Emergency use != load following. The fact that sometimes energy needs to be dumped != system cannot be throttled. And a huge number of nuke plants are already

Emergency use != load following. The fact that sometimes energy needs to be dumped != system cannot be throttled. And a huge number of nuke plants are already on the coast so, they have just as much water as a sub (not that this really matters). And I suspect size isn't really a factor here, its more about time variance, which I suspect is higher on a ship than its is on the grid. The grid wouldn't be swinging its power usage as drastically or completely as one would expect from propulsion onboard a ship. This is more about whether its possible to run the reactor at say 50% rated capacity for long periods of time, which AFAIK naval reactors can do, and to a certain extent so can some civilian plants, rod placement controls not just criticality but in the end heat generation, which translates to power output.