The bhangmeter results and other data suggested the bomb yielded around , which was the accepted yield in technical literature until 1991, when Soviet scientists revealed that their instruments indicated a yield of . As they had the instrumental data and access to the test site, their yield figure has been accepted as more accurate. In theory, the bomb would have had a yield in excess of if it had included a uranium-238 fusion tamper but, because only one bomb was built to completion, that capability has never been demonstrated. AN602 (Tsar Bomba) was a modification of the RN202 project.