What are the operating experiences of the first Russian Generation III+ nuclear reactor?

Novovoronezh 6 is the first Generation III+ unit in operation. It has now undergone its first scheduled outage for refuelling. It is therefore worth taking a closer look at the initial experience with this unit and at the overall situation surrounding Russia's new advanced reactors.

Construction of the Novovoronezh 6 reactor began on 24 June 2008 and was completed in 2015. Following testing and fuel loading, a fission chain reaction was initiated on 20 May 2016. It was connected to the grid and supplied its first electricity on 5 August 2016. Very thorough testing then continued and its output was gradually increased. In 2016, it already supplied 873 GWh to the grid. Commercial operation began on 27 February 2017.

The reactor is a VVER-1200, in this case the V-392M model. Its thermal capacity is 3200 MWt, its gross electrical output is 1180 MWe and its net output is 1114 MWe. The reactor core contains 163 fuel assemblies. A 12-month cycle is used for gradual fuel replacement. Under standard operation, 42 fresh fuel assemblies are loaded each year and the core is reconfigured. At present, the core is fresh, so it only needs to be rearranged. Such a planned outage for refuelling (core reconfiguration), as well as maintenance and inspections, began on 17 March 2018. It ended on 28 April 2018 and the reactor was restarted. The fact that not everything is yet ideal is also shown by the smooth start-up being disrupted by the need for additional tests.

In 2017, the reactor generated 6.49 TWh, corresponding to an annual capacity factor of 61 %. This is below the standard target, which is expected to be close to 90 %. However, it should be recalled that the unit only began commercial operation at the end of February, a number of tests were carried out continuously, and the optimum operating mode is still being fine-tuned. The course of events so far therefore corresponds to the situation at similar units. Only the coming years will show whether the equipment and economic parameters can be optimised to the expected level. However, the first cycle between scheduled outages proceeded essentially as expected, which is a good sign.

Work on completing Novovoronezh 7 is progressing intensively. Turbine installation began in March 2018 and should be completed in May. The turbine is being installed by the same company as for the previous unit, and the modifications being made reflect experience with the earlier equipment. At the same time, important tests of all systems are being carried out progressively, along with preparations for start-up. This should take place as early as the turn of this year and next.

Another interesting operation took place at the Novovoronezh plant in April. The reactor pressure vessel of Novovoronezh 4 was annealed. This is one of the first VVER-440 units. Annealing lasted 150 hours at a temperature of 475˚C and made it possible to largely restore the original properties of the steel used. Annealing is part of the overall refurbishment and modernisation of this unit, which began operation in 1972. The refurbishment should make it possible to extend operation by a further 15 years. It could thus operate until 2032, for a total of 60 years. This is also of interest to us because more modern units of this type are operated at Dukovany, and it cannot be ruled out that we will need to ensure their operation beyond 2035.

It should be recalled that the first unit of the second phase of the Leningrad nuclear power plant is in the start-up phase. This is also a VVER-1200 reactor, but this time the V-491 model. Fuel loading began on 8 December 2017; on 6 February 2018, it reached minimum controlled power, and on 23 February preparations began to reach sufficient output (around 35 % of nominal) for grid connection, which took place on 9 March, followed by a gradual increase to 50 % of nominal output. The unit reached this level on 13 April. The reactor should enter commercial operation this year. The second unit will be completed next year.

On 30 April, the first concrete was poured for the reactor island foundation of the first unit of the second phase of the Kursk nuclear power plant. AEM Technology also completed the lower section of the reactor pressure vessel for the first unit. The first two new VVER-1200 units of the VVER-TOI model are being built there; this is an optimised version of this Generation III+ unit. It will be the main asset of the Russian nuclear industry in the coming decades. Russia is thus not only completing reactors, but also launching new construction projects. The construction of another two units is planned there. As at the Leningrad plant, these units will replace old RBMK units.

Two VVER-1200 units are being completed at the Belarusian Ostrovets nuclear power plant, with the first expected to start up in 2019 and the second in 2020. Construction of a number of these units is being prepared in several countries. More details can be found in the overview of nuclear energy last year.

It is clear that Russia is able to launch construction of nuclear units both at home and abroad. At the same time, it is succeeding in completing them and operating the new units successfully. As the first reactor manufacturer in the world, it is beginning to gain experience in operating Generation III+ reactors. By the end of the year, two will be in commercial operation in Russia, and by the end of 2020 there will be six in total across Russia and Belarus.

Finally, I would mention one interesting piece of information about the operation of new reactors. The BN-800 fast sodium reactor (Beloyarsk 4), which entered commercial operation in 2016, had an annual capacity factor of 72 %. This is a very good figure for the start of operation of an entirely new prototype reactor. It still lags behind the figures above 86 % that the BN-600 fast sodium reactor (Beloyarsk 3) has managed to maintain in recent years. However, it is approaching the long-term standard of the older unit.

Written for the Oenergetice and Osel websites.

Opening photograph: Refuelling at the Novovoronezh 6 reactor (source: Novovoronezh nuclear power plant/Rosenergoatom)