Modular head assembly and method of retrofitting existing nuclear reactor facilities

A modular head assembly for a nuclear reactor, comprising:

• a closure head adapted to be fixedly secured atop a nuclear reactor pressure vessel;
• a plurality of control rod drive mechanisms (CRDMs) fixedly mounted within said closure head so as to project vertically upwardly above said closure head;
• a plurality of lift rods fixedly secured to said closure head for enabling lifting and lowering of said closure head relative to said pressure vessel;
• a seismic support platform, in the form of an annular plate-like disc, fixedly supported upon said lift rods;
• a missile shield plate, in the form of a flat circular plate, vertically spaced above said seismic support platform, fixedly supported upon said lift rods;
• cooling baffle means operatively associated with said control rod drive mechanisms for defining coolant air flow paths for said control rod drive mechanisms;
• and
• flow conduit means, fluidically connected to said cooling baffle means, comprising a lower air manifold disposed vertically below said cooling baffle means and interposed between said cooling baffle means and said closure head, and duct means extending vertically upwardly from said lower air manifold, said vertically extending duct means passing through said seismic support platform, and exhaust fan means, disposed atop said vertically upwardly extending duct means, fluidically connected to said flow conduit means, mounted upon said closure head and disposed entirely within the peripheral envelope of said closure head, for causing said coolant air to flow through said coolant air flow paths past said control rod drive mechanisms so as to cool said control rod drive mechanisms and to be exhausted outwardly from said modular head assembly.

A modular head assembly for a nuclear reactor, comprising:

• a closure head adapted to be fixedly secured atop a nuclear reactor pressure vessel;
• a plurality of control rod drive mechanisms (CRDMs) fixedly mounted within said closure head so as to project vertically upwardly above said closure head;
• a plurality of lift rods fixedly secured to said closure head for enabling lifting and lowering of said closure head relative to said pressure vessel;
• a seismic support platform, in the form of an annular plate-like disc, fixedly supported upon said lift rods;
• a missile shield plate, in the form of a flat circular plate, vertically spaced above said seismic support plarform, fixedly supported upon said lift rods;
• cooling baffle means operatively associated with said control rod drive mechanisms for defining coolant air flow paths for said control rod drive mechanisms;
• and
• flow conduit means fluidically connected to said cooling baffle means, comprising a lower air manifold disposed vertically below said cooling baffle means and interposed bwtween said cooling baffle means and said closure head, and duct means extending vertically upwardly from said lower air manifold, said vertically extending duct means passing through said missile shield plate, and exhaust fan means disposed atop said vertically upwardly extending duct means, connected to said flow conduit means, mounted upon said closure head and disposed entirely within the peripheral envelope of said closure head, for causing said coolant air to flow through said coolant air flow paths past said control rod drive mechanisms so as to cool said control rod drive mechanisms and to be exhausted outwardly from said modular head assembly.

A modular head assembly for a nuclear reactor, comprising:

• a closure head adapted to be fixedly secured atop a nuclear reactor pressure vessel;
• a plurality of control rod drive mechanisms (CRDMs) fixedly mounted within said closure head so as to project vertically upwardly above said closure head;
• a plurality of lift rods fixedly secured to said closure head for enabling lifting and lowering of said closure head relative to said pressure vessel;
• a seismic support platform, in the form of an annular plate-like disc, fixedly supported upon said lift rods;
• a missile shield plate, in the form of a flat circular plate, vertically spaced above said seismic support platform, fixedly supported upon said lift rods;
• cooling baffle means operatively associated with said control rod drive mechanisms for defining coolant air flow paths for said control rod drive mechanisms;
• and
• flow control means fluidically connected to said cooling baffle means, comprising a lower air manifold disposed vertically below said cooling baffle means and interposed between said cooling baffle means and said closure head, and duct means extending vertically upwardly from said lower air manifold, said vertically extending duct means passing through both said seismic support platform and said missile sheild plate, and exhaust fan means disposed atop said vertically upwardly extending duct means, connected to said flow conduit means, mounted upon said closure head and disposed entirely within the peripheral envelope of said closure head, for causing said coolant air to flow through said coolant air flow paths past said control rod drive mechanisms so as to cool said control rod drive mechanisms and to be exhausted outwardly from said modular head assembly.