Agent Name

Californium

CAS Number

7440-71-3

Formula

Cf

Major Category

Physical/Radiation

Category

Radionuclides

Description

A man-made, radioactive metal with a melting point of 900 degrees C; [Merck Index # 1716]

Sources/Uses

Californium is a byproduct of plutonium production. Two of the californium isotopes (Cf-249 and Cf-251) have half-lives longer than 20 years and are defined as transuranic wastes (TRU) produced in nuclear reactors. Of the ten known isotopes, only Cf-252 is used commercially in industrial radiography and in brachytherapy to treat cancer. About 3% of decays are by spontaneous fission producing neutrons and gamma rays. Cf-252 is a strong emitter of neutrons at a rate of 170 million neutrons per minute. [Argonne]

Comments

Most Important Radionuclide: Cf-252; Source: Usually from neutron irradiation in a nuclear reactor; Half-Life: 2.6 years Effective Half-Life: 2.2 years Specific Activity (Ci/gm): 540 Decay Mode: Alpha GI Absorption: 0.05% Lung Clearance Half-Time: Years for oxides and hydroxides; Weeks for all other compounds; Critical Organ: Bone Internal Toxicity: Very High Annual Limit on Intake: 0.00002 mCi Radiation Energy (MeV): Spontaneous fission (3.1%); Alpha 6.075 (15%); Alpha 6.12 (81.6%); [See Glossary for references.] See "Radiation, ionizing."

Exposure Assessment
Half Life

Biological half-life: 20 years (liver) and 50 years (bone); [ANL Radiological Fact Sheets]

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