In this study, irradiation effects of CHF on bare and porous honeycomb surfaces in downward-face saturated pool boiling with different downward inclination angles were investigated. After irradiation, the hydrophilicity of copper and porous honeycomb structure increased compared to that of the non-irradiated surface. For bare surface cases, CHF enhancement cannot be observed at downward inclination angles of 10° and 20° after irradiation. This is likely to be because under higher downward inclination, the bubble film departure frequency (BFDF) is larger than that of the 5° case. So there is no enough time for water to be supplied to the surface, which weakens the effect of vapor-liquid mixture area, leading to an unchanged CHF performance. In honeycomb surface cases, no CHF enhancement is observed after irradiation. This is because the macro structure became the dominant factor to determine bubble behavior, which resulted in no further enhancement in CHF. Irradiation cannot affect BFDF values for both bare and honeycomb surface. BFDF is determined by the macro structure of the surface, instead of the micro structure of the surface. The results also show that CHF is not deteriorated by irradiation in some cases, which is a good news to real-world nuclear power plants.