Uranium–235 undergoes the following fission reaction when it absorbs a thermal neutron:

PHYSICS · Multi-part · CBSE · Physics · Nuclei · Nuclei

Problem

^{235}_{\;92}\text{U}+^{1}_{0}\text{n}\;\to\;^{141}_{\;56}\text{Ba}+^{92}_{36}\text{Kr}+3^{1}_{0}\text{n}

(a) Given the following atomic masses:

^{235}\text{U}=235.0439\,\text{u}

^{141}\text{Ba}=140.9144\,\text{u}

^{92}\text{Kr}=91.9262\,\text{u}

^{1}\text{n}=1.00866\,\text{u}

, calculate the energy released per fission event in \text{MeV}. Take

1\,\text{u}=931.5\,\text{MeV}/c^{2}

. Assume atomic–electron masses cancel out. (b) If all the nuclei in

1\,\text{kg}

of pure

^{235}\text{U}

could undergo the fission of the type given in part (a), estimate the total energy obtainable in \text{kWh}. (Avogadro number

N_{\!A}=6.022\times10^{23}\,\text{mol}^{-1}

1\,\text{eV}=1.6\times10^{-19}\,\text{J}