def calc_total_fission_product(thePd_apostrophe, t0, ts, read_data)
      g = 1.0 + ((3.24E-06 + 5.23E-10 * ts) * (t0 ** (4.0E-01)) * read_data.phi)
      if g >= 1.1
        g = 1.1
      end
      thePd_apostrophe * g
    end
def calc_total_fission_product(thePd_apostrophe, t0, ts, read_data)
      g = 1.0 + ((3.24E-06 + 5.23E-10 * ts) * (t0 ** (4.0E-01)) * read_data.phi)
      if g >= 1.1
        g = 1.1
      end
      thePd_apostrophe * g
    end
Calculate total fission product decay heat power
 at t(ts) sec after shutdown from an operating history of T(t0) sec duration. (from ANS-5.1-1979 Eq.1 and 11)
 need t0, ts and data with thermal fission(from class DataForANS_5_1_1979)
 ts: Time after remove (sec)
 t0: Cumulative reactor operating time (sec)

 calc_total_fission_product(thePd_apostrophe, t0, ts, read_data)

 return Pd