Boiling water reactor nuclear power plant and its construction method

A boiling water reactor nuclear power plant, in which a cooling water is circulated, comprising, in an installed state thereof:

• a reactor building;
• a reactor containment vessel positioned in the reactor building;
• said reactor containment vessel having dual cylindrical structure having inner and outer wall sections;
• a reactor pressure vessel disposed inside the containment vessel;
• a dry well defined, inside the reactor containment vessel, by the inner wall section thereof;
• a pressure suppression pool provided inside the reactor containment vessel and outside the dry well between the inner and outer wall sections of the reactor containment vessel;
• a containment vessel cooling system pool disposed above the suppression pool;
• a reactor core mounted with fuel assemblies supported by a reactor core support plate and an upper grid plate provided plate provided in an inner base portion of the reactor pressure vessel, said reactor core being disposed below said pressure suppression pool;
• a reactor core shroud surrounding the reactor core and the upper grid plate;
• control rod guide tubes positioned in the reactor core shroud and over the upper grid plate;
• control rods inserted in the control rod guide tubes;
• and
• control rod drive mechanisms operative for inserting and withdrawing the control rods from an upper portion of the reactor core, said control rod drive mechanisms being arranged at a portion above the control rod guide tubes and inside the reactor core shroud,
• said inner and outer wall sections of the reactor containment vessel having an inner hollow structure, the double-wall structure being communicated with the containment vessel cooling system pool, wherein said cooling water therein flows and circulates in the hollow portion of the double-wall structure to cool the dry well, the double-wall structure being provide with a plurality of ribs.