Study on influence to core and fuel design by adopting vibro-packed fuel and sphere-pac fuel

Naganuma, Masayuki  ; Aida, Tatsuya*; Hayashi, Hideyuki

In the core and fuel design of sodium-cooled MOX fuel FR of FS, core designs with pellet fuel were mainly evaluated. However, vibro-packed fuel and sphere-pac fuel are also considered one of the candidates. Besides, the design must be affected by difference of the fuel behavior, however, the influence had not yet been evaluated adequately. Thus, authors examined the fuel thermal design model and evaluated the influences to the core and fuel design quantitatively. As a result, in the fuel thermal design model, selection of restructuring conditions was found to be important. Proper values were evaluated from the viewpoint of fitting PIE results. In applying this model, limitation of the stationary LHR was reduced to 390 W/cm. For FS phase-II reference cores, though it is required to modify specifications due to the decrease of LHR, the influence to nuclear performance is found to be benign. Therefore, the design that meets the requirements and targets of FS is possible for those fuels.