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TVEL Corporation has a considerable experience in nuclear fuel manufacturing for water-water reactors (VVER).
The water-water reactor is a pressurized water reactor, in which water acts both as the coolant and moderator of neutrons. Presently, in Russia there are two reactors of this type – VVER-440 and VVER-1000. VVER-440 fuel assemblies (FA) have been manufactured since 1963, and VVER-1000 FAs - since 1978.
Fuel for both types of VVER reactors represents a bundle of fuel rods with zirconium-alloy claddings, which are filled with fuel pellets of uranium dioxide. To improve physical characteristics and safety some fuel rods are filled with pellets, containing gadolinium oxide.
A VVER FA has a hexagonal cross section. Besides fuel rods, fuel assembly has a number of structural elements: cap, tailpiece, spacing grids and in some cases – a shroud tube. A cap is designed for gripping during load – unloading operations, and a tailpiece ensures the FA placement in to the reactor and provides channel for coolant for fuel rods.
A VVER-440 FA is composed of 126 fuel rods. A VVER-1000 FA has 311-312 fuel rods. There are different modifications of fuel for this type of reactors, designed for 3-, 4-, 5- year fuel cycles.
At present, two designs of fuel assemblies for VVER-1000 reactors – TVSA and TVS-2 - with a higher rigidity skeleton.
This strengthened skeleton is the key feature of the fuel assemblies. In TVSA it is formed by spacers and 6 angles joined by spot welding that provide higher rigidity and strength of the structures. In TVS-2 the skeleton is formed by spacers spot-welded to guides to provide more rigid and strong structure.
Depending on fuel pellet material, uranium fuel rods and gadolinium fuel rods are distinguished. The former use uranium dioxide (UO2) and the latter are fitted also with an integrated burnable poison – gadolinium oxide (Gd2O3).
There are makes of VVER-440 and VVER-1000 reactor fuel assemblies which are different in a uranium-235 and gadolinium oxide content in the said fuel rods, which are designed for four- and five-year operating cycles.
Currently, JSC Mashinostroitelny Zavod and JSC Novosibirsk Chemical Concentrates Plant manufacture the new generation fuel assemblies for VVER-1000 reactor – TVSA and TVSA- 2. The Plants make it possible for nuclear reactors to transfer to extended fuel cycles.
More information about VVER-440, VVER-1000.
If you are interested in these products, please contact us for further information by e-mail commerce@tvel.ru.  Printable version
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