Originally Posted by
rickair7777
That part is manageable since airplanes don't need to remain fully fueled for extended periods like days, weeks or months. The ground storage infrastructure would leak a little bit but that would be a cost of doing business.
The big leaks which scrubbed those launches were not caused by H2 molecules, they were caused by mechanical sealing problems which were likely due to cryogenic temps... that would be a technical problem for airplane fuel but I'm sure it can be solved. I think NASA's current problems are caused by NASA, not by H2. Shuttle used H2 for several decades.
Sorry for lack of clarity.
In electrical power plants, H2 is used for cooling the stator of the generator. After all the welding of the metal is complete, pressure tests with Air and then He are done. Any leaks corrected. Then H2 is introduced. Several leaks with H2 are found that were not found with He. This is typical.
In my previous life, I have witnessed this first hand, on the construction site.
H2 lower flammability limit is 4%. It is not how much fuel leak is tolerable, for cost of fuel losses. It is how far away from the leak it can be set off by a spark or other ignition source.
Unlike Jet A, it requires no vaporization. Unlike methane (CH4, natural gas) H2 is much more susceptible to getting out through tiny leaks.