Patent ID: 7983376

Claim:
A boiling water nuclear reactor comprising: a core; a reactor pressure vessel containing the core; a reactor containment vessel including: a dry well containing the reactor pressure vessel, and a wet well containing a pressure suppression pool; a vent pipe connecting the dry well and the pressure suppression pool; a gravity-driven water injection pool arranged at a position higher than the core to hold boric acid aqueous solution therein; an emergency core water-injection piping system for causing the boric acid aqueous solution in the gravity-driven water injection pool to fall by gravity so as to be injected into the reactor pressure vessel in case of a reactor accident; a static containment vessel cooling system pool arranged outside the reactor containment vessel; a static containment vessel cooling system heat exchanger arranged in the static containment vessel cooling system pool; a dry well connection pipe connecting an upper part of the static containment vessel cooling system heat exchanger and the dry well; a gas vent pipe for discharging noncondensible gas in the static containment vessel cooling system heat exchanger into an inside of the pressure suppression pool; an intra dry well heat exchanger arranged in the dry well; an external heat exchanger arranged outside the reactor containment vessel; a dry well cooling water pipe connecting the intra dry well heat exchanger and the external heat exchanger in order to discharge heat obtained by the intra dry well heat exchanger at the external heat exchanger; and a boric acid aqueous solution heating device configured to heat the boric acid aqueous solution in the gravity-driven water injection pool by using part of the heat obtained by the intra dry well heat exchanger.