New Brazilian steam generators ready

18 March 2008

Eletronuclear, operator of Brazil's only nuclear power plant, has officially received two new steam generators for Angra unit 1. The plant is currently undergoing preparatory work in readiness for the installation of the new steam generators, due to take place in September.


Eletronuclear president Othon Luiz Pinheiro da Silva is formally to take delivery of the new components in a ceremony attended by Minister of Science and Technology Sergio Machado Rezende.


Steam generators (SGs) transform the heat produced in the reactor's core into steam that drives the electricity generation turbines. The new SGs for Angra 1 have been manufactured by Brazil's Nuclebras Heavy Equipment (Nuclep), with technical assistance from Areva of France. The new SGs are 21 m long and 4.5 m in diameter, and weigh in at 343 tons each. Eletronuclear took the decision to replace the SGs in Angra 1 after it was discovered that alloys used in the tubes of the existing generators were showing some susceptibility to corrosion, necessitating frequent integrity tests. The new SGs, which the company says are made of more resistant materials, will help to improve the plant’s efficiency and performance as well as helping to extend its life.


The unit itself is currently off line for refuelling and maintenance as well as preparatory work in advance of the SG installation. It is scheduled to return to service on 15 April, and will go off line again in September for the SG installation, which is expected to take about four months. Westinghouse has been contracted to carry out the actual replacement work. Replacement of SGs is a major undertaking, but Eletronuclear points out that similar work has been carried out at other nuclear power plants around the world and by 2011, some 20 plants will have undergone SG replacements.


In November 2007, Eletronuclear placed an order with Mitsubishi Heavy Industries (MHI) of Japan for a new reactor vessel closure head for Angra 1. The reactor vessel closure head, another major plant component, will also help make operations at the Brazilian plant more reliable and economical.


Angra is home to two pressurized water reactors (PWRs). Construction began on both plants in the 1970s but Brazil's economic problems meant that building work was interrupted. The 626 MWe Angra 1 started up in 1985. In its early years it was beset by steam supply system problems, but it has performed well since 1999 although there is still room for improvement – its 2006 annual load factor of 52.9% was well below that of most of the world's nuclear power reactors which performed at load factors of 75% and above. Angra 2, which has a capacity of 1270 MWe, started up in 2000.


In July 2007, the Brazilian president formally gave his backing to the completion of a third unit at Angra. Angra 3, a sister unit to Angra 2, had previously been suspended after about 70% of the necessary equipment had been delivered, although construction work had not actually begun. In addition to Angra 3, Brazil has plans to build up to eight new nuclear units by 2030 and is reported to be planning to select a new site some time this year.