The reliability and effectiveness of the US stockpile of nuclear weapons needed to be periodically evaluated in a zero-threat environment. Tests were conducted underground at the Nevada Test Site and also in the Pacific Ocean, where physicists and nuclear engineers conducted numerous time-of-flight-experiments in determining the yield of a device. Also measured were the maximum neutron output, maximum temperature plus number of gamma rays emanating from a devise. Theoretical and experimental comparisons were conducted to see if theory and reality were congruent or not.
Listed below are a few unclassified articles on these issues.