"Hibakusha" literally means RADIOACTIVELY-POLLUTED PEOPLE. Or radioactively comtaminated people. It writes 「被曝者」, and explosion-affected literally 「被爆者」. Very different.
Hibakusha is the term widely used in Japan referring to victims of the atomic bombings of Hiroshima and Nagasaki. The Japanese word translates literally to "explosion-affected people".