The human factor is always an issue, I knew a couple technicians who work in our local nuclear generator station, and while they've never been too worried about a problem(like calling home worried!), there's seen some stuff happen that shouldn't, and some people that should be a bit more careful. That said, another couple of guys I know in passing that are doing Homer Simpson's job are smart, no BS guys, so I suppose that's reassuring.
Just out of curiosity I had a look at the sea wall around our local plants on Lake Ontario. Looks sufficient for a likely level hurricane type storm surge, but I don't know about the worst case scenario tsunami wave from an underwater sediment slump? I can't find any data for it in a brief online search.
Maybe there's not enough sediment depth and slope anywhere in the lake to make it worth worrying about? There is also meteotsunamis
https://www.canr.msu.edu/news/are_there_tsunamis_in_the_great_lakes_msg16_breederland16 but hopefully these were accounted for.
Think the only lake big enough for anything notable to happen on (and it would still be small compared to what happens on the ocean, I'm just thinking large wave height) would be Superior, and we don't have any nukes on Superior.
They mention a 10ft wave which isn't very high.
Of course the description of a meteotsunami means that many of us have seen them:
A meteotsunami is defined as a rapidly moving wave that can be generated by quickly changing air pressure or high wind speeds or a combination of both.
I've seen them on Rosseau due to an incoming thunder storm for example and they created some reasonably strong (3-4ft) waves, which can be fun if you are out in your boat or if it hits your dock.
That said, that's not the same, nor anywhere near the same magnitude as what is generated by an earthquake, tsunamis from which Japan has experienced several. Notable tsunamis of this nature are:
- 1667 Emp Boso-oki earthquake (Japan), which was estimated to be an 8.4 and created 23ft waves
- 1896 Meiji Sanriku earthquake (Japan), which was estimated to be a 7.6, created 125ft waves and killed 22,000 people
- 1933 Showa Sanriku earthquake (Japan), which was an 8.5, created 95ft waves and killed 3,000 people
- 1960 Great Chilean earthquake (General, including Japan), which was a 9.4-9.6, created 85ft waves and hit Japan with 20ft waves, killing 138 people
- 1993 Hokkaidō Nansei-oki earthquake (Japan), which was a 7.7, created a 98ft run up in places and 51ft waves that hit Okushiri, topping their sea wall.
- 2004 Boxing Day Tsunami (Indonesia), which killed 220,000 people and was caused by a 9.1-9.3 magnitude quake that created 100ft tall waves
Onagawa NPP had a 48.5ft sea wall, Fukushima Dai-ichi had a 18.7ft sea wall.
It is important to note that run-up, that is, the height the water can go when impacting a surface from a tsunami wave, can be twice as high as the maximum wave height. The biggest wave to hit Fukushima Dai-ichi was ~45ft, well over the height of the sea wall. Ground level of the plant was 33ft. Had the sea wall been higher, it would have only, or mostly been, run-up to go over the wall, which would have had considerably less impact. The fact that the emergency generators were in the basement was mind boggling, given the frequency of tsunamis in the reason, and that was again, part of the grandfathering that the plant had been able to operate under without doing upgrades.