Element wise thermal fission chain yield of 235U, 239Pu
The final stable products of the thermal fission chain of ²³⁵U (Uranium-235) and ²³⁹Pu (Plutonium-239) are either long lived fission products or stable elements after undergoing multiple beta decays. Fission Chain Reaction in Uranium-235 and Plutonium-239 235 U + n → 92 K r + 141 B a + 3 n + 200 MeV 239 P u + n → 144 B a + 95 K r + 3 n + 200 MeV {}^{239}Pu + n \rightarrow {}^{144}Ba + {}^{95}Kr + 3n + 200 \text{ MeV} {}^{235}U + n \rightarrow {}^{92}Kr + {}^{141}Ba + 3n + 200 \text{ MeV} Lets see the decay of mass number 141 54 141 X e → 1.7 sec , β − 55 141 C s → 25 sec , β − 56 141 B a → 18 min , β − 57 141 L a → 3.9 hr , β − 58 141 C e → 32.5 d , β − 59 141 P r ( Stable ) {}^{141}_{54}Xe \xrightarrow{1.7 \text{ sec}, \beta^-} {}^{141}_{55}Cs \xrightarrow{25 \text{ sec}, \beta^-} {}^{141}_{56}Ba \xrightarrow{18 \text{ min}, \beta^-} {}^{141}_{57}La \xrightarrow{3.9 \text{ hr}, \beta^-} {}^{141}_{58}Ce \xrightarrow{32.5 \text{ d}...