fermium-257 Directory References Discover Weapons of World War I Spies Like Us: 10 Famous Names in the Espionage Game The 6 Deadliest Earthquakes Since 1950 What’s the Difference Between Bison and Buffalo? 7 Deadliest Weapons in History Timeline of the 2000s Timeline of the American Civil Rights Movement Contents Ask the Chatbot a Question fermium-257 chemical isotope Ask the Chatbot a Question Learn about this topic in these articles:fermium In fermium6-hour half-life), and fermium-257 (100.5-day half-life) have been produced in a high-neutron-flux reactor by the intense slow-neutron irradiation of elements of lower atomic number, such as plutonium.Read More Britannica ChatbotChatbot answers are created from Britannica articles using AI. This is a beta feature. AI answers may contain errors. Please verify important information using Britannica articles. About Britannica AI.