Photo: ATF fuel bundle (Photo credit: Rosatom)Rosatom on 20 September began pilot operation of fuel elements of a new generation of Russian accident tolerant fuel (ATF) at unit 2 of the Rostov NPP.

During a scheduled refuelling outage,  three combined fuel assemblies of the TVS-2M design were loaded into the VVER-1000 core, each containing 12 fuel elements in an innovative design: six fuel elements were made using chromium as a structural material with nickel alloy 42ХНМ and six fuel rods with cladding made of zirconium alloy with chromium coating. These technological solutions make it possible to either completely eliminate or significantly slow down the development of the cycronium steam reaction in the reactor core in the event of an emergency situation.

Before the start of pilot operation of the ATF, a team of specialists from Rosatom’s fuel, mechanical engineering and energy divisions  carried out extensive work to justify the loading of innovative fuel into a commercial reactor and obtain the appropriate licence from the Federal Service for Environmental, Technological and Nuclear Supervision (Rostekhnadzor). For testing in a high-power power reactor, a conservative version of experimental fuel rods with a standard fuel composition was chosen in line with global practice. Existing ATF development programmes elsewhere in the world also suggest that the introduction of new fuel and structural materials should be carried out in stages.

“Operating the fuel in a power reactor is an important step for the further commercialisation of this product. It is symbolic that this landmark milestone of a strategically important project coincided with the 25th anniversary of the founding of Rosatom’s TVEL Fuel Company,” said TVEL President Natalya Nikipelova. “The development of ATF is a key trend in the global nuclear power industry in recent years, which aims to increase the safety of nuclear power plants to a qualitatively new level, practically eliminating the likelihood of accidents with negative consequences for the environment. Moreover, certain ATF variants with alternative fuel compositions can make operation more economically efficient without increasing the uranium enrichment level. According to international experts, this product will dominate the global market in a relatively short time. ” 

Rostov NPP Director Andrey Salnikov explained that fuel loading at NPPs is carried out during scheduled maintenance campaigns. “The ninth repair campaign since Rostov 2 was commissioned  and   which has now ended, has become special as a result of loading  assemblies with new generation nuclear fuel. This development by Russian scientists is designed to provide additional safety during the operation of power units. Safety is our main priority and the key to the further successful development of nuclear energy. "

Rosatom has been testing Russian-designed ATF fuel for light-water reactors since 2018. Experimental fuel assemblies, which have undergone two full cycles of reactor tests in the MIR research reactor at the Research Institute of Atomic Reactors (NIIAR) in Dimitrovgrad  contain fuel elements with four options for combinations of cladding materials and a fuel pellets: in addition to uranium dioxide, a fuel composition is used based on a uranium-molybdenum alloy with high thermal conductivity. Depending on the research results,   the optimal combination of structural and fuel materials will be selected, taking into account technical and economic parameters. After two test cycles, all fuel elements are hermetically sealed.