Abstract: An improved method for determining the nuclear radiation threshold of a non-metallic material with the aid of a computer is disclosed, in which differently irradiated samples of the material are subjected to thermogravimetric analysis. From the resultant pyrolytic weight-loss, temperature and elapsed time data, the reaction rates are determined for different orders of reaction values and are plotted against inverse temperature values to obtain the activation energy corresponding to each sample. By plotting activation energy against radiation dose for each sample, the radiation threshold of the material is obtained.

Abstract: A velocity limiting device providing greater resistance to motion through a fluid in one direction than in the opposite direction. The device includes a toroidally shaped control member having a smooth generally conical surface on one side for low resistance movement through the fluid in the one direction. On its opposite side the control member is formed with at least one groove providing a concave surface spaced from which is an arrangement of vanes forming a jet for directing a stream of fluid into the groove upon movement in the opposite direction whereby the resultant increase in fluid turbulence increases resistance to rapid movement in this opposite direction.

Abstract: A system for determining the radioactive materials content of the ash or residue from an incinerator of contaminated materials contained in cans. The system includes can handling apparatus, a neutron source for activating the material and neutron and gamma ray detectors for detecting emissions from the materials by which fissile/fertile material content is determined.

Abstract: A method and apparatus are disclosed for monitoring the operation of a boiling water nuclear reactor for the occurrence of a superheated condition. The invention provides redundant monitoring of the level of coolant water in the reactor independently of existing water level gauges. A closed system vapor pressure device, located outside the reactor, probes the temperature of the reactor steam. The temperature of the steam determines the internal vapor pressure developed in the device, the latter being directly compared, externally of the reactor, to the steam pressure in the reactor vessel. The differential between the compared pressures is an indication of a superheated reactor condition and, hence, of a low water level in the vessel.

Abstract: Disclosed is apparatus and method which, in cooperation with an electrical system, analyzes signals generated by detectors placed in a flux field of gamma rays and neutrons. A first detector with a first sensor is coupled to the electrical system. A second detector with a second sensor is coupled to the first sensor and the electrical system. A fissile material is housed in the first detector, and is heatable by gamma ray and neutron capture to in turn heat the first sensor, which generates a first signal which is delivered to the electrical system. A non-fissile material is housed in the second detector, and is heatable by gamma ray capture to in turn heat the second sensor, which generates a second signal. The first and second signals are analyzed in the electrical system to determine the power level, neutron flux, and gamma ray flux within the flux field. Also provided is a microtechnology apparatus and method for measuring neutron flux.

Abstract: A radiation dosimeter includes a plurality of air wall type ionization chambers for radiation detection. Each ionization chamber is connected in series with a selectively actuable switching element under the control of a data processor. The ionization chamber switching element pairs are connected in parallel and the entire group is further connected in series with a load resistor and a source of known potential. A voltage threshold detector is connected across the load resistor and is effective to develop a signal proportional to the peak potential appearing across the load resistor when each of the switching elements is actuated to recharge the various ionization chambers. The voltage peak is proportional to the radiation rate. An A/D converter converts the output of the voltage threshold detector into useful data for a data processor which performs the functions of process control and calculation of radiation rate and cumulative dosage.

Abstract: A method for making a nuclear fuel channel is disclosed having a high degree of dimensional accuracy which uses the thermal expansion of a mandrel to precisely size the channel. An assembly of the mandrel and a channel preform is pulled through a die to die sink the preform into substantial surface-to-surface contact with the mandrel prior to the heating step.

Abstract: The present invention described a signal conditioner. A thermocouple produces a signal that is present at a summing node input of a conditioning amplifier. The conditioning amplifier has a plurality of selectable gain values by which amplifier sensitivity may be varied to complement that of the thermocouple. Provision is made at the summing node input of the summing amplifier for thermocouple cold junction compensation and range offset. The present invention finds application in monitoring thermal conditions in an industrial process, such as a nuclear reactor. The high degree of precision and reliability required in such processes is maintained by including a test circuit which provides a selectable test pulse to the summing node input of the conditioning amplifier. One aspect of the present invention is the provision for testing during actual circuit operation in a process and irrespective of selected conditioning amplifier sensitivity.

Abstract: In a fuel assembly for a nuclear reactor a fuel element spacer formed of an array of laterally positioned cojoined tubular ferrules each providing a passage for one of the fuel elements, the elements being laterally supported in the ferrules between slender spring members and laterally oriented rigid stops.

Abstract: A stabilizer and aligning support plate arrangement for a vertically and rotatably positionable undervessel platform in a nuclear reactor including a pressure vessel, said arrangement facilitating mobilization of said platform for servicing operation.

Abstract: A redundant reactivity control system, operating in conjunction with other systems in a nuclear power plant, to mitigate the potential consequences of an anticipated transient without scram event, is described. The invention interfaces to a boiling water nuclear reactor with the reactor's neutron monitoring system, standby liquid control system, control rod drive system, reactor recirculation system, reactor water clean-up feed water control system, and control room and local panels. Two divisionally separated control panels include associated detection and actuation logic and the necessary interface logic to other systems to perform the specific functions in response to an anticipated transient without scram event. Each separate division includes two identical channels. Actuation of any associated reactor system by the invention requires the agreement of the two channels within a division.

Abstract: A method for fabricating a thermocouple unit for service in and about nuclear reactors and other radioactive environments. The method provides a thermocouple encapsulated within a sphere of fissile material.

Abstract: A rhodium self-powered detector, a fission chamber, and appropriate electronic circuitry for combining the output of the self-powered detector and the fission chamber are disclosed in combination wherein the combined output of the self-powered detector and the fission chamber is always proportional to the local reactor power level or neutron flux density in a nuclear reactor.

Abstract: An electronic circuit provides various accurate counts of detected neutrons to enable the assaying of fissile material in a neutron emitting radioactive source. The circuit develops a time correlated window associated with each detected neutron, and delays these windows to develop uncorrelated windows. These windows are used to develop separate detected neutron counts which distinguish between time correlated fission neutron detections and time uncorrelated singular neutron detections. The circuit also develops a count of all detected neutrons.

Abstract: Radiation detectors measuring gamma radiation from radioactive accumulations in an incinerator through low density refractory windows therein for burning combustible, contaminated wastes from nuclear fuel manufacturing activities.

Abstract: There is provided a nuclear fuel element having a zirconium alloy cladding tube with improved corrosion resistance. The cladding tube comprises a metallurgical gradient across the width of the tube wall wherein the tube has a more corrosion-resistant metallurgical condition at the outer circumference and a less corrosion-resistant metallurgical condition at the inner circumference. The metallurgical gradient can be generated by heating an outer circumferential portion of the tube to the high alpha or mixed alpha plus beta range while maintaining the inner surface at a lower temperature, followed by cooling of the tube.

Abstract: A method of replacing a defective circumferential butt joint in a metal pipe is disclosed. An annular metal bridge ring, having a smaller wall thickness than the pipe but the same inside diameter, is positioned coaxial with the pipe in the relatively wide gap created by the removal of the defective joint. The ring becomes an integral part of the weld by being welded in place, thereby partially filling the gap between the edge surfaces of the pipe exposed by the removal of the defective joint. Subsequent layers of fusible material are weld deposited in place on top of the ring until the gap is filled to the exterior pipe surface. Use of the ring in the gap enables replacement of the defective joint with a single weld.

Abstract: An improved method for compression molding of typically brittle ceramic materials comprising uranium dioxide which enhances their compacting and cohering properties in the manufacture of nuclear fuel products. The uranium dioxide is mixed with a fugitive binder comprising a high molecular weight acrylic acid polymer and ammonium bicarbonate. The mixture is then pressed and sintered to expel the binder and to give a fissionable nuclear fuel pellet.

Abstract: A method and system for quality control of nuclear fuel materials, said system including amplifier/integrator circuitry, signal processors, and drift control feedback circuitry. The invention permits the qualitative and quantitative measurement of paramagnetic additives such as gadolinium for example in a paramagnetic base nuclear fuel material including ferromagnetic impurities. Drift problems relating to temperature and other effects are solved electrically and mechanically. Analysis can be conducted irrespective of the form or composition of the nuclear fuel.

Abstract: In a nuclear fuel assembly spacer providing passages for fuel rods or other elongated elements, a spring component of H-shape including a pair of spaced spring members of hairpin-like configuration connected by a retaining strap wherein an arched side of one of the spring members projects into one of the passages and the arched side of the other of the spring members projects into an adjacent one of the passages for resilient engagement with the fuel rods or other elongated elements extending through the passages.