Co60

Co-60, or cobalt-60, is a radioactive isotope of cobalt. It is not found naturally in meaningful amounts and is produced in nuclear reactors by irradiating cobalt-59 with neutrons. Co-60 has a half-life of 5.2714 years and decays by beta minus emission to nickel-60, accompanied by the emission of two gamma rays with energies of 1.173 MeV and 1.332 MeV.

The gamma photons produced by Co-60 make it a useful high-energy gamma-ray source for industrial and medical applications. In sealed radioactive sources, cobalt-60 is encapsulated in corrosion-resistant capsules and surrounded by shielding to limit exposure. Because the radiation is penetrating, substantial shielding of lead or steel is required, and handling is done with remote systems.

Production and use: Co-60 is produced by neutron activation of cobalt-59 in a nuclear reactor, with reactors being the common method; occasionally alternative production methods are used in specialized facilities. Commercial sources are used in gamma irradiation facilities for sterilization of medical equipment and supplies and for food irradiation to reduce microbial load. Gamma radiography uses Co-60 to inspect metal welds and structural components.

In medical therapy, cobalt-60 has historically provided external beam radiotherapy (teletherapy) before the development of more versatile linear accelerators; it remains in use in some settings where appropriate equipment exists. Safety and regulatory controls govern its production, transport, storage, and disposal because of the persistent radioactivity and the hazard posed by gamma radiation. Handling requires strict licensing, shielding, monitoring, and accident preparedness.