1. undergoing nuclear fission; splitting into two or more parts
Usage: physics; present participle of fission

Examples

• The uranium atom is fissioning in the reactor core.
• Scientists observed the heavy nucleus fissioning into lighter elements.
• The fissioning process releases enormous amounts of energy.
• Plutonium-239 is capable of fissioning when struck by neutrons.
• The fissioning material must be carefully controlled in nuclear reactors.
• Researchers studied the rate at which the isotope was fissioning.