What was found
PDIS 690 28-21 3548 05MAY21 PDX OPEN U RIGHT INNER TANK VALVES INDICATED CLOSED CLIMBING THROUGH FL180. RT INNER TANK VALVE SELECTORS WERE IN THE OPEN POSITION. NO CIRCUIT BREAKERS WERE POPPED. FUEL IMBALANCE WAS GETTING WORSE. NO HELP WITHIN QRH. DECLARED EMERGENCY AND RETURNED TO KPDX. SHGN 05MAY21 18:15 PDX U PERFROMED LATERAL IMBALANCE CHECK IN REFERENCE TO AIRBUS AMM 05-51-46-00. NO ALTERATIONS OR DEFECTS NOTED. REF. 05-50 3550 SHGN 05MAY21 18:20 PDX U PERFORMED OVERWEIGHT LANDING INSPECTION IN REFERENCE TO AIRBUS AMM 05-51-11-00. NO ALTERATIONS OR DEFECTS NOTED. REF. 05-50 3549 REPLACED RIGHT INNER FUEL TANK ISOLATION VALVE ACTUATOR IAW A300 AMM 28-22-52-04. REPLACED RELAY 40QB IAW IPC 28-22-08-02B, ITEM 10, AWM 28-22-05, & ESPM 20-46-50. REPLACED RH INNER FUEL TANK ISOL VALVE PSBSW 6QB IAW IPC 28-22-08-01C & ESPM 20-45-11. CHECKS SAT IAW A300 AMM 28-22-00-05. RAN RIGHT ENGINE WITH RIGHT INNER FUEL TANK PUMPS PER A300 JRH FOR 10 MINUTES; ALL PARAMETERS NORMAL.