Joe-1

RDS-1
The first Soviet atomic bomb, "RDS-1", was an implosion-type, like the U.S. "Fat Man" bomb, even in appearance; the front "eyes" are radar fuzes.
Type	Nuclear weapon
Place of origin	Soviet Union
Specifications
Blast yield	22 kt (92 TJ)

Coordinates: 50°26′15″N 77°48′51″E / 50.43750°N 77.81417°E / 50.43750; 77.81417

The RDS-1 (Russian: РДС-1), also known as Izdeliye 501 (device 501) and First Lightning (Первая молния, Pervaya molniya), was the nuclear bomb 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 detonated on 29 August 1949 at 7:00 a.m., at Semipalatinsk, Kazakh SSR, after top-secret research and development as part of the Soviet atomic bomb 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. Plutonium for the bomb was produced at the industrial complex Chelyabinsk-40.

The RDS-1 explosion yielded 22 kilotons of TNT, similar to the American Gadget and Fat Man bombs. At Lavrentiy Beria's insistence, the RDS-1 bomb was designed as an implosion weapon similar to the Fat Man bomb dropped on Nagasaki, Japan; RDS-1 also had a solid plutonium core. The bomb designers had developed a more sophisticated design (tested later as RDS-2), but rejected it due to the known reliability of the Fat Man type design, the USSR having received extensive intelligence on the design of the Fat Man bomb during World War II.