The Soviet RDS-202 hydrogen bomb (code name Ivan or Vanya), known by Western nations as Tsar Bomba (Russian: Царь-бо́мба, tr. Tsar'-bómba, IPA: [t͡sarʲ ˈbombə], lit. 'Tsar bomb'), was allegedly the most powerful nuclear weapon ever created. Tested on 30 October 1961 as an experimental verification of calculation principles and multi-stage thermonuclear weapon designs, it also remains the most powerful explosive ever detonated.
The bomb was detonated at the Sukhoy Nos ("Dry Nose") cape of Severny Island, Novaya Zemlya, 15 km (9.3 mi) from Mityushikha Bay, north of Matochkin Strait. The detonation was secret but was detected by US Intelligence agencies. The US apparently had an instrumented KC-135R aircraft (Operation SpeedLight) in the area of the test, close enough to have been scorched by the blast.
The bhangmeter results and other data suggested the bomb yielded about 58 megatons of TNT [Mt] (240 PJ), and that was the accepted yield in technical literature until 1991 when Soviet scientists revealed that their instruments indicated a yield of 50 Mt (210 PJ). As they had the instrumental data and access to the test site, their yield figure has been accepted as more correct. In theory, the bomb would have had a yield in excess of 100 Mt (420 PJ) if it had included a uranium-238 tamper, but because only one bomb was built, that capability has never been demonstrated.