The contribution of nuclear hydrogen safety knowledge to emerging hydrogen technologies

TThe transformation of the energy sector away from fossil fuels is underway worldwide. In addition to CO2-free nuclear energy generation, the focus is on the increased use of so-called renewable energy sources such as water, sun and wind. In order to enable the technical use of these in parts highly fluctuating sources, energy storage technologies will be of particular importance in the future. Hydrogen is generally regarded as a future energy carrier due to its suitability as energy storage as well as a fuel. The foreseeable large-scale application of hydrogen raises questions of safety-related nature. 

Hydrogen safety has played an important role in the context of water-cooled nuclear power plants for decades. At least since the TMI reactor accident in 1979, significant efforts have been made internationally in industry and research to investigate open safety issues and to develop and implement suitable preventive and mitigative measures. This expertise is now at hand to play a significant role in the risk assessment of current and future hydrogen technologies. 

In fact, expertise from the nuclear community is in demand when hydrogen safety needs to be ensured. This is reflected by the key participation of institutions with originally nuclear background in safety-related projects. Some of these projects are presented in the paper: 

1. Within the Team “Hydrogen Safety” in the Living Lab Energy Campus (LLEC) at Forschungszentrum Jülich, knowledge in the field of hydrogen distribution and mitigation is used to analyse hydrogen leakage scenarios in large scale installations. 
2. Methodologies developed to assess the hydrogen explosion risk in nuclear power plants are used in the German-French-Japanese STACY project (Towards safe storage and transportation of cryogenic hydrogen) to enhance the safety in maritime transportation of liquid hydrogen. 
3. In NPHyCo, the feasibility of hydrogen generation near a nuclear power plant will be investigated. In this project, GRS is working on the licensing requirements and safety-related impacts of hydrogen cogeneration. In addition, GRS is investigating the effects of a possible explosion pressure wave on the immediate vicinity of the electrolyser. 
4. The hydrogen department at the Institute for Thermal Energy Technology and Safety of the Karlsruhe Institute of Technology (KIT-ITES) was funded to investigate theoretically and experimentally the hazards connected with hydrogen in NPPs. In the last decade its activities shifted strongly towards hazard evaluations of non-homogeneous, partially confined mixtures and towards safety assessment of cryogenic hydrogen for the up-scaling of hydrogen as an energy carrier. 

This paper describes the increasing interest in hydrogen technologies and corresponding safety challenges. It gives an overview of hydrogen safety expertise within the nuclear community. Finally, several examples demonstrate how nuclear expertise is used in current hydrogen safety projects.