1 Jane Goodall: While the physicists are occupied debating Devonshire tea, let's grab the fissile material.
2 Jane Goodall: It should be in this lead canister. I'll just open the lid…
3 Professor 1: Look out!! That's a huge disaster happening there!
4 Professor 1: The tea trolley's gone out of control!

I distinctly recall the worst accident involving radioactive sources that happened in my undergraduate physics labs at university.

In the second year lab, we had some experiments that used radioactive sources, which were relatively low powered and not really dangerous with short exposure. To minimise exposure, when not actively in use they were kept in a lead box on one of the benches. This was a simple rectangular box, with a removable lid. The lid was also made of lead and had a handle so you could lift it off. Being lead, it was rather heavy. It wasn't latched on in any way, it just lifted off.

One woman in my class thought rather than take the lid off and carry the exposed sources to the experiment desk, she would carry the entire lead box. She grabbed the handle on top and used it to slide the box across the desk, intending to slide it off and carry it.

As the box reached the edge of the bench, the bottom half of the box fell. Onto the floor. Via her foot.

She was on crutches for the next few labs.

As horrible as this sounds, this is not the worst accident that happened to someone I knew in a university lab. But I'll save that one for another day. (It did not involve radioactive sources.)