Evaluation of Flow-Induced Vibration of Cruciform Control Rod Guide TubesUsing Numerical Flow Analysis

摘要

The control rod guide tube (CRGT) for the next generation ABWR (ABWR-II), being developed by the Japanese BWRUtilities and Plant Suppliers, has a cruciform shape in contrast to the cylindrical one used in conventional BWR reactordesign. This design change is due to the use of larger size fuel bundles and K lattice core. The new design may have potentialfor flow-induced vibration (FIV) because the cruciform CRGT hydraulic resistance against lateral flow is considered to belarger than the conventional one.Some modifications of analysis methods to evaluate FIV are reported in this paper. The introduction of porous mediafor the structure modeling is one such modification. Improvement in accuracy was successfully confirmed by comparisonbetween analysis results and measured stresses of the ABWR. In this analysis, an ordinal forcing coefficient for cylindricalstructures was used for the CRGT of the current ABWR. Flow-induced vibration stresses on the cruciform CRGT were thenestimated by this new method, and its results show that the stress amplitudes are within the level of allowance. Designverification will continue as a 1/5 scale reactor model test in the next phase.