Russia’s OKB Gidropress, a subsidiary of state nuclear corporation Rosatom, has completed "longevity testing" of fuel assembly models with an optimised hydro-uranium ratio for VVER-440 reactors, Russian fuel company TVEL announced on 5 December. The new fuel is initially intended for the Paks NPP in Hungary and the Loviisa NPP in Finland.

TVEL said the key longevity testing demonstrates the behaviour of structural materials in conditions similar to those inside the reactor core. The behaviour of the fuel assembly models was studied for 1500 hours in a coolant flow within parameters "as close as possible" to reactor conditions in terms of consumption, temperature, pressure and pressure pulsations, it added.

The new modification of second-generation VVER-440 nuclear fuel enables an increase in the coolant volume inside the reactor core and optimisation of the hydro-uranium ratio, which would have a positive impact on both the technical and economic performance of the power unit. According to Alexander Ugryumov, TVEL’s vice president for research and development, the new fuel is based on a "unified solution" that would enable  TVEL to create an "exclusive final product" to meet each customer's own fuel cycle strategy and other individual requirements.

"Our technical solution with higher uranium mass enables us and our customer either to make nuclear plant operation more economically efficient by reducing the amount of fuel assemblies, or to lower the level of uranium enrichment," he said. TVEL signed an engineering services contract with Hungary’s MVM Paks Ltd at the end of last year and an addendum with Finnish Fortum Power and Heat Oy early this year. After the full testing cycle, batch production and licensing of the nuclear fuel will begin, with deliveries of the newly modified fuel assemblies expected to start in 2021/2022.

TVEL is the sole supplier of nuclear fuel for Russian nuclear plants and provides fuel for 72 power reactors in 14 countries and for research reactors in eight countries as well as for the Russian nuclear fleet.   

Photo: The modified fuel will be used at the Paks nuclear plant