I am currently designing a whole-core for small PWR. I am calculating core life (years) vs. FdH and RFF. What is the difference between "Enthalpy rise hot channel factor (FdH)" and "Radial form factor (RFF)"? I have calculated "CHANNEL FDH" which is same as "RFF". Do I have to try "CHANNEL PIN FDH" for getting the correct result for "Enthalpy rise hot channel factor (FdH)"?