RDS-1
The RDS-1 (Russian: РДС-1), also known as Izdeliye 501 (article 501) and First Lightning (Первая молния, Pervaya molniya), was used in the Soviet Union's first nuclear weapon test, the United States assigned it the code-name Joe-1, in reference to Joseph Stalin. It was exploded on 29 August 1949, at Semipalatinsk, Kazakh SSR, after a top-secret R&D project. The weapon was designed at the Kurchatov Institute—at the time officially known as "Laboratory № 2," but designated as the "office" or "base" in internal documents—starting in April 1946. A uranium-235 plant was built near Chelyabinsk in 1948.
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