ORIGINAL REPORT HERE FROM THE WALL STREET JOURNAL ( Sorry, it’s behind a pay wall ):
Moscow Times article
https://www.themoscowtimes.com/2019/08/20/4-russian-nuclear-monitors-went-silent-following-rocket-explosion-wsj-a66923
And an exclusive: Exclusive: Russian Doctors Say They Werent Warned Patients Were Nuclear Accident Victims
One doctor was reportedly later found to have a radioactive isotope in their muscle tissue.
By Evan Gershkovich and Pjotr Sauer