ArmInfo. An installation for the reduction annealing (heat treatment) of the reactor vessel metal was delivered to the Armenian NPP. The plant will be prepared for the final part of the work on extending the service life, which will take place in 2021 - the reactor will be annealed, which will return it to its original state by 80-85%.
Reactor annealing is the most effective way to restore the physicomechanical properties of the reactor vessel metal, which change during operation under the influence of constant radiation exposure. The reactor vessel is the "heart" of the power unit, and it is its resource that determines the period of the station's operation extension.
The body is annealed with complete unloading of fuel assemblies (FA) into the spent fuel pool. This is necessary for inspection of the vessel and installation of the annealing unit inside the reactor vessel. Using an annealing unit, the reactor vessel is heated to a temperature of 475 degrees, kept at this temperature for several days, after which it slowly cools down. The structure of the metal restores its properties, which increases its service life.
The procedure will be carried out by several organizations, each of which is responsible for its own area of work. The technology has been developed and the necessary calculations are being made by the National Research Center "Kurchatov Institute", OKB "GIDROPRESS" and TsNIIKM "Prometey", and the enterprises - "Atomenergoremont" and "TsNIITMASH" will perform work at the station itself.
For the first time, the technology of the reduction annealing of the reactor pressure vessel metal was applied in 1987 at the third power unit of the Novovoronezh NPP. Now this procedure is being carried out at all stations where the service life is being extended. Reduction annealing has already been carried out at VVER-440 reactors of such nuclear power plants as Kola NPP (Russia), Rovno NPP (Ukraine), Kozloduy NPP (Bulgaria) and Loviisa NPP (Finland).
Let us remind that recently the Armenian NPP after scheduled preventive maintenance was connected to the country's energy system. For the fifth year now, the Armenian NPP has been combining scheduled preventive maintenance with the implementation of a program to extend the life of the second power unit of the plant. A budget loan of 63.2 billion drams (about $ 130 million) will be provided to complete the station's program. For the implementation of the program, Armenia previously attracted a loan of $ 270 million from the Russian Federation and a grant of $ 30 million, and as of today the residual resource of these funds was $ 107 million. For objective and subjective reasons, it was not possible to agree with Russian partners on this residual resource. For this reason, a decision was made to attract a budgetary loan of 63 billion drams. In 2020, the Armenian NPP will receive 18.7 billion drams from these funds, in 2021 - 31.5 billion drams and in 2022 - 13 billion drams. The maturity of each tranche is 12 years, of which the first 2 years will be concessional. The interest rate will be equivalent to the interest rate of the borrowed funds of the Russian Federation raised earlier. The loan is provided without collateral. The Ministry of Finance of the country will issue government treasury bonds under the program. Within the framework of the project, it is also envisaged to form an interdepartmental tender commission, which will carry out all tender procedures and monitor the process of implementing the program.