Abstract: Fuel assemblies of a boiling-water nuclear reactor are inverted during refueling methods. Assemblies burned in a first orientation are subjected to greater burnup near their bottoms and greater conversion of fertile fuel to fissile fuel near their tops. Inverting the assemblies promotes burnup of the actinide products from the conversion of the last cycle. Thus, the procedure greater energy production efficiency and reduced actinide radioactive waste are achieved. One inverted fuel assemblies can be removed for disposal. Alternatively, they can be reinverted to burnup actinide fissile fuel generated at the bottom (while it was downstream of the top) during the second operating cycle. Further inversions are provided for, but the major gains occur during the first and second inversions.

Abstract: An excore neutron flux power level detector assembly includes a neutron flux detector subassembly and a moderator subassembly having the form of a dual-wall canister of annular cross-section for receiving the detector subassembly in coaxial and telescoping relationship therein and having moderator material, preferably high density polyethylene, in the annular space between the dual-walls thereof for converting epithermal neutrons in leakage flux from a nuclear reactor to thermal neutrons having a power level detectable by the flux detector subassembly. Insulating spacer elements affixed concentrically about and axially displaced along the surface of the cylindrical housing of the detector provide lateral, structural support and spacing therebetween and electrical insulation of the detector subassembly from the moderator subassembly.

Abstract: A process of separating transuranium actinide values from uranium values present in spent nuclear oxide fuels containing rare earth and noble metal fission products as well as other fission products is disclosed. The oxide fuel is reduced with Ca metal in the presence of Ca chloride and a U-Fe alloy which is liquid at about 800.degree. C. to dissolve uranium metal and the noble metal fission product metals and transuranium actinide metals and rare earth fission product metals leaving Ca chloride having CaO and fission products of alkali metals and the alkali earth metals and iodine dissolved therein. The Ca chloride and CaO and the fission products contained therein are separated from the U-Fe alloy and the metal values dissolved therein.

Abstract: To stabilize boiling water reactors against neutron flux oscillations caused by thermal-hydraulic instabilities, random core-wide reactivity perturbations are induced in the reactor either to suppress the onset of asymmetric (regional) mode oscillations or, in response to the detection of asymmetric mode oscillations, to stabilize the reactor in a symmetric (core-wide) oscillation mode. The reactivity perturbations are produced by effecting random changes in dome pressure, core flow or coolant enthalpy.

Abstract: Bottom end fuel assembly reconstitution is permitted by elimination of weld of Inconel lower grid perimeter strip to stainless steel lower end fitting. Slots in 2 or 3 sides of L.E. Fitting capture ribbed sections of grid perimeter strip, locking screws hold L.E. Fitting in position on guide thimbles. Grids lip on perimeter strip is interlocked by sliding in L.E. Fitting groove.

Abstract: An electrical device is provided for the conversion of molecules of one molecular weight into molecules of another molecular weight. A reaction chamber comprises an array of dynodes, each of which possesses a plurality of apertures. External voltages are available which are applied between dynodes, producing an electric field. During operation, electrons and ions strike the interior surfaces of the dynode apertures, ionizing neutral molecules absorbed on the surfaces, which are desorbed by the energy of the impact, and which are accelerated by the electric field to a new dynode surface location, where they combine with absorbed molecules there to form a variety of new, larger molecules, or different, smaller molecules. Certain ones of the ions created are repetitively moved to one end of the device, where they may be pumped away separately.

Abstract: The transfer cupboard (1) comprises a solid body (2) made of a radiation-absorbing material, in which is provided an axially directed receptacle (3) for receiving the assembly (4). The cupboard (1) comprises at least one circuit (15) for cooling the assembly (4) by gas and integrated in the body (2) of the cupboard (1). The cooling circuit comprises at least one main axially directed gas-circulating channel (16) formed in the body (2) of the cupboard, at least one device (18) for the circulation of gas in the cooling circuit (15), and at least one device (17) for purifying the circulating gas, which are arranged in the vicinity of one end of the main channel (16). Two secondary channels (20, 21) formed in the body (2) of the cupboard make it possible to connect each of the ends of the main channel (16) to a corresponding end of the receptacle (3) for the fuel assembly (4), by which the cooling circuit is closed again.

Abstract: ADU (ammonium diuranate) is prepared in particle form directly by reacting ammonium gas with liquid droplets of atomized uranyl compound solutions. Generation of liquid filtrate is prevented by using concentrated solutions of uranyl compounds as feed solutions, or drying the wet ADU particles formed before their settlement when a feed of low concentration is used. The ADU particle thus prepared is finely divided and easy-handling. No filtration operation is necessary in the preparation. The UO.sub.2 powder consequently obtained after calcining and reduction has consistent quality from batch to batch and has good pelletizing and sintering properties. Uranium dioxide with low fluorine content can be prepared from uranyl fluoride solution. Gadolinium-uranium oxide can also be prepared with the present method using an aqueous mixture of gadolinium nitrate and uranyl nitrate as a feed solution.

Abstract: Fiber-reinforced thermoplastic honeycomb is prepared in a continuous manner one half cell at a time by laying down a corrugated web of thermoplastic, with and without fiber-reinforcement atop a honeycomb, selectively fusing the node-antinode demes and repeating the process until a honeycomb of the desired depth is prepared.

Abstract: A reactivity control system includes a reservoir containing a liquid nuclear poison, at least one stationary, hollow control blade extending vertically into a reactor core, and a poison conduit disposed in flow communication between the reservoir and the control blade for channeling the poison between the reservoir and control blade. The level of the poison in the control blade is controlled for selectively varying nuclear reactivity in the core.

Abstract: A unique resin processing system for providing and removing resin to large demineralizer vessels during chemical decontamination of nuclear reactor primary systems is disclosed. Resin is premeasured in a batching tank for accurate filling of demineralilzer resin bed while minimizing personnel radioactivity exposure. Sluice water transfers spent resin to a storage tank and, thereafter, is recycled for subsequent sluicing operations. Spent resin from the storage tank is periodically delivered to high integrity containers for ultimate disposal.

Abstract: A vessel for solidifying radioactive waste pellets includes a vessel body, an inner lid mounted within the vessel body and fixedly secured to an upper portion of the vessel body, and a device for preventing the pellets from floating fixedly secured one end thereof to the inner lid. The inner lid has an opening formed at a generally central portion thereof, and the pellet float prevention device is extended into the opening of the inner lid to define gaps therebetween allowing the passage of a solidifying material in the state of a liquid or a slurry therethrough but preventing the passage of the radioctive waste pellets therethrough. The pellet prevention device, when receiving a downward urging force, is bent downward to enlarge the gaps therebetween for allowing the radioactive waste pellets to pass therethrough. The pellet float prevention device is returned by a resilient restoring force to its initial position when the downward urging force is released.

Abstract: A strip (16) for an eggcrate-type nuclear fuel assembly grid (10), in which the fuel rod support springs (30,36) are formed by beams (75,77) and a connecting arch (78). More particularly, the strip has a substantially flat body (56), upper and lower edges (84,86) defining the strip vertical height, and opposed side edges (80) defining the length of the body. The fuel rod support structure (30) projects transversely from the body and comprises a plurality of spring members spaced apart in the longitudinal direction along the body, each spring member having a pedestal portion (75,77) resiliently supported by the body and a contact portion (78) integrally formed on and projecting from the pedestal portion. The pedestal portion preferably includes a beam integrally constrained at both ends by the body. By integrally fixing the ends, the spring member can be considerably smaller and produce the same force for a given deflection as a conventional grid.

Abstract: A nuclear reactor includes a pressure vessel enclosing a plenum, a core in the pressure vessel, a pressure-tight encapsulation in the pressure vessel communicating with the plenum, and control members passing through the encapsulation and having first and second control member segments. The second control member segment has an absorber part to be at least partly inserted into and retracted out of the core for controlling reactivity. The first control member segment has an outer drive part. A control drive is associated with the outer drive part for adjusting the control member along the longitudinal direction thereof. An antieject device for restraining ejection of the control member out of the pressure vessel due to a leak at the encapsulation includes a rod coupling having a disengageable coupling catch interconnecting the first and second control member segments and remaining in engagement during normal control motion of the control member and means for unlocking the coupling catch.

Abstract: The invention relates to a composition for the volumetric generation of radiation, wherein a first substance functions as a source of exciting radiation, and a second substance interacts with the exciting radiation to provide a second radiation. The compositions comprise a porous substrate which is loaded with: a source of exciting radiation, a component capable of emitting radiation upon interaction with the exciting radiation, or both. Preferably, the composition is an aerogel substrate loaded with both a source of exciting radiation, such as tritium, and a component capable of interacting with the exciting radiation, e.g., a phosphor, to produce radiation of a second energy.

Abstract: An organometallic chromium compound in the gaseous phase is brought into contact with a substrate consisting of the inner surface of the zirconium alloy tubular cladding (5) of the fuel element, or the outer surface of the pellets of fuel material, the substrate being kept at a temperature between 300.degree. and 600.degree. C. The organo metallic compound may consist of chromium acetylacetonate. The process enables a chromium oxide coating to be obtained inside the tubular cladding (5) and/or on the outer surface of the nuclear fuel pellets. Pellet/cladding interaction is thus prevented or limited when this fuel element is used in the reactor.

Abstract: An air purifying apparatus that has an ozone generator which generates plasma field in the ultraviolet region. It utilizes a pair of electrodes in the form of plates that are separated by an insulator. The plates are connected to a high-voltage transformer through diodes in such a way that only a negative and less positive charges appear on the plates. The generator is provided with a self-cleaning apparatus in which the circulating air fan that is provided for normally forcing air through the electrostatic plates may be turned off for a period of time and the ozone generated by the plates at that point in time will tend to combine with the contaminates and oxidize the same.

Abstract: A thermocouple assembly includes a protective housing, preferably made of glass, a thermocouple suspended in the housing, and a thermally conductive material that fills the space between the inner wall of the housing and the thermocouple. In a preferred embodiment, a compressible ring is used to both confine the thermally conductive material and prevent damage to the thermocouple assembly caused by thermal expansion or contraction.

Abstract: The process of the present invention is for the surface treatment on both sides of a substrate by means of electric corona discharge, while simultaneously treating both surfaces of the substrate with a carrier gas/aerosol mixture introduced into the corona discharge zone. The arrangement for carrying out this process comprises a corona discharge device, consisting of a generator, high voltage electrodes, to which alternating current is applied by the generator, as well as grounded counter electrodes, a device for the atomization of liquid into a suspendable aerosol, which is connected via a transport line for the aerosol to the corona discharge device, and a blower, which is connected to the atomizer device and conveys the carrier gas/aerosol mixture to the corona discharge device. The electrodes and counter electrodes together form a gap for the substrate to be treated.

Abstract: An improved method of disposing of radioactive or hazardous liquid aqueous waste compositions having a substantial amount of dissolved solids comprises mixing the liquid under a high mechanical shear with a clay selected from the group consisting of attapulgite, sepiolite, and mixtures thereof. Water soluble or miscible organic liquids as well as liquid hydrocarbon mixtures thereof may also be solidified by utilizing the aforesaid clays together with an organic ammonium montmorillonite having at least 10 carbon atoms, the amount of montmorillonite used being proportional to the amount of liquid hydrocarbon present.