Armenian reactor vessel checked for extended operation

Work has begun to assess changes in the properties of the metal of the reactor vessel of unit 2 at the Metsamor nuclear power plant in Armenia. The work is being carried out as part of preparations for extending operation of the VVER-440 unit for a further ten years.

Russian state nuclear corporation Rosatom said its JSC Rosatom Service subsidiary has installed material samples in the reactor vessel of the unit during its current ongoing scheduled maintenance outage. The samples are installed in the reactor vessel in special containers.

The data obtained will be used to decide on the possible extension of the unit's operation until 2036.

Monitoring changes in the actual characteristics of the metal (such as strength, brittleness, etc) is carried out using special samples made of metal identical to the reactor vessel, Rosatom noted. As the nuclear power plant operates, these samples are removed so that they can be analysed in laboratory conditions. The unloading of samples installed at the Metsamor plant for research purposes will begin in 2025 and will be carried out annually.

"Rosatom has started the second extension of the country's only nuclear power plant," said Evgeny Salkov, director general of Rosatom Service JSC. "We scrupulously follow safety priorities; starting in 2025, Rosatom specialists will annually extract samples from the reactor vessel of the Armenian NPP and monitor the properties of the metal and changes in its structure. In this way, we ensure reliable control and detailed monitoring of one of the most important devices of the nuclear power plant."

In November 2021, it was announced that the service life of Metsamor unit 2 had been extended to 2026 after collaboration with Rosatom which saw the unit's emergency cooling system, engine room, turbines and steam generators modernised, and a unique operation was carried out to anneal the reactor pressure vessel. This restored the properties of the vessel metal by 85%, ensuring the possibility of its further operation.

In December last year, a corresponding agreement was signed between Rosatom Service JSC and Armenian NPP within the framework of the next intergovernmental commission on economic cooperation between Russia and Armenia. In preparation for the repeated extension of service life in 2023-2024, JSC Rosatom Service, JSC OKB Gidropress and other industry enterprises have developed research programmes and developed and manufactured material samples from metals and alloys specially selected for the Armenian plant.

Rosatom signed an agreement with the management of the Armenian nuclear power plant in January 2022 to look into the possible building of new Russia-designed units on the site of the current plant at Metsamor. Armenia has long been in discussions with Russia about replacing Metsamor, which comprises two Russian-built 376 MWe VVER reactors which started operating in 1976 and 1980, respectively. Both units were taken offline in 1988 due to safety concerns regarding seismic vulnerability. Unit 2 was restarted in 1995, and accounts for some 39% of total electricity generation in the country. Unit 1 is now being decommissioned.