I don't think India would go for nuclear carriers BTW. The Navy has rightly said that a 65K T 'mixed' carrier is the best way forward- a conventional carrier that flies both piloted planes and unpiloted drones. This will reduce a lot of human staff/quarters requirement while maintaining offensive capability. The old days of large carriers with catapults, dozens of planes and huge personnel deployments are gone.
So it will be gas engines then? I think going for a nuclear carrier is way too much when better cost effective solutions exist. India also needs it's nuclear material for weapons and its civilian nuclear reactors.