TVEL Fuel Company of Russia’s Rosatom, which has built 2 X 1,000-MWe VVER reactors at Kudankulam for the Nuclear Power Corporation of India Limited (NPCIL) and is constructing four more reactors of a similar capacity, has started supplying the first batches of TVS-2 M nuclear fuel to the two functioning units of the Kudankulam Nuclear Power Project.
Once the new TVS-2 M fuel is used in the next refuelling, the reactor will start operations with the 18-month fuel cycle. It means the reactor, which has to be stopped for every 12 months for removing the spent fuel and inserting the fresh fuel bundles and allied maintenance, will have to be stopped for every 18 months.
Thus, TVEL has fulfilled the agreement with the NPCIL on the implementation of a comprehensive project that included introduction of TVS-2 M fuel and elongation of the fuel cycle from 12 to 18 months for both the VVER-1,000 reactors.
Compared with the UTVS fuel model, which was supplied previously, TVS-2 M fuel assemblies have a number of advantages making them more reliable and cost-effective.
First, it is the rigidity of a bundle. Because of the welded frame, the fuel assemblies in the reactor core retain their geometry. The spacer grids protect the fuel rod cladding from fretting wear and the additional spacer grid makes the fuel assemblies more vibration-resistant.
Secondly, the new fuel has increased uranium capacity — one TVS-2 M assembly contains 7.6% more fuel material than that of UTVS. The special feature of the Kudankulam fuel is the new generation anti-debris filter ADF-2, which protects the bundles from damage from debris (small 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 refueling less frequently, the power units can produce more electricity. Besides, the plant needs to buy less fuel, and as the result, has to deal with smaller amounts of spent fuel.
