Simplify the following text for a Grade 8 native English-speaking person.
Original: During the years from 1950 until 1991 , when the nearby large port of Vladivostok was closed to foreigners and foreign shipping , Nakhodka became the primary deep water port in the Russian Far East .
Simplified: After Vladivostok started being used by foreigners in 1991 , the port of Nakhodka is not used as much as before .