A B747-400 HAS FORWARD CARGO COMPARTMENT UNUSABLE PER MEL. 15000 LBS PAYLOAD FUEL ADDED FOR CTR OF GRAVITY. AT LEVELOFF AT FL310; FOUND PAYLOAD FUEL BEING SCAVENGED FROM CTR TANK.

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FORWARD CARGO COMPARTMENT ROLLER BROKEN RESULTING IN COMPARTMENT UNUSABLE FOR CONTAINERS. 15000 LBS FUEL ADDED AS PAYLOAD FUEL FOR CTR OF GRAVITY. RELEASE 2 ARRIVED ON ACARS DURING LAST MINS OF SETUP. DEPARTED ZZZZ AND ON LEVELOFF AT FL310 FOUND PAYLOAD FUEL IN CTR TANK SCAVENGING TO MAIN TANKS. ACARS'ED DISPATCH AND THEN MAINT CTL FOR HELP ON STOPPING SCAVENGING. DISPATCH WAS SURPRISED WE HAD THE 15000 LBS EXTRA PAYLOAD FUEL IN ADDITION TO CLRED FUEL. THEY THOUGHT IT WAS PART OF CLRED FUEL AND WERE GOING TO DIVERT US TO ZZZZ1. ON RELEASE 2; WE THEN NOTICED; DID NOT ADD THE 15000 LBS OF FUEL. WONDERED WHY RELEASE 2 WAS SENT (HAD ASSUMED IT WAS BECAUSE OF THE ADDED PAYLOAD FUEL DISCUSSED WITH ZZZZ OPS)? RELEASE 3 ARRIVED. MAINT CTL OFFERED NO SOLUTIONS FOR STOPPING THE SCAVENGING. ASKED IF AND WHERE A CIRCUIT BREAKER WAS AND WAS TOLD IT WAS IN THE E&E COMPARTMENT. CALLED A FLT ATTENDANT TO THE COCKPIT WHILE CAPT WENT TO E&E COMPARTMENT TO PULL THE BREAKER. DIVERTING TO ZZZZ1 WOULD NOT HAVE DONE ANYTHING TO HELP AS FUEL WOULD HAVE XFERRED BY LNDG; CAUSING THE SAME PROB. EVERYONE AGREED. AFTER PULLING THE CIRCUIT BREAKER; THE SCAVENGING STOPPED AND FLT CONTINUED TO A SMOOTH LNG BY ME; THE FO; IN ZZZZ2. DISPATCH CONFIRMED THE 13.5K IN THE CTR TANK WAS IN LIMITS OR LNDG. OBSERVATIONS: DID DISPATCH KNOW OF EITHER THE ROLLER PROB (IT WAS ON THE MAINT RELEASE) AND/OR THE CTR OF GRAVITY PROB BEFORE TKOF (OR DID ZZZZ ADD THE FUEL ON THEIR OWN)? WE WERE TOLD COMPANY DOES NOT HAVE PROC TO STOP SCAVENGING PAYLOAD FUEL. SEEMS STRANGE THAT IF PAYLOAD FUEL IS CARRIED THERE; AS I AM SURE IT IS SOMETIMES; IT WOULD ALWAYS SCAVENGE ITSELF OUT OF BAL. WE ASKED FOR AN MEL PLACARD PRIOR TO TKOF FOR THE FORWARD CARGO PROB BUT WERE TOLD THERE WAS NOT ONE AND WE WERE NOT SMART ENOUGH TO THINK ABOUT THE FUEL AUTOMATICALLY SCAVENGING.