Abstract: A method of decontaminating radio nuclide-contaminated corrosion products, which are sparingly soluble in acid, from primary system surfaces in reactors of the pressurized water reactor type and the boiler reactor type with hydrogen dosage and similar, by oxidation and concurrent dissolution in an acidic decontamination solution of the acid soluble corrosion products obtained by said oxidation. The characteristic feature of the method is that said oxidation is performed with Ce.sup.4+ ions, ozone and chromic acid in the presence of perhalogen acid, preferably perchloric acid, at a pH below 3.

Abstract: A method for chemical decontamination of the surface of a metal component of a nuclear reactor plant includes treating the surface of the metal component in a single-step method with an aqueous solution that is free of carbonic acid oxalic acid and contains a different carbonic acid.

Abstract: A method of restraining a diffusion of tritium and an apparatus for same are disclosed. The method includes the step of disposing a hydrogen-absorbing metal in a tritium passage in a direction of diffusion of tritium so that the hydrogen-absorbing metal absorbs tritium to be diffused. The apparatus includes a hydrogen-absorbing metal surrounding a device of a fast breeder reactor. The tritium to be diffused can be readily captured. An arrangement of capturing the tritium permeating the device is simplified in the present invention.

Abstract: A nuclear power plant installation comprises a nuclear reactor that is disposed in an underground reactor room and connected to power generating equipment on the ground surface by pipes which pass between the underground reactor room and the ground surface. A plurality of underground cavities are disposed above the underground reactor room, each of said cavities comprising steel bridgework that defines the sides and tops of the cavity and an unreinforced concrete floor which supports a mass of particulate shielding material within the cavity. An explosive charge embedded within each such mass may be detonated in the event of a malfunction of the reactor to fracture the floor structure in the cavity if the floor has not been fractured by the reactor malfunction, thereby to cause tons of mixed sand and boron powder to fall from said cavities into the reactor room and bury the malfunctioning reactor within a few seconds after the explosion.

Abstract: A self-actuating passive pressure relief device for nuclear reactor containments is described. The pressure relief device passively releases gases from within a reactor containment when the containment pressure exceeds a designated threshold pressure. The pressure relief device automatically reseals itself when the containment pressure drops below the threshold pressure. Any containment gases that are vented by the pressure relief device from the containment are scrubbed and cleansed before they are released into the atmosphere. To accomplish this, a sealed fluid chamber is placed in direct communication with the reactor containment for holding a liquid material such as water. A standpipe having its lower end extend into the sealed container and has an opening below the normal operating liquid level within the chamber.

Abstract: A method and apparatus for pressure relief of a nuclear power plant includes the feeding of fluid from an outlet opening of a containment through a filter to a stack. The filter is operated with sliding pressure regulated as a function of the pressure in the containment.

Abstract: Gases and entrained particulate matter are automatically vented from a nuclear containment as pressure approaches a set point of the containment design during a postulated accident scenario. A porous bed filter is submerged in a tank of water, affording a first stage of filtration of the vented gases and entrained particulate matter passing in an upward flow from the bottom of the tank through the porous filter bed and a second, pool scrubbing stage as the flow proceeds upwardly through a central region of the water above the filter with accompanying decay heat removal prior to release of the gases from the water surface and discharge to atmosphere. The water returns through a down-flow path defined by an annular boundary region surrounding the central region of the water volume, in a pumping function for repeating the mixing and two-stage flow, and purges the porous filter bed.

Abstract: A process for removing radioactive species such as technetium from surfaces of components such as those formed from aluminum, and a process of treating the resulting effluents. For example, technetium trapped under an oxide layer present on an aluminum component is removed by removing the oxide layer with sulphuric acid, and treating the exposed technetium with a complexing agent such as citrate in the presence of an oxidizing agent. An oxide scavenger may be added to prevent reformation of the oxide layer. Actinides can be removed from the effluent by use of a chelating ion exchange material, and technetium by oxidation and use of a basic ion exchange material.

Abstract: Apparatus for the controlled venting of gases from the containment housing of a chemical or nuclear reactor. The vent path is configured as a manometer filled with a low melting point metal. Gases passing through the manometer are exhausted to a tank of scrubbing solution where toxic materials are removed prior to venting the gases from the containment housing.

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: Disclosed is a method of decontaminating metal surfaces contaminated with a radioactive deposit by passing over the coating an aqueous solution of a water soluble condensation reaction product of (1) a hydrazine compound having the general formula ##STR1## where each R group is independently selected from hydrogen and alkyl to C.sub.4 and (2) a water soluble aliphatic polycarboxylic acid. The method includes the additional last steps of passing an aqueous oxidizing solution over the deposit followed by passing a decontamination solution over the deposit a second time. The solution is circulated through a cationic exchange column which can be preloaded with hydrazine ion. The decontamination solution can be decomposed by the addition of an oxidant to form nitrogen, carbon dioxide, and water.

Abstract: A process for the controlled discharge from a reactor containment structure of a gas cooled nuclear power plant and the installation for achieving this process include parallel discharge circuits from a reactor containment structure to a discharge stack. The flow of discharge from the reactor containment structure normally flows in a primary discharge circuit and may be directed wholly or partially to the parallel secondary discharge circuit. The secondary discharge circuit contains means for reduction of the temperature of the discharge, means for deposition of particulate fission products and they also contain means for recombination of combustible gases and means for filtration of the discharge. Nuclear power plant installations and processes for controlling the discharge from a reactor containment structure in this fashion permit safe discharge of naturally occurring leakage for gas cooled nuclear reactors, as well as leakage occurring in the event of reactor failure.

Abstract: Structures are constructed and arranged on a camp site to provide shelter to evacuees seeking survival, as a GROUP, in case of a nuclear attack on or near their city. The construction, disposition, arrangement and shapes of the structures are such that people inside these structures are not affected by the blast of the nuclear explosion, for peak overpressure levels well above those which conventional structures cannot survive. The structures and the camp site are equipped to provide the elimination of fallout dust in a short time so as to bring the total exposure of the evacuees to radioactivity levels low enough to be safe, until the radioactivity within miles has decayed down to levels acceptable for long time exposure. The sheltering structures are interlinked to provide a quasi normal indoor way of life during the period of necessary confinement of the evacuees, so that no evacuee feels the urge to leave the protection provided within the compound against the surrounding grounds radioactivity.

Abstract: A nuclear reactor, particularly a light water reactor or a helium-cooled high-temperature reactor, is provided with a pressure relief system for relieving pressure resulting under fault conditions from coolant in the reactor pressure vessel and/or the protective vessel of the reactor, wherein the coolant is conducted from the vessel or vessels to a pressure relief station downstream thereof. At the pressure relief station the coolant is fed into a liquid reservoir 4 from which the coolant in gaseous or vapor form is fed sequentially through a washing cyclone 13 and a drying cyclone 25. Most of the radioactive fission products carried by the coolant will have been removed by the liquid reservoir 4 and the washing cyclone 13, and the coolant leaving the cyclone 25 may be safely discharged to atmosphere. Both the liquid reservoir 4 and the washing cyclone 13 are provided with cooling circuits 8 to 12 and 14 to 23 respectively for the liquids.

Abstract: Disclosed is a method of decontaminating the metal surfaces in the cooling system of a nuclear reactor by contacting the metal surfaces with an aqueous solution containing about 0.5 to about 3% of a ceric acid which can be tetrasulfato ceric acid, hexasulfamato ceric acid, hexaperchlorato ceric acid, or mixtures thereof, and about 1 to about 5% of an inorganic acid that forms a complex with the ceric acid.The cerium III in the aqueous solution can be oxidized to cerium IV to increase the life and effectiveness of the solution. After oxidation, the aqueous solution can be passed through a hydrogen form cation exchange column to remove metal ions. If the aqueous solution contains uranyl or plutonyl ions these can be recovered by extraction for use in making fuel.Also disclosed is a decontaminating solution of water containing about 0.

Abstract: A passive method of adjusting the pH of the liquid used to flood the containment structure of a nuclear reactor following an accident such as loss of primary or secondary coolant. Perforated containers or baskets, which contain a pH adjusting chemical which is soluble in the flooding liquid (usually a slightly acidic solution of borated water) and which are covered or encapsulated with a plastic protective material, which is like soluble in the flooding liquid, are located in the emergency containment sumps.

Abstract: The invention is directed to a method of performing remotely-manipulated ntenance work on upwardly extending conduits in a radioactively-ladened cell such as a large-area cell of a nuclear facility for reprocessing irradiated nuclear fuel. A conduit segment is sawn out of a vertical conduit and a new conduit segment welded into place. The removal of cutting chips from the lower vertical end portion of the conduit after the conduit segment has been sawn out is achieved by freezing the liquid medium in the conduit to form frost plugs above and below the tube portion to be removed. A third frost plug is formed in the lower portion of the vertical conduit above the frost plug which has already been produced therein. Thereafter, the tube portion to be removed is cut and separated from the conduit. Then an anchor member is lowered into the lower end portion of the conduit onto the third frost plug.

Abstract: There is disclosed in the present application, a decontamination system for reactor vessels. The system is operatable without entry by personnel into the contaminated vessel before the decontamination operation is carried out and comprises an assembly which is introduced into the vertical cylindrical vessel of the typical boiling water reactor through the open top. The assembly includes a circular track which is centered by guideways permanently installed in the reactor vessel and the track guides opposed pairs of nozzles through which water under very high pressure is directed at the wall for progressively cutting and sweeping a tenacious radioactive coating as the nozzles are driven around the track in close proximity to the vessel wall. The whole assembly is hoisted to a level above the top of the vessel by a crane, outboard slides on the assembly brought into engagement with the permanent guideways and the assembly progressively lowered in the vessel as the decontamination operation progresses.

Abstract: Apparatus is disclosed for decontaminating a nuclear reactor pressure vessel. It comprises a buoyant annular frame which descends into the vessel as the water level within it is lowered. Spray nozzles move around the frame on trolleys in a reciprocating fashion and spray water under high pressure on the inner surface of the vessel wall, resulting in automatic washdown of the reactor vessel.