Evaluation for the Impact of Debris Settling on the In-vessel Downstream Effect Tests of the APR1400 Design

Four tests were run to evaluate hot-leg break conditions with a four safety injection (SI) flow rate varying particle to fiber (P/F) ratios of 0.5, 1, 2, and 10. Seven tests were run to evaluate cold-leg (CL) break conditions with a core boil-off rate at 700 seconds after a LOCA with varying P/F ratios of 1, 10, 20, 30, 40, 50, and 60. The phenomenon of debris settling was observed at the inlet of test column when simulating cold-leg beak. In this paper, the applicability of the test results was evaluated by providing pressure drops through debris bed in which condition debris settling did not occur under the same P/F mass ratio. The impact of debris settling on the validity of testing that has been conducted to address in-vessel downstream effects of the APR1400 was evaluated in this study. The test results that have been conducted with some debris settling are valid with a margin of approximately 52.3% under the cold-leg break condition