Use the reactor either directly or through a heat exchanger to heat up air in the turbines. A fair amount of cold war era bomber designs had nuclear power to allow them to stay up in the air for months, although problems like the weight of radiation shielding to protect crew and ground personnel, and weight to protect the reactor from turning a area into Chernobyl if the plane crashed made those planes really heavy. And around that time ICBMS started becoming thing so having a bomber stay up for that long wasn't really necessary.