Tests start on modified VVER-440 fuel for Dukovany

OKB Gidropress - an enterprise of Russian state nuclear corporation Rosatom's machinery division Atomenergomash - is carrying out the work under a contract between Rosatom's TVEL JSC nuclear fuel manufacturing subsidiary and Czech utility ČEZ. The contract includes the design and implementation of this fuel modification at the Dukovany plant, which comprises four VVER-440 units.

The durability tests started after the successful completion of hydraulic tests of the mock-up fuel assembly aimed at determining the hydraulic resistance of the modified fuel, referred to as RK3+. TVEL said the tests are being carried out on a full-scale research hot run-in test bench VVER-440 and will last for a total of 1500 hours.

The RK3+ design has enhanced physical and thermo-hydraulic properties compared with previous generations of VVER-440 fuel, TVEL said, and has a longer fuel rod pitch that streamlines the water-uranium ratio in the reactor core and increases the efficiency of the fuel.

"Introduction of RK3+ will make it possible to operate all four power units at increased thermal capacity and also to extend the fuel cycle at the Dukovany nuclear power plant, which will improve economic efficiency of the power plant operation," said Alexander Ugryumov, vice president for research and development at TVEL.

TVEL signed a contract with ČEZ in July 2019 to introduce the RK 3+ modification of its VVER-440 fuel for the Dukovany plant. The project takes into account the operating experience of the prototype of such fuel at unit 4 of the Kola nuclear power plant in the Murmansk region of Russia's Kola peninsula, where it has been in use since 2010.

The 2040 MWe Dukovany plant has four VVER-440 reactors which were commissioned in succession between 1985 and 1987. It generates about 13 terawatt hours of power annually, providing about 20% of the country's electricity demand, TVEL said. The Dukovany and Temelín plants produce about 35% of the national electricity output, making the Czech Republic one of the world' top 10 countries in terms of the share of nuclear in its energy mix, it added. Temelín comprises two VVER-1000 units. Both plants have been operated with fuel manufactured by TVEL's Machine-Building Plant, in Elektrostal, in the Moscow region, since their commissioning.