This documentary contains several staged recreations of conditions inside of the nuclear core. While dressed in protective suits, power plant employees are shown taking radiation measurements with Geiger counters emblazoned with the Civil Defense logo. These counters were issues to the general public during the Cold War and would not be used to take measurements inside of the plant. These counters would be used common citizens, and indeed in actual archival footage shown later, only residents use these devices.
The word: "nuclear" was correctly pronounced during the entire episode.
Regarding the "China syndrome": Earth's gravity is strongest near the core, one of a few reasons why a nuclear meltdown "China syndrome" style is pure "Hollywood hogwash".