In ENUSA we manufacture nuclear fuel in our Juzbado facility (Salamanca), where the activities focus on procurement of the uranium and components required for the process and on the engineering and manufacturing of fuel assemblies for Spanish and European nuclear power plants, using the most innovative technologies and latest market advances. There are three types of fuel:

  • PWR: Pressurized water reactors, under Westinghouse license
  • BWR: Boiling water reactors, General Electric
  • VVER: Pressurized water reactors, in collaboration with Westinghouse

Fuel assembly manufacturing is divided into two processes:

Ceramic process in which uranium oxide powder is used to manufacture pellets; these pellets are inserted into zirconium alloy tubes which, once they are loaded, pressurized and sealed, are called fuel rods.

Mechanical process in which the fuel rods are assembled to form the fuel assemblies that are sent to the power plants.

Ceramic Process>

The first operation is reception of the drums with the uranium oxide powder. The next step is the mixing; this stage consists of creating a uniform mix of virgin uranium oxide powder (UO2) and the clean recycled material (U3O8), normally a pore-former.

The next stage is pre-pressing and granulating, which consists of pressing the powder to form a pellet with a greater density and that after being sieved produces a granulated powder with good fluidity characteristics.

The granulated powder is mixed beforehand with a lubricating powder in an appropriate homogenizer to favor the formation of the pellet in the pressing process and to lengthen the life of the press.

The pressed pellets then pass on to a sintering process, i.e. to obtain pellets with the right density and integrity for use in a nuclear reactor. The pellets are sintered at high temperatures, resulting in a more solid, harder structure.

The next step is the rectification. The nuclear fuel for a reactor is designed with a specific pellet diameter and cladding. This pellet diameter allows for a certain separation between the inside wall of the cladding and the pellet, according to drawings.

Finally the pellets are measured with laser methods and superficially examined with robotic systems for artificial vision inspection with high definition cameras. In this way, the pellets that do not comply with the required quality standards are identified and eliminated.

Recovery of the uranium oxide by oxidation: The pellets eliminated in any stage, and especially during the inspection stage, are oxidized and recovered as recycled uranium oxide that is put back again into the mixing stage.


Mechanical Process>

In this second phase, the plugs are manufactured first. For this purpose, the factory receives the zircaloy bars from which the plugs are made. After the plugs are inspected, they are used to close off the fuel rods.

The fuel rod manufacturing process begins with tubes to which the lower plug has previously been welded at one end, and then the rod loading takes place, i.e. the pellets are inserted into the tubes. Once they are loaded, the tubes are placed inside a spring and the second plug is put into place. After pressurization with an inert gas, the second plug is welded to produce the finished rod.

When the rod is completed, it is subject to a series of quality controls (ultrasound, X-ray, He leaks, induced current and scanner) to verify that it meets all the specification requirements.

The next step is fabrication of the skeleton, a structure formed by rods, nozzles and grids and which, after inspection, will serve as the support for insertion of the fuel rods.

Final assembly: Due to their differing constitution, a difference is made between PWR and BWR type fuel assemblies. Generally speaking, this final operation in the process consists of inserting the fuel rods into the support skeleton and finally installing nozzles and support structures.

The fuel assemblies are subject to several inspections before being packed in casks certified for transport. Some designs include a cleaning stage before packing.



From the beginning, our factory has committed to a continuous process of technological development of its manufacturing and inspection equipment in collaboration with cutting-edge companies. In the facility itself, we develop the equipment and processes required to make the different products with the highest standards of safety, quality and efficiency. Thanks to the development and optimization of the inspection and manufacturing equipment that we use, ENUSA is in a privileged position to supply highly advanced equipment to nuclear fuel factories, a business line on which we have been working for several years, either individually or in collaboration with other partners such as Tecnatom.

Avanced Fresh fuel manufacturing and inspection equipment

  • Artificial vision systems for automatic pellet inspection
  • Laser systems for measuring pellet diameters
  • Robots for handling green pellets
  • Ultrasound inspection systems for plug-to-fuel tube welds
  • Passive scanner for inspection of fuel rods of uranium and gadolinium oxide
  • Active scanner for inspection of fuel rods of uranium oxide
  • Passive scanner for inspection of fuel rods of uranium and gadolinium oxide
  • Eddy current inspection equipment for fuel tube surfaces and inclusion defect
  • Robotic rod transport and positioning systems for final fuel assembly
  • Artificial vision systems for welding stations
  • Seal weld X-ray analysis systems
  • Robotic systems for fuel rod leak inspection

If you are interested in the ENUSA equipment technology, please contact us by clicking here.