Avoiding BWR channel distortion

摘要

In boiling water reactors (BWRs), a fuel bundle is enclosed in a fuel channel that directs coolant up through the fuel assembly. Distortion of these channels can alter the clearance between neighbouring channels and may restrict control blade movement. More than half of the 35 BWRs in the United States have reported control blade interference due to channel distortion since 2000. The problem surfaced with the migration from Zircaloy 4 (Zr-4) to Zircaloy 2 (Zr-2) channels and longer cycle lengths (18 months). Channels manufactured by all major BWR fuel suppliers have been affected.