 During an extended power uprate test on March 5, 2002 (designed to extend the power efficiency of existing BWR reactors), Quad Cities Unit 2 began to experience vibrations in a steam line.On March 29 the plant was manually shut down due to high vibrations causing leaks in the main turbine control system.Unit 2 was restarted on April 2, but vibration broke a main steam pipe drain line.