Perhaps you should look at a fault map of California. Diablo, the only nuclear plant still operating, sits on an active fault that wasn't discovered until 2008. Not surprising, many new faults have been discovered recently. The Hollywood Fault was mapped in 2014 and many buildings in Los Angeles sit on it. Zoning was changed because of that discovery.
The coast of California is eroding through a combination of rising seas and sediment reduction. In 2010, an entire city block in Pacifica was red tagged because it was close to falling into the ocean. Many asked, why were these buildings allowed that close to the cliff? Well, in 1962 they were about fifty feet away.
Perhaps you should do some reading on the California Coastal Commission. The consensus is we need to retreat from the coast.
Let us imagine we can build magic nuclear plants. Where are we going to build them? Not Southern California. Well, maybe Camp Pendleton or Vandenberg, but that is federal land and they would be operated by the military. Maybe we can sneak one in the top of the northern coast near Oregon.