Press Information

MHI Completes Delivery of Two Replacement Reactor Vessel Heads
For Southern California Edison's SONGS Units 2 and 3
-- Enhances MHI Position as Top Japanese Producer of Nuclear Components --


Tokyo, December 14, 2010 - Mitsubishi Heavy Industries, Ltd. (MHI) has completed delivery of two replacement reactor vessel heads (RRVHs) for Units 2 and 3 at the San Onofre Nuclear Generating Station (SONGS) of Southern California Edison (SCE), one of the largest U.S. electric utilities. The two RRVHs will replace original components in order to enable continued operation and enhance plant efficiency. MHI has received multiple orders for major replacement components for SONGS Units 2 and 3, and the latest shipment of RRVHs follows two earlier shipments of replacement steam generators (RSG): two for Unit 2 in February 2009 and another two for Unit 3 in October 2010.

SONGS is located in northern San Diego County, approximately 100 kilometers (60 miles) southeast of Los Angeles. Units 2 and 3 are 1,100 MWe (megawatts of electricity) pressurized water reactors (PWR) that went into operation in 1983 and 1984, respectively. The RRVHs are crucial components of PWR nuclear power plants (NPP); they are made of low-alloy steel, each measuring approximately 5 meters (16.4 feet) in diameter and weighing 75 metric tons (82.67 short tons). Reactor vessels are manufactured with strong low-alloy steel made of manganese, molybdenum and nickel steel, a combination highly resistant to the strong pressures characteristic of pressurized reactor coolants. MHI received the order from SCE in 2005 and manufactured the RRVHs at its Kobe Shipyard and Machinery Works.

Since 2002, MHI has received orders from U.S. utilities for 15 RRVHs, 6 RSGs and 1 replacement pressurizer. The orders were placed based on the excellent reputation MHI enjoys among its customers for its sophisticated capabilities in managing quality, manufacturing processes and delivery schedules. The company has also sold its nuclear components in other major NPP world markets, with totals now reaching 19 RRVHs and 31 RSGs, making MHI Japan's top company in the export of NPP components.

At a time of increased efforts to control emissions of carbon dioxide and greenhouse gases, global demand is growing both for replacement nuclear components at existing NPPs and for the construction of new NPPs. MHI is firmly responding to this trend as a world-leading supplier with capabilities in basic planning, design, manufacture, inspection, installation, test operation and post-startup services for PWR plants. MHI is aggressively pursuing NPP component export opportunities in order to contribute significantly to improvement of social infrastructure to enable a low-carbon society - a commonly shared global challenge.


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Mitsubishi Heavy Industries (MHI) Group is one of the world’s leading industrial groups, spanning energy, smart infrastructure, industrial machinery, aerospace and defense. MHI Group combines cutting-edge technology with deep experience to deliver innovative, integrated solutions that help to realize a carbon neutral world, improve the quality of life and ensure a safer world. For more information, please visit or follow our insights and stories on