I'm afraid to take a nuclear cardiac stress test because it sounds radioactive. is it dangerous?

No: It uses a very low dose of a radioactive chemical that dissipates quickly after administration. It's not much different than a ct scan.

Nope: There is radioactivity involved, but the dose is not considered in the range that it presents a risk and is comparable with other radiology exams. If a physician is ordering the exam, there is typically a good reason that would present more of a "risk" than the nuclear scan. I would not worry about the word "nuclear" in the test and take care of your heart.