A typical nuclear fusion reaction is given by :

$\begin{array}{r}{ }_1{\mathrm{H}}^2{+}_1{\mathrm{H}}^2{\to }_1{\mathrm{H}}^3{+}_1{\mathrm{H}}^1+4.0\mathrm{MeV}\\ { }_1{\mathrm{H}}^2{+}_1{\mathrm{H}}^2{\to }_2{\mathrm{He}}^4{+}_0{\mathrm{n}}^1+17.6\mathrm{MeV}\end{array}$

The net result of two reactions is :

$3{\times }_1{\mathrm{H}}^2{\to }_2{\mathrm{He}}^4{+}_0{\mathrm{n}}^1{+}_1{\mathrm{H}}^1+21.6\mathrm{MeV}$

The energy released per nucleon of the reactant, in the above thermonuclear reaction is :