One Curie is the radiation of a gram of radium. In 1957 this place emitted millions of curies. Not counting before or after.

Damned interesting: [https://www.damninteresting.com/in-soviet-russia-lake-contam...]

Chelyabinsk (that one) is nearby. [https://web.archive.org/web/20140204004304/http://wentz.net/...]