Atucha Nuclear Power Plant, Argentina

There have been further problems at the Argentine Atucha nuclear site in Lima, about 100 miles from Buenos Aries. The 357MW Atucha-1 unit has for several years seen unplanned shutdowns for repairs. Meanwhile, construction of the long delayed 750MW Atucha-2 is not yet complete. Work is underway, though, with completion planned for later this year.

Both units were designed to take a Siemens heavy water cooled, moderated pressurised heavy water reactor (PHWR). Atucha-1 operated well until a major shutdown to make internal reactor repairs in 1989. The fuel channels were then completely replaced, but there have been more shutdowns since then.

Siemens main contractor for Atucha-1

Atucha-1 was opened in 1974, nearly two years late. It was Latin America's first nuclear power plant. Siemens was the main contractor, but much of the work was done by domestic Argentine companies.

Atucha-1 used the original Siemens pressurised HWR line. Improvements since then have included reducing the tritium content and incorporating hydraulically driven control rods.

Atucha-1 has a reinforced concrete reactor building with spherical stainless-steel housing for containment. It uses a mix of natural and enriched uranium (0.85%), with heavy water for moderation and cooling. The single pressure vessel holds the whole reactor core. Neutron economy is good, so allowing once-through natural uranium fuel cycle. The circular reactor core has vertical fuel assemblies, each in a fuel channel. Coolant channels pass through a circular tank with moderator water inside the pressure vessel. The heat from this moderator tank preheats the feedwater. Electricity is delivered at 220kV to the grid.

In 1994, the Autoridad Regulatoria Nuclear (ARN) Agency took over regulatory responsibilities from the CNEA nuclear energy agency. Operation of Atucha-1 was given to Nucleoeléctrica Argentina SA (NASA). This was done in preparation for an unsuccessful privatisation. When Siemens left the nuclear energy business, it transferred Atucha-1 to Framatome, now Areva NP. Siemens instead transferred Atucha-2 to NASA so that the project could be completed. Siemens is also supplying electrical equipment and services to help complete the project.

Atucha-2 not yet complete

Atucha-2 was proposed in 1979, with Siemens and CNEA having formed ENACE to act as architect / engineer. In 1981, ENACE started construction of the 700MW Siemens reactor next to Atucha-1.

The original cost was to be around $1.5bn, and Atucha-2 was initially scheduled to be finished in 1987. The pressure vessel was eventually installed at the end of 1999, but building stopped when about 80% complete because of lack of funding.

The IAEA reported several main items to complete including the electro-mechanical, I&C mounting, heavy-water inventory and first core fuel deliveries.

The Argentine government in 2005 announced building would restart at a cost of about $700m, rescheduling the opening for 2008. The government had discussed updated designs for Atucha-2 with Atomic Energy of Canada Limited (AECL).

Argentina still has nuclear plans

Argentina has been looking at nuclear power to fill its energy gap and reduce gas usage. It does have (inactive) uranium mines in the country, and is able to enrich uranium and process fuel rods. The Argentine government in August 2006 announced a $3.5bn strategic plan that included finishing Atucha-2 and extending the Atucha-1 lifetime (it is currently scheduled to close in 2014). The government has also started a feasibility study for a $2bn fourth reactor.

Besides the lack of funding (Atucha-2 is now reported to have over $1bn debt), the major obstacles to completion have been technological obsolescence of the original design, with a new set of companies now involved. Argentina also still has no solution to getting rid of radioactive waste from its plants.