structural:summarization, information:filtering
Applications

Californium-252 has a number of specialized uses as a strong neutron emitter; it produces 139 million neutrons per microgram per minute. This property makes it useful as a startup neutron source for some nuclear reactors and as a portable (non-reactor based) neutron source for neutron activation analysis to detect trace amounts of elements in samples. Neutrons from californium are used as a treatment of certain cervical and brain cancers where other radiation therapy is ineffective. It has been used in educational applications since 1969 when Georgia Institute of Technology got a loan of 119 μg of Cf from the Savannah River Site. It is also used with online elemental coal analyzers and bulk material analyzers in the coal and cement industries.

Neutron penetration into materials makes californium useful in detection instruments such as fuel rod scanners; neutron radiography of aircraft and weapons components to detect corrosion, bad welds, cracks and trapped moisture; and in portable metal detectors. Neutron moisture gauges use Cf to find water and petroleum layers in oil wells, as a portable neutron source for gold and silver prospecting for on-the-spot analysis, and to detect ground water movement. The main uses of Cf in 1982 were, reactor start-up (48.3%), fuel rod scanning (25.3%), and activation analysis (19.4%). By 1994, most Cf was used in neutron radiography (77.4%), with fuel rod scanning (12.1%) and reactor start-up (6.9%) as important but secondary uses. In 2021, fast neutrons from Cf were used for wireless data transmission.

Cf has a very small calculated critical mass of about 5 kg (11 lb), high lethality, and a relatively short period of toxic environmental irradiation. The low critical mass of californium led to some exaggerated claims about possible uses for the element.

In October 2006, researchers announced that three atoms of oganesson (element 118) had been identified at Joint Institute for Nuclear Research in Dubna, Russia, from bombarding Cf with calcium-48, making it the heaviest element ever made. The target contained about 10 mg of Cf deposited on a titanium foil of 32 cm area. Californium has also been used to produce other transuranic elements; for example, lawrencium was first synthesized in 1961 by bombarding californium with boron nuclei.