Nothing. To begin with, this material is very heavy. So, unlike iodine, it won't disperse in the air. Workers at the plant MAY be affected. So, I'd caution them to be careful. But I don't think the public should worry. For example, 50 years ago when I was born, the amount of plutonium was 1000 times higher than now.
MC: "Oh, why?"
Because of nuclear testing. So, even if the amount has now increased somewhat, in fact it's still much less than before. However, if it is released into the ocean through exhaust water, that's a problem. Once outside, plutonium hardly decreases.