It's almost like a mirror.
But, my Mother was USMC and my Father was USN. I joined the Nuke program right after the Iranian hostage crisis (wonderful thing Jimmy Carter did, 10% unemployment, but the Navy was still hiring). It will be a shocker for you son in BC. They don't care if he is Rickover's grandson, he will get no slack.
If he washes out ANYWHERE in the Nuke process (lack of effort, laziness, or stupidity), the Navy still owns him for six to eight years. And be sure to tell him, he will not see a dime of the Nuke bonus until he finishes prototype (all of it, including ELT or Nuke welding school) and reports to his first unit. IF HE SCREWS UP in the first year and gets de-nuked, he pays back the ENTIRE bonus (including the taxes he taken out)
The good part, he will never see combat or be in a combat zone. If he is, it will only be as a bystander or the bottom has dropped out and we (the USA) are in a slugging match with Russia or China. If he is on a fast attack (SSN), he will outlive everyone (there is no better service in the Navy). Ballistic missile subs (SSBN) hide best, but when you launch, the whole world knows you are out there and can backtrack the missiles. Aircraft carriers are premier targets and may last, but doubtful (a 5 Mton warhead leaves a big hole in the ocean and there ain't no such thing as a near miss).
Have him start planning for his future. Nuke plants are being built and the present manning of Sr. Reactor Operators is ancient (avg age 50). Tell him to work on college (get a degree) and take whatever he can. Get out after a second enlistment (or do twenty for the retirement and benefits) and go job hunting BEFORE EAOS. Join the American Nuclear Society and network, network, and did I mention, network.
If he's smart and not a royal screw-up, he may get an opportunity and a career. If he's screw-up and stupid, the Navy has a very smart bilge rat to scrape and paint the missile absorbers (frigate screen around carriers).
Give him a kiss on his way to BC and write often. Have Dad write honestly about the hazards of overseas ports of call. Keep his nose clean and always support him.
Best of luck and Good Journeys,
BA