Nuclear power energy is a negative or positive?

Nuclear waste disposal is a significant problem, becoming more hazardous to the environment. This is because plethora sites are located near ocean, and the lees that energy is discarded to that ones, but these wastes are difficult to parse, consisting of high-level garbages. If this occurs day-by-day, it will damage the living environment. In the US, there are around 80 nuclear sites located in Gulf Mexico, and also those venues in a day dispose 50 kg waste, containing the uranium substance. Therefore, this needs a thousand year to deactivate the substances, and it tends to threat the sea animals.