Sorry, no definitions found. You may find more data at nak.
Sorry, no etymologies found.
There are other better heat transport choices but more expensive such as NaK.
The United Nations nuclear watchdog agency, the IAEA, says of radioactive sodium: Sodium and sodium-potassium eutectic NaK have been used as coolants in several research reactors as well as in a small group of prototype and commercial nuclear reactors with fast neutrons.
* This system, called a pumped NaK (sodium potassium) loop, was used to transfer thermal power in all 34 of the space fission systems flown to date.
Liquid Metal type: Sodium Potassium* (NaK) * Please read the security instructions in this document carefully.