Abstract: A method for replacing a cesium trap includes freezing the cesium trap which partially contains cesium and is located within a shielded cell and. The cesium trap is then decoupled and removed from the shielded cell. A second cesium trap is inserted into the shielded cell and attached to the shielded cell.

Abstract: The present invention provides an efficient and low cost method for processing radioactively-contaminated water. The method for processing radioactively-contaminated water comprising a freeze concentration step of generating ice having lowered concentration of radioactive substance from radioactive substance containing contaminated water and concentrating the radioactive substances in the residual contaminated water by the interface progressive freeze concentration process. Preferably, the method further comprises a nitrogen substitution step of reducing dissolved oxygen in the contaminated water and adding nitrogen gas to the contaminated water, as a previous step of the freeze concentration step. Preferably, the radioactive substance is radioactive cesium.

Abstract: A radioactive debris trap to be installed in a steam generator for removing debris in the primary flow of a nuclear power plant's primary heat transport system. The debris trap includes an outer cylinder and a coaxial inner cylinder both having a top end and a bottom end. A top plate connects the top ends of the outer and inner cylinders. A bottom plate which encloses the trap is connected to the bottom end of the outer cylinder. There is a gap between the bottom end of the inner cylinder and the bottom plate through which primary flow enters a settling chamber located in an annular gap between the outer and inner cylinders. Several small holes are located at the top end of the outer cylinder through which liquid exits the debris trap. A means for fixedly connecting the debris trap to the steam generator is provided on the outer surface of the outer cylinder. Also included is a means for removing the radioactive debris trap from the steam generator without exposing personnel to excessive radiation.

Abstract: A radioactive debris trap to be installed in a steam generator for removing debris in the primary flow of a nuclear power plant's primary heat transport system. The debris trap includes an outer cylinder and a coaxial inner cylinder both having a top end and a bottom end. A top plate connects the top ends of the outer and inner cylinders. A bottom plate which encloses the trap is connected to the bottom end of the outer cylinder. There is a gap between the bottom end of the inner cylinder and the bottom plate through which primary flow enters a settling chamber located in an annular gap between the outer and inner cylinders. Several small holes are located at the top end of the outer cylinder through which liquid exits the debris trap. A means for fixedly connecting the debris trap to the steam generator is provided on the outer surface of the outer cylinder. Also included is a means for removing the radioactive debris trap from the steam generator without exposing personnel to excessive radiation.

Abstract: This invention relates to a nuclear plant having a reactor vessel and a fluid circuit including flow path defining means, defining a flow path for circulating a reactor coolant fluid from and to the reactor vessel. The nuclear plant includes a particle collection zone defined along at least part of the length of the flow path, and particle deflection means arranged in particle deflecting relationship with the flow path to deflect particles from a fluid stream in the flow path into or toward the particle collection zone.

Abstract: A process for the treatment of radioactive graphite which includes the following steps: (i) reacting the radioactive graphite at a temperature in the range of from 250° C. to 900° C. with superheated steam or gases containing water vapor to form hydrogen and carbon monoxide; (ii) reacting the hydrogen and carbon monoxide from step (i) to form water and carbon dioxide; and (iii) reacting the carbon dioxide of step (ii) with metal oxides to for carbonate salts. The process enables radioactive graphite, such as graphite moderator, to be treated either in-situ or externally of a decommissioned nuclear reactor.

Abstract: A method for purifying liquid metal heat exchange fluids uses a contacting drum in combination with purifiers to control metal hydride precipitation in a process with high hydrogen permeation. The contacting drum receives a slip stream of a circulating liquid metal stream and removes hydrogen from dissolved hydride by providing a high interfacial surface area and sufficient temperature for hydride decomposition under vacuum conditions. The liquid metal with a reduced hydride level may be returned to the circulating heat exchange stream or undergo further purification by hydride precipitation and filtration in a cold trap. The drum may be integrated with the cold traps to decompose re-dissolved hydride from a regenerant stream that dissolves precipitated hydride from the cold traps.

Abstract: A method for removing oxides from a liquid metal heat exchange fluid following the initial startup of the heat exchange system fixes oxygen by locating an oxygen scavenging material in a drain tank. During initial fabrication and periods of maintenance metal surfaces of the conduits, heat exchange elements and other equipment become coated with an oxide layer. This invention eliminates the need for the sacrificial traps in the circulating system that are used to remove this initial oxide loading by placing an oxygen scavenging material in the drain tank. The drain tank is ordinarily provided to retain the inventory of liquid metal when it is not circulating in the heat exchange volume. A simple drain down of the liquid metal inventory can thereby remove from the liquid metal inventory essentially all of the oxide impurities that usually accompany an initial startup of such a system.

Abstract: A supercritical water oxidation reactor includes a vessel with an interior urface, two cooling sections, a heat exchanger, an oxygenating section, a pump, and a trap. The interior surface of the vessel has a corrosion-resistant, artificial ceramic or diamond-like coating. The artificial diamond coating is thin and crystal-like in structure. The heat exchanger is located between the two cooling sections. The heat exchanger and the two cooling sections surround the exterior of the vessel. The oxygenating section comprises a porous cylindrical baffle positioned within the vessel. The porous baffle transfers oxygen, hydrogen peroxide, or other oxygenating substances to an aqueous hazardous waste introduced into the reactor.In accordance with another aspect of the invention, the oxygenating section includes a shaft having a helical extension. The shaft has a corrosion-resistant, artificial diamond or diamond-like coating on its outer surface.

Abstract: In a liquid-metal cooled nuclear reactor using liquid metal as a coolant and having vessels and pipings for accommodating the liquid metal coolant, at least pat of the region surrounding a coolant pressure boundary defined at outer wall surfaces of the vessels and piping is occupied by a mass of a solidified liquid metal. The solid mass (e.g. sodium) actually forms the coolant pressure boundary so that it is not so necessary to ensure the soundness of the steel walls of the vessels and pipings which accommodate the liquid metal coolant.

Abstract: Installation and method to regenerate cold traps loaded with the hydride and oxide of a metal, such as sodium, in its liquid state. A forced circulation of the orginal liquid metal of a tank (11) is created at a temperature sufficient to dissolve the solid deposits. The hydrogen and tritium ions are filtered and end up at a storage tank (42) where they are fixed, whereas the oxygen ions recombine so as to form a new oxide deposit in another trap (23) cooled to a temperature enabling only the oxide to be deposited. An application is for fast neutron nuclear reactors and fusion reactors.

Abstract: A primary coolant circuit for cooling a nuclear reactor has wetted mechanically stressed nickel base alloy components such as Alloy 600 tubes in steam generators having oxidized surfaces comprising 1-10 w/o zinc, which tubes are inhibited against primary water stress corrosion cracking. The crack initiation times may be delayed by a factor of two in pressurized water nuclear reactors.

Abstract: The coolant is circulated thorugh the core of the reactor by a pump between a higher-pressure plenum and a lower-pressure plenum. The impurities are removed by a cold trap between the higher-pressure plenum and the lower-pressure plenum. The trap is an integrated unit including an inner tube and an outer tube defining between them an annulus which contains packing. The outer surface of the outer tube is cooled to a temperature such that the impurities are precipitated from the coolant. Since the packing is coldest on the outside, the precipitation progresses axially upstream to downstream and radially inwardly. The precipitation in the outer part of the annulus insulates the inner part of the annulus thermally so that the reduction of the temperature of the coolant to saturation level in the inner part is delayed precluding premature blocking of the cold trap. The cooled coolant in the annulus also precools the coolant flowing in through the inner tube.

Abstract: It comprises an enclosure (1), a supply pipe (8) for introducing the liquid metal to be purified into enclosure (1), a distributor (10) for distributing the liquid metal on the periphery of the enclosure, cooling means (30, 32, 34) positioned externally of the enclosure (1) and downstream of distributor (10) for producing a cooling zone (28) for the liquid metal to purified, at least one oxide retention element (58), a discharge pipe (22) for discharging the purified liquid metal, structures (44) for the attachment of the hydrides located within the enclosure (1) and level with the external cooling means (30, 32, 34).

Abstract: Cold trap for the purification of liquid metals containing dissolved impurities comprises several independently operating cooling modules, so as to bring about the crystallization of impurities, a liquid metal supply pipe, a purified liquid metal discharge pipe and a series of filter assemblies arranged in a staggared manner and on which the impurities crystallize. The cold trap is particularly suitable for the purification of the molten sodium used in nuclear power stations.

Abstract: A getter trap to remove hydrogen and oxygen from a liquid metal, such as liquid sodium, includes an elongated, closed housing having an inlet at one end thereof and an outlet at the other end. A getter material is randomly diposed within the housing comprising a zirconium-containing substrate of hollow, tubular sections having a coating thereon of a gettering alloy of zirconium, vanadium and iron. As a liquid metal flows through the inlet into the housing and through the getter material, and is discharged from the housing through the outlet, hydrogen and oxygen impurities are removed from the liquid metal. The getter trap is particularly useful in an improved liquid metal cooled nuclear reactor system.

Abstract: To separate tritium from gases and/or vapors escaping accidentally from a clear reactor, before the gases or vapor are discharged into the atmosphere, the gases or vapor are fed through a line 5 into a reservoir 3 of deionized light water which is maintained at its boiling point in a heat insulated vessel 1. The tritium is accumulated in the water in the reservoir 3 and any tritium which passes from the reservoir 3 in light water steam is condensed by surface condensors 8 in a steam dome 9. Any possible residue of tritium in the steam leaving through an outlet 10 at the top of the dome 9 is separated out in the form of droplets by a drier cyclone connected directly downstream of the outlet 10.

Abstract: Device for purifying liquid metal coolant for a fast neutron nuclear reactor, comprising a pump (6) for circulating the liquid metal, the metal then being purified and heated after purification, as well as a filter (24) of metallic fibers. It consists of an assembly of annular chambers with a vertical axis, closed at their lower part by a base plate (10) and defined and separated from each other by an assembly of coaxial cylindrical metallic shells. The device comprises, from the exterior inwards, a degassing chamber (12), a chamber enclosing an economizer-exchanger (14, 16), a thermal insulation wall (18), a cooling chamber (20) and a purifying chamber (22) in the central part of which is a filter cartridge (24). In the central part of the cartridge (24) is a channel (25) for collecting the purified liquid metal in communication with a basin (44) for collecting the purified liquid metal rising above the device.

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: An apparatus for removing a radioactive substance from a molten metal which comprises a cold trap for crystallizing an impurity out of the molten metal; a radioactive substance-adsorbing unit which communicates with the cold trap and in which a radioactive substance-adsorbing material is filled with a specific surface area of at least 10 cm.sup.2 /cm.sup.3 to eliminate a radioactive substance from the impurity; means for heating the molten metal conducted from the cold trap to the radioactive substance-adsorbing unit; and means for controlling the temperature of the heating means by measuring the temperature of the cold trap and radioactive substance-adsorbing unit.

Abstract: Method for removal of radioactive cesium from a hot vapor, such as high temperature steam, including the steps of passing input hot vapor containing radioactive cesium into a bed of silicate glass particles and chemically incorporating radioactive cesium in the silicate glass particles at a temperature of at least about 700.degree. F.