A cylindrical reactor core is 4 ft in diameter and 4.8 ft high. The maximum neutron flux is 10 ¹³  The extrapolation lengths are 0.186 ſt in the radial direction and 0.3 ft in the axial direction. The fuel is 20 percent -enriched UO ₂  ν̂ _f  = 500 b. 

Determine 

(a) the neutron flux at the upper and lower rims, and 

(b) the maximum heat generated in the fuel in Mev/sec cm ³  and Btu/hr ft.