Auxiliary pressure relief device

The invention relates to an auxiliary pressure relief device which is used for discharging gas in a containment of a nuclear power plant and comprises a shunting pipeline and a pressure relief assembly. The shunting pipeline comprises a mounting end and a connecting end, and the mounting end is used for being detachably connected and communicated with an exhaust pipe of the containment; the air inlet end of the pressure relief assembly is connected and communicated with the connecting end, and the exhaust end of the pressure relief assembly is used for being communicated with the external environment; at least part of gas flowing through the exhaust pipe can flow to the pressure relief assembly along the flow dividing pipeline so as to be exhausted. When the pressure test of the containment is completed and the test gas in the containment is discharged, the gas can be simultaneously discharged through the pressure relief system of the containment and the auxiliary pressure relief device, so that the pressure