Naturally occurring ruthenium (₄₄Ru) is composed of seven stable

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

s. Additionally, 27 radioactive isotopes have been discovered. Of these radioisotopes, the most stable are ¹⁰⁶Ru, with a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable ato ...

of 373.59 days; ¹⁰³Ru, with a half-life of 39.26 days and ⁹⁷Ru, with a half-life of 2.9 days. Twenty-four other radioisotopes have been characterized with atomic weights ranging from 86.95 u (⁸⁷Ru) to 119.95 u (¹²⁰Ru). Most of these have half-lives that are less than five minutes, except ⁹⁴Ru (half-life: 51.8 minutes), ⁹⁵Ru (half-life: 1.643 hours), and ¹⁰⁵Ru (half-life: 4.44 hours). The primary

decay mode Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

before the most abundant isotope, ¹⁰²Ru, is

electron capture Electron capture (K-electron capture, also K-capture, or L-electron capture, L-capture) is a process in which the proton-rich nucleus of an electrically neutral atom absorbs an inner atomic electron, usually from the K or L electron shells. Thi ...

and the primary mode after is beta emission. The primary

decay product In nuclear physics, a decay product (also known as a daughter product, daughter isotope, radio-daughter, or daughter nuclide) is the remaining nuclide left over from radioactive decay. Radioactive decay often proceeds via a sequence of steps ( ...

before ¹⁰²Ru is technetium and the primary product after is

rhodium Rhodium is a chemical element with the symbol Rh and atomic number 45. It is a very rare, silvery-white, hard, corrosion-resistant transition metal. It is a noble metal and a member of the platinum group. It has only one naturally occurring isoto ...

. Because of the very high volatility of

ruthenium tetroxide Ruthenium tetroxide is the inorganic compound with the formula RuO4. It is a yellow volatile solid that melts near room temperature. It has the odor of ozone. Samples are typically black due to impurities. The analogous OsO4 is more widely used ...

() ruthenium radioactive isotopes with their relative short half-life are considered as the second most hazardous gaseous isotopes after

iodine-131 Iodine-131 (131I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nuc ...

in case of release by a nuclear accident.Ronneau, C., Cara, J., & Rimski-Korsakov, A. (1995)
Oxidation-enhanced emission of ruthenium from nuclear fuel
Journal of Environmental Radioactivity, 26(1), 63-70.Backman, U., Lipponen, M., Auvinen, A., Jokiniemi, J., & Zilliacus, R. (2004)
Ruthenium behaviour in severe nuclear accident conditions
Final report (No. NKS–100). Nordisk Kernesikkerhedsforskning.Beuzet, E., Lamy, J. S., Perron, H., Simoni, E., & Ducros, G. (2012)
Ruthenium release modelling in air and steam atmospheres under severe accident conditions using the MAAP4 code
Nuclear Engineering and Design, 246, 157-162. The two most important isotopes of ruthenium in case of nuclear accident are these with the longest half-life: ¹⁰³Ru (≥ 1 month) and ¹⁰⁶Ru (≥ 1 year).

List of isotopes

, - , ⁸⁷Ru , style="text-align:right" , 44 , style="text-align:right" , 43 , 86.94918(64)# , 50# ms 1.5 µs, β⁺ , ⁸⁷Tc , 1/2−# , , , - , ⁸⁸Ru , style="text-align:right" , 44 , style="text-align:right" , 44 , 87.94026(43)# , 1.3(3) s .2(+3−2) s, β⁺ , ⁸⁸Tc , 0+ , , , - , ⁸⁹Ru , style="text-align:right" , 44 , style="text-align:right" , 45 , 88.93611(54)# , 1.38(11) s , β⁺ , ⁸⁹Tc , (7/2)(+#) , , , - , ⁹⁰Ru , style="text-align:right" , 44 , style="text-align:right" , 46 , 89.92989(32)# , 11.7(9) s , β⁺ , ⁹⁰Tc , 0+ , , , - , ⁹¹Ru , style="text-align:right" , 44 , style="text-align:right" , 47 , 90.92629(63)# , 7.9(4) s , β⁺ , ⁹¹Tc , (9/2+) , , , - , rowspan=3 style="text-indent:1em" , ^91mRu , rowspan=3 colspan="3" style="text-indent:2em" , 80(300)# keV , rowspan=3, 7.6(8) s , β⁺ (>99.9%) , ⁹¹Tc , rowspan=3, (1/2−) , rowspan=3, , rowspan=3, , - , IT (<.1%) , ⁹¹Ru , - , β⁺, p (<.1%) , ⁹⁰Mo , - , ⁹²Ru , style="text-align:right" , 44 , style="text-align:right" , 48 , 91.92012(32)# , 3.65(5) min , β⁺ , ⁹²Tc , 0+ , , , - , ⁹³Ru , style="text-align:right" , 44 , style="text-align:right" , 49 , 92.91705(9) , 59.7(6) s , β⁺ , ⁹³Tc , (9/2)+ , , , - , rowspan=3 style="text-indent:1em" , ^93m1Ru , rowspan=3 colspan="3" style="text-indent:2em" , 734.40(10) keV , rowspan=3, 10.8(3) s , β⁺ (78%) , ⁹³Tc , rowspan=3, (1/2)− , rowspan=3, , rowspan=3, , - , IT (22%) , ⁹³Ru , - , β⁺, p (.027%) , ⁹²Mo , - , style="text-indent:1em" , ^93m2Ru , colspan="3" style="text-indent:2em" , 2082.6(9) keV , 2.20(17) µs , , , (21/2)+ , , , - , ⁹⁴Ru , style="text-align:right" , 44 , style="text-align:right" , 50 , 93.911360(14) , 51.8(6) min , β⁺ , ⁹⁴Tc , 0+ , , , - , style="text-indent:1em" , ^94mRu , colspan="3" style="text-indent:2em" , 2644.55(25) keV , 71(4) µs , , , (8+) , , , - , ⁹⁵Ru , style="text-align:right" , 44 , style="text-align:right" , 51 , 94.910413(13) , 1.643(14) h , β⁺ , ⁹⁵Tc , 5/2+ , , , - , ⁹⁶Ru , style="text-align:right" , 44 , style="text-align:right" , 52 , 95.907598(8) , colspan=3 align=center, Observationally StableBelieved to undergo β⁺β⁺ decay to ⁹⁶Mo with a half-life over 6.7×10¹⁶ years , 0+ , 0.0554(14) , , - , ⁹⁷Ru , style="text-align:right" , 44 , style="text-align:right" , 53 , 96.907555(9) , 2.791(4) d , β⁺ , ^97mTc , 5/2+ , , , - , ⁹⁸Ru , style="text-align:right" , 44 , style="text-align:right" , 54 , 97.905287(7) , colspan=3 align=center, StableTheoretically capable of

spontaneous fission Spontaneous fission (SF) is a form of radioactive decay that is found only in very heavy chemical elements. The nuclear binding energy of the elements reaches its maximum at an atomic mass number of about 56 (e.g., iron-56); spontaneous breakdo ...

, 0+ , 0.0187(3) , , - , ⁹⁹Ru , style="text-align:right" , 44 , style="text-align:right" , 55 , 98.9059393(22) , colspan=3 align=center, Stable , 5/2+ , 0.1276(14) , , - , ¹⁰⁰Ru , style="text-align:right" , 44 , style="text-align:right" , 56 , 99.9042195(22) , colspan=3 align=center, Stable , 0+ , 0.1260(7) , , - , ¹⁰¹Ru

Fission product Nuclear fission products are the atomic fragments left after a large atomic nucleus undergoes nuclear fission. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons, the release ...

, style="text-align:right" , 44 , style="text-align:right" , 57 , 100.9055821(22) , colspan=3 align=center, Stable , 5/2+ , 0.1706(2) , , - , style="text-indent:1em" , ^101mRu , colspan="3" style="text-indent:2em" , 527.56(10) keV , 17.5(4) µs , , , 11/2− , , , - , ¹⁰²Ru , style="text-align:right" , 44 , style="text-align:right" , 58 , 101.9043493(22) , colspan=3 align=center, Stable , 0+ , 0.3155(14) , , - , ¹⁰³Ru , style="text-align:right" , 44 , style="text-align:right" , 59 , 102.9063238(22) , 39.26(2) d , β⁻ , ¹⁰³Rh , 3/2+ , , , - , style="text-indent:1em" , ^103mRu , colspan="3" style="text-indent:2em" , 238.2(7) keV , 1.69(7) ms , IT , ¹⁰³Ru , 11/2− , , , - , ¹⁰⁴Ru , style="text-align:right" , 44 , style="text-align:right" , 60 , 103.905433(3) , colspan=3 align=center, Observationally StableBelieved to undergo β⁻β⁻ decay to ¹⁰⁴Pd , 0+ , 0.1862(27) , , - , ¹⁰⁵Ru , style="text-align:right" , 44 , style="text-align:right" , 61 , 104.907753(3) , 4.44(2) h , β⁻ , ¹⁰⁵Rh , 3/2+ , , , - , ¹⁰⁶Ru , style="text-align:right" , 44 , style="text-align:right" , 62 , 105.907329(8) , 373.59(15) d , β⁻ , ¹⁰⁶Rh , 0+ , , , - , ¹⁰⁷Ru , style="text-align:right" , 44 , style="text-align:right" , 63 , 106.90991(13) , 3.75(5) min , β⁻ , ¹⁰⁷Rh , (5/2)+ , , , - , ¹⁰⁸Ru , style="text-align:right" , 44 , style="text-align:right" , 64 , 107.91017(12) , 4.55(5) min , β⁻ , ¹⁰⁸Rh , 0+ , , , - , ¹⁰⁹Ru , style="text-align:right" , 44 , style="text-align:right" , 65 , 108.91320(7) , 34.5(10) s , β⁻ , ¹⁰⁹Rh , (5/2+)# , , , - , ¹¹⁰Ru , style="text-align:right" , 44 , style="text-align:right" , 66 , 109.91414(6) , 11.6(6) s , β⁻ , ¹¹⁰Rh , 0+ , , , - , ¹¹¹Ru , style="text-align:right" , 44 , style="text-align:right" , 67 , 110.91770(8) , 2.12(7) s , β⁻ , ¹¹¹Rh , (5/2+) , , , - , ¹¹²Ru , style="text-align:right" , 44 , style="text-align:right" , 68 , 111.91897(8) , 1.75(7) s , β⁻ , ¹¹²Rh , 0+ , , , - , ¹¹³Ru , style="text-align:right" , 44 , style="text-align:right" , 69 , 112.92249(8) , 0.80(5) s , β⁻ , ¹¹³Rh , (5/2+) , , , - , style="text-indent:1em" , ^113mRu , colspan="3" style="text-indent:2em" , 130(18) keV , 510(30) ms , , , (11/2−) , , , - , rowspan=2, ¹¹⁴Ru , rowspan=2 style="text-align:right" , 44 , rowspan=2 style="text-align:right" , 70 , rowspan=2, 113.92428(25)# , rowspan=2, 0.53(6) s , β⁻ (>99.9%) , ¹¹⁴Rh , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ¹¹³Rh , - , rowspan=2, ¹¹⁵Ru , rowspan=2 style="text-align:right" , 44 , rowspan=2 style="text-align:right" , 71 , rowspan=2, 114.92869(14) , rowspan=2, 740(80) ms , β⁻ (>99.9%) , ¹¹⁵Rh , rowspan=2, , rowspan=2, , rowspan=2, , - , β⁻, n (<.1%) , ¹¹⁴Rh , - , ¹¹⁶Ru , style="text-align:right" , 44 , style="text-align:right" , 72 , 115.93081(75)# , 400# ms 300 ns, β⁻ , ¹¹⁶Rh , 0+ , , , - , ¹¹⁷Ru , style="text-align:right" , 44 , style="text-align:right" , 73 , 116.93558(75)# , 300# ms 300 ns, β⁻ , ¹¹⁷Rh , , , , - , ¹¹⁸Ru , style="text-align:right" , 44 , style="text-align:right" , 74 , 117.93782(86)# , 200# ms 300 ns, β⁻ , ¹¹⁸Rh , 0+ , , , - , ¹¹⁹Ru , style="text-align:right" , 44 , style="text-align:right" , 75 , 118.94284(75)# , 170# ms 300 ns, , , , , , - , ¹²⁰Ru , style="text-align:right" , 44 , style="text-align:right" , 76 , 119.94531(86)# , 80# ms 300 ns, , , 0+ , , * Geologically exceptional samples are known in which the isotopic composition lies outside the reported range. The uncertainty in the

atomic mass The atomic mass (''m''a or ''m'') is the mass of an atom. Although the SI unit of mass is the kilogram (symbol: kg), atomic mass is often expressed in the non-SI unit dalton (symbol: Da) – equivalently, unified atomic mass unit (u). 1&nbs ...

may exceed the stated value for such specimens. * In September 2017 an estimated amount of 100 to 300 TBq (0.3 to 1 g) of ¹⁰⁶Ru was released in Russia, probably in the Ural region. It was, after ruling out release from a reentering satellite, concluded that the source is to be found either in nuclear fuel cycle facilities or radioactive source production. In France levels up to 0.036mBq/m³ of air were measured. It is estimated that over distances of the order of a few tens of kilometres around the location of the release levels may exceed the limits for non-dairy foodstuffs.
Detection of ruthenium 106 in France and in Europe, IRSN France (9 Nov 2017)

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** ** {{Navbox element isotopes Isotopes of ruthenium, Ruthenium Ruthenium