Technetium-99

Technetium-99, 99Tc
General
Symbol99Tc
Namestechnetium-99, 99Tc, Tc-99
Protons (Z)43
Neutrons (N)56
Nuclide data
Natural abundancetrace
Half-life (t1/2)211100±1200 years
Spin9/2+
Excess energy−87327.9±0.9 keV
Binding energy8613.610±0.009 keV
Decay products99Ru
Decay modes
Decay modeDecay energy (MeV)
Beta decay0.2975
Isotopes of technetium
Complete table of nuclides

Technetium-99 (99Tc) is an isotope of technetium which decays with a half-life of 211,000 years to stable ruthenium-99, emitting beta particles, but no gamma rays. It is the most significant long-lived fission product of uranium fission, producing the largest fraction of the total long-lived radiation emissions of nuclear waste. Technetium-99 has a fission product yield of 6.0507% for thermal neutron fission of uranium-235.

The metastable technetium-99m (99mTc) is a short-lived (half-life about 6 hours) nuclear isomer used in nuclear medicine, produced from molybdenum-99. It decays by isomeric transition to technetium-99, a desirable characteristic, since the very long half-life and type of decay of technetium-99 imposes little further radiation burden on the body.