Yes, my initial homebrew attempt at reactor site design made me wonder why such plants are not built high up, but my guess is that a reliable source of nearby water is a vital design component, and the proximity to the sea in this case seems to have been useful for emergency cooling. A mountain top nuclear power plant is probably a lot harder to access (everything needs to be airlifted) and you couldnt easily guarantee water when you really needed it.
I'm bored programming shit. Nuclear power plant design seems to be where its at. Where do I sign up? Ill bet after this General Electric and the japs will design and build plants verging on sci-fi levels of safety (I'm already impressed / jealous at the fantastic job they appear to have done already, I hope the guys who designed it get medals).