Since the enriched uranium is provided as uranium hexafluoride(UF6), conversion to sinterable uranium dioxide(UO2) powder is needed.
Our company has operated the dry conversion(DC) process since 1998 replacing the AUC process which had been used previously. The DC process needs simpler facility design and is more economical because of less manufacturing cost than the AUC process.
Our company has operated the dry conversion(DC) process since 1998 replacing the AUC process which had been used previously. The DC process needs simpler facility design and is more economical because of less manufacturing cost than the AUC process.
UO2 powder made from the Dry Conversion process is homogenized by the homogenizer. The homogenized powder is then pressed into cylindrical form of 10mm in length.
After being sintered in a high-temperature sintering furnace, the surface of the pellets is machined by a centerless grinder and then cleaned. The pellets are completed after being dried by an electro-round heating plate. A UO2 pellet is the weight of 5.2g and the diameter of 8mm. A fuel rod inserted there are about 365 pellets in a fuel rod and 96,000 pellets in a fuel assembly.
After being sintered in a high-temperature sintering furnace, the surface of the pellets is machined by a centerless grinder and then cleaned. The pellets are completed after being dried by an electro-round heating plate. A UO2 pellet is the weight of 5.2g and the diameter of 8mm. A fuel rod inserted there are about 365 pellets in a fuel rod and 96,000 pellets in a fuel assembly.
A fuel rod consists of a cladding tube, top and bottom end plugs, plenum spring and fuel pellet. To eliminate any remaining moisture, the pellets are again dried at 150℃ for one and a half hours in the drying furnace. The pellets are then loaded into vacuum-tight cladding tubes which are bottom-end plug welded. Plenum spring is inserted into the tubes and then the tubes are pressurized with helium and top-end plug welding is performed.
The zircaloy cladding tube plays a role to contain the fission gas generated from the pellets, during irradiation on the reaction.
The zircaloy cladding tube plays a role to contain the fission gas generated from the pellets, during irradiation on the reaction.
The skeleton keeps rods firm and fixed within fuel assembly. The skeleton consists of top and bottom end pieces, spacer grids and instrumentation tube, and guide thimbles, all of which are manufactured and assembled in the separate component fabrication facilities.
After these components are perfectly fixed to the assembling rack, the skeleton is finished by spot-welding. Lacquer is then applied to the rod surfaces in order to protect the rod from being scratched and to protect spring in the spacer grids.
The fuel rods being inserted into the skeleton, top and bottom and pieces are fitted. After delacquering of completed fuel assembly, inspection is carried out to confirm that the distance between rods, torsion, length and other dimension are perfect. Results of quality control inspection performed during all major processes are evaluated and integrated by a DOM computer system, and the only products that are deemed to be 100% perfect are passed for shipping to nuclear power plants.
After these components are perfectly fixed to the assembling rack, the skeleton is finished by spot-welding. Lacquer is then applied to the rod surfaces in order to protect the rod from being scratched and to protect spring in the spacer grids.
The fuel rods being inserted into the skeleton, top and bottom and pieces are fitted. After delacquering of completed fuel assembly, inspection is carried out to confirm that the distance between rods, torsion, length and other dimension are perfect. Results of quality control inspection performed during all major processes are evaluated and integrated by a DOM computer system, and the only products that are deemed to be 100% perfect are passed for shipping to nuclear power plants.