There has recently been historic rainfall from typhoon Hagibis in Japan, which has caused a number of nuclear decontamination waste bags to be swept into the river. Those bags were holding tonnes of radioactive waste that came from the Fukushima nuclear plant.
It's an accident that government officials might not mind seeing as it had recently been on the discussion table to eventually dump the remaining radioactive material into the ocean at some point. They need to find a place to dump it at some point seeing as they are running out of room.
So far, at least 17 bags were recovered but several of them had spilled the contents into the water already, at least 10 of them. The bags had contained radioactive wood, dirt, leaves, and grass.
It's reported that thousands of bags were left out in the open without so much as a sheet used for protection during the recent storm.
The Environmental Ministry has already insisted that it's likely to have little impact on the environment and has urged that there has been no increase in radiation in the places where the bags were stored or released. Not everyone has been quick to brush away concerns though.
“It looks like some of these bags got washed out to sea. And of course, the authorities say, ‘Oh, it’s no big deal, even if the bags break open, it’s no big deal.’ So it begs the question: so why did you gather that stuff up in the first place, if it’s no big deal?’ This is radioactively contaminated material. It’s unfortunate, but it’s kind of a lingering after-impact of the catastrophe.” - K. Kamps, Radioactive Waste Watchdog at the organization Beyond Nuclear,
Though several bags might have been recovered already, it's still reported that it's unclear just how many bags might still be missing. You can see the clean-up operation in the image below. It's alleged that more than 2,667 bags had been left out in the open during the recent storm, without much protection, in the holding area in Tamura.
Because of the heavy flooding and rain, officials say that the contents of the bags were swept to the Furumichi River, this river connects to another which eventually flows into the Pacific Ocean.