Technetium-99

Technetium-99 (⁹⁹Tc) is an isotope of uranium-235.

The weak beta emission is stopped by the walls of laboratory glassware. Soft X-rays are emitted when the beta particles are stopped, but as long as the body is kept more than 30 cm away these should pose no problem. The primary hazard when working with technetium is inhalation of dust; such radioactive contamination in the lungs can pose a significant cancer risk.

As of 2005, technetium-99 is available to holders of an ORNL permit for US$83/g plus packing charges.^[1]

Due to its high fission yield, relatively long half-life, and mobility in the environment, technetium-99 is one of the more significant components of nuclear waste. Measured in becquerels per amount of spent fuel, it is the dominant producer of radiation in the period from about 10⁴ to 10⁶ years after the creation of the nuclear waste.^[2] The next shortest-lived fission product is neutron capture have halflives in the intermediate range.

An estimated 160 TSellafield plant, which released an estimated 550 TBq (about 900 kg) from 1995-1999 into the Irish Sea. From 2000 onwards the amount has been limited by regulation to 90 TBq (about 140 kg) per year.^[3]

The long half-life of technetium-99 and its ability to form an anionic species makes it (along with ¹²⁹I) a major concern when considering long-term disposal of high-level radioactive waste. In addition, many of the processes designed to remove fission products from medium-active process streams in reprocessing plants are designed to remove cationic species like caesium are much more able to bind to soil particles. For this reason, the environmental chemistry of technetium is an active area of research.

An alternative disposal method, ruthenium (¹⁰⁰Ru).

nuclear medicine.