Isotopes of ruthenium

Naturally occurring ruthenium (44Ru) is composed of seven stable isotopes (of which two may in the future be found radioactive).

Twenty-four other radioisotopes have been characterized with atomic weights ranging from 86.95 u (87Ru) to 119.95 u (120Ru).

The primary decay mode before the most abundant isotope, 102Ru, is electron capture and the primary mode after is beta emission.

Because of the very high volatility of ruthenium tetroxide (RuO4) ruthenium radioactive isotopes with their relative short half-life are considered as the second most hazardous gaseous isotopes after iodine-131 in case of release by a nuclear accident.

[4][5][6] The two most important isotopes of ruthenium in case of nuclear accident are these with the longest half-life: 103Ru (39.26 days) and 106Ru (373.59 days).