Is there a static substance that reflects loose neutrons? I thought that the choices for a substance were either to let the neutron pass through, or to absorb the neutron
If you're already working with plutonium, whose dust is also very, very toxic (in addition to being radioactive), the additional danger of beryllium doesn't seem so great in comparison.
I routinely handled beryllium for a couple of years as it is present in certain electronic RF power amplifiers. It’s perfectly safe in solid form. If you drill it or smash it, a different matter!
I knew a software engineer who made a lot of money in a startup and bought himself an ultralight bike of titanium and beryllium. They ceased the beryllium parts at the Canadian border and I don't think he ever managed to get them released to him.
I think only about 2% of the population is sensitive to beryllium. I was in a beryllium monitoring program (yearly blood tests) at work. A few coworkers are sensitive, one getting really sick.