A power station must deliver of electrical energy.

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

Problem

A power station must deliver

1.0\,\text{GWh}

(=3.6\times10^{12}\,\text{J})

of electrical energy. (i) If each fission of

^{235}\!\text{U}

releases

200\,\text{MeV}

and the overall efficiency of converting nuclear energy to electricity is

30\%

, calculate the number of fission events required. (ii) Determine the mass of

^{235}\!\text{U}

consumed. \newline (Take the atomic mass of

^{235}\!\text{U}

235\,\text{u}

1\,\text{u}=1.6605\times10^{-27}\,\text{kg}

, Avogadro number

N_A=6.02\times10^{23}\,\text{mol}^{-1}

.) (iii) For a deuterium–tritium fusion reaction that releases

17.6\,\text{MeV}

per event with an overall efficiency of

40\%

, calculate the combined mass of deuterium and tritium required to produce the same

1.0\,\text{GWh}

of electricity. \newline (Atomic masses:

^{2}\!\text{H}=2\,\text{u}

^{3}\!\text{H}=3\,\text{u}

.) (iv) From your answers, obtain the ratio of fuel mass required for fission to that required for fusion.