It's not. Not only is it a completely negligible amount (~one 50-gallon barrel per reactor per year), it's easy to store (literally kitty litter) and can be re-enriched (renewable).
> it's easy to store (literally kitty litter)
I showed your comment to someone who is currently writing their PhD on how to store nuclear waste safely. I barely understood half of what they said in the following rant, but they referenced the situation of the Sellafield site several times.
Also you are forced to deal with it one way or another, instead of just dumping it in the atmosphere and washing your hands of it.
Okay, not all of this is accurate. I am not against nuclear (although in recent years it has not been very cost effective), but here are some figures with citations:
- The U.S. generates about 2,000 metric tons of spent fuel each year (from 94 reactors/97 GW) : https://www.energy.gov/ne/articles/5-fast-facts-about-spent-... . For the whole world it's 7,000 tons (375-400 GW) : https://www.iaea.org/publications/14739/status-and-trends-in...
- Storing it is easy in the short term, but unfortunately any leaks are a big deal and you have to store it basically forever, which is a challenge. If Yucca Mountain were to be restarted it's estimated storing existing and new waste through 2031 there would cost in the neighborhood of $100 billion : (warning: large PDF) https://www.gao.gov/assets/gao-21-603.pdf
- It's possible to recycle the fuel, but currently an order of magnitude more expensive than digging up more : https://www.belfercenter.org/publication/economics-reprocess...