26 November 2018 (Balakovo, Russia) - ROSATOM has completed the annealing of a large capacity reactor vessel on power unit 1 (VVER-1000) at Balakovo NPP (Saratov region, 900 km from Moscow) for the first time in the world. This unique technology, designed by Russian scientists from National Research Center “Kurchatov institute”, allows to extend reactor service life by using heat treatment that recovers physical parameters of the metal in a reactor vessel.
The project opens up cost-effective life-extension opportunities for the fleet of aging 1GW installed capacity reactors across the globe.  
ROSATOM CEO Alexey Likhachev said: “Today, there are about 37 VVER-1000 around the world. Annealing [of a reactor vessel] is the new and, currently, only technology in the world that allows to extend the service life of a reactor. This technology will be available for export”.
Annealing could extend the service life of VVER-1000 by 15-30 years, thus helping to prevent up to 7.8 billion tons of global CO2 emissions in total, as well as boosting the safety and economic performance of nuclear power plants. It is estimated that, for the extended operational lifetime, the cost of power generation (so-called LCOE) could decrease to as much as $29 per MWt-hour, which is cheaper than the marginal cost of coal-fired power generation.
Mikhail Kovalchuk, President of NRC “Kurchatov Institute” said: “The long-term operation of VVER-type reactors under neutron irradiation leads to the degradation of the metal properties in reactor pressure vessels. This limits the lifetime of the whole NPP. Scientists at NRC “Kurchatov Institute” have developed and patented the VVER-1000 nuclear reactor vessel’s recovery annealing technology, which can be adapted for water-moderated nuclear power reactors of any design and capacity. The pilot recovery annealing of the 1st unit of the Balakovo NPP vessel was carried out in mid-November. It led to the recovery of the structure and mechanical properties of the pressure vessel metal to its original state. According to the annealing results, this VVER-1000 reactor pressure vessel received an additional 15 years of service life”.
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Previously, similar technology was tried and tested at smaller reactors of medium capacity (VVER-440) at Novovoronezh and Cola NPPs in Russia, Rivne NPP in Ukraine, Armenian NPP, Greifswald NPP in Germany and Kozloduy NPP in Bulgaria. Annealing allowed to extend their life cycle from 45 to 60 years.
The VVER-1000 vessel is larger in diameter and has thicker steel inlayings in comparison with VVER-440 vessels. So, scientists from the Kurchatov Institute have developed a brand new technology for the annealing of a vessel of a large-capacity reactor. The metal in the reactor vessel was slow heated to a temperature of +565 degrees Celsius, after which it began a stationary annealing, which lasted 100 hours. Then, the metal was slowly cooled.
All the technical data gathered during the procedure will be compiled into a report that will be submitted to the national regulator (Rostekhnadzor) for approval, to conduct further reactor operations. 
Notes to the editor:
ROSATOM is the only company in the world to offer integrated clean energy solutions across the nuclear supply chain and beyond, including the design, build and operation of nuclear power stations, uranium mining, conversion and enrichment, the supply of nuclear fuel, decommissioning, spent fuel storage and transportation and safe nuclear waste disposal. With seventy years’ continuous experience, the company is the world leader in high-performance solutions for all kinds of nuclear power plants. It is also working in the segments of wind generation, nuclear medicine, energy storage and other. Headquartered in Moscow, the company brings together over 300 enterprises and organizations and over 250,000 employees. Globally, the company has the second biggest uranium reserves, has 40% of the world’s enrichment market, and is the world's biggest builder of the latest generation nuclear power stations and US$133 billion 10-years export order book.
The NRC “Kurchatov institute” is the initiator of the nuclear power industry and the invariable research supervisor of all the works on the creation, improvement, reliability justification and ensuring the safe operation of thermal neutron reactors, including the water-moderated power reactors. The institute has the most modern complex of experimental and research equipment for solving reactor-physical and material science problems arising from both the creation of new reactors and the maintenance of existing reactor plants, as well as their improvement.
Specialists from the Kurchatov institute developed and implemented the recovery annealing technology of VVER-440 reactors. It allowed to extend the lifetime of the 17 operating VVER-440 reactors in Russia and abroad up to 45 years. Three Russian VVER-440 power units were re-annealed, which extended their service life up to 60 years. 
The NRC “Kurchatov institute”, on its own initiative, developed and patented the recovery annealing mode for VVER-1000 reactor pressure vessels materials. Despite the great successful experience in lifetime extension of VVER-440 reactors, VVER-1000 reactors required a new recovery annealing mode. This is caused by differences in the composition and, accordingly, in the radiation degradation mechanisms of reactor vessels’ metal properties, revealed by the NRC “Kurchatov institute”. The developed annealing mode assumes heating at (565±15)оС during 100 h. The NRC “Kurchatov institute” further carried out work, commissioned by ROSATOM, on the creation and justification of the industrial recovery annealing technology of VVER-1000 reactor pressure vessels. The pilot recovery annealing of VVER-1000 reactor pressure vessels at the first unit of Balakovo NPP was successfully completed in mid-November. The specialists from the Kurchatov institute performed scientific management, supervision, and controlling compliance of the required annealing parameters and modes to the annealing technology. As a result of the accumulated experience in creation and technical implementation of recovery annealing, the NRC “Kurchatov Institute” has unique competencies that allow, if necessary, to develop and implement similar technologies for a water-moderated power reactors of any design and capacity. 


Source: Communications Department of ROSATOM, press service of NRC “Kurchatov institute”