| 摘要 |
<p>A fuel bundle (B) is disclosed in which interspersed part length fuel rods (16) define between the end of the fuel rods and the upper tie plate (20) void regions which are not otherwise occupied. Full length fuel rods (18) adjacent to these regions are provided with an expanded upper plenum region (P) which effectively increases the fuel rod diameter at the end of the upper two phase region of the fuel bundle (B). Under normal circumstances and a fuel bundle (B) with only full length fuel rods, such an expansion of the upper regions of the fuel rods would cause unacceptable pressure drop. Where such expansion occurs adjacent the vacated volumes created by the part length fuel rods (16), unacceptable pressure drop does not occur. Consequently, and with the expanded plenum volume (P), a longer length of active fuel pellets can be accommodated within the full length fuel rods (18). <IMAGE></p> |
