This is the 16273rd most frequent Russian word.
реактора
The Russian word "реактора" means "reactor" in English, often referring to a device for generating energy or facilitating chemical reactions.
The word "реактора" refers to a specific entity (a nuclear reactor) in the sentence, used as the object in the genitive case to describe what is being maintained.
Ядерного реактора поддерживают в стабильном состоянии.
The nuclear reactor is maintained in a stable condition.
"Реактора" here is used in the genitive case to specify the subject (reactor efficiency) that is being discussed.
Достигли нового уровня эффективности реактора.
A new level of reactor efficiency has been achieved.
In this sentence, "реактора" is in the genitive case indicating possession or association with 'this' reactor.