MHI Completes Replacement Work On Reactor Vessel Head At Nuclear Power Plant In Brazil

Company's First Component Replacement Job for Overseas NPP

Mitsubishi Heavy Industries, Ltd. (MHI) has completed work to replace the reactor vessel head (RVH) at Angra 1, a pressurized water reactor (PWR) nuclear power plant (NPP) owned by Eletrobrás Termonuclear S.A. (Eletronuclear), a government-controlled electricity company in Brazil. The event marks the first large-scale component replacement with installation undertaken by MHI for a NPP overseas.

The work performed by MHI was to replace the NPP's existing components with a new RVH and control rod drive mechanisms (CRDM) - huge components that form the closure head of the nuclear vessel, both delivered by MHI in April 2010 and August 2012, respectively. After disassembling and removing the existing closure heads, the new RVH and CRDMs were assembled at the nuclear reactor containment vessel and installed.

In the replacement work, MHI took charge of all coordination details. Disassembly of the existing components and welding of the new CRDMs on the new RVH and their installation in the containment vessel were performed by Aquilex WSI of the U.S. Transco Products Inc., also of the U.S., was responsible for production and installation of thermal insulation material. The replacement work commenced under MHI's management in January of this year to coincide with a periodical inspection; all tasks were successfully executed as planned and Angra 1 was place back on line on March 6.

Eletronuclear's 657 MWe (electric megawatt) Angra 1 PWR NPP located approximately 130 kilometers west of Rio de Janeiro, began commercial operation in 1985. Replacement of the RVH aimed at making plant operations more reliable and economical.

Eletronuclear is a subsidiary of Centrais Eletricas Brasileiras S.A. (Eletrobrás), Brazil's main electricity corporation, in which the national government and Banco Central do Brasil, Brazil's central bank, collectively have a greater than 60% equity stake. Eletronuclear also owns and operates the Angra 2 NPP, with the Angra 3 NPP currently under construction.

In Brazil, development of new energy sources and their diversification have become major issues as the country's economy expands. As a result, at the same time the construction of new NPPs is gathering momentum, large-size NPP component replacements have been installed in existing plans to their extend the operational lives.

MHI has supplied its nuclear power equipment in major NPP markets worldwide and, to date, has exported numerous components, including 15 replacement RVH units to the U.S. Going forward, the company will continue to contribute to safe NPP operation and stable power supply through provision of replacement components and maintenance technology that will help enhance the safety, reliability and economic efficiency of such plants.