atomgradとは 意味・読み方・使い方

During the Cold War the Soviet Union created at least ten closed cities, known as Atomgrads, in which nuclear weapons-related research and development took place. After the dissolution of the Soviet Union, all of the cities changed their names (most of the original code-names were simply the oblast and a number). All are still legally "closed", though some have parts of them accessible to foreign visitors with special permits (Sarov, Snezhinsk, and Zheleznogorsk).