I used to train people how to operate nuclear power plants and my students were always interested in stories about radiation sickness. Radiation poisoning or radiation sickness is a form of damage to organ tissue caused by excessive exposure to ionizing radiation. The term is generally used to refer to acute problems caused by a large dosage of radiation in a short period of time, however it can also refer to cases when somebody has been repeatedly exposed to high doses. Symptoms prior to death can include severe nausea, vomiting, and diarrhea, rapid hair loss, infections, edema, high fever, and coma.