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 Water-moderated water-cooled VVER-440 power reactor is a pressurized water reactor where the water is both the coolant and neutron moderator.
Nuclear fuel for VVER-440 reactors is manufactured and delivered in the form of fuel assemblies designed for generation and transfer of thermal energy to the coolant flow (water) in VVER-440 reactor core. The core of VVER-440 reactor is loaded with working fuel assemblies and control fuel assemblies consisting of the fuel follower of control rod and absorbing extension. Working fuel assemblies remain fixed during in-pile operation. A working fuel assembly consists of fuel rods, spacer grids, top and bottom nozzles and a shroud. The design of the fuel follower of control rods is similar to that of working fuel assemblies, the only difference is top and bottom nozzle design.
Operating VVER-440 reactors can use different fuel cycle designs, viz.:
I – ADVANCED 3-YEAR FUEL CYCLE
Application of such fuel cycles provides for the possibility of weekly reactor power manoeuvring (within the range of 70=105 % from the nominal power).
II – 4-YEAR FUEL CYCLE
Implementation of this fuel cycle results in more efficient uranium consumption and reduction of the number of manufactured, transported and stored fuel assemblies. This fuel cycles provides for the possibility of weekly reactor power manoeuvring as well.
III – 4-YEAR FUEL CYCLE AT 105 % REACTOR POWER
Such fuel cycles shall be considered as an evidence of the possibility to efficiently operate reactor cores with an increased capacity factor leading to the enhancement of performance indicators of the power unit.
 IV – 5-YEAR FUEL CYCLE
Compared to the 4-year fuel cycle, 5-year fuel cycles provide for the additional decrease in natural uranium consumption and number of manufactured, transported and stored fuel assemblies. U-Gd fuel is widely used for this fuel cycle.
V – FUEL CYCLE WITH RELOADS COMING IN 18 MONTHS
The fuel cycles of this type are not practically used and require the use of burnable absorbers.
Design specifications
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Parameters |
Fuel cycle type
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For full core |
For the core containing screen assemblies |
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Advanced 3-year |
4-year |
5-year without U-Gd fuel/ 5-year with U-Gd fuel |
Advanced
3 – year |
4- year |
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Reactor thermal power, MW
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1375
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1375
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1375
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1375
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1375
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Number of fuel assemblies in the core, pcs.
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349
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349
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349
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313
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313
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Total uranium weight in the core, t
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41,8
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41,8
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41,8
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37,4
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37,4
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Time between refuellings, months |
12 |
12 |
12 |
12 |
12 |
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Number of annually replaced fuel assemblies, pcs.
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117,5
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90,5
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78,5/66
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102,5
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81,5
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Average enrichment of make-up fuel, % |
3,28 |
3,62 |
4,01/4,21 |
3,59 |
4,01 |
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Average discharge fuel burn up, MWd./kg U |
29,37 |
38,29 |
42,66/49,89 |
33,08 |
41,95 |
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Specific consumption of natural uranium, kg/MW day |
0,247 |
0,212 |
0,211/0,193 |
0,242 |
0,215 |
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Specific volume of separative work, swu/mwd |
0,134 |
0,119 |
0,123/0,115 |
0,136 |
0,126 |
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Fuel rods
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Type |
Smooth-pin type Cylindrical |
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Dimensions, mm
- length
- outer diameter
- inner cladding diameter
Cladding material |
Generation I/ generation II
2536/ 2608
9,1/ 9,07
7,73
Zr + 1% Nb alloy |
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Fuel |
Sintered uranium dioxide pellets |
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U-235 enrichment depending on the design, % |
1,6; 2,4; 3,0; 3,3; 3,6; 4,0; 4,6
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Pellet dimensions, mm |
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Diameter |
7,54…7,57/7,57: 7,60 |
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Height |
9…12 |
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Central hole nominal diameter |
1,4/ 1,2 |
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