Yield Nuclear fission product

fission product yields mass thermal neutron fission of u-235, pu-239, combination of 2 typical of current nuclear power reactors, , u-233 used in thorium cycle.

each fission of parent atom produces different set of fission product atoms. however, while individual fission not predictable, fission products statistically predictable. amount of particular isotope produced per fission called yield, typically expressed percent per parent fission; therefore, yields total on 200% (because of ternary fissions), not 100%.

while fission products include every element zinc through lanthanides, majority of fission products occur in 2 peaks. 1 peak occurs @ (expressed atomic number) strontium ruthenium while other peak @ tellurium neodymium. yield dependent on parent atom , on energy of initiating neutron.

in general higher energy of state undergoes nuclear fission, more 2 fission products have similar mass. hence neutron energy increases and/or energy of fissile atom increases, valley between 2 peaks becomes more shallow. instance, curve of yield against mass pu-239 has more shallow valley observed u-235 when neutrons thermal neutrons. curves fission of later actinides tend make more shallow valleys. in extreme cases such fm, 1 peak seen.

the adjacent figure shows typical fission product distribution fission of uranium. note in calculations used make graph, activation of fission products ignored , fission assumed occur in single moment rather length of time. in bar chart results shown different cooling times — time after fission.

because of stability of nuclei numbers of protons and/or neutrons, curve of yield against element not smooth curve tends alternate. note curve against mass number smooth.