You’re two paragraphs contradict each other. Which is it?
I don’t see that his paragraphs contradict each other. Hydrogen atoms are small enough to squeeze between pretty much anything.
They are independent statements. Which is the reason they are paragraphs.
A. The shuttle deaths were not related to H fuel.
B. Hydrogen is difficult to contain because it is so small.
I think you are confused about something. You might need more coffee!