Thoughts on the 20th anniversary of CP-1

To the members of the nuclear project in Chicago, the establishment of a nuclear chain reaction did not appear at the time to be as significant an event as it is viewed today. Theoretical work, based on nuclear constants obtained both in the United States and abroad, shows that the chain reaction could be established with a sufficient amount of materials of the right purity. The conviction in the possibility of a chain reaction with natural uranium was not based on theoretical work alone. Fermi has experimentally demonstrated the possibility of a self-sustaining reaction. At that time the scientists could not fully realize the magnitude and the character of the changes which nuclear energy was to bring to our world. The author's memories about these events are presented in the article.