fissiotuoteisotoopit

Fissiotuoteisotoopit, or fission product isotopes, are the radioactive nuclides produced when a heavy nucleus splits during nuclear fission. In a fission event, isotopes of uranium-235, plutonium-239, or other actinides divide into lighter fragments that are typically neutron-rich and unstable. Most fission products decay by beta emission toward stable isotopes, often emitting gamma rays along the way. The resulting nuclide mix depends on the fissile material and the neutron spectrum.

Production and characteristics: Fission products are generated in nuclear reactors, weapons tests, and other fission events. Thousands of different nuclides can be formed, with a bimodal mass distribution giving rise to fragments near mass numbers around 95 and 135. Their half-lives span from milliseconds to decades, meaning some disappear almost immediately while others persist and contribute to long‑term radioactivity. A few well-known isotopes include iodine-131 (short-lived, 8 days, thyroid uptake), cesium-137 (about 30-year half-life, gamma emitter), strontium-90 (about 29 years, bone-seeking), and xenon-133 (a noble gas used in diagnostics). Other fission products such as ruthenium-106 and cerium-144 also appear in reactor effluents and fallout.

Impact and significance: Fission product isotopes are the primary source of radiological decay heat after a reactor is shut down and play a central role in environmental monitoring, radioprotection, and nuclear safeguards. Their emissions determine the radiological hazard in accidents and influence cleanup strategies. While some fission products have medical or industrial applications when produced in other ways, their production in fission events is mainly a consideration for reactor physics, safety, and environmental science.

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