A sensor for passively measuring a maximum temperature within a nuclear reactor comprises a substrate, and a plurality of melt wires within a cavity defined within the substrate, at least one melt wire of the plurality of melt wires exhibiting a variable melting temperature along a length of the at least one melt wire. Related sensors and methods of forming the sensors are also disclosed.

An optical fiber-based gamma-ray calorimeter (OFBGC) sensor array which uses a thermal mass with a low thermal conductivity is provided. Advantages of the OFBGC sensor array include: 1) the number of sensors in the OFBGC sensor array is adjustable and limited only by the spatial resolution of the OFBGC sensors, within the OFBGC sensor array, and 2) the OFBGC sensor design is simpler to build than a conventional optical fiber-based gamma thermometer (OFBGT) sensor array. One purpose of the OFBGC is to determine the power distribution in nuclear reactors.

An optical fiber-based gamma-ray calorimeter (OFBGC) sensor array which uses a thermal mass with a low thermal conductivity is provided. Advantages of the OFBGC sensor array include: 1) the number of sensors in the OFBGC sensor array is adjustable and limited only by the spatial resolution of the OFBGC sensors, within the OFBGC sensor array, and 2) the OFBGC sensor design is simpler to build than a conventional optical fiber-based gamma thermometer (OFBGT) sensor array. One purpose of the OFBGC is to determine the power distribution in nuclear reactors.

A measurement core for measuring nuclear heating, the core extending in a longitudinal direction and having a main plane, includes at least: a first layer of material, forming a first sample; a first thin layer of electrical insulation on the first sample; a thin conductive layer forming a heating electrical resistor on the first layer of electrical insulation; and a second thin layer of electrical insulation on the heating electrical resistor. A calorimetric sensor includes: an outer jacket; a gas contained in the jacket; a measurement core disposed in the jacket; a link for holding the core in the jacket and transferring the heat between the core and the jacket; and temperature measurement capable of measuring the temperature at a hot point, and the temperature at a cold point.

A dry cask storage system for spent nuclear fuel includes a detection apparatus having a resonant electrical circuit, with resonant electrical circuit being situated within an interior region of a metallic vessel wherein the SNF is situated. The detection apparatus includes a transmitter that generates an excitation pulse that causes the resonant circuit to resonate and to generate a response pulse. The resonant circuit includes an inductor that is formed with a core whose magnetic permeability varies with temperature such that the frequency of the resonant circuit varies as a function of temperature. The response pulse is then used to determine the temperature within the interior of the vessel where the SNF is situated. Pressure detection is also provided.

A dry cask storage system for spent nuclear fuel includes a detection apparatus having a resonant electrical circuit, with resonant electrical circuit being situated within an interior region of a metallic vessel wherein the SNF is situated. The detection apparatus includes a transmitter that generates an excitation pulse that causes the resonant circuit to resonate and to generate a response pulse. The resonant circuit includes an inductor that is formed with a core whose magnetic permeability varies with temperature such that the frequency of the resonant circuit varies as a function of temperature. The response pulse is then used to determine the temperature within the interior of the vessel where the SNF is situated. Pressure detection is also provided.

A system that provides a direct indication of peak fuel rod centerline temperature and peak fuel rod clad temperature than conventionally inferred from the power distribution by directly and continuously measuring the fuel temperatures of the fuel pellets in one or more of the hottest fuel elements in the core. The peak fuel rod clad temperature is then obtained from the maximum measured peak fuel rod centerline temperature in combination with the maximum coolant core exit temperature and the minimum coolant flow rate.

A system that provides a direct indication of peak fuel rod centerline temperature and peak fuel rod clad temperature than conventionally inferred from the power distribution by directly and continuously measuring the fuel temperatures of the fuel pellets in one or more of the hottest fuel elements in the core. The peak fuel rod clad temperature is then obtained from the maximum measured peak fuel rod centerline temperature in combination with the maximum coolant core exit temperature and the minimum coolant flow rate.

A multi-loop natural circulation experimental device under six-degree-of-freedom motion conditions and a method therefor are provided. The device includes: a six-degree-of-freedom motion simulation platform; a multi-loop main circulation loop including a serpentine pre-heater, an experimental section, two sleeve-type condensers, and a pressurized circulating pump, a voltage stabilizer and related equipment; and a cooling water system including a sleeve condenser, a plate heat exchanger, a cooling tower, a cooling fan, a cooling water tank and related equipment; and an electric heating system including a DC power supply, a low voltage power controller and a transformer. The present invention also provides an experimental method of the device.

A multi-loop natural circulation experimental device under six-degree-of-freedom motion conditions and a method therefor are provided. The device includes: a six-degree-of-freedom motion simulation platform; a multi-loop main circulation loop including a serpentine pre-heater, an experimental section, two sleeve-type condensers, and a pressurized circulating pump, a voltage stabilizer and related equipment; and a cooling water system including a sleeve condenser, a plate heat exchanger, a cooling tower, a cooling fan, a cooling water tank and related equipment; and an electric heating system including a DC power supply, a low voltage power controller and a transformer. The present invention also provides an experimental method of the device.