PURPOSE: To enable the height of a reactor building to be lowered, by means of direct arranging the sealed vessel on the basis of the reactor building and of lowering the mounting position of the reactor vessel.
CONSTITUTION: A sealed vessel 11 in which a reactor vessel 10 is built, is contained in a reactor building 9. The sealed vessel is laid on the basis of a reactor building and the reactor container is constituted of the sealed vessel 11 and a prenum chamber 13 by means of allowing the prenum chamber 13 of a torus type as if it may surround the underpart of the sealed vessel 11. A dry well 14 is separated from the reactor vessel 10, and is connected by the prenum chamber 13 and vent tubes 15. The bottom part of the dry well 14 is formed of a condensing water storing chamber 18 in which a constant level water is stored at the normal operation, and a connecting tube 16 in which a cheque valve 17 is set up at the middle, is connected between this chamber and the necessary water level of the prenum chamber 13.
OCHIAI KANEHIRO
UCHIYAMA YUUICHI
