The RDS-37 tests at the Semipalatink Site proved to bring the Soviet Union back into the arms race with the United States . A large part of this was due to the fact that the Soviet Union was the first nation to successfully employ the use of lithium deuterium as a thermonuclear fuel . Another important factor to consider was the accuracy with which the Soviets were able to predict the energy yields of their bombs . The predictions for the RDS-6 tests were accurate up to 30 % and the RDS-37 tests were accurate to within 10 % , whereas the American counterpart energy yield predictions were off by a factor of two and a half in the Castle Bravo test . The Soviets also delivered a weapon-ready design for the RDS-37 . On the American side of the arms race , the bombs being tested were remotely detonated . " The test was the culmination of many years of labor , a triumph that has opened the way to the development of a whole range of devices with diverse high-performance characteristics . " The report on the RDS-37 , written by Zel ' dovich and Sakharov , stated that the new principle of atomic compression as seen in the RDS-37 was a " shining example of creative teamwork . " The report boasted enormous amounts of design-oriented , experimental and technological efforts carried out under the supervision of Design Bureau 11 's chief designer , Khariton
Castle Bravo
Castle Bravo
RDS-37