Dear Venkat
If you want to know the list of used Internal Orders. Use SE38-in program give RKCOWUSL-Select attributes-execute. It will take you to a new screen. There you execute last option "Run where used list (TSRUN). From application select RKACSHOW-AUFNR all usage of order.Here you can give your required parameter such as Internal order,Cost center,Activity Type etc. to find where it is used. Now only thing left to compare your total internal order list with this used order list with the help of excel.This is just a work around.
Regards
Rajneesh Saxena