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Hydrogen Production
Published in Herbert F. Mataré, Energy: Facts and Future, 1989
Justi and Bockris1 point out that hydrogen can be the basis for a new energy industry and that the costs for hydrogen transport are by far lower than electricity transfer through high-voltage lines or especially cables. Also, in special cases liquid hydrogen can be stored and transported.2 The idea to combine solar-electric energy with hydrogen production has been discussed by many authors and is a logical plan for the future.3
Considerations for Hydride Moderator Readiness in Microreactors
Published in Nuclear Technology, 2023
M. Nedim Cinbiz, Chase N. Taylor, Erik Luther, Holly Trellue, John Jackson
The design of the moderator can follow several options. The metal hydride can be a zirconium- or yttrium-base material or their alloys. The metal hydride can be bonded with the cladding or vice versa. Furthermore, a plenum volume can be present with hydrogen and noble gases. All these combinations affect the hydrogen transport characteristics and the expected hydrogen loss behavior from the moderator. The fundamental design expectations from the hydride moderator are as follows: Maintaining the moderating power at the design limits over the lifetime of the reactor is the fundamental function of the moderator. However, hydrogen loss over time (chronic hydrogen loss) from the intact cladding may cause loss of moderation power, which disables the normal operation characteristic of the reactor.Ensuring the predictable and stable behavior of the moderator during normal and transient conditions is critical to evaluating the moderator’s performance for long-term operation. Accurate prediction of the hydrogen inventory in the moderator establishes the reactor design parameters. In particular, hydrogen transport under temperature gradients can cause neutronic instability due to thermal transport and irradiation-enhanced diffusion. Hydrogen accumulates at lower temperatures due to its high mobility and thermal diffusion (e.g., Soret effect). This may cause mechanical failure of the moderator due to embrittlement of the metal hydride and extensive volumetric expansion if yttrium trihydride is formed.
Effect of hydrogen addition on the explosion characteristics of methane-hydrogen-air mixture in T-shaped bifurcation pipe
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2022
Ning Zhou, Xuwei Li, Xue Li, Pengfei Ni, Weiqiu Huang, Huijun Zhao, Xiongjun Yuan, Linlin Cao
Hydrogen energy is regarded as an important energy carrier in the future because of its clean and efficient advantages, which promotes the rapid development of fuel cells and hydrogenation stations. However, due to the impact of hydrogen transportation cost, the hydrogen price is high, and it is difficult to compete with the traditional oil and gas fuel. In all kinds of transportation mode, pipeline transportation is considered to be the most potential transportation mode of hydrogen energy. However, due to the special physical and chemical properties of hydrogen, the hydrogen transport pipe is expensive. Previous study has shown that the natural gas-hydrogen mixture with a volume ratio of less than 20% can be transported directly by natural gas pipeline (Marianne et al. 2002). Therefore, the existing natural gas pipelines can be used to reduce the cost at the early stage of hydrogen-energy development. Then, hydrogen can be purified from the mixed gas or methane-hydrogen mixed fuel can be directly used in existing gas equipment. Combustion efficiency can be improved by hydrogen doped in gas mixture (Nie et al. 2020a). Meanwhile, hydrogen energy can reduce carbon emissions (Nie et al. 2020b). However, hydrogen has the dangerous properties of high combustion rate, low ignition energy, and wide combustion limit. The addition of hydrogen will not only enhance the combustion performance of the natural gas but also exert influence on the safety of mixed gas. Hydrogen will broaden the lower limit of ignition energy of premixed gas (Emdai et al. 2015). The flame velocity and maximum explosion pressure increase with the increase of hydrogen volume fraction (Wang et al. 2019). Once the mixed gas is ignited, fire and explosion accidents are very easy to occur, and the explosion shock wave generated at this time will produce a strong stress load on the pipeline (Zhou et al. 2020a).
Fusion Blankets and Fluoride-Salt-Cooled High-Temperature Reactors with Flibe Salt Coolant: Common Challenges, Tritium Control, and Opportunities for Synergistic Development Strategies Between Fission, Fusion, and Solar Salt Technologies
Published in Nuclear Technology, 2020
Charles Forsberg, Guiqiu (Tony) Zheng, Ronald G. Ballinger, Stephen T. Lam
The combination of a lower-cost salt and no gamma dose reduces the design and cost constraints for any tritium removal systems including carbon beds and gas sparging systems in secondary systems. Options such as a large gas stripping tower with a fill material (secondary salt going downward with stripping gas going upward) may become attractive. There are several candidate salts, each with different characteristics: Flinak: Flinak (LiF/NaF/KF) has been proposed for the secondary loop because it is compatible with flibe and is relatively nontoxic. For an FHR or MSR, the major question about Flinak is whether to use isotopically separated 7Li. If natural lithium is used, a small leak of Flinak into the primary system would shut down the reactor. This would be a much smaller concern in a fusion system where one burns out lithium at a significant rate to produce tritium and thus must include some system to readjust the lithium isotopics over time.Potassium-zirconium fluoride: The nonlithium alternative to Flinak is a mixture of potassium and zirconium fluorides with relatively low cross sections to parasitic neutron capture.Sodium-potassium-magnesium-chloride salts: The next-generation CSP system designs13,27 propose using a sodium-potassium-chloride salt with a melting point of ~420°C. It is extremely cheap and proposed for large-scale multigigawatt-hour heat storage systems. It is currently proposed to be used in the intermediate heat transfer loop of the TerraPower MCFR and would be a leading candidate for the intermediate loop of any other chloride salt reactor. To minimize corrosion, small amounts of magnesium metal are dissolved in the salt creating a chemically reducing environment. We are not aware of any studies of hydrogen transport and behavior in these systems.