25 years in the making: Brazil’s Angra 2 starts up20 February 2001
Brazil’s second nuclear power plant, Angra 2, entered full operation on 21 December. It had fed its first power into the Brazilian grid in July 2000 and undergone power ascension testing and a 28-day trial run.
The owner and operator of Angra 2 is state-owned company Eletronuclear – Eletrobrás Termonuclear SA. For Eletrobras, the 1309MWe plant, located on the Atlantic coast, about 130km southwest of Rio de Janeiro, is an opportunity to improve the power supply situation in the economic area of Rio de Janeiro/São Paulo, where there have been frequent supply failures in recent months. At Brazil’s annual per capita consumption level of 1850 kWh Angra 2 is capable of supplying five million people with electricity.
According to Eletrobras’s partner and contractor Siemens, “Angra 2 represents the current safety standard of nuclear power plants in Germany and is thus one of the most modern nuclear power plants in the world.” However, the Angra 2 startup comes a full 15 years after completion of its companion plant. The long-awaited commissioning may be seen as a cause for celebration by some in the nuclear community. But such celebrations may be muted by the fact that the rarity of a nuclear plant start-up only serves to highlight the doldrums that the industry currently finds itself in.
For the main contractor, Siemens, this is the first nuclear plant it has completed in more than a decade: its most recent plant was Neckar 2 in Germany, which was completed eleven years ago. The original contracts were signed with Siemens KWU, which has undergone many changes over the years, most recently merging its nuclear activities with long-time competitor, Framatome. What is more, besides Angra 2 is the foundation for its twin unit Angra 3, where all construction work was halted more than ten years ago.
The contracts for supplies and engineering services for Angra 2 and 3 were concluded between the then Brazilian electric utility Furnas and Siemens KWU as long ago as 1976. The basis for these contracts was the Brazilian/German intergovernmental agreement on the peaceful use of nuclear energy signed in 1975.
The reference plant for Angra 2 and 3 is Grafenrheinfeld in Germany, which went commercial in 1982 and has achieved an excellent lifetime load factor of well over 80 per cent. This PWR design has a four-loop nuclear steam supply system, with four safety trains. The tandem-compound turbine generator set comprises one high-pressure and three low-pressure cylinders and runs at a speed of 1800 rpm. The condensers of the three low pressure casings are seawater-cooled, while the condenser tubing material is titanium.
Angra 2 was licensed by the Brazilian nuclear regulatory authority CNEN (Comissão Nacional de Energia Nuclear), which counts, among others, on advisory services from the GRS, the German reactor safety consulting organisation.
According to Siemens, during Angra 2’s construction period the plant has been continuously brought into line with advances made in Germany, and it can be said to represent the “state of the art”. So although Grafenrheinfeld was the reference plant, technical advances achieved with later plants up to Neckar 2, the most recent unit in Germany, have also been incorporated.
Construction of Angra 2 began in 1977. After pile foundation work in the bay of Angra dos Reis was completed, erection of the civil structures began, in 1981. All heavy engineering equipment for both Angra 2 and 3, such as the components of the NSSS and the turbine generator set, were shipped to Brazil in the early 1980s. Siemens, together other German companies, provided supplies and services amounting to US$1.3 billion for Angra 2, while technology transfer allowed Brazilian companies to provide over 50 per cent of the supplies and services for the plant.
In 1985, Brazil’s economic situation and ensuing financing problems meant work on Angra 2 was run down to a minimum and Angra 3 was entirely halted. Work on Angra 2 was restarted in 1995 when, spurred by the rapid growth in electricity demand in the region, with its population of fifty million, the Brazilian government’s attitude changed and it gave Angra 2 high priority to reduce its the power supply deficit.
Completing Angra 3
For Siemens and many Brazilian companies the continuing rapid growth in electricity demand, the successful completion of Angra 2 and the large investment already made, all speak in favour of completing Angra 3.
The foundations for the plant buildings were prepared in the early 1980s – the plant buildings would be constructed directly on bedrock some 1500m south of Angra 2 and this would make an elaborate piled foundation unnecessary.
Since Angra 3 will replicate the design of unit 2 all the engineering documents for the construction already exist, although knowledge gained during the construction and commissioning of Angra 2, and from experience at operating plants, can be incorporated.
Should Angra 3 go ahead it is likely that the electrical and I&C systems would be updated, relative to Angra 2. Angra 2 has mainly analogue I&C systems, as employed widely in existing German plants. For Angra 3, installation of Siemens digital systems Teleperm XS (for safety I&C) and Teleperm XP (for operational I&C) is being evaluated.
On Angra 3, Brazilian contractors would carry out a large proportion of the work, and modern software tools would be used for planning and control of all engineering, construction, installation and commissioning activities.
Brazil is evaluating completion of Angra 3 and construction times of 60 months have been mooted. But completion schedules measured in months have been developed for Angra 2 and Angra 3 many times in the past.
However, with Angra 2 completed, Brazil may now be in a position in the not too distant future to make a commitment to completing Angra 3.