Isotopes of tantalum

Natural <a href="/facts/Tantalum/VwaxMm33">tantalum</a> (73Ta) consists of two stable <a href="/facts/Isotope/KD9B1y6o">isotopes</a>: 181Ta (99.988%) and 180mTa (0.012%).
There are also 35 known artificial <a href="/facts/Radioisotope/5WpCfbdq">radioisotopes</a>, the longest-lived of which are 179Ta with a half-life of 1.82 years, 182Ta with a half-life of 114.43 days, 183Ta with a half-life of 5.1 days, and 177Ta with a half-life of 56.56 hours. All other isotopes have half-lives under a day, most under an hour. There are also numerous isomers, the most stable of which (other than 180mTa) is 178m1Ta with a half-life of 2.36 hours. All isotopes and <a href="/facts/Nuclear_isomers/L8DHcqnk">nuclear isomers</a> of tantalum are either radioactive or <a href="/facts/Observationally_stable/vC0VVvqN">observationally stable</a>, meaning that they are predicted to be radioactive but no actual decay has been observed.
Tantalum has been proposed as a "<a href="/facts/Salted_bomb/6MpT828Q">salting</a>" material for <a href="/facts/Nuclear_weapon/QVdBcMdm">nuclear weapons</a> (<a href="/facts/Cobalt/gqhScEw4">cobalt</a> is another, better-known salting material). A jacket of 181Ta, irradiated by the intense high-energy neutron flux from an exploding thermonuclear weapon, would transmute into the radioactive isotope 182Ta with a <a href="/facts/Half-life/kGVH8BAB">half-life</a> of 114.43 days and produce approximately 1.12 <a href="/facts/MeV/YMT1fqX9">MeV</a> of <a href="/facts/Gamma_ray/5Drf913J">gamma radiation</a>, significantly increasing the radioactivity of the weapon's <a href="/facts/Nuclear_fallout/I1kJkLKt">fallout</a> for several months. Such a weapon is not known to have ever been built, tested, or used. While the conversion factor from <a href="/facts/Absorbed_dose/jbqUFt9v">absorbed dose</a> (measured in <a href="/facts/Gray_(unit)/GFDaGPSL">Grays</a>) to <a href="/facts/Effective_dose_(radiation)/DVoke3hy">effective dose</a> (measured in <a href="/facts/Sievert_(unit)/8HLEH1vG">Sievert</a>) for gamma rays is 1 while it is 50 for alpha radiation (i.e., a gamma dose of 1 Gray is equivalent to 1 Sievert whereas an alpha dose of 1 Gray is equivalent to 50 Sievert), gamma rays are only <a href="/facts/Attenuation/XP4vX360">attenuated</a> by shielding, not stopped. As such, alpha particles require incorporation to have an effect while gamma rays can have an effect via mere proximity. In military terms, this allows a gamma ray weapon to <a href="/facts/Area_denial/sVtRam7L">deny an area</a> to either side as long as the dose is high enough, whereas <a href="/facts/Radioactive_contamination/Rd6dcVM9">radioactive contamination</a> by alpha emitters which do not release significant amounts of gamma rays can be counteracted by ensuring the material is not incorporated.

Isotopes of tantalum open-in-new

Isotopes of tantalum