Abstract: The aim of the invention is to measure the partial pressure of very small amounts of free hydrogen gas at various sites in the core of a nuclear reactor. A further aim is to construct such a device to be so rugged as to survive in the reactor environment. Another aim is to construct such a device of materials which will not significantly affect reactivity.

Abstract: The device comprises, in addition to a gamma thermometer with two junctions and insulated output conductive wires placed in a traversing sheath, an instrument placed outside the reactor for measuring the total current circulating between at least one of the conductive wires and the sheath under the action of the neutron and gamma fluxes in the core.

Abstract: This device is intended to measure the thermal power released locally in an area of the core of a nuclear reactor and comprises a conduit in the core of the reactor from the outside which contains a body which absorbs gamma radiations located at the measuring area and associated with a measuring thermocouple. A first junction of the thermocouple is placed so that it is brought to a temperature essentially representative of that of the reactor coolant and slightly affected by the gamma flux, and a second junction is placed so that it is brought to a temperature representative of that of the body which absorbs the radiations. The device comprises a supplementary thermocouple which has a first junction located near that of the measuring thermocouple and a second junction brought to a reference temperature.

Abstract: Double-junction thermocouple sensors located at axially spaced measurement zones within an elongated probe are interconnected in series to produce a combined output from differential signals generated by the sensors in response to unequal heating of the junctions. Axial heat flow between measurement zones is controlled to modify the combined output in a corrective direction with respect to a linear function of liquid level between the measurement zones.

Abstract: A liquid coolant measuring instrument for a nuclear reactor vessel measures the liquid coolant level by utilizing the thermal characteristics of the medium surrounding the instrument. The instrument has an elongated cylindrical body having a number of difference thermocouples disposed within at various levels. A sectional electrical resistance heating element is located within the elongated body. The heating element heats one junction of each difference thermocouple and by monitoring the increase in temperature signal at different levels within the vessel, the liquid level can be determined. The instrument is also provided with a shield tube that surrounds the instrument forming an annular space therebetween. Liquid coolant enters the tube through a bore having a baffle that strips entering liquid of entrained non-liquid bubbles such as steam and gasses, thereby providing measurement for the actual liquid coolant level and not the expanded coolant level.

Abstract: A hydrogen measuring apparatus comprising two gamma thermometers. Both gamma thermometers are mounted adjacent and parallel to each other. Each is provided with a plurality of annular enclosed spaces formed in an elongated rod. Each annular space is provided with a hot junction of a difference thermocouple. The annular spaces of one of the gamma thermometers is either filled with a gas other than hydrogen, or surrounded by a hydrogen blocking material to prevent hydrogen contamination of the annular spaces. The annular spaces in the other gamma thermometer are placed in a vacuum and become contaminated with hydrogen. By comparing the power generation readings of the two thermometers free hydrogen partial pressure can be calculated.

Abstract: Direct power shape monitoring in parallel with precision power monitoring is effected by use of gamma sensors in the fuel core and signal processing that includes compensation for slow signal response and takes advantage of a substantially direct relationship of sensor signal to linear power generation rate. Continuous readout from the direct power shape monitor is available during readout interruptions in the precision monitor.

Abstract: Zircaloy metal is utilized to form the heat generating core and internal lining of a high strength pressure barrier for a gamma thermometer. The internal lining which is cross-sectionally smaller than the core, forms a hydrogen gas barrier to prevent deterioration of the low thermal conductivity of the thermal resistance region in the thermometer.

Abstract: An electrical heater cable is positioned within an assembly of multiple junction thermocouple cables associated with the elongated gamma heated body of a local power measuring unit to electrically heat the body from an external source during a calibration period. The signal outputs of the thermocouples are measured during the calibration period for steady state analysis of the signal response to changes in heating rate produced either by additional electrical heating, by abrupt termination of electrical heating or by supply of sinusoidally varied heating current to the heater cable.

Abstract: Thermocouple junctions located in the hot and cold regions of an elongated heat conductive body extending through a measurement zone of a power monitoring device, are interconnected in series to provide a differential temperature signal of increased signal strength and fast signal response. The signal is free of the error heretofore arising from asymmetrical axial heat flow through the heat conductive body.

Abstract: The elongated monolithic radiation absorbing body of a gamma ray sensor has its entire external surface exposed to coolant for establishing a uniform heat sink temperature throughout. Cold junction regions are formed in portions of the elongated body of reduced cross-sectional area sufficient to produce measurable signal levels from a differential temperature thermocouple. A removable low melting filler in the reduced cross-sectional portions of the body enable accurate electrical calibration of the sensor.

Abstract: The faster acting junction of a difference junction thermocouple associated with a gamma sensor is located vertically above the other junction to ordinarily monitor local power generation in the fuel core of a nuclear reactor and in response to a reversal in the signal voltage polarity indicate a drop in level of coolant to thereby also function as a coolant monitor. An internal electrical heater enhances the coolant monitoring capability of the sensor, which may also be extended into the dome of the reactor vessel for monitoring conditions therein.

Abstract: Direct power shape monitoring in parallel with precision power monitoring is effected by use of gamma sensors in the fuel core and signal processing that includes compensation for slow signal response and takes advantage of a substantially direct relationship of sensor signal to linear power generation rate. Continous readout from the direct power shape monitor is available during readout interruptions in the precision monitor.

Abstract: A gamma sensor is supported coaxially in a bore, extending through the core of a nuclear reactor, by centering means which span the annular space between the gamma sensor and the bore. Said centering means also acts as a thermal bridge so that the portion of the gamma sensor contacted by the centering means will assume a thermal temperature close to that of the bore. Since poor thermal contact between the gamma sensor and the bore is thereby avoided, the accuracy of sensor readings is improved.

Abstract: A gamma thermometer is supported coaxially in a bore, extending through the core of a nuclear reactor, by spring means which span the annular space between the gamma thermometer and the bore. Said spring means acts, in addition, as a thermal bridge, so that the portion of the gamma thermometer contacted by the spring means will assume a thermal temperature close to that of the bore. Since poor thermal contact between the gamma thermometer and the bore is therefore avoided, the accuracy of readings is improved.

Abstract: A gamma thermometer for use with a nuclear reactor is provided with two thermocouple junctions which are connected so as to output the difference voltage. The two thermocouple junctions are spaced closely enough so that, considering the scale of the nuclear reactor, they experience the same gamma-ray flux. However, the thermal paths to a common heat sink for the two thermocouple junctions are different, so that the junctions exhibit a temperature difference which depends on, and therefore measures, the heating produced by the gamma-ray flux and, thereby, the gamma-ray flux itself. The gamma thermometer is built on a miniature scale, so that it can be traversed through a small, often dry, bore extending through the core of a nuclear reactor. The temperature difference mentioned above will be affected to some extent by the temperature of the common heat sink.