- 143 -


    00 (r'rr     )cos n(8'-O)]S(r',I)

    n=l  Rzn    r



 + I R                    r  r   r n     n(-')]
   +  r'dr' [kn( )- - I R(  n     ,nco    (
   r                 n=l  R      r


                         x S(r' ,')'}              (8.22)


Since the fission heat generation is considered to be isotropic, S(r',e') will be independent of e' and the temperature distribution (8.22) reduces to the form (8.15),



        T(r) = TR + 1    n {n(R  r'S(r')dr' R R                           0



               +f r'Zn (- S(r')dr'}                (8.23)
                  r


        The heat generation rate, which is proportional to the fission rate, is given by


S(r) = C f Ef(r,E)c(rE)dE = CNU (r) f af(E)c(rE)dE (8.24)

where

          C = conversion factor which expresses the fission
              rate in units of energy/cc/sec
      N u(r) = uranium density distribution


         af = microscopic fission cross section


f(r,E) = neutron flux