Modular nuclear reactor for a land-based power plant and method for the fabrication, installation and operation thereof

A transportable prefabricated fast-breeder nuclear heat supply module for shipment to and erection at an electric-power generating facility comprising:

• a primary vessel, a containment vessel surrounding said primary vessel, and a confinement vessel surrounding said containment vessel, said containment vessel being close-coupled to said primary vessel to defne a first interstitial region therebetween and said confinement vessel being close-coupled to said containment vessel to define a second interstitial region therebetween, said confinement vessel having outer dimensions sized for shipment on a railway car;
• a fast-breeder reactor core unit mounted within said primary vessel and including a plurality of control rods;
• a counterflow heat exchanger mounted within said primary vessel and extending about said reactor core unit, said heat exchanger having a first wall in common with said primary vessel, said heat exchanger having an inlet at a lower extremity thereof and an outlet at an upper extremity thereof for secondary coolant at said first wall;
• inlet means and outlet means communicating through said confinement and containment vessels with said heat exchanger inlet and outlet, respectively, said inlet means and said outlet means being adapted for connection to a secondary cooling system;
• an electromagnetic pump mounted within said primary vessel directly underneath the reactor core unit for pumping a liquid metal primary coolant upwardly through said reactor core unit and said heat exchanger;
• first means defining an inlet plenum positioned intermediate the pump and the overlying reactor core unit, said pump and said reactor core unit communicating directly with said intermediate inlet plenum to define a direct upward primary coolant flow path from said pump to said reactor core unit;
• wherein a second wall of said primary vessel and a third wall of said heat exchanger define a flow path for said primary coolant from said reactor core unit to said heat exchanger, said third wall having an inlet at an upper extremity thereof for primary coolant and to provide a downward flow path for said primary coolant through the heat exchanger in counterflow to a secondary coolant;
• and wherein a fourth wall and a fifth wall define a flow path for said primary coolant from a lower extremity of said heat exchanger to an inlet of said pump mounted underneath the reactor core unit;
• and
• a control rod drive unit mounted within said containment vessel outside said primary vessel and operatively connected through said primary vessel to said control rods;
• whereby said primary coolant flows upward through said reactor core unit and to the upper extremity of said heat exchanger, and downward through said heat exchanger and to said pump inlet in a flow path devoid of piping and said nuclear heat supply module is in fluid communication with the balance of said electric-power generating facility only through said secondary coolant inlet means and outlet means.

A segmented shell for assembly about a nuclear heat supply module comprising:

• a nuclear heat supply module having an outer wall;
• a plurality of shell segments adapted to be joined to one another in surrounding relation to said nuclear heat supply module, the joined shell segments defining an inner wall immediately adjacent the outer wall of said nuclear heat supply module, an outer wall spaced apart from said inner wall and an intermediate wall spaced apart from said inner and outer walls to define therebetween an inner interstitial region providing a water jacket and an outer interstitial region for receiving a cementatious material;
• a plurality of heat exchange loops secured to said segments, each loop having an inner branch defining a first heat exchange area disposed at the inner wall of the shell segments for placement intimate to the outer wall of said heat supply module and an outer branch defining a second heat exchange area disposed at the outer surface of said segmented shell outer wall;
• whereby said segmented shell when assembled about said heat supply module provides a form for the pouring and curing of a biological shield of cementatious material and said heat exchange loops provide an emergency heat removal system.

A modular nuclear reactor comprising:

• a primary vessel having a removable recessed head;
• an outer vessel surrounding said primary vessel and close-coupled thereto to define a first interstitial region therebetween;
• a reactor core unit mounted within said primary vessel, said reactor core unit including a plurality of control rods;
• a heat exchanger mounted within said primary vessel, said heat exchanger having an inlet and an outlet for secondary coolant;
• inlet means and outlet means communicating through said outer and primary vessels with said heat exchanger inlet and outlet, respectively, said inlet means and said outlet means being adapted for connection to a secondary cooling system;
• a pump mounted within said primary vessel directly underneath the reactor core unit for pumping a primary coolant upwardly through said reactor core unit and said heat exchanger;
• first means defining an inlet plenum positioned intermediate the pump and the overlying reactor core unit, said pump and said reactor core unit communicating directly with said intermediate inlet plenum to define a direct upward primary coolant flow path from said pump to said reactor core unit;
• second means defining a primary coolant flow path from said reactor core unit to said heat exchanger and downwardly therethrough in counterflow to an upwardly flowing secondary coolant, and third means defining a primary coolant flow path from said heat exchanger to an inlet of said pump mounted directly underneath the reactor core unit, said second means and said third means being devoid of piping;
• and
• a control rod drive unit mounted within the recess defined by said recessed head and operatively connected to said control rods;
• an annular shell surrounding said outer vessel, said shell having an inner wall adjacent the outer wall of said outer vessel and an outer wall spaced apart from said inner wall to define therebetween a second interstitial region;
• a plurality of heat exchange loops, each having an inner branch defining a first heat exchange area disposed intimate to said outer vessel outer wall and an outer branch defining a second heat exchange area disposed at the outer surface of said segmented shell outer wall thereby to provide emergency heat removal from said nuclear reactor;
• and
• a hardened cementatious material within said second interstitial region providing a biological shield for said nuclear reactor;
• wherein said secondary coolant inlet means and outlet means extend through said biological shield and said annular shell to provide fluid communication between said modular reactor and the balance of an electric-power generating facility.