I can't believe the Navy would consider Fill Systems important enough to install gas turbines or conventional boilers.
Navy Reactors are not, and never have been "licenseable" to 10 CFR 50 (NRC) standards. You'll find ECCS Requirements for Light Water Zirconium Clad reactors in 10 CFR 50.46.
Have you ever seen a DBA LOCA analysis for Navy Reactor?
A Loop breaks in two, ad to that a concurrent Loss of AC Electrical Power (we'd call that Loss of Offsite Power in the civilian world), now add a Single Active Component Failure. One EDG doesn't start, or an ECCS Pump doesn't start...
You get the picture, these plants are built to vastly different safety standards. Navy Reactors power warships, and do so with an impressive safety record - but are not built to mitigate the same conditions as a licensed commercial reactor.
Fill Pumps are a gesture, but not a commitment to safety, as you would have in a commercial power plant. Have you ever heard of a Navy Reactor shutting down and cooling down due to a bad Fill Pump?
Stout system margins used in Navy applications make LOCAs less likely, they are not - at all - built to mitigate them.