UPDATE 1-Shell shuts unit at Motiva Texas refinery

NEW YORK, Aug 19 (Reuters) - Royal Dutch Shell Plc said it shut down an unspecified unit at its joint-venture600,000 barrel-per-day (bpd) Motiva refinery in Port Arthur,Texas, on Saturday, following an operational problem. "Several units that are integrated to this will runat reduced rates and others are being shut down," while repairsare underway, shell spokeswoman Kimberly Windon said in an emailon Monday. Sources said Motiva shut a hydrocracker at the refineryfollowing a fire on Saturday. This is the latest in a series of setbacks at the refinerywhere the newest crude unit is expected to run up to 75,000 bpdbelow capacity due to a piping problem. The 325,000 bpd crude unit called VPS-5 was beset byvibration problems when Motiva attempted to run it at or nearits full capacity, as Reuters exclusively reported on Friday. The first attempt to start the unit, at the end of a 5-year,$10 billion expansion of the plant, was hampered by a chemicalleak in June 2012. The unit has been running at reduced rates ranging between250,000 bpd and 285,000 bpd since it began production early thisyear. Motiva is a joint venture between Royal Dutch Shell Plc andSaudi Refining. (Reporting by Shrutee Sarkar and Selam Gebrekidan)