Pressure suppression device

Purpose: To decrease the effects of load weight due to changes in air bubble pressures by increasing the air volume in a discharge pipe as much as possible. Constitution: In the case where a main steam release valve is actuated in a BWR type reactor, steams from the valve are at first passed by way of a discharge pipe for the main steam release valve in a dry well to the header of the main steam release pipe in a pressure suppression chamber, and then released from the header into the pool water in the pressure suppression chamber by way of a discharge pipe. Preceeding to the flow of the released steams, airs that stayed so far in the main steam release valve discharge tube from the instance the steams are jetted out from the main steam release valve are rapidly compressed to increase pressure due to the steams. However, the rate of pressure increase is sufficiently moderated and reduced by the provision of the main steam release pipe header surrounding the bent header. As the result, the pressurized airs whose pressure increasing rate is moderated are discharged by way of the discharge pipe into pool water. (Horiuchi, T.)