From Voyage to the Bottom of the Sea, a TV series in the 1960s set in a nuclear submarine. However, the stories were set in the 1970s and 1980s, hence the nuclear reactor had to look futuristic. For that reason it looks a bit unrealistic.
It first appeared in the submarine in the third season, but an earlier version of it was seen in a nuclear bunker in the second season episode The Deadliest Game.
The model itself is not that accurate and the back is not complete.