Tin-111

Main isotopes of tin

Iso­tope Decay abun­dance half-life (t1/2) mode pro­duct 112Sn 0.97% stable 114Sn 0.66% stable 115Sn 0.34% stable 116Sn 14.54% stable 117Sn 7.68% stable 118Sn 24.22% stable 119Sn 8.59% stable 120Sn 32.58% stable 122Sn 4.63% stable 124Sn 5.79% stable 126Sn trace 2.3×105 y β− 126Sb
Standard atomic weight (Ar, standard)	118.710(7)

Tin (₅₀Sn) is the element with the greatest number of stable isotopes (ten; three of them are potentially radioactive but have not been observed to decay), which is probably related to the fact that 50 is a "magic number" of protons. 29 additional unstable isotopes are known, including the "doubly magic" tin-100 (¹⁰⁰Sn) (discovered in 1994) and tin-132 (¹³²Sn). The longest-lived radioisotope is ¹²⁶Sn, with a half-life of 230,000 years. The other 28 radioisotopes have half-lives less than a year.

Tin-121m is a radioisotope and nuclear isomer of tin with a half-life of 43.9 years.

In a normal thermal reactor, it has a very low fission product yield; thus, this isotope is not a significant contributor to nuclear waste. Fast fission or fission of some heavier actinides will produce ^121mSn at higher yields. For example, its yield from U-235 is 0.0007% per thermal fission and 0.002% per fast fission.

Tin-126 is a radioisotope of tin and one of only 7 long-lived fission products. While tin-126's halflife of 230,000 years translates to a low specific activity that limits its radioactive hazard, its short-lived decay product, antimony-126, emits high-energy gamma radiation, making external exposure to tin-126 a potential concern.

¹²⁶Sn is in the middle of the mass range for fission products. Thermal reactors, which make up almost all current nuclear power plants, produce it at a very low yield (0.056% for ²³⁵U), since slow neutrons almost always fission ²³⁵U or ²³⁹Pu into unequal halves. Fast fission in a fast reactor or nuclear weapon, or fission of some heavy minor actinides like californium, will produce it at higher yields.

...
Wikipedia