English to Spanish Tech/Engineering Petroleum Eng/Sci Measurement methods, measurement instruments, measurement

Hello everybody,

I have a problem with the word *nucleonic.*
I haven't found an equivalent in Spanish because there is no information about this measurement method, I only know that as they are devices that can be outside the vessel where you have to measure the fluid, they are safe when it comes to dangerous fluids.
Does nucleonic refer to 'nuclear' or to something similar?
Can I use *dispositivo de medición de núcleo* o *nuclear* in Spanish?

Here an explanation paragraph:
The measurement system consists of a gamma emitting radioactive source, a detector and a control unit.
Gamma radiation from the source is directed through the vessel to the detector unit.