PWR
Pressurized water reactors, developed under license from Westinghouse ( United States ); the main components are:
- Fuel rod formed of ZIRLO ® or Zircaloy tube, Zircaloy plugs, stainless steel spring and UO2 pellets (they may also include UO2 pellets with gadolinium).
- ZIRLO ® or Zircaloy thimble tubes.
- Inconel and ZIRLO ® or Zircaloy grids.
- Stainless steel nozzles (upper and lower).
The fuel assemblies with PWR technology that Enusa currently makes are:
- 17x17 MAEF: the 17x17 MAEF fuel is for the Ascó I & II, Vandellós II and Almaraz I & II power plants (Spain). It is composed of a bundle of 264 fuel rods. These rods are arranged in a square array with 17x17 positions, and they are supported by 12 grids –two end grids, six intermediate grids, three intermediate mixing grids (IFM) and one protective grid. The grids, together with 24 thimble tubes, one instrumentation tube and two nozzles at the ends, form the structural shell of the fuel tube.
Fuel Assembly |
| Array |
17x17 |
| No. of fuel rods |
264 |
| No. of fuel rods |
24 |
| No. of instrumentation tubes |
1 |
| No. of grids (without IFM) |
9 |
| No. of IFM grids |
3 |
Materials |
| End grids |
INCONEL – 718 |
| Intermediate grids |
ZIRLO TM |
| IFM grid |
ZIRLO TM |
| Protective grid (band and projections) |
INCONEL - 718 |
| Upper nozzle |
Acero inoxidable |
| Lower nozzle |
Acero inoxidable |
| Spring |
INCONEL - 718 |
| Thimble tube |
ZIRLO TM |
| Instrumentation tube |
ZIRLO TM |
Fuel Rod |
|
Pellet composition |
UO2 |
| Neutron poison pellet composition |
UO2 – Gd2O3 |
| Cladding material |
ZIRLO TM |
| Spring material |
Acero inoxidable |
| Plug material |
ZIRLO TM |
Diagram of the 17 x 17 MAEF Fuel Assembly
- RFA 900: this fuel is similar to the 17x16 MAEF fuel but it is supplied to Electricité de France (EDF) plants in France. There are some differences in the materials used to make its components and in the design of its thimble tubes, which incorporate an absorber tube on the inside.
- RFA 1300 y 17x17 MAEF-XLR: Intended for Electricité de France (EDF) plants in France and Electrabel plants in Belgium , which operate PWR reactors with a 17x17 section. Both kinds of fuel share general features with MAEF: 17x17 array, number of thimble tubes, total number of rods, etc. The two designs differ in the total length of the fuel assembly (the XL design is approximately 60 cm higher) and in incorporation of the absorber tube inside the thimble tubes. The MAEFXLR design for Belgium includes guide studs in the upper nozzle to enable rapid refueling.
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