I wouldn't be so sure about that one. In a ship with 4 screws there should be 4 steam turbines. Distributing the heat from 2 reactors to 4 turbines (with space between them) might be using a lot of space. There are other complications associated with these matters too. Raw weight and space aren't the only considerations and reactor cores themselves don't use a lot of space compared to the rest of the power plant. Submarine reactor cores are known to be shorter than humans.Is there any actual advantages of having 4 reactors? It'll definitely take up much more space than twin reactors, and modern reactor failure is basically unheard off.

Remind you, there are still a lot of auxiliary mechanisms there
I explained this in a previous post:
"Call me weird but I've always "wanted" the Chinese to build a carrier with 4 nuclear reactors.
why?
This would open the possibility to creating a nuclear powered version of the Type 055.
If a carrier has 4 reactors each rated at 75,000 hp then 2 reactors would provide the right amount of power for the Type 055.
The PLA navy can create a modular design where the exact same reactors are used for both their aircraft carriers and cruisers.
This would lower construction costs."
PLAN building a nuclear powered surface combatant remains unlikely.