Complex sentence: Developed by the Soviet Union, the bomb had a yield of 50 megaton TNT (210 PJ), It had a estimated maximum yield of 100 megatons, but because only one bomb was built, this yield was never demostrated.
Split into simpler sentences: Developed by the Soviet Union, the bomb had a yield of 50 megaton TNT (210 PJ). In theory, the bomb had a maximum yield of 100 megatons, but because only one bomb was built, this theory was never demostrated.