Used to be (on slightly older reactors for the S6G power plant), you replaced the core every other major overhaul.
This much damage?
I'd use use her for a new reactor training boat. Keep it pierside.
When I was in Charleston there was talk of adding a retiring 688 to the two S5W Moored Training Ships. Since all of the S5W boats were going away it seemed to make more sense to train the nukes on a more modern powerplant. I think you have just made the case to do this.