Operators of nuclear plant are civilians. They are not part of force. Civilians can be captured, they cannot surrender, because nobody asks them to do that. I never heard that police or army asks somebody unarmed to surrender.
I don't understand the statement. Either it is completely oblivious to daily reality, or it is hinging on some pedantic / language dependent semantic detail that should really be explicitly addressed.
So yes, those in charge of the plant surrendered it to the attackers.