This is not really a history question, but a scientific one, that I (as a scientist) can answer.

In the early C20th, uranium nitrate was often added to glass to colour it and because it made it fluorescent in UV light. Whilst blacklights were not particularly common, sunlight contains enough UV for uranium glass to fluoresce noticeably.

Uranium nitrate, as with various other uranium salts, is a yellowy-green colour. Various different uranium salts were included in glass, but they were all the same greenish colour - and the fluorescence is always green.

Once uranium began to be used as a nuclear fuel, the supply available for integrating into glassware massively reduced, so it almost universally stopped being made.

You can still find uranium glass today in flea markets and the like for a small price. I have a few pieces myself. It is radioactive, but only very, very mildly (at least in the pieces that I've tested with a Geiger counter).

Edit: a further thought.

Uranium glass was sold very cheaply or given away for much of its production time. It was probably what people first thought of when they heard of uranium being used for atom bombs.

Furthermore, whilst Uranium Nitrate fluoresces, but doesn't glow in the dark, radium, another radioactive element, was often used in glow-in-the-dark displays, like on watches. It's not glow-in-the-dark itself, but can "charge"¹ the phosphorescent paint in the same way that a bright light does. The glow on these dials is the same familiar cream/green colour as modern phosphorescent paint, but it didn't fade as it was constantly being "recharged". The paint was (and still is) highly radioactive, and the radium does a similar thing to those exposed to it as phosphorus - if gets into your jaw and ruins the bones, like phossy jaw. Being radioactive, it also causes cancer, so the women who used the paint to decorate dials often ended up very, very ill.

Lastly, similar to the radium paint, but much safer, is the currently available tritium lighting. It relies on the same principle as the radium paint, but used relatively harmless tritium as the radioactive source. The colour of the light is the same.

All of these things lead to an association between radiation and the colour green.

¹It's nothing to do with charge per se, it's electrons being temporarily promoted to higher energy levels by being hit with radiation/light, and then taking a while to fall back down again. Fluorescence is the same process, just without the delay. Anyway, the difference between fluorescence and phosphorescence is probably beyond the scope of this sub.

The first encounters that "popular culture" had with radioactivity were green. Notably, in the form of radium paint, which used a copper-tinged zinc sulfide phosphor to glow in the dark. Clocks with radium paint do indeed glow with a ghostly green. Consequently most radium-associated products used green/yellow to convey their radioactivity. And when said products became associated with death — in the wake of the Radium Girls cases, and the Eben Byers affair — the color association seems to have followed.

It is unclear to me how much association there was between radioactivity and uranium glass, which is also green. Uranium glass was largely popular before radioactivity was discovered, and it isn't clear that people associated the two until well after the fact. Radium was a much bigger deal, and directly associated green with radioactivity.