The waste is not simply the spent nuclear fuel, but much of the machinery and systems around it, plus the discarded items used daily in the management of a plant (clothes etc).

This low level nuclear waste while 'only' dangerous for 100 to 500 years, is huge - vastly bigger than the 76000 metric tons of spent fuel:

http://www.nei.org/Knowledge-Center/Nuclear-Statistics/On-Si...

I don't have the tonnage of the low level waste to hand, but it is certainly much larger than the high level waste.