Nuklida · stabil · alami

Kripton-84 (⁸⁴Kr)

Kripton-84 (⁸⁴Kr) adalah isotop stabil kripton dengan 36 proton dan 48 neutron (nomor massa 84). Kelimpahan alaminya 0.569 87(15).

Data nuklida

Unsur: Kripton (Kr, Z = 36)
Nomor massa (A): 84
Proton (Z): 36
Neutron (N): 48
Massa atom: 83.91149772708 ± 0.0000000041 u
Waktu paruh: Stabil
Mode peluruhan: Tidak meluruh
Kelimpahan alami: 0.569 87(15)
Tahun penemuan: 1920
Sumber data: IAEA Atomic Mass Data Center (NUBASE) and IUPAC CIAAW, via PubChem

85Kr has minimal natural production in the Earth, but its concentration in the atmosphere has increased steadily because of human activities related to the nuclear industry. 85Kr enters oceans, lakes, and groundwater through equilibration of the water with air. 85Kr is produced terrestrially as a fission product of nuclear reactors and released into the atmosphere with the noble gases. It is also produced in the atmosphere via the cosmic ray neutron-activation reaction, 84Kr (n, γ) 85Kr. Thus, the 85Kr specific activity can be used to determine the time since water was isolated from the atmosphere (Fig. IUPAC.36.1). This approach provides a valuable addition to the use of tritium (3H) as an indicator of ocean circulation and groundwater age on decadal (a period of 10 consecutive years) time scales,. Krypton stable isotopes react in the upper atmosphere by cosmic-ray-induced spallation and neutron activation to produce radioactive 81Kr, with a half-life of approximately 2.1×105 years. In the atmosphere, 81Kr is chemically inert and has a long residence time; because of these characteristics, it is expected that 81Kr has a relatively constant and well-constrained atmospheric source. Natural cosmogenic 81Kr is incorporated from air into infiltrating groundwater and has been used to determine the age of groundwater over time scales ranging to over 106 years,,,.