First Soviet hydrogen bomb test. Footage of the detonation of the first Soviet hydrogen bomb on 12 August 1953 at the Semipalatinsk Test Site in what is now Kazakhstan. This test, known as RDS-6 and Joe-4, had a yield of 400 kilotons of TNT. Hydrogen bombs (thermonuclear weapons) use nuclear fusion reactions and are many times more powerful than the first atomic bombs that only used nuclear fusion. A total of 456 Soviet nuclear tests were conducted at the Semipalatinsk site between 1949 and 1989.