The French nuclear submarine Redoutablespent the '70s and '80s at sea and was home to 135 sailors for months at a time. The missile boat-turned-museum resides in the French seaside town of Cherbourg after extensive refurbishment. See inside this massive submarine and silent threat of nuclear annihilation through many pictures and a bunch of words.
It's pretty much impossible to get a full shot of the sub, given where it rests. Let's just say, it's big.
After the reactor generates steam, this steam spins some turbines, the turbines hit a reduction gear (all of this you'll see in a moment), and eventually it hits the prop shaft, which was cut away so you can walk more easily (the yellow cap is the end).
This was the reactor room. It was wise that they removed the reactor completely for the museum refurb, since there was only a small space along the spine that allowed passage from the bow areas of the ship to the stern.
With nearly unlimited energy, a lot of very useful things can happen. You get propulsion, sure, but also electricity. And with electricity, you can take seawater and make pure drinking water. You can also separate out those pesky H molecules and make as much oxygen as your crew needs too.
CO2 scrubbers (lower left) take out that deadly gas.
Through the (not original, obviously) glass in the floor, you can see the chair of the ship's doctor, which doubles as the dentist's chair, for the ship's dentist, who also doubles as the ship's doctor.