I know that Sequoyah (TVA) and Palo Verde have their own "fire departments" therefore operators don't have to be fire brigade qualified. Other than that, I don't know, but when you read the various job postings from different plants, most will indicate if you need to be fire brigade qualified. That should clue you in.
I have been an operator at Crystal River, ANO and Kewaunee and all three required operators to be on the fire brigade.