Neutron Calculations for Reactors
Let us consider the equation of balance (4.87), which is the starting point of the multigroup theory. The slowing down source can be written in general for energy E (§4.4.3): g
fEh-l I (E' )P (E' -+ E )¢(E' )dE' s 2 g ~h
div J + (I + zR,g) <I> I: z (h -+ g)<l>h + Q g a,g g h=l s g (9.4)
g side is known, since at this stage the flux ~h is known, the equations being solved successively according to increasing values of g(for g = 1 the sum over h disappears).