An insertable flux thimble interface for use in a bottom nozzle of a fuel assembly in a nuclear reactor (i.e., a bottom nozzle insert) is disclosed herein. In various aspects, the bottom nozzle insert has properties that are different from traditional bottom nozzle flux thimble interfaces. The properties of the bottom nozzle insert may mitigate wear phenomena observed on the flux thimble. For example, the bottom nozzle insert may be constructed from material that is different from the material of the bottom nozzle. In some aspects, the bottom nozzle insert is constructed from material that has a hardness that is less than the hardness the bottom nozzle material. In other aspects, the bottom nozzle insert is constructed from a material that has a hardness that is less than the hardness of the flux thimble material.

A nuclear reactor includes a coolant fluid thermal monitoring array configured to monitor coolant fluid circulation in a downcomer flow channel of a nuclear reactor. The thermal monitoring array includes one or more flowmeter assemblies configured to monitor coolant fluid flow through separate flow channel portions. Each flowmeter assembly includes a first sensor coupled to a heating element and at least one second sensor at least partially insulated from the heating element. The first and second sensors may measure temperatures of separate flowstreams of coolant fluid through a downcomer flow channel portion. Temperature data generated by the first and second sensors of the flowmeter assemblies may be processed to monitor coolant fluid flow through the downcomer flow channel portions. The temperature data may be processed to monitor coolant fluid temperature. The temperature data may be processed to monitor a location of a fluid two-phase interface in the downcomer flow channel.

A system for servicing a nuclear reactor module comprises a crane operable to attach to the nuclear reactor module, wherein the crane includes provisions for routing signals from one or more sensors of the nuclear reactor module to one or more sensor receivers.

A system for servicing a nuclear reactor module comprises a crane operable to attach to the nuclear reactor module, wherein the crane includes provisions for routing signals from one or more sensors of the nuclear reactor module to one or more sensor receivers.

Method of optimizing output of sensor for indicating location of metallic object. Sensor having primary electromagnetic coil to generate time varying magnetic field; secondary electromagnetic coil to detect time varying magnetic field as affected, by object to output, on basis of detected time varying magnetic field, signal indicative of location of object. Method includes steps of: supplying primary coil with alternating-current to result generated time varying magnetic field; locating object in first-position and recording signal output by secondary electromagnetic coil for range of frequencies of supplied alternating-current; locating object in second-position and recording signal output by secondary electromagnetic coil for range of frequencies of supplied alternating-current; calculating, for each of frequencies, a value for span to offset ratio of measured signals on basis of respective signals measured for object in first and second positions; determining frequency of supplied alternating-current which provides maximum span to offset ratio on basis of calculations.

Method of optimizing output of sensor for indicating location of metallic object. Sensor having primary electromagnetic coil to generate time varying magnetic field; secondary electromagnetic coil to detect time varying magnetic field as affected, by object to output, on basis of detected time varying magnetic field, signal indicative of location of object. Method includes steps of: supplying primary coil with alternating-current to result generated time varying magnetic field; locating object in first-position and recording signal output by secondary electromagnetic coil for range of frequencies of supplied alternating-current; locating object in second-position and recording signal output by secondary electromagnetic coil for range of frequencies of supplied alternating-current; calculating, for each of frequencies, a value for span to offset ratio of measured signals on basis of respective signals measured for object in first and second positions; determining frequency of supplied alternating-current which provides maximum span to offset ratio on basis of calculations.

A nuclear fission reactor, flow control assembly, methods therefor and a flow control assembly system. The flow control assembly is coupled to a nuclear fission module capable of producing a traveling burn wave at a location relative to the nuclear fission module. The flow control assembly controls flow of a fluid in response to the location relative to the nuclear fission module. The flow control assembly comprises a flow regulator subassembly configured to be operated according to an operating parameter associated with the nuclear fission module. In addition, the flow regulator subassembly is reconfigurable according to a predetermined input to the flow regulator subassembly. Moreover, the flow control assembly comprises a carriage subassembly coupled to the flow regulator subassembly for adjusting the flow regulator subassembly to vary fluid flow into the nuclear fission module.

The present invention relates to a lower end fitting for reducing flow resistance due to an in-core instrument in a nuclear fuel assembly, that is, a lower end fitting (100) having a plurality of flow holes for a nuclear fuel assembly, in which the flow holes (121) are formed under an assembly groove in which an instrumentation tube (131) for a nuclear fuel assembly is inserted, and at least two or more flow holes (121) are formed at a predetermined distance from the central axis (C) of the instrumentation tube (131).

Illustrative embodiments provide a nuclear fission reactor, that includes a reactor vessel, a nuclear fission fuel element capable of generating a gaseous fission product, a valve body defining a plenum for receiving the gaseous fission product, and a valve in operative communication with the plenum for controllably venting the gaseous fission product from the plenum.

A system for monitoring a condition of a nuclear reactor pressure vessel disposed in a radioactive environment includes an instrument structured to monitor a condition of the nuclear reactor pressure vessel; a powered wireless transmitting modem disposed in the radioactive environment, the wireless transmitting modem being electrically coupled to the instrument; a receiving modem disposed in the line of sight of the transmitting modem, the receiving modem being in wireless communication with the transmitting modem; and a signal processing unit electrically coupled to the receiving modem, the signal processing unit being structured to determine the condition of the nuclear reactor pressure vessel from the instrument. The transmitting modem is powered by a thermocouple disposed in or on the reactor pressure vessel.