Manhattan Project by Goodyear Tire to encase the reactor. On 2 December 1942, a team led by Enrico Fermi initiated the first artificial self-sustaining nuclear chain reaction in an experimental reactor known as Chicago Pile-1. The point at which a reaction becomes self-sustaining became known as "going critical". Compton reported the success to Conant in Washington, D.C., by a coded phone call, saying, "The Italian navigator [Fermi] has just landed in the new world." In January 1943, Grafton's successor, Major Arthur V. Peterson, ordered Chicago Pile-1 dismantled and reassembled at Red Gate Woods, as he regarded the operation of a reactor as
Shutdown (nuclear reactor) Shutdown (nuclear reactor) In a nuclear reactor, shutdown refers to the state of the reactor when it is subcritical by at least a margin defined in the reactor's technical specifications. Further requirements for being shut down may include having the reactor control key be secured and having no fuel movements or control systems maintenance in progress. The shutdown margin is defined in terms of reactivity, frequently in units of delta-k/k (where k is taken to mean k-effective, the effective multiplication factor) or occasionally in dollars (the dollar is a unit equal to the change in reactivity needed to go from