Complex sentence: Launched on 21 July 1959, she was in service between 1962--1972 as one of only four nuclear-powered cargo ships ever built, while Soviet ice-breaker "Lenin" launched on 5 December 1957, was the first nuclear-powered civil ship.
Split into simpler sentences: Launched on 21 July 1959, she was in service between 1962--1972. NS "Savannah" is one of only four nuclear-powered cargo ships ever built, while Soviet ice-breaker "Lenin" launched on 5 December 1957, was the first nuclear-powered civil ship.