M'bishi Heavy aware of design problem before radiation leak

Mitsubishi Heavy Industries Ltd. and a local utility firm in California were aware of a design flaw in Mitsubishi-made steam generators for a California nuclear reactor before a radiation leak in January 2012, according to a document recently released by the U.S. nuclear regulator.

A report submitted by Mitsubishi Heavy to the U.S. Nuclear Regulatory Commission on the accident showed that the Japanese manufacturer and Southern California Edison Co., the operator of the nuclear reactor, explored the possibility of changing designs in 2005 to curb the vibration of the fine tubing in the steam generators.

But the two companies decided not to change the design, according to the report. A steam generator is a critical part of a pressurized water reactor.
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