Nuclear chain reaction the last one called ""Perfectionnement aux charges explosives"" was the first patent for the atomic bomb and is filed as patent n°445686 by the Caisse nationale de Recherche Scientifique. In parallel, Szilárd and Enrico Fermi in New York made the same analysis. This discovery prompted the letter from Szilárd and signed by Albert Einstein to President Franklin D. Roosevelt, warning of the possibility that Nazi Germany might be attempting to build an atomic bomb. On December 2, 1942, a team led by Enrico Fermi produced the first artificial self-sustaining nuclear chain reaction with the Chicago Pile-1 (CP-1) experimental reactor in
TOPAZ nuclear reactor TOPAZ nuclear reactor The TOPAZ nuclear reactor is a lightweight nuclear reactor developed for long term space use by the Soviet Union. Cooled by liquid metal, it uses a high-temperature moderator containing hydrogen and highly enriched fuel and produces electricity using a thermionic converter. In initial discussions, it was unclear that TOPAZ and the somewhat similar YENISEI reactors were different systems, and when the existence of the two Russian thermionic reactors became generally known, US personnel began referring to TOPAZ as TOPAZ-I and YENISEI as TOPAZ-II. The first thermionic converter reactors were discussed by scientists at the Los Alamos Scientific