Why is the transmutation of actinides helpful in radioactive waste management?
The transmutation of actinides converts long-lived isotopes to shorter-lived ones.
Uranium-238 captures neutrons during the operation of nuclear reactors. It then decays into hazardous, long-lived nuclides. These include the actinides neptunium, plutonium, americium, and curium.
These isotopes are long-lived. They have half-lives of many thousands of years. Examples are Np-237 (2.14 × 10⁶ y), Pu-239 (24 100 y), Pu-240 (6563 y), Am-243 (7370 y), and Cm-248 (340 000 y). Society must store these nuclides for many years.
Actinides absorb neutrons in a nuclear reactor and undergo nuclear fission. This destroys the original isotopes and produces fission products with shorter half-lives.
For example, Pu-239 absorbs neutrons and undergoes fission to form Mo-99 with a half-life of 66 h.
But many of the fission products have half-lives of 30 years or more. Thus, they still need decades of storage to become safe.
From a waste management viewpoint, the transmutation of actinides eliminates a long-term radioactive hazard. It produces a shorter-term radioactive hazard instead.
Deep underground storage is still required, but not for as long.