Abstract: A hermetically sealed connector for a glove box and a method for exchanging such connectors in which leakage of radioactive material from within the glove box is minimized and an auxiliary glove box is not needed to exchange the connectors. The connector is formed as a cylindrical member having a flange portion hermetically sealed to a packing provided in a through hole in the wall of the glove box. To exchange connectors, a nut is removed from the outer end of the old connector and a tube is screwed thereto. The other end of the tube is fitted to the inner end of the new connector. The tube is then shoved through the packing until the flange of the new connector aligns with the packing. The tube is then removed from the inner end of the new connector and a nut is screwed on in replacement for the tube.

Abstract: An end cap with a tag gas capsule adapted to close an end of a cladding tube of a nuclear fuel element and to introduce a tag gas into the fuel element. The end cap is fixed to the tag gas capsule to form a unitary structure. The end cap has a specific shape or description on its outer surface corresponding to information concerning the specific tag gas and the capsule, so that the description or shape of the end cap can identify the specific capsule and the tag gas contained in the capsule.

Abstract: A condenser microphone utilizable at high temperature and intense radioactive rays. The microphone has a tension ring and a backplate, both of which are made of a metal having a small coefficient of linear expansion relative to the other parts of the microphone. The tension ring is fitted to a tension ring holder, and the backplate is mounted on the tension ring holder through an insulating material so that the tension ring and the backplate are held together to form a unitary structure.

Abstract: A system and a method of confirming the operation of a steam relieving safety valve for a water-cooled nuclear reactor are provided. Acoustic vibration generated by steam relieved from the safety valve when the latter is opened is detected by an acoustic emission sensor. The acoustic emission sensor is mounted on the safety valve or a steam relief pipe connected to the safety valve.

Abstract: A process for the treatment of radioactive sodium is provided which comprises the steps of forming radioactive sodium amalgam by mixing radioactive sodium with mercury; reacting the radioactive sodium amalgam with water to form mercury and radioactive sodium hydroxide; recycling the mercury into the step of forming radioactive sodium amalgam to be mixed with the radioactive sodium; and solidifying the radioactive sodium hydroxide in the presence of a solidifying material to be confined in a stable solidified body.

Abstract: A method and apparatus for measuring uranium isotope enrichment in a sample uranium solution. In the invention, the concentration of uranium in the uranium solution is determined by K-edge densitometry. The quantity of uranium-235 in the uranium solution is then measured by detecting the gamma rays emitted from the uranium-235 by using a high-purity germanium detector. A value of the uranium isotope enrichment is obtained from the ratio of the quantity of uranium-235 in the uranium solution to the uranium concentration. The invention is designed to provide the improved construction of a radiation source suitable for the K-edge densitometry and to provide the accurate measurements by correcting any error in the measured quantity of uranium-235 in the uranium solution due to the self-absorption of the gamma rays emitted from the uranium-235.

Abstract: Improvements on a DC plasma jet generator for emission spectrochemical analysis wherein two anode blocks and one cathode block are positioned in an inverted Y shape, and each of the anode blocks has a cylinder, a piston, an an anode received by a recess in the end of the piston. Each anode can be secured in the recess at the end of the piston in the corresponding anode block by magnetic force. Each of the anode and cathode blocks is pivotable so that the associated electrode attached to each block can be fixed upright with the free end thereof directed upward. This means that the electrodes can be replaced easily as well as speedily by remote control using manipulators.

Abstract: An apparatus for melting and treating metal wastes including radioactive wastes, including a melting and treating vessel formed of the upper surface of a truck and split mold, wherein metal wastes are charged into the vessel in a closed system and melted by an electroslag melting method using a non-consumable electrode. This invention also provides a method which includes the steps of charging a slag melt starting agent and slag into the vessel in layers, and passing electricity through the non-consumable electrode to thereby heat the starting agent.

Abstract: A method of minimizing corrosion deterioration and hydrogen absorption embrittlement of tantalum encountered in performing acid digestion of organic waste matter put in an acid digestion kettle of tantalum containing high temperature high concentration sulfuric acid includes the addition of nitric acid, nitrous acid, nitrates, nitrites and/or nitrogen oxides to the sulfuric acid bath.

Abstract: An apparatus for detecting the location of a failed fuel assembly among a number of in-core fuel assemblies, which utilizes a combination of a tag gas system and a selector valve system. The fuel assemblies are divided into a plurality of groups and all the fuel assemblies in the same group are tagged with the same tag gas. Coolants flowing out from the respective fuel assemblies are individually sampled by sampling pipes and led into intermediate mixers wherein the coolants are mixed. The groups of fuel assemblies are mutually connected via the sampling pipes to the intermediate mixers such that each group of fuel assemblies has the sampling pipes extending therefrom and connected to each of the intermediate mixers. The group to which the failed fuel assembly belongs is identified by the tag gas system, and the selector valve system identifies which mixed coolant from the intermediate mixers contains fission products released from the failed fuel assembly.

Abstract: A double-cylinder selector valve for detecting and locating failed nuclear fuel assemblies including a fixed outer cylinder provided on the circumferential wall surface thereof with a plurality of outer sampling holes arranged in a grid in both the longitudinal and circumferential directions, and a movable inner cylinder disposed rotatably within the fixed outer cylinder and provided on the circumferential wall surface thereof with a plurality of inner sampling holes. Each of coolant sampling pipes extending from the coolant outlets of each of a plurality of nuclear fuel assemblies is connected to one of the outer sampling holes. The inner sampling holes communicate with some of the plurality of outer sampling holes in the fixed outer cylinder at one position of the movable inner cylinder and with others of the outer sampling holes at other positions of the movable inner cylinder.

Abstract: Removal of hydrogen impurities from a secondary cooling system of a liquid sodium cooled, fast breeder reactor is accomplished by providing a hydrogen-removing container, which may be a tank, in the secondary cooling system. The container has a sodium coolant inlet and outlet means, a gas phase zone statically containing a cover gas therein, and a cover gas inlet and outlet means. Sodium mist is deposited on the inner surface of the gas phase zone which faces the cover gas and functions as a hydrogen-getter means. Thus, the sodium mist deposit captures and accumulates hydrogen previously accumulated in the cover gas. By intermittently heating the inner surface of the container, the hydrogen captured by the sodium mist deposit is released into the cover gas. The hydrogen-containing cover gas is then discharged from the system and fresh cover gas is contemporaneously introduced and may be obtained by refining the hydrogen-containing cover gas to render it fresh and reusable.

Abstract: A spacer for supporting a plurality of fuel rods forming a nuclear fuel assembly. The spacer comprises a peripheral band surrounding a bundle of the fuel rods and a plurality of spacer framework units, each holding therein one fuel rod. The spacer framework units are welded or brazed to the peripheral band so as to be arranged inside the peripheral band. Spring members are integrally formed on each of the spacer framework units. The spacer framework units, the spring members and the peripheral band are made of a zirconium alloy containing 5-25% by weight niobium and 0.1-1% by weight chromium and/or iron.

Abstract: A heat treating apparatus using microwaves for continuously treating a substance containing nuclear materials with consideration of the criticality safety of the nuclear materials. The apparatus has a stationary outer cylinder and a rotatable inner cylinder to form therebetween an annular passage for the continuous heat treatment of the substance. The outer cylinder has inlet and outlet ports for the material and at least one microwave waveguide. The material supplied into the annular passage is heat treated and transferred to the outlet port during rotation of the inner cylinder.

Abstract: An apparatus for continuously concentrating and denitrating a radioactive nitrate solution by microwave includes a rotatably supported concentrating and denitrating vessel disposed within an oven into which microwave is applied through waveguides. The concentrating and denitrating vessel comprises a circular vessel body supported rotatably about its center and a plurality of partition plates positioned radially inside the vessel body so as to divide the interior of the vessel body into a plurality of compartments. The nitrate solution supplied into the vessel is heated, evaporated, concentrated and denitrated in sequence in each of the compartments during one rotation of the vessel to form a denitrated oxide powder. The denitrated powder produced in one of the compartments is transferred into a receiving pan positioned adjacent to the outer periphery of the vessel.

Abstract: A liquid metal mechanical pump having therein a liquid metal free surface and a cover gas space over the liquid metal free surface and which is equipped with an emergency syphon system. This system has a syphon pipe and a liquid metal dump tank disposed outside the pump. The syphon pipe connects the pump and the dump tank so that the liquid metal in the tank flows out into the dump tank when the free surface of the liquid metal in the pump rises to a predetermined level higher than that of the normal operation of the pump.

Abstract: A method for improving ruthenium decontamination efficiency in a nitric acid recovery system in which a nitric acid solution containing ruthenium is subjected to an evaporation treatment in a nitric acid evaporator. The method is characterized by carrying out the evaporation treatment of the nitric acid solution in the presence of hydrazine in a concentration of 20 to 5000 mg per liter of the solution in the evaporator. By the action of hydrazine, the evaporation of ruthenium contained in the solution is suppressed during the evaporation treatment, and hence the ruthenium decontamination efficiency is remarkably improved.

Abstract: A liquid metal mechanical pump, having therein a liquid metal free surface and a cover gas space over the liquid metal free surface, is equipped with an emergency gas line shut-off system. This system can shut off a cover gas line by the solidification of liquid metal to thereby prevent the leakage of cover gas and the rise of the liquid metal level in the pump at the time of the failure of the cover gas line. The mechanical pump may further be equipped with an emergency syphon system which can discharge liquid metal when the liquid metal level in the pump exceeds a predetermined level.

Abstract: A tagging gas releasing element which is contained in a nuclear fuel rod to release a tagging gas for detecting a failed fuel. The element comprises an inorganic solid material holding the tagging gas therein. The tagging gas is composed of a rare gas, and is held in the inorganic solid material in an injected or adsorbed state.

Abstract: A nuclear reactor in which the space between a reactor vessel and a guard vessel disposed outside the reactor vessel is kept in a pressurized, sealed state. The sealed space and the space outside the guard vessel are communicate only through a liquid manometer structure, which is kept sealed with liquid.