Abstract: A system is provided which employs in-core thermocouples for determining the condition of a water cooled nuclear reactor core, especially monitoring the progress of degradation of the nuclear reactor core during various accidents. A water cooled and moderated nuclear reactor core includes tons of zirconium alloy structures. During various accidents these structures become overheated and exothermic chemical reactions between the zirconium alloy structures and the water lead to accelerated destruction of the nuclear reactor core. The very severe accidents at Three Mile Island Unit-2 during April 1979 and the Fukushima units in Japan during March 2011 were unforeseen and instrumentation was not in place to monitor the course of those accidents. Timely data on the initiation and progress of the degradation of a nuclear reactor core is provided with the inventor's apparatus and his methods of using of the apparatus regardless of the path of an accident.

Abstract: An apparatus and method for determining the presence of dissolved gas in a fluid under pressure. A test cell capable of containing the pressurized fluid has a test instrument disposed therein. The test instrument has two platinum leads connected by a sensor element. The platinum leads are connected to an external source of electrical power. A thermocouple is mounted in the test instrument. The apparatus is calibrated using degassed, demineralized fluid at a known pressure by applying power to the platinum leads in a stepwise manner and recording the resistance of the sensor element versus applied power. The test cell is connected to fluid suspected of having gas dissolved therein and power is applied in a stepwise manner to the platinum leads. The power applied versus the resistance of the sensor element is recorded. A comparison between the power versus resistance for the degassed fluid and the suspect fluid discloses the presence of dissolved gas.

Abstract: A device for monitoring the bulk density and/or mass flow rate of a material within a vessel using positron scattering and annihilation radiometry techniques. The positron source is disposed on one side of the vessel having walls while an annihilation region preferably forming a portion of the vessel walls is disposed on the other side of the vessel. A gamma ray detector disposed externally of the vessel and collimated from the positron source detects the absorption of the positrons within the annihilation region. Monitoring the number of positrons absorbed within the annihilation region facilitates estimating bulk density and mass flow rates.

Abstract: The invention disclosed is the method of exact calibration of gamma ray detectors called gamma thermometers prior to acceptance for installation into a nuclear reactor core. This exact calibration increases the accuracy of determining the power distribution in the nuclear reactor core. The calibration by electric resistance heating of the gamma thermometer consists of applying an electric current along the controlled heat path of the gamma thermometer and then measuring the temperature difference along this controlled heat path as a function of the amount of power generated by the electric resistance heating. Then, after the gamma thermometer is installed into the nuclear reactor core and the reactor core is operating at power producing conditions, the gamma ray heating of the detector produces a temperature difference along the controlled heat path.

Abstract: There is disclosed an elongated cylindrical rod of heat-conducting and electrically-conducting material having a central bore containing a plurality of thermocouples, the hot and cold junctions of which are placed respectively in separate zones along the rod. In each zone, the hot junction of one thermocouple is fixed generally in position axially at the midway of an annular reduced-section portion of the cylindrical rod, the cold junction is located generally axially between two reduced-diameter portions and an annular insulating chamber is defined annularly opposite to each reduced-diameter portion by an outer shielding tube. The outer tube surrounds the cylindrical rod. The completed unit is to be placed within a reactor core fuel assembly to be monitored.