UCC28070: Inductor specification is too large.

Hello Jeon, 

Your design is correct. 

The Excel tool calculates the value of inductance necessary to keep each inductor current in CCM over the entire line cycle at the operating points that you specified :1400W total Pout and 240Vrms input. 

When inductor current is in CCM, the THDi is low (providing that Rsynth is properly sized).  
When inductor current starts to have some DCM near the AC-line zero-crossings, THDi starts to go up. 
If the inductor current has a lot of DCM over most or all of the AC line cycle, then THDi is very high. 

The Excel tool cannot calculate what the THDi value will be for any given amount of DCM, it can only calculate how much inductance is necessary to maintain CCM over the entire cycle. 
So, you can design a lower inductance than what is recommended for CCM, but be aware that as the amount of DCM increases, the amount of THDi also increases. 
If low THDi is important at light load and high line, then inductance must be higher (as calculated).  
If it is not important, then inductance can be lower. 

Regards,
Ulrich