Three kinds of tests have been carried out to confirm the integrity of containment penetrations under accidnet management (AM) conditions and to investigate its failure criteria beyond AM conditions and to demonstrate fission product (FP) aerosol trapping effects along the leakage path of its degraded penetrations. Tests were carried out using the actual containment penetrations in a BWR plant. Cesium iodide (CsI) was selected as a representative species of a FP aerosol. All prototypical containment penetrations were intact under AM conditions (200℃, 0.8MPa). Temperature not pressure governed the penetration failure, and the failure temperature was much higher (over 70℃) than the temperature of AM conditions. Total leak area estimated from the test was about 1/10 time smaller than the used in current severe accident (SA) analysis codes. Aerosol trapping effect of the leakage path were evaluated as a decontamination factor (DF) in all cases and the total DF in actual plant was estimated to be about 400.