Shell restarts Martinez hydrocracker - source

HOUSTON, May 16 (Reuters) - Shell's 156,000 barrel per day San Francisco Bay-area refinery in Martinez, California, restarted a hydrocracker on Thursday, according to a source familiar with refinery operations.

A Shell spokesman was not available to discuss refinery operations.

The refinery reported a compressor upset to California pollution regulators on May 8, but had not said to which unit the compressor belonged. (Reporting by Erwin Seba)