Atucha II: after the damage, the country's largest nuclear power plant will start operating again in July

Starting in June, a team of engineers from the Atucha II nuclear power plant will enter the building where the country's largest reactor is located. In 24-hour working days that will require surgical precision, they will proceed to repair a defect, after having planned the intervention for 5 months. This Tuesday, Ámbito toured the plant to know how the procedure will be carried out, 14 meters deep inside the reactor, in a radioactive environment.

Argentina has 3 nuclear power plants: Atucha I, Atucha II and Embalse, which generate around 7% of the energy matrix. As a result of the malfunction, Atucha II stopped operating in October, so the contribution of nuclear energy to the energy matrix was reduced by almost half, since it has a power of 745 MWe.

During the tour of Atucha II, José Luis Antúnez, president of Nucleoeléctrica Argentina, the state-owned company that manages the nuclear power plants, anticipated that in June they will proceed to repair the reactor, and it is expected that in July the plant will start operating again. The return to operation in July, in the middle of winter (those who most celebrate today this warm weather is in the Secretariat of Energy) is important partly from a macroeconomic point of view.

Atucha II, inaugurated in 2014, is the most important nuclear power plant in Argentina. Official sources estimate that it bills u$s1 million per day for electricity generation, although the generation cost is much lower than that of other energy sources. In addition, they calculate that for each month of operation, the State saves 1 ship of LNG imports.

However, the calculation made by Nucleoeléctrica is not the millions lost because Atucha II has been out of operation for 9 months, nor the u$s20 million that the repair will cost. But what it could have cost if they had gone ahead with the arrangement proposed by the original designers of the plant from Germany: they suggested to dismantle the whole reactor, something that would take at least 3 years of plant shutdown, at a cost of u$s400 million.

"It would have implied losing 3% of Argentina's energy every day", said Antúnez. Furthermore, Nucleoeléctrica wants Atucha II to start operating again quickly, since Atucha I will cease to operate next year. The operating license expires in 2024, which marks the end of its first useful life cycle. Therefore, a refurbishment will be carried out until 2026, with an investment of u$s450 million, so that the plant can generate clean energy for two more decades.

Within the framework of the energy transition and the global crisis of energy shortage as a result of the war in Ukraine, nuclear energy became more relevant worldwide. Alejandro Estévez, one of the directors of Nucleoeléctrica, explained that one of its advantages is that it does not emit greenhouse gases and generates low waste intensity.

The official objective, which Antúnez revealed in Ámbito Debate last week, is for nuclear energy to increase from 7 to 10% of the energy matrix. Argentina is a country with a nuclear tradition: Atucha I, which began to be built in 1968, was the first power plant in America south of Rio Grande. However, today the objective is far from being achieved: the consumption of electric energy increases year by year, while for nuclear generation to grow, new nuclear power plants would have to be built.

Nucleoléctrica's first objective is to move forward with the construction of Atucha III, for which they have already signed a contract with China. They have already reserved the site to build it: next to Atucha I and II, located in the municipality of Zarate, in the province of Buenos Aires. One of the obstacles is the financing: the Government wants China to finance 100% of the plant, which has a cost of u$s8000 million.

But according to official sources, today the obstacle is more geopolitical: last year, members of the U.S. Embassy visited Nucleoeléctrica's top management and told them not to move forward with the Chinese-designed plant. "This year it is likely that no progress will be made on anything, especially with what we depend on the IMF", commented a source who preferred not to be named.

Engineering the fix

"It's a complex repair for a simple mechanical malfunction," Antúnez described it. What happened was the detachment of one of the four supports of the nuclear reactor. Therefore, the repair involves removing it and welding the other three. The company clarified that the mechanical failure "does not imply risks for the safety of people or the environment", and that what it caused was that the plant had to operate at a lower intensity.

The option chosen by the Nucleoeléctrica team, which implies lower costs and shorter terms, consists in not having to disassemble the whole reactor. Instead, they developed, together with a Buenos Aires SME, a tool to cut the displaced support and remove it through the reactor cover. The complexity lies in the fact that the detached support is located 14 meters deep inside the reactor. The EDM (underwater) cutting, like the pressure welding method, was done with local suppliers.

Currently, what is happening in Atucha II is to test how those 24 hours of procedure will be when they enter the building where the reactor is located. Therefore, in the turbine building there is what they call a "mock up", a blue tank several meters high, where with a crane, robots, clamps and cameras they recreate with a real scale model the conditions of how the repair procedure will be, they test the tools and train the personnel. The mock up had been used in 1988 when Atucha I was repaired.

The last step is the one that will take place in June: for 24 hours, teams of about eight people (engineers and technicians) will enter with special suits to proceed with the repair inside the reactor, once the nuclear regulatory authority approves the maneuvers.