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               lim(  1    dT                       (80, r < 54)
               r 0 r + 850 d   r         0

This approximation is equivalent to solving (8.49) for T(r) dT 
in the interval [0,R], with the assumption that dr    0 and T = T in [0,E0].

        Since the Rosseland opacity defined by (8.2) and (8.1) is a macroscopic quantity, the composite opacity associated with a mixture of N different plasma species is

                           N
                  K (T)       K (T)                (8.55)
                  R       i=1R
            i~

where KI is opacity of the i-th species. In the present model of the plasma core reactor, the opacity is due to uranium, hydrogen, and any seeding materials which may be mixed with the fuel or coolant. The composite opacity for this model is

                       U    H    S                 (8.56)
                  R    R    R    R

where


        KU =    KUi, opacity of all uranium species
              i


        KR =    KHi, opacity of all hydrogen species

              1
          K=  [ KR ,S opacity of all seed species
              i