I suspect they created a narrative, about a lost container.

I'm skeptical about radiation risk. It's another fake bogeyman.

There's photos of Oppenheimer handling refined nuclear cores, which should be deadly beyond description if the story is legit.

But he was fine.

Someone had to machine the radioactive material to shape the cores, so it was handled significantly; and there aren't scary fabricated "demon core" stories about the machinists who had to precision-grind the cores into hemispheres, or whatever shape. Grinding is the only method that can be used to precisely form a hard and dense material.
They were all just fine.

Oppenheimer was standing at Trinity ground zero, with no issues.. With a group of generals. In a photo op. No issues.

The radiation hysteria was created around the time that nuclear power was becoming a threat to the oil companies monopoly control of energy.
It wasn't as if they suddenly noticed that everyone who was exposed to radioactive material b was dying, because there weren't. It's another hoax that we grew up with, and have accepted as a fact.

Similarly, If the world was fooled by the mask hysteria, then we'd be wearing masks forever in public.
It's all bullshit.