"He was imprisoned not in the gulag but in his own institute in Moscow...."

The term GULAG is an acronymn for Glavnoye Upravlyeniye Ispravityel'no-Trudovih Lagyeryey i koloniy, which translates from Russian to The Chief Administration for Corrective Labour Camps and Colonies.

There were approximately 500 of these camps, with some located in the arctic regions of the Soviet Union. 

Over 14 million people were committed to Russian gulags from 1929 to 1953, and over half of them were committed without trial.