Sanded all surfaces to be taped in today's layups as well as future layups. Opened bosses for fuel fittings through interrior skin and bids. Re-tapped bosses through skin and bid. Cored sides of fwd and aft tank ends. Filled cored area with micro. Blocked tank components in place in fuselage. Added 4 inch wide 3 bid carbon tapes into corners. Peel plyed.