Just my uninformed guess, but I believe you go back to your reserve unit. The only way you go active duty out of the Academy is 1) you graduate 2) you fail out/get kicked out/resign after you sign your "2 for 7" papers at the begining of your 2/C (Junior) year. Before you go to class on the first day of Junior year, you don't owe the government a dime, or anytime. If you're prior enlisted active duty, I think you go back to the fleet, depending on how much time was left on your contract. But if you're thinking you might DOR, do someone a big favor and don't take their spot.