: a radioactive chemical element with atomic number 98 that is produced artificially from the decay of berkelium and that is used chiefly as a neutron source in radiography and to start nuclear reactors see Chemical Elements Table
Example Sentences
Recent Examples on the WebBut the chase for 120 is on hold until researchers obtain the amount of californium—a rare element produced in high-flux nuclear reactors—needed for 120’s target. Daniel Clery, Science | AAAS, 12 Feb. 2021