Well, it's a mixture of water and radioactive isotopes. The million tons of water isn't a danger to the Pacific Ocean, but the stuff it's mixed with may or may not be.
If the title had said "a million tons of tritium" it would be wrong, but it didn't.
The information is wrong. The article is talking about waste water that has a total of 2.1 g of pure tritium diluted in 860,000 m3 of stored water.
The legal limit for tritium emissions for a nuclear plant in the US is a total of 0.2kg per year according to NRC. A metric ton is 1000kg. In order to get a million tons you would need 5x10^9 nuclear plants all releasing their maximum amount of tritium. If the amount would then be as diluted as in the article, ie 860,000 tons water for every 2.1 gram, you would then need 4*10^18 tons of water. There isn't enough water on earth to do so.
Water which ... is nuclear waste as it is from a nuclear power plant that had a core meltdown? Of course wastewater would have been more specific, but in the end they ARE dumping nuclear waste into the ocean.
Nuclear waterwaste != nuclear waste. Water cannot be radioactive, and in fact water is a fantastic insulator for radiation. The water had contaminates in it and the argument is whether or not the current level of contaminates is safe.
The article's title makes it sound like they're just going to dump the Elephant Foot directly into the pacific. It's clearly a sensationalistic anti-nuclear title edit.
While water is indeed a fantastic radiation shield, tritium is a radioactive isotope of hydrogen and quite capable of replacing normal hydrogen in a water molecule, so even pure water can absolutely be radioactive.
It’s one of the least dangerous radioisotopes out there, so I’m not particularly fussed, but it is incorrect to say water can’t be radioactive.
In this case, the water is radioactive. They are talking about releasing water in which a small fraction of the molecules are composed of Hydrogen, Tritium and Oxygen (HTO), rather than ordinary H20. HTO acts chemically just like H20, and is literally radioactive water.
To start, seawater has more things than water. Both Hydrogen and Oxygen have isotopes that can decay and emit radioactivity, so yes, water can definitely be radioactive, by definition. For a relatively short time because is not plutonium of course, but it can be.
And, unlike Plutonium, the problem is that life beings are mostly made of water and we didn't coevolved with a such rare element as tritium is in nature. Water is freely allowed to enter and travel and has granted access to every part of the human body. We trade a big danger for other, but this does not mean that radioactive water can't harm us.
Tritium has a biological half-life in humans of 8 days. It's not a "big danger". Japan has gone out of their way to take all the precautions here, but since it's nuclear you know somebody is going to raise a stink anyway.
If the title had said "a million tons of tritium" it would be wrong, but it didn't.