Fission Product Yield
Nuclear fission splits a heavy nucleus such as uranium or plutonium into two lighter nuclei, which are called fission products. Yield refers to the fraction of a fission product produced per fission.
Yield can be broken down by:
- Individual isotope
- Chemical element spanning several isotopes of different mass number but same atomic number.
- Nuclei of a given mass number regardless of atomic number. Known as "chain yield" because it represents a decay chain of beta decay.
Isotope and element yields will change as the fission products undergo beta decay, while chain yields do not change after completion of neutron emission by a few neutron-rich initial fission products (delayed neutrons), with halflife measured in seconds.
A few isotopes can be produced directly by fission, but not by beta decay because the would-be precursor with atomic number one greater is stable and does not decay. Chain yields do not account for these "shadowed" isotopes; however, they have very low yields (less than a millionth as much as common fission products) because they are far less neutron-rich than the original heavy nuclei.
Yield is usually stated as percentage per fission, so that the total yield percentages sum to 200%. Less often, it is stated as percentage of all fission products, so that the percentages sum to 100%. Ternary fission, about 0.2% to 0.4% of fissions, also produces a third light nucleus such as helium-4 (90%) or tritium (7%).
Prop: Unit: |
t½ a |
Yield % |
Q * keV |
βγ * |
---|---|---|---|---|
155Eu | 4.76 | .0803 | 252 | βγ |
85Kr | 10.76 | .2180 | 687 | βγ |
113mCd | 14.1 | .0008 | 316 | β |
90Sr | 28.9 | 4.505 | 2826 | β |
137Cs | 30.23 | 6.337 | 1176 | βγ |
121mSn | 43.9 | .00005 | 390 | βγ |
151Sm | 90 | .5314 | 77 | β |
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Read more about Fission Product Yield: Mass Vs. Yield Curve, Ordered By Yield (thermal Neutron Fission of U-235), Ordered By Mass Number, Ordered By Halflife, Ordered By Thermal Neutron Neutron Absorption Cross Section
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