Effect of ECC Injection Angle on the Flow Distribution in a Downcomer Annulus During LBLOCA Reflood Phase in the Air-Water Test

The comparison tests for the direct ECC bypass fraction were experimentally performed with a typical DVI nozzle and an ECC column nozzle having injection angle to the gravity axis. The ECC column nozzle is newly introduced to make an ECC water column in the downcomer region. The injection angle of the ECC water relative to the gravity axis is varied from 0 to ± 90 degrees stepped by 45 degrees. The tests are performed in the air-water separate effect test facility (DIVA), which is 1/7.07 linearly scaled-down of the APR1400 nuclear reactor. The test results show that the direct ECC bypass fraction is affected by the ECC injection angle when the ECC water is injected using an ECC column nozzle as a single water column. The injection angle of an ECC water column relative to the circumferential air jet in the DVI system affects the direct ECC bypass fraction during the reflood phase of a LBLOCA. (authors)