g/s vertical hydrogen release for 240 s from an orifice of 20 mm diameter into a rectangular room (garage) of dimensions 3.78x7.2x2.88 m in width length and height respectively. Two small openings at the front and bottom side of the room assured constant pressure conditions. During the test hydrogen concentration time histories were measured at 12 positions in the room for a period up to 5160 s after the end of release covering both the release and the subsequent diffusion phases. The benchmark was organized in two phases. The first phase consisted of blind simulations performed prior to the execution of the tests. The second phase consisted of post calculations performed after the tests were concluded and the experimental results made available. The participation in the benchmark was high: 12 different organizations (2 non-HYSAFE partners) 10 different CFD codes and 8 different turbulence models. Large variation in predicted results was found in the first phase of the benchmark between the various modelling approaches. This was attributed mainly to differences in turbulence models and numerical accuracy options (time/space resolution and discretization schemes). During the second phase of the benchmark the variation between predicted results was reduced.

For safety issues related to the storage of hydrogen under high pressure it is necessary to determine how the gas is released in the case of failure. In particular there exist limited quantitative information on the near-field properties of the gas jets which are important for establishing proper decay laws in the far-field. This paper reports recent CFD results for air and helium obtained in the near-field of the highly under-expanded jets. The gas jets are released from a 30-bar tank with the same opening (orifice). The Reynolds number based on the diameter of the orifice and corresponding gas conditions at the exit was well beyond 106 . The 3D Compressible Multi-Component Navier-Stokes equations were solved directly without relying on the compressibility-corrected turbulence models. The numerical model was initially tested on a one-component (air-air) case where a few aerospace-driven data sets are available for validation. The shock geometry is characterized through the Mach disk position and diameter. These are compared to the results known from the literature and to the scaling laws developed based on the dimensional analysis. In the second two-component (helium-air) jet scenario the density field was validated and examined together with other fields in the attempt to suggest potential initial conditions for the forthcoming far-field simulations.

With the development of technologies in recent decades and the imposition of international standards to reduce greenhouse gas emissions car manufacturers have turned their attention to new technologies related to electric/hybrid vehicles and electric fuel cell vehicles. This paper focuses on electric fuel cell vehicles which optimally combine the fuel cell system with hybrid energy storage systems represented by batteries and ultracapacitors to meet the dynamic power demand required by the electric motor and auxiliary systems. This paper compares the latest proposed topologies for fuel cell electric vehicles and reveals the new technologies and DC/DC converters involved to generate up-to-date information for researchers and developers interested in this specialized field. From a software point of view the latest energy management strategies are analyzed and compared with the reference strategies taking into account performance indicators such as energy efficiency hydrogen consumption and degradation of the subsystems involved which is the main challenge for car developers. The advantages and disadvantages of three types of strategies (rule-based strategies optimization-based strategies and learning-based strategies) are discussed. Thus future software developers can focus on new control algorithms in the area of artificial intelligence developed to meet the challenges posed by new technologies for autonomous vehicles.

Hydrogen (H₂) shows great promise as zero-carbon emission fuel but there are several challenges to overcome in regards to storage and transportation to make it a more universal energy solution. Gaseous hydrogen requires high pressures and large volume tanks while storage of liquid hydrogen requires cryogenic temperatures; neither option is ideal due to cost and the hazards involved. Storage in the solid state presents an attractive alternative and can meet the U.S. Department of Energy (DOE) constraints to find materials containing > 7 % H₂ (gravimetric weight) with a maximum H₂ release under 125 °C.

While there are many candidate hydrogen storage materials the vast majority are metal hydrides. Of the hydrides this review focuses solely on sodium borohydride (NaBH4) which is often not covered in other hydride reviews. However as it contains 10.6% (by weight) H₂ that can release at 133 ± 3 JK−1mol⁻¹ this inexpensive material has received renewed attention. NaBH4 should decompose to H₂g) Na(s) and B(s) and could be recycled into its original form. Unfortunately metal to ligand charge transfer in NaBH4 induces high thermodynamic stability creating a high decomposition temperature of 530 °C. In an effort make H₂ more accessible at lower temperatures researchers have incorporated additives to destabilize the structure.

This review highlights metal additives that have successfully reduced the decomposition temperature of NaBH₄ with temperatures ranging from 522 °C (titanium (IV) fluoride) to 379 °C (niobium (V) fluoride). We describe synthetic methods employed chemical pathways taken and the challenges of boron derivative formation on H₂ cycling. Though no trends can be found across all additives it is our hope that compiling the data here will enable researchers to gain a better understanding of the additives’ influence and to determine how a new system might be designed to make NaBH4 a more viable H2 fuel source.

The approach developed aims to identify the methodology that will be used to deliver the minimum cost for hydrogen infrastructure deployment using a mono-objective linear optimisation. It focuses on minimizing both capital and operation costs of the hydrogen transportation based on transportation via truck which represents the main focus of this paper and a cost-minimal pipeline system in the case of France and Germany. The paper explains the mathematical model describing the link between the hydrogen production via electrolysers and the distribution for mobility needs. The main parameters and the assumed scenario framework are explained. Subsequently the transportation of hydrogen via truck using different states of aggregation is analysed as well as the transformation and storage of hydrogen. This is used finally to build a linear programming aiming to minimize the sum of costs of hydrogen transportation between the different nodes and transformation/storage within the nodes.

The objective of this project is to take into account the mechanical constraints formed by diffusion of hydrogen or tritium in watertight palladium alloy cathode. To know the origin of these it was necessary to discriminating the damaging effects encountered. Effectively hydrogen and isotope induce deformation embrittlement stress corrosion cracking and cathodic corrosion in different regions of cathode. Palladium can be alloyed with silver or yttrium to favourably increase diffusion and reduce these constraints. Effects of electrochemical factors temperature cathode structure adsorbed transient complex of palladium and porous material support are given to estimate and to limit possible damage.

We present results from hydrogen dispersion simulations from a pressurized reservoir at constant flow rate in the presence and absence of a wall. The dispersion simulations are performed using a commercial finite volume solver. Validation of the approach is discussed. Constant concentration envelopes corresponding to the 2% 4% and 15% hydrogen concentration in air are calculated for a subcritical vertical jet and for an equivalent subcritical horizontal jet from a high pressure reservoir. The consequences of ignition and the resulting overpressure are calculated for subcritical horizontal and vertical hydrogen jets and in the latter case compared to available experimental data.

The manuscript firstly describes the data collection and validation process for the European Hydrogen Incidents and Accidents Database (HIAD 2.0) a public repository tool collecting systematic data on hydrogen-related incidents and near-misses. This is followed by an overview of HIAD 2.0 which currently contains 706 events. Subsequently the approaches and procedures followed by the authors to derive lessons learned and formulate recommendations from the events are described. The lessons learned have been divided into four categories including system design; system manufacturing installation and modification; human factors and emergency response. An overarching lesson learned is that minor events which occurred simultaneously could still result in serious consequences echoing James Reason's Swiss Cheese theory. Recommendations were formulated in relation to the established safety principles adapted for hydrogen by the European Hydrogen Safety Panel considering operational modes industrial sectors and human factors. This work provide an important contribution to the safety of systems involving hydrogen benefitting technical safety engineers emergency responders and emergency services. The lesson learned and the discussion derived from the statistics can also be used in training and risk assessment studies being of equal importance to promote and assist the development of sound safety culture in organisations.