Modified fuel assemblies developed for Loviisa units

TVEL says increasing the mass of uranium in each fuel rod will enable a reduced level of uranium enrichment without a reduction of thermal power generation in the reactor. In turn, a lower uranium enrichment will reduce the cost of the nuclear fuel production chain, as well as facilitate handling irradiated fuel, it said.

The company noted the project has involved the participation of a number of Russian nuclear industry enterprises, such as OKB Gidropress (part of Rosatom's machine-building division Atomenergomash), Bochvar Institute (TVEL's material science research facility), Elemash Machine-building plant and the Kurchatov Institute national research centre. The new fuel passed a range of hydraulic, longevity and vibration tests at the site of OKB Gidropress research and experiment facility.

Finnish utility Fortum signed a contract with TVEL in March 2018 for the supply of the modified fuel for use at its twin VVER-440 Loviisa plant. It followed the signing in November 2017 of a similar contract between TVEL and MVM Paks for development of the new VVER-440 fuel for use in the Paks plant in Hungary.

The new modification of second-generation VVER-440 fuel for the Paks plant enables an increase in the coolant volume inside the reactor core and optimisation of the hydro-uranium ratio, which will have a positive impact on both the technical and economic performance of the power unit, TVEL said.

"Using the new design of a fuel bundle with increased uranium capacity, we have developed two different solutions of VVER-440 fuel cycle strategy for our customers in Hungary and Finland, taking into account their individual requirements," said Alexander Ugryumov, vice president for Research, Development and Quality at TVEL JSC. "While the Paks plant in Hungary will enhance economic efficiency by decreasing the amount of fuel bundles loaded in the reactor core, the team at the Loviisa plant decided to maintain the same number of fuel assemblies, but lower their uranium enrichment level. In both cases, our engineering projects will make power plant operation in Finland and Hungary more efficient."