It only makes sense if it means Russia/USSR doing the tests and nuclear fuel reprocessing on the Far East but rather strange to call it "in Europe".

Can't see any other country in Europe which could've caused it from that statement.

This news shows the progresss by 2019, but couldn't find more recent updates.

https://www.nucnet.org/news/plans-progress-for-orano-to-buil...

Nuclear fuel reprocessing plants release iodine into the atmosphere. The prevailing wind direction at European latitudes is west to east, so when the iodine comes back down in rain, it'll likely do so over Russia (emptying into the Arctic Ocean), Central Asia (emptying into the Caspian Sea and various lakes) or Northeast Asia (emptying into the nortwestern Pacific Ocean, including the Yellow Sea.) This paper has an illustration: https://www.sciencedirect.com/science/article/abs/pii/S03043...

This is the problem with the "nuclear is completely safe" people: there's only one biosphere, and anything you put in it eventually ends up very thinly spread everywhere.

You'd see other isotopes if it was something recent. It's hard to hide things like this, see the Ruthenium plume that was detected over Europe in 2017 [0]. Radiation instruments are very sensitive!

[0] https://cen.acs.org/safety/industrial-safety/caused-plume-ra...

Which "the images" are you talking about? The article has exactly one image and it is an image of an island without any rivers.

> Is it possible that china is hiding something?

By publishing recent studies showing a smoking gun?

  UP MSI said the results were consistent with recent Chinese studies linking iodine-129 in the Yellow Sea to decades-old nuclear weapons tests and nuclear fuel reprocessing facilities in Europe, ...

China has a great many reactors, nuclear warheads, acres of low level waste from rare earth processing .. they have as much to hide as the US does, that said there's not a lot to gain here by pretending they don't have potential sources - but isotope fingerprints can be verified and all the byproducts from > 2,000 test explosions and the creation of 10,000+ warheads globally do get mapped and tracked.

You are right that due to its very long life we cannot know when it has been produced, perhaps decades ago.

However the fact that only iodine was detected is to be expected, as the other radioactive products of nuclear fission are much less likely to form chemical compounds that are soluble in sea water, so they could be somewhere on the sea bottom.

It's a crappy title - the sea is full of vast amounts of radioactive elements.

The part of the article that caught me was that European Companies used to just drain nuclear waste (not sure what type), into the rivers in China and they would eventually flow into the sea

I wanted to resist a pun, but that would be a drop in the ocean.

Seeding a large body of water with radioactive chemicals would take a ship quite a while.