We can ban fissible material from being imported from foreign countries under the Commerce Clause. I told you that already.
Currently there is no enumerated power to ban or regulate fissible material in interstate commerce. Unelected career bureaucrats regulate it anyway, and the end result is that our nuclear industries are crippled, being unable to produce isotopes needed for medical and industrial purposes and leaving us dependent on foreign countries for our supplies.
You cry "We the People have a right and responsibility to ban dangerous substances!", and don't seem to care who does it or how. That's exactly how we ended up with CO2 being declared a "pollutant".
Why you would want to pick the Commerce Clause is beyond me. I regard it as a Defense issue, not an issue of Commerce. But the point remains. If we can legitimately ban the import of fissile material under the Commerce Clause, we can likewise legitimately ban the import of Drugs under the Commerce Clause.
I'm not going to bother with the rest of your message.