The third mistake was that, because the workers were allowed to bypass the time-consuming mixing process in the tower, with its automatic controls for preventing such things happening, they were free to dump their material into a vessel that was not designed to prevent the accumulation of a critical mass sufficient to support a chain reaction.
Third, in terms of the process of reaching national security decisions, I am adopting in total the Tower Report's model of how the NSC process and staff should work.