Nuclear fission product
![Fission product yields by mass for thermal neutron fission of U-235, Pu-239, a combination of the two typical of current nuclear power reactors, and U-233 used in the thorium cycle.](/Images/godic/202501/30/ThermalFissionYield.svg5615.png")
![The external gamma dose for a person in the open near the Chernobyl disaster site.](/Images/godic/202501/30/Totalexternaldoseratecher5615.png")
![The portion of the total radiation dose (in air) contributed by each isotope versus time after the Chernobyl disaster, at the site thereof. Note that this image was drawn using data from the OECD report, and the second edition of 'The radiochemical manual'.[8]](/Images/godic/202501/30/AirDoseChernobylVector.svg5615.png")
![Per capita thyroid doses in the continental United States of iodine-131 resulting from all exposure routes from all atmospheric nuclear tests conducted at the Nevada Test Site. See also Downwinders.](/Images/godic/202501/30/US_fallout_exposure5615.png")
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 of heat energy (kinetic energy of the nuclei), and gamma rays. The two smaller nuclei are the fission products. (See also Fission products (by element)).