def thePi
      hash = HashWithThermalFission.new

      hash.thermal_fission[:U235]  = 0.98
      hash.thermal_fission[:Pu239] = 0.01
      hash.thermal_fission[:U238]  = 0.01

      hash.thermal_fission
    end
def thePi
      hash = HashWithThermalFission.new

      hash.thermal_fission[:U235]  = 0.98
      hash.thermal_fission[:Pu239] = 0.01
      hash.thermal_fission[:U238]  = 0.01

      hash.thermal_fission
    end
thePi is Pi in ANS-5.1-1979.