That's a common reaction, but it doesn't stand to much scrutiny. Before radiation gets to the public, about 4 or 5 different barriers have to fail. The first is the fuel pin, then the cladding metal, then the coolant itself (which can often absorb problematic fission products), then the reactor vessel, then the containment, and then dispersal. You're focusing on containment/dispersal.
But how do the first ones fail? The answer is that lack of decay heat removal allows the earlier barriers to heat up, melt, and fail. Well, if you have an intimate connection to an infinite heat sink (the sea), you don't ever lose decay heat cooling. You can't! So your fuel and clad stay intact in almost all scenarios.
Earthquakes? No problem, the sea buffers you.
Tsunamis? No problem, stay in moderately deep water and the wavelengths are so long that you'll barely notice them.
Heavy weather? The world's largest ship (Prelude) is designed to stay operating (it's a LNG facility) during Cat 5 cyclones.
Military attack? Sink and cool passively until a designed recovery operation can occur
Ship collision? Stay out of shipping lanes; worse case, sink and don't leak.
Also, keep people out of your exclusion zone by being a few km offshore.
Honestly it's a pretty slick low-carbon rapid deployment scenario that improves construction cost and safety. Operation will likely be more expensive, but maintenance maybe not (since you can go home to the shipyard and be relieved by a spare).
But how do the first ones fail? The answer is that lack of decay heat removal allows the earlier barriers to heat up, melt, and fail. Well, if you have an intimate connection to an infinite heat sink (the sea), you don't ever lose decay heat cooling. You can't! So your fuel and clad stay intact in almost all scenarios.
Earthquakes? No problem, the sea buffers you. Tsunamis? No problem, stay in moderately deep water and the wavelengths are so long that you'll barely notice them. Heavy weather? The world's largest ship (Prelude) is designed to stay operating (it's a LNG facility) during Cat 5 cyclones. Military attack? Sink and cool passively until a designed recovery operation can occur Ship collision? Stay out of shipping lanes; worse case, sink and don't leak.
Also, keep people out of your exclusion zone by being a few km offshore.
Honestly it's a pretty slick low-carbon rapid deployment scenario that improves construction cost and safety. Operation will likely be more expensive, but maintenance maybe not (since you can go home to the shipyard and be relieved by a spare).