Editing Nuclear reactor (section)

== Terminology ==
During early 1940s nuclear research, the phrase "atomic pile" was used for any assembly involving uranium and attempts at neutron multiplication, including the majority which were subcritical. After [[Chicago Pile-1]] demonstrated a self-sustaining chain reaction, the "reactor" terminology became more common. The phrases "nuclear pile" and "atomic reactor" were also common.  

[[Critical mass]] experiments, while being far simpler, are sometimes referred to as research reactors, such as the [[Godiva device]]. 

"Nuclear reactor" is predominantly used to refer to the nuclear fission reactor. It can also refer to a [[nuclear fusion reactor]], of which only net negative power systems have been constructed. [[Radioisotope thermoelectric generator|Radioisotope thermoelectric generators]] and [[Radioisotope heater unit|radioisotope heater units]], while deriving power from nuclear decay reactions, are not referred to as nuclear reactors as they do not ''induce'' reactions.