Reactor safety facility

An opening of a bent tube in communication with an upper dry well and a pressure suppression chamber is disposed higher by not less than 2m than the lower end of the pressure vessel, and an opening of an upper and lower dry well communication pipe is disposed lower than the opening of the bent tube, further, a flow channel in communication with the upper and lower portions of a support of the pressure vessel is disposed. A flow channel for cooling water or steams is formed between the outer wall of the pressure vessel and a heat insulation wall, and an opening/closing mechanism which is closed during normal operation and opened upon occurrence of accident is disposed at least to one place of the channel. Cooling water supplied to the upper dry well flows to the lower dry well from the opening of the upper and lower dry well communication pipe, accumulates in the upper dry well and reaches at a height of the opening of the bent tube and flows into the pressure suppression chamber only after submerging the pressure vessel. Thus, the water level of the pressure suppression chamber is not elevated for cooling the pressure vessel, and an external water source is not necessary. (N.H.)