BWR
Boiling water reactors, developed under license from General Electric (United Status). BWR fuel assemblies are manufactured in Juzbado for the Garoņa and Cofrentes plants in Spain and the European plants of Olkiluoto (Finland), Forsmark (Sweden) and Gundremmingen (Germany).
The main components of the BWR fuel assembly are:
- Fuel rod formed of Zircaloy tube and plugs, stainless steel spring, and UO2 pellets (they may also include UO2 pellets with gadolinium).
- Zircaloy water rod.
- Zircaloy and Inconel grid.
- Stainless steel nozzles (upper and lower).
Enusa is currently manufacturing two kinds of fuel assemblies: GE14 and GNF2
- GE14. This fuel assembly is formed by 92 fuel rods (78 full length plus 14 partial length), two central water rods, one lower nozzle, one upper nozzle and eight grids.
The fuel rods (some 4 meters high) are arranged in a 10x10 array. The lower fuel rod plug is supported on the lower nozzle. The latter is what supports the weight of the fuel assembly during operation. The upper plugs of the rods cross through the upper nozzle drill holes. The fuel is secured through the upper nozzle for transport and handling. The 8 fuel grids are located at different heights to provide solidity and maintain the distance between the rods all along their length. The 2 water rods are located in the central spaces of the matrix, and water flows through them to moderate the fuel. In addition, the fuel assembly is surrounded by a shroud called a channel, which acts as a guide for passing water to ensure the fuel is cooled.
- GNF2. This fuel offers advantages that differentiate it from GE14, e.g. enhanced economy, greater reliability and more robustness in relation to the increasingly demanding operating conditions of our customers. Structurally, GNF2 is similar to GE14, except for the arrangement of the partial rods inside the matrix, the insertion of another partial length rod (in GNF2 there are partial fuel rods of two lengths), an antiparticle filter in the lower nozzle, differing distribution of the grids throughout the fuel assembly, improved channel, different grid material, etc., which all provide for excellent fuel assembly performance in the reactor.
Main features:
Fuel Assembly |
| Array |
10 x 10 |
| No. of complete fuel rods |
78 |
| No. of partial fuel rods |
14 |
| No. of water rods |
2 |
| No. of grids |
8 |
Material¡s |
| Grids |
Zircaloy-2Ac |
| Upper nozzle |
Acero inoxidable |
| Lower nozzle |
Acero inoxidable |
| Water rods |
Zircaloy-2Ac |
Fuel Rods |
| Pellet composition |
UO2 |
| Neutron poison pellet composition |
UO2 – Gd2o3 |
| Cladding material |
Zircaloy-2 |
| Spring material |
Stainless steel |
| Plug material |
Zircaloy-2 |
|
