Nuclear Technology / Volume 160 / Number 1 / October 2007 / Pages 100-111
Technical Paper / Annular Fuel
This paper summarizes the work performed to examine the feasibility of manufacturing internally and externally cooled annular fuel for high-power-density pressurized water reactors (PWRs) and to demonstrate commercially viable manufacturing processes at bench scale. Five different manufacturing processes were considered, and two were selected for further development and demonstration. These are (a) the traditional press and sinter technique currently used in solid pellet manufacture and (b) the vibration compaction (VIPAC) technique, in which granulated and sintered urania fuel particles are vibration compacted into a prefabricated annular space. Two separate pellet manufacturing trials were undertaken, one at the Westinghouse, Columbia, South Carolina, plant and one at INVAP facilities in Argentina. At the INVAP plant the pellets were loaded between small and large cladding tubes and seal welded to demonstrate the entire manufacturing steps. At Atomic Energy of Canada Limited, the VIPAC approach was used to perform short test segments as well as 1219-mm (4-ft)-long fuel rods. The overall conclusion of the work is that the press and sinter technique can produce annular pellets and annular fuel elements that meet the density and dimensional needs of the annular fuel design and hence is a viable approach toward fabrication of such high-power-density fuel. This process is most like that used in current commercial fuel production and hence would pose the least disruption in any future annular fuel use in commercial PWRs. This work also demonstrated that the VIPAC approach is capable of making high-quality annular fuel elements, but not with the fuel density required for adequate performance. Addition of uranium metal powder to the vibrated compact was found to be necessary to achieve the required uranium fuel loading.