There are 34 known

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 of

krypton Krypton (from grc, κρυπτός, translit=kryptos 'the hidden one') is a chemical element with the symbol Kr and atomic number 36. It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is often ...

(₃₆Kr) with

atomic mass number The mass number (symbol ''A'', from the German word ''Atomgewicht'' tomic weight, also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. It is approximat ...

s from 69 through 102. Naturally occurring krypton is made of five

stable isotope The term stable isotope has a meaning similar to stable nuclide, but is preferably used when speaking of nuclides of a specific element. Hence, the plural form stable isotopes usually refers to isotopes of the same element. The relative abundanc ...

s and one () which is slightly

radioactive 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 ...

with an extremely long half-life, plus traces of

radioisotopes A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

that are produced by

cosmic rays Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...

in the

atmosphere An atmosphere () is a layer of gas or layers of gases that envelop a planet, and is held in place by the gravity of the planetary body. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A s ...

List of isotopes

, - , ⁶⁹Kr , style="text-align:right" , 36 , style="text-align:right" , 33 , 68.96518(43)# , 32(10) ms , β⁺ , ⁶⁹Br , 5/2−# , , , - , ⁷⁰Kr , style="text-align:right" , 36 , style="text-align:right" , 34 , 69.95526(41)# , 52(17) ms , β⁺ , ⁷⁰Br , 0+ , , , - , rowspan=2, ⁷¹Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 35 , rowspan=2, 70.94963(70) , rowspan=2, 100(3) ms , β⁺ (94.8%) , ⁷¹Br , rowspan=2, (5/2)− , rowspan=2, , rowspan=2, , - , β⁺, p (5.2%) , ⁷⁰Se , - , ⁷²Kr , style="text-align:right" , 36 , style="text-align:right" , 36 , 71.942092(9) , 17.16(18) s , β⁺ , ⁷²Br , 0+ , , , - , rowspan=2, ⁷³Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 37 , rowspan=2, 72.939289(7) , rowspan=2, 28.6(6) s , β⁺ (99.32%) , ⁷³Br , rowspan=2, 3/2− , rowspan=2, , rowspan=2, , - , β⁺, p (.68%) , ⁷²Se , - , style="text-indent:1em" , ^73mKr , colspan="3" style="text-indent:2em" , 433.66(12) keV , 107(10) ns , , , (9/2+) , , , - , ⁷⁴Kr , style="text-align:right" , 36 , style="text-align:right" , 38 , 73.9330844(22) , 11.50(11) min , β⁺ , ⁷⁴Br , 0+ , , , - , ⁷⁵Kr , style="text-align:right" , 36 , style="text-align:right" , 39 , 74.930946(9) , 4.29(17) min , β⁺ , ⁷⁵Br , 5/2+ , , , - , ⁷⁶Kr , style="text-align:right" , 36 , style="text-align:right" , 40 , 75.925910(4) , 14.8(1) h , β⁺ , ⁷⁶Br , 0+ , , , - , ⁷⁷Kr , style="text-align:right" , 36 , style="text-align:right" , 41 , 76.9246700(21) , 74.4(6) min , β⁺ , ⁷⁷Br , 5/2+ , , , - , ⁷⁸Kr Primordial

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transfer ...

, style="text-align:right" , 36 , style="text-align:right" , 42 , 77.9203648(12) , align=center, 9.2 y , Double EC , ⁷⁸Se , 0+ , 0.00355(3) , , - , ⁷⁹Kr , style="text-align:right" , 36 , style="text-align:right" , 43 , 78.920082(4) , 35.04(10) h , β⁺ , ⁷⁹Br , 1/2− , , , - , style="text-indent:1em" , ^79mKr , colspan="3" style="text-indent:2em" , 129.77(5) keV , 50(3) s , , , 7/2+ , , , - , ⁸⁰Kr , style="text-align:right" , 36 , style="text-align:right" , 44 , 79.9163790(16) , colspan=3 align=center, Stable , 0+ , 0.02286(10) , , - , ⁸¹KrUsed to date

groundwater Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidate ...

, style="text-align:right" , 36 , style="text-align:right" , 45 , 80.9165920(21) , 2.29(11)×10⁵ y , EC , ⁸¹Br , 7/2+ , trace , , - , rowspan=2 style="text-indent:1em" , ^81mKr , rowspan=2 colspan="3" style="text-indent:2em" , 190.62(4) keV , rowspan=2, 13.10(3) s , IT (99.975%) , ⁸¹Kr , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , EC (.025%) , ⁸¹Br , - , ⁸²Kr , style="text-align:right" , 36 , style="text-align:right" , 46 , 81.9134836(19) , colspan=3 align=center, Stable , 0+ , 0.11593(31) , , - , ⁸³Kr

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" , 36 , style="text-align:right" , 47 , 82.914136(3) , colspan=3 align=center, Stable , 9/2+ , 0.11500(19) , , - , style="text-indent:1em" , ^83m1Kr , colspan="3" style="text-indent:2em" , 9.4053(8) keV , 154.4(11) ns , , , 7/2+ , , , - , style="text-indent:1em" , ^83m2Kr , colspan="3" style="text-indent:2em" , 41.5569(10) keV , 1.83(2) h , IT , ⁸³Kr , 1/2− , , , - , ⁸⁴Kr , style="text-align:right" , 36 , style="text-align:right" , 48 , 83.911507(3) , colspan=3 align=center, Stable , 0+ , 0.56987(15) , , - , style="text-indent:1em" , ^84mKr , colspan="3" style="text-indent:2em" , 3236.02(18) keV , 1.89(4) µs , , , 8+ , , , - , ⁸⁵Kr , style="text-align:right" , 36 , style="text-align:right" , 49 , 84.9125273(21) , 10.776(3) y , β⁻ , ⁸⁵Rb , 9/2+ , trace , , - , rowspan=2 style="text-indent:1em" , ^85m1Kr , rowspan=2 colspan="3" style="text-indent:2em" , 304.871(20) keV , rowspan=2, 4.480(8) h , β⁻ (78.6%) , ⁸⁵Rb , rowspan=2, 1/2− , rowspan=2, , rowspan=2, , - , IT (21.4%) , ⁸⁵Kr , - , style="text-indent:1em" , ^85m2Kr , colspan="3" style="text-indent:2em" , 1991.8(13) keV , 1.6(7) µs
.2(+10-4) µs, , , (17/2+) , , , - , ⁸⁶KrFormerly used to define the meter , style="text-align:right" , 36 , style="text-align:right" , 50 , 85.91061073(11) , colspan=3 align=center,

Observationally Stable Stable nuclides are nuclides that are not radioactive and so (unlike radionuclides) do not spontaneously undergo radioactive decay. When such nuclides are referred to in relation to specific elements, they are usually termed stable isotopes. Th ...

Believed to decay by β⁻β⁻ to ⁸⁶Sr , 0+ , 0.17279(41) , , - , ⁸⁷Kr , style="text-align:right" , 36 , style="text-align:right" , 51 , 86.91335486(29) , 76.3(5) min , β⁻ , ''⁸⁷Rb'' , 5/2+ , , , - , ⁸⁸Kr , style="text-align:right" , 36 , style="text-align:right" , 52 , 87.914447(14) , 2.84(3) h , β⁻ , ⁸⁸Rb , 0+ , , , - , ⁸⁹Kr , style="text-align:right" , 36 , style="text-align:right" , 53 , 88.91763(6) , 3.15(4) min , β⁻ , ⁸⁹Rb , 3/2(+#) , , , - , ⁹⁰Kr , style="text-align:right" , 36 , style="text-align:right" , 54 , 89.919517(20) , 32.32(9) s , β⁻ , ^90mRb , 0+ , , , - , ⁹¹Kr , style="text-align:right" , 36 , style="text-align:right" , 55 , 90.92345(6) , 8.57(4) s , β⁻ , ⁹¹Rb , 5/2(+) , , , - , rowspan=2, ⁹²Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 56 , rowspan=2, 91.926156(13) , rowspan=2, 1.840(8) s , β⁻ (99.96%) , ⁹²Rb , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (.033%) , ⁹¹Rb , - , rowspan=2, ⁹³Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 57 , rowspan=2, 92.93127(11) , rowspan=2, 1.286(10) s , β⁻ (98.05%) , ⁹³Rb , rowspan=2, 1/2+ , rowspan=2, , rowspan=2, , - , β⁻, n (1.95%) , ⁹²Rb , - , rowspan=2, ⁹⁴Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 58 , rowspan=2, 93.93436(32)# , rowspan=2, 210(4) ms , β⁻ (94.3%) , ⁹⁴Rb , rowspan=2, 0+ , rowspan=2, , rowspan=2, , - , β⁻, n (5.7%) , ⁹³Rb , - , ⁹⁵Kr , style="text-align:right" , 36 , style="text-align:right" , 59 , 94.93984(43)# , 114(3) ms , β⁻ , ⁹⁵Rb , 1/2(+) , , , - , ⁹⁶Kr , style="text-align:right" , 36 , style="text-align:right" , 60 , 95.942998(62) , 80(7) ms , β⁻ , ⁹⁶Rb , 0+ , , , - , rowspan=2, ⁹⁷Kr , rowspan=2 style="text-align:right" , 36 , rowspan=2 style="text-align:right" , 61 , rowspan=2, 96.94856(54)# , rowspan=2, 63(4) ms , β⁻ , ⁹⁷Rb , rowspan=2, 3/2+# , rowspan=2, , rowspan=2, , - , β⁻, n , ⁹⁶Rb , - , ⁹⁸Kr , style="text-align:right" , 36 , style="text-align:right" , 62 , 97.95191(64)# , 46(8) ms , , , 0+ , , , - , ⁹⁹Kr , style="text-align:right" , 36 , style="text-align:right" , 63 , 98.95760(64)# , 40(11) ms , , , (3/2+)# , , , - , ¹⁰⁰Kr , style="text-align:right" , 36 , style="text-align:right" , 64 , 99.96114(54)# , 10# ms
300 ns, , , 0+ , , , - , rowspan=3 , ¹⁰¹Kr , rowspan=3 , 36 , rowspan=3 , 65 , rowspan=3 , unknown , rowspan=3 , >635 ns , β⁻, 2n , ⁹⁹Rb , rowspan=3 , unknown , rowspan=3 , , rowspan=3 , , - , β⁻, n , ¹⁰⁰Rb , - , β⁻ , ¹⁰¹Rb , - , ¹⁰²Kr , style="text-align:right" , 36 , style="text-align:right" , 66 , , , , , 0+ , , * The isotopic composition refers to that in air.

Notable isotopes

Krypton-81

Radioactive krypton-81 is the product of

spallation reaction Spallation is a process in which fragments of material (spall) are ejected from a body due to impact or stress. In the context of impact mechanics it describes ejection of material from a target during impact by a projectile. In planetary p ...

s with

cosmic ray Cosmic rays are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the Solar System in our own ...

s striking gases present in the Earth atmosphere, along with the six stable or nearly stable krypton

s. Krypton-81 has 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 about 229,000 years. Krypton-81 is used for dating ancient (50,000- to 800,000-year-old)

and to determine their

residence time The residence time of a fluid parcel is the total time that the parcel has spent inside a control volume (e.g.: a chemical reactor, a lake, a human body). The residence time of a set of parcels is quantified in terms of the frequency distribution ...

in deep

aquifer An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...

s. One of the main technical limitation of the method is that it requires to sample very large volumes of water: several hundred liters or a few cubic meters of water. This is particularly challenging for dating

pore water Groundwater is the water present beneath Earth's surface in rock and soil pore spaces and in the fractures of rock formations. About 30 percent of all readily available freshwater in the world is groundwater. A unit of rock or an unconsolidated ...

in deep

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay par ...

aquitard An aquifer is an underground layer of water-bearing, permeable rock, rock fractures, or unconsolidated materials (gravel, sand, or silt). Groundwater from aquifers can be extracted using a water well. Aquifers vary greatly in their characterist ...

s with very low

hydraulic conductivity Hydraulic conductivity, symbolically represented as (unit: m/s), is a property of porous materials, soils and rocks, that describes the ease with which a fluid (usually water) can move through the pore space, or fractures network. It depends on th ...

Krypton-85

Krypton-85 Krypton-85 (85Kr) is a radioisotope of krypton. Krypton-85 has a half-life of 10.756 years and a maximum decay energy of 687 keV. It decays into stable rubidium-85. Its most common decay (99.57%) is by beta particle emission with maximum energy ...

is a radioisotope of krypton that has a half-life of about 10.75 years. This isotope is produced by the

nuclear fission Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radio ...

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

and

plutonium Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibi ...

nuclear weapons testing Nuclear weapons tests are experiments carried out to determine nuclear weapons' effectiveness, Nuclear weapon yield, yield, and explosive capability. Testing nuclear weapons offers practical information about how the weapons function, how detona ...

and in

nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ...

s, as well as by cosmic rays. An important goal of the Limited Nuclear Test Ban Treaty of 1963 was to eliminate the release of such radioisotopes into the atmosphere, and since 1963 much of that krypton-85 has had time to decay. However, it is inevitable that krypton-85 is released during the reprocessing of

fuel rod Nuclear fuel is material used in nuclear power stations to produce heat to power turbines. Heat is created when nuclear fuel undergoes nuclear fission. Most nuclear fuels contain heavy fissile actinide elements that are capable of undergoing ...

s from nuclear reactors.

Atmospheric concentration

The atmospheric concentration of krypton-85 around the

North Pole The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True North Pole to distinguish from the Mag ...

is about 30 percent higher than that at the

Amundsen–Scott South Pole Station The Amundsen–Scott South Pole Station is the United States scientific research station at the South Pole of the Earth. It is the southernmost point under the jurisdiction (not sovereignty) of the United States. The station is located on the ...

because nearly all of the world's nuclear reactors and all of its major nuclear reprocessing plants are located in the

northern hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...

, and also well-north of the

equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...

. To be more specific, those

nuclear reprocessing Nuclear reprocessing is the chemical separation of fission products and actinides from spent nuclear fuel. Originally, reprocessing was used solely to extract plutonium for producing nuclear weapons. With commercialization of nuclear power, the ...

plants with significant capacities are located in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

, the

French Republic France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

, the

Russian Federation Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

Mainland China "Mainland China" is a geopolitical term defined as the territory governed by the People's Republic of China (including islands like Hainan or Chongming), excluding dependent territories of the PRC, and other territories within Greater China. ...

(PRC),

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the north ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

, and

Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...

Krypton-86

Krypton-86 was formerly used to define the meter from 1960 until 1983, when the definition of the meter was based on the wavelength of the 606 nm (orange) spectral line of a krypton-86 atom.

Others

All other

radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

s of krypton have half-lives of less than one day, except for krypton-79, a positron emitter with a half-life of about 35.0 hours.

References

* Isotope masses from: ** * Isotopic compositions and standard atomic masses from: ** ** * Half-life, spin, and isomer data selected from the following sources. ** ** **

External links

Brookhaven National Laboratory: Krypton-101 information
{{Navbox element isotopes Krypton

Krypton Krypton (from grc, κρυπτός, translit=kryptos 'the hidden one') is a chemical element with the symbol Kr and atomic number 36. It is a colorless, odorless, tasteless noble gas that occurs in trace amounts in the atmosphere and is often ...