For the first time, unique work was carried out at the Armenian NPP on the recovery annealing of the PWR-440 reactor vessel of the second power unit. Their goal was to extend the service life of NPPs until 2026.

The annealing process took place in the reactor hall of the plant; the reactor was in its original place. An annealing plant with a height of a two-story building was delivered to the NPP disassembled, then it was assembled and installed in the reactor vessel. The metal was slowly heated to a temperature of 475 degrees Celsius, held for 150 hours and also gradually cooled. In total, the whole process took 10 days.

The reactor vessel is the main non-replaceable element of a nuclear power plant. Annealing will return the operational characteristics of the metal shell of the reactor to its original state by 80-85%.

Annealing is recognized worldwide as an effective way to ensure the safe and reliable operation of reactor facilities and for the first time this technology was applied by Rosenergoatom in 1987 at the third power unit with a PWR-440 reactor at the Novovoronezh NPP. The technology for annealing the reactor vessel was developed by the specialists of CNIITMASH Rosatom.

 “The Armenian NPP is a guarantee of our security and the development of the Armenian economy. The reliability and working capacity of the reactor vessel largely determines the safety of NPP operation as a whole. Thanks to the experience and high competencies of Russian specialists, the key works on the extension project went well,” said Eduard Martirosyan, general director of the Armenian Nuclear Power Plant.

The annealing work was performed by specialists of Atomenergoremont (a subsidiary of Roenergoatom) and the Armenian NPP together with specialists from Russian companies and organizations, including OKB GIDROPRESS, CNIITMASH, Kurchatov Institute Research Center, CNIIKM "Prometheus". The organization of work under the modernization contract is carried out by Rusatom Service, which is part of the electric power division of ROSATOM.

“Earlier, Atomenergoremont had already carried out annealing of the reactor vessel metal at nuclear power plants in Russia, Bulgaria and Ukraine. In order to carry out work at the Armenian NPP, the specialists of the repair company prepared all the necessary technical documentation, brought and assembled the annealing plant itself, tested it with the customer and installed it directly into the reactor. During the heating of the body metal, our operators monitored the temperature regime around the clock, which made it possible to quickly and efficiently make the necessary technical improvements,” said Alexey Chernikov, first deputy general director, chief engineer of Atomenergoremont.

 “At this stage, we have completed a very important procedure for the modernization of the station. This became possible thanks to the well-coordinated work of the Armenian and Russian atomic scientists. And we hope that the result of our joint efforts will make it possible to further increase the safety of the NPP and extend it until 2026, and in the future for another 10 years,” said Yuri Sviridenko, the head of the project to extend the service life of the ANPP from the Russian side.

“The reactor vessel annealing technology is a Russian know-how that has good export potential. Let me remind you that in 2018 Rosenergoatom, with the assistance of OKBM Gidropress and Kurchatov Institute Research Center for the first time in the world carried out work on annealing the vessel of a more powerful reactor – PWR-1000 of power unit No. 1 of Balakovo NPP. As a result, it received an additional 15 years of the authorized service life. Now this technology can not only be used for all PWR-1000 reactors operating both in Russia and abroad, but also bring significant economic benefits,” explained Anatoly Chukharev, director of the Rosenergoatom International Business and Development Department.

Recovery annealing was carried out at PWR-440 reactors of such nuclear power plants as Kola NPP (Russia), Rovno NPP (Ukraine), Kozloduy NPP (Bulgaria) and Loviisa NPP (Finland).

For reference:

Rosenergoatom is a part of the Electric Power Division of Rosatom State Corporation, is the largest generating company in Russia and the second largest in the world in terms of nuclear generating capacity. In total, 11 nuclear power plants in Russia operate 38 power units with a total installed capacity of over 30.5 GW.

The Armenian NPP is the only nuclear power plant in the South Caucasus. It produces more than a third of all electricity generated in Armenia. The key project of Russia and Armenia in the field of nuclear energy is the project to modernize and extend the service life of the second power unit of the ANPP. Armenia has accumulated unique experience in the operation of the ANPP. The second power unit was restarted after being in conservation for 6.5 years. The plant plays an important role for the development of the energy system of Armenia and the entire socio-economic life of the Republic.

The general contractor of the project to extend the service life of the Armenian NPP is Rusatom Service, whose main tasks are to restore the service life and prolong the operation of the plant, increase its safety and efficiency.