[4] Zavenyagin was made plant manager of the Magnitogorsk Iron and Steel Works in August 1933 and served in that capacity until 1936 when he was appointed the assistant to the People's Commissar of Heavy Industry.

9887ss/ov "On the Special Committee [on the use of atomic energy] under the State Defense Committee," Zavenyagin was responsible for the following areas of work: Another important area of work was the solution of personnel issues: by Lavrentiy Beria's order, Mikhail Pervukhin, Vyacheslav Malyshev, Boris Vannikov, and Zavenyagin staffed the council sections with scientific and engineering personnel and selected experts to resolve individual issues.

In addition, Zavenyagin participated in the selection of construction sites for plants of projects 817 (Mayak Production Association) and 813 (Ural Electrochemical Combine).

These were metallurgists, chemists and physicists, including Nikolaus Riehl and Manfred von Ardenne, totalling 70 people in 1945 and over three hundred by 1948.

[16] A protégé of Lavrenti Beria,[2] Zavenyagin survived the purge after the death of Joseph Stalin because of a long friendship with Nikita Khrushchev, which dated back to the 1920s.

During the Khrushchev era, he headed the Ministry of Medium Machine Building, responsible for nuclear weapons production, for two years.

[20] A memorial plaque was installed in 2001 for the 100th anniversary of Zavenyagin's birth on the management building of the mining and metallurgical company Norilsk Nickel.