TVEL fuel company of Rosatom has fulfilled the agreement with Nuclear Power Corporation of India Limited (NPCIL) on implementing a comprehensive engineering project, including introducing TVS-2M nuclear fuel and elongating the fuel cycle from 12 to 18 months for both VVER-1000 reactors. TVEL has supplied the first batches of TVS-2M nuclear fuel to India for the two functioning units of Kudankulam NPP, powered by VVER-1000 reactors. After the nearest refuelling, the power unit 1 will start operations in an 18-months fuel cycle.
Compared to the UTVS fuel model, which was supplied to Kudankulam NPP previously, TVS-2M fuel assemblies have several advantages making them more reliable and cost-efficient. First is the rigidity of a bundle: because of the welded frame, the fuel assemblies in the reactor core retain their geometry, and the spacer grids protect fuel rod cladding from fretting wear (preventing depressurisation), and the additional spacer grid makes fuel assemblies more vibration-resistant. Secondly, the new fuel has increased uranium capacity – one TVS-2M assembly contains 7.6% more fuel material than UTVS. Besides, the unique feature of the Kudankulam fuel is the new generation anti-debris filter ADF-2, protecting bundles from debris damage, which may be caused by small-size intrus objects in the reactor core.
Operation in longer fuel cycles also enhances the economic efficiency of a plant, as reactors have to undergo stoppage and refuelling less frequently, so the power units produce more electricity. Besides, the power plant needs to purchase less fresh fuel and, as a result, has to deal with smaller amounts of spent nuclear fuel, which also requires expenses.