Nuclear ships are not a trivial matter. Here is an interesting part of the wikipedia page for the Russian nuclear icebreaker Lenin:
"The second accident was a cooling system leak which occurred in 1967, shortly after refueling. Finding the leak required breaking through the concrete and metal biological shield with sledgehammers. Once the leak was found, it became apparent that the sledgehammer damage could not be repaired; subsequently, all three reactors were removed, and replaced by two OK-900 reactors."
Poor bastards had to break into a nuclear reactor with sledgehammers.
"The second accident was a cooling system leak which occurred in 1967, shortly after refueling. Finding the leak required breaking through the concrete and metal biological shield with sledgehammers. Once the leak was found, it became apparent that the sledgehammer damage could not be repaired; subsequently, all three reactors were removed, and replaced by two OK-900 reactors."
Poor bastards had to break into a nuclear reactor with sledgehammers.