This three stage weapon was actually a 100 megaton bomb design, but the uranium fusion stage tamper of the tertiary (and possibly the secondary) stage(s) was re

This three stage weapon was actually a 100 megaton bomb design, but the uranium fusion stage tamper of the tertiary (and possibly the secondary) stage(s) was replaced by one(s) made of lead. This reduced the yield by 50% by eliminating the fast fissioning of the uranium tamper by the fusion neutrons, and eliminated 97% of the fallout (1.5 megatons of fission, instead of about 51.5 Mt), yet still proved the full yield design. The result was the "cleanest" weapon ever tested with 97% of the energy coming from fusion reactions. The effect of this bomb at full yield on global fallout would have been tremendous. It would have increased the world's total fission fallout since the invention of the atomic bomb by 25%. [1] 1: http://nuclearweaponarchive.org/Russia/TsarBomba.html http://nuclearweaponarchive.org/Russia/TsarBomba.html