U.S. commercial reactors have generated about 90,000 metric tons of spent fuel since the 1950s. If all of it were able to be stacked together, it could fit on a single football field at a depth of less than 10 yards. Nuclear waste is solid, it's not that difficult to store it. We get more nuclear waste leaked into our nature from coal plants.

As a reference, here is the room that Switzerland stores their nuclear waste.