A pressurized water reactor (PWR) includes a vertical cylindrical pressure vessel having a lower portion containing a nuclear reactor core and a vessel head defining an integral pressurizer. A reactor coolant pump (RCP) mounted on the vessel head includes an impeller inside the pressure vessel, a pump motor outside the pressure vessel, and a vertical drive shaft connecting the motor and impeller. The drive shaft does not pass through the integral pressurizer. The drive shaft passes through a vessel penetration of the pressure vessel that is at least large enough for the impeller to pass through.

Pressurized water reactor with upper vessel section providing both pressure and flow control

Disclosed herein is a decay heat removal system, including: a decay heat exchanger that absorbs decay heat generated by a nuclear reactor; a heat pipe heat exchanger that receives the decay heat from the decay heat exchanger through a sodium loop for heat removal and then discharges the decay heat to the outside; and a sodium-air heat exchanger that is connected to the heat pipe heat exchanger through the sodium loop and discharges the decay heat transferred thereto through the sodium loop to the outside. According to the decay heat removal system, a heat removal capability can be realized by the heat pipe heat exchanger at such a high temperature at which the safety of a nuclear reactor is under threat, and a cooling effect can be obtained through the sodium-air heat exchanger at a temperature lower than that temperature.

Decay heat removal system comprising heat pipe heat exchanger

A nuclear reactor (1), in particular a liquid-metal-cooled reactor, is provided with at least one compact primary heat exchanger (11), in particular a steam generator, which has a plurality of heat-exchange tubes (27) having respective spiral portions (37) set in levels on top of one another to form an annular tube bundle (40) delimiting a substantially cylindrical internal central zone (17), which houses, at the bottom, a circulation pump (10) and is pre-arranged for supply from below with primary fluid (liquid metal), which then traverses the tube bundle radially.

Nuclear reactor, in particular liquid metal cooled nuclear reactor, with compact primary heat exchanger

Configurations of molten fuel salt reactors are described that utilize neutron-reflecting coolants or a combination of primary salt coolants and secondary neutron-reflecting coolants. Further configurations are described that circulate liquid neutron-reflecting material around a reactor core to control the neutronics of the reactor. Furthermore, configurations which use the circulating neutron-reflecting material to actively cool the containment vessel are also described. A further configuration is described that utilizes a core barrel between a reactor core volume of molten fuel salt and a reflector volume, in which the reflector volume contains a plurality of individual reflector elements separated by an interstitial space filled with molten fuel salt.

Molten fuel nuclear reactor with neutron reflecting coolant

A dynamic neutron reflector assembly for a “breed-and-burn” fast reactor incrementally adjusts neutron spectrum and reactivity in a reactor core. The composition of materials in the dynamic neutron reflector may be adjusted to change neutron reflectivity levels, or to introduce neutron moderating or absorption characteristics. The dynamic neutron reflector may contain a flowing reflecting liquid of adjustable volume and/or density. Submergible members may be selectively inserted into the flowing reflecting liquid to alter its volume and introduce other neutron modifying effects such as moderation or absorption. Selective insertion of the submergible members allows for concentration of the neutron modifying effects in a selected portion of the reactor core. The flowing reflecting liquid may also act as a secondary coolant circuit by exchanging heat with the molten fuel salt.

Neutron reflector assembly for dynamic spectrum shifting

A nuclear reactor ( 1 ) is provided, in particular a nuclear reactor cooled with a liquid metal (for example, a heavy liquid metal, such as lead or lead-bismuth eutectic), of the type having a cylindrical inner vessel ( 15 ) that divides a hot collector ( 6 ) over a core ( 4 ) from a substantially annular cold collector ( 7 ) surrounding the hot collector; housed in the cold collector ( 7 ) is a plurality of integrated circulation and heat-exchange assemblies ( 20 ), each of which includes a pump ( 9 ), two heat exchangers ( 10 ) set at the sides of the pump, and a conveying structure ( 21 ) through which a primary fluid ( 8 ) for cooling the core passes from the pump to the heat exchanger, all of which are fixedly connected to one another to form a unitary structure; each integrated assembly has an inlet ( 26 ) connected to the hot collector ( 6 ) and two outlet sections ( 34 ) in the cold collector ( 7 ).

Cinotti Luciano

Papers

Nuclear Reactor, In Particular a Liquid-Metal-Cooled Nuclear Reactor