How safe is nuclear power really? Did you know Yucca Mountain is on a fault line? They discovered it in 2007. OOPS.
http://articles.latimes.com/2007/sep/25/nation/na-yucca25
Not really a big deal. The reason they picked Yucca Mountain, as explained by Penn & Teller, is specifically because it's an area with no water. Ground water contamination is the worst possible thing that could happen, so logically they want to put nuclear waste in an area that doesn't have any ground water.
The other thing is that nuclear waste is not a liquid or a slurry. It's just solid material. This really is what nuclear waste looks like:
If there is a hardcore earthquake
and it destroys the containers
and nuclear waste falls out, you just pick it up and put it in another container
My main complaint with nuclear waste is that it takes so long to break down. We are not talking a couple of decades, or a couple of centuries, we are talking thousands of years.
Ironically this is what makes nuclear waste relatively safe. Slower decay means..... well.... slower decay. Some things are insanely radioactive and the decay rate is less than a day, less than an hour, or even less than a second. If you touch that material, you have cancer and rad poisoning immediately and you're totally screwed. If you're talking about something where the half life is 10,000 years, then that means it's decaying pretty damn slow and the exposure to such material is no worse than getting a chest x-ray.
(edit: getting chest x-rays are bad as well. I'm not saying x-rays are safe. I just mean that proper containment is possible and is not overly difficult)
To put it all into perspective, radioactive iodine that is given to diagnose certain medical problems has a half life of 59 days. This stuff is waaaay more radioactive than nuclear waste is.