Hot springs in non-volcanic areas are attributed to the interaction of water with hot rocks deep in the earth's crust:
In non-volcanic areas, the temperature of rocks within the Earth also increases with depth—this temperature increase is known as the Geothermal Gradient. If water percolates deeply enough into the crust, it comes into contact with hot rocks and can circulate to the surface to form hot springs.
Hot Springs/Geothermal Features, National Park Service
If I understand correctly, this heat comes from the decay of radioactive isotopes:
... the vast majority of the heat in Earth's interior—up to 90 percent—is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 contained within the mantle.
Probing Question: What heats the earth's core?
Question: Are hot springs in non-volcanic areas radioactive?
I'm guessing the answer is either "no" or "yes, but not very", because people swim in them. But it seems like radioactive isotopes should be seeping into the water.