BP Texas City ultracracker shut for work -sources

HOUSTON May 11 (Reuters) - An ultracracker was shut on Monday at BP Plc's (BP.L) 467,720 barrel per day (bpd) Texas City, Texas, refinery for unplanned repairs, according to sources familiar with refinery operations.

A BP spokesman declined to discuss refinery operations.

Repairs are planned on the ultracracker's cooling system, which malfunctioned on Monday morning, triggering the shutdown, according to the sources.

An ultracracker is a type of hydrocracking unit, which uses hydrogen under high heat and pressure to boost the motor fuels refined from a barrel of crude oil, especially cheaper oils with high sulfur content. (Reporting by Erwin Seba)