Piping loops can carry either forced or natural circulation coolant flow from and back to a reactor depending on reactor and coolant state, and can transition between the two. The loop flows into a heat exchanger that significantly cools the coolant and may even condense the coolant. The heat exchanger can drive natural circulation coolant flow, and a pump on the loop can drive forced circulation. Coolant direction may be reversed through the heat exchanger in different modes. Loops may be installed directly on existing ICSs, come off of a primary loop generating electricity commercially, or be their own loop around and penetrations to the reactor. Actuation valves may isolate and actuate the system merely by disallowing or allowing coolant flow. Different flow modes and coolant direction may be similarly achieved by pump actuation and/or valve opening/closing. Beyond the pump and simple valve actuation, loops may be entirely passive.

Piping loops can carry either forced or natural circulation coolant flow from and back to a reactor depending on reactor and coolant state, and can transition between the two. The loop flows into a heat exchanger that significantly cools the coolant and may even condense the coolant. The heat exchanger can drive natural circulation coolant flow, and a pump on the loop can drive forced circulation. Coolant direction may be reversed through the heat exchanger in different modes. Loops may be installed directly on existing ICSs, come off of a primary loop generating electricity commercially, or be their own loop around and penetrations to the reactor. Actuation valves may isolate and actuate the system merely by disallowing or allowing coolant flow. Different flow modes and coolant direction may be similarly achieved by pump actuation and/or valve opening/closing. Beyond the pump and simple valve actuation, loops may be entirely passive.

A method of cleaning a jet pump assembly of a nuclear reactor may comprise evacuating an interior of the jet pump assembly that is filled with a first liquid by injecting a gas to purge the first liquid from the interior to provide an evacuated surface. In addition, the method may comprise directing a jet of a second liquid onto the evacuated surface.

A method of cleaning a jet pump assembly of a nuclear reactor may comprise evacuating an interior of the jet pump assembly that is filled with a first liquid by injecting a gas to purge the first liquid from the interior to provide an evacuated surface. In addition, the method may comprise directing a jet of a second liquid onto the evacuated surface.

A nuclear reactor controlled by moving a liquid fuel between a reservoir and chambers in the core is provided. No pumps or moving parts within the reactor vessel are needed to move the fuel. The control system moves the liquid fuel between the core and the reservoir by moving a separate control gas. It can monitor the internal state of the core through the control connections. The fuel chamber is shaped so that evolved gases escape the core and can be collected at the control connections. The core reverts to a safe state on power failure.

An ultrasonic phased array transducer assembly having a single housing in which a plurality of phased array transducer subassemblies are mounted at a skewed angle relative to a leading face of the housing and to each other, with each transducer mounted on composite wedge(s) at different orientations within the housing.

An ultrasonic phased array transducer assembly having a single housing in which a plurality of phased array transducer subassemblies are mounted at a skewed angle relative to a leading face of the housing and to each other, with each transducer mounted on composite wedge(s) at different orientations within the housing.

A method of cleaning a jet pump assembly of a nuclear reactor may comprise inserting a cleaning tool into the jet pump assembly such that a front face of the cleaning tool is adjacent to an inner surface of the jet pump assembly and below a level of a first liquid in the jet pump assembly. The method may additionally comprise directing a plurality of front jets of a second liquid from a plurality of front orifices on the front face of the cleaning tool such that the plurality of front jets of the second liquid strikes the inner surface of the jet pump assembly. The method may further comprise maintaining a standoff distance between the front face of the cleaning tool and the inner surface of the jet pump assembly during the cleaning of the jet pump assembly.

A method of cleaning a jet pump assembly of a nuclear reactor may comprise inserting a cleaning tool into the jet pump assembly such that a front face of the cleaning tool is adjacent to an inner surface of the jet pump assembly and below a level of a first liquid in the jet pump assembly. The method may additionally comprise directing a plurality of front jets of a second liquid from a plurality of front orifices on the front face of the cleaning tool such that the plurality of front jets of the second liquid strikes the inner surface of the jet pump assembly. The method may further comprise maintaining a standoff distance between the front face of the cleaning tool and the inner surface of the jet pump assembly during the cleaning of the jet pump assembly.

A method and apparatus of limiting power of a boiling water nuclear reactor system includes a reactor pressure vessel, a reactor core disposed in the reactor pressure vessel, a core shroud surrounding the reactor core, a downcomer region disposed between an inner surface of the reactor pressure vessel and the core shroud, a steam line connected to an upper end of the reactor pressure vessel and a condenser system that receives steam from the reactor pressure vessel. A portion of the condenser system condensate is returned to the reactor pressure vessel of the boiling water reactor inside the core barrel above the core rather than into the downcomer. Returning the condensate in this way increases the effectiveness of an isolation condenser system or if the condensate is a portion of the feedwater from the main condenser it provides an effective means to regulate core flow and core power.