Abstract: An apparatus for ultrasonic testing comprising a pulsed ultrasonic transducer, means for detecting echoes from bubbles in a liquid and means for determining the volume of the bubbles.

Abstract: A nuclear reactor having a core structure comprising a plurality of closely packed parallel fuel element assemblies. Each assembly comprises a cluster of parallel fuel pins enclosed by a tubular casing through which coolant flow is directed. There is provided barrier means extending longitudinally through the cluster to define inner and outer coolant flow ducts each containing fuel pins. Gagging means for the ducts provides that the temperature of the coolant leaving the outer duct is lower than that leaving the inner duct so that the tubular casing is maintained relatively cool thereby to reduce irradiation growth and consequent bowing of the casing. The fuel pins in the outer duct may be of breeder material further to reduce the operating temperature of the casing.

Abstract: A machine for making bags out of thermoplastics material including a rotating drum having pockets, a feed station including means for feeding material into the pockets at a predetermined rate to form loops, the rate of feed being linked to the rotational speed of the drum by a feed-back control means to ensure that the loops are of a predetermined size. The loops are welded and cut by a laser to form bags.

Abstract: An apparatus for purifying exhaust waste gases including a catalytic element comprising a substrate of metal carrying a surface layer compatible with and supporting a coating of catalytic material, a major proportion of the surface coating of catalytic material comprising an unagglomerated atomic dispersion. An example of such a substrate is an aluminum bearing ferritic steel which has been heat treated in air to form an essentially alumina surface layer.

Abstract: A catalyst suitable, for example, for the treatment of car exhaust emissions comprises an unagglomerated atomic dispersion, said coated particles being in association with support material compatible with the coated particles, such that the support material and the coated particles are adhered together.

Abstract: A method of manufacturing a body comprising the steps of forming a single strip of material with at least one plain region and at least one region of protrusions, such as corrugations, bumps or ridges. The single strip of material is then laid on itself in a manner so as to provide two or more layers of the material and locate a plain region of one layer alongside a region of protrusions of an adjacent layer. The laying step may be accomplished by winding the strip into a coil.

Abstract: A shielded electrical cable is described having improved interference immunity and radio frequency screening by virtue of the mode of application of the shield. The shield is insulated from the inner conductor or conductors and comprises a pair of coaxial wire braid layers separated by a continuous metal tube which is flexible and does not bind upon the underlying braid. The tube is peferably formed from mu-metal or other metal tape wound onto the braid in partially overlapping helical turns, the winding tension is insufficient for the overlapping margin to compress the underlying margin of the previous turn, this latter operation being performed in a rotary tubular die whose bore allows for a small annular clearance to be preserved between the wound tape tube and the underlying wire braid.

Abstract: A process for the treatment of irradiated fissile material in solution in nitric acid in which tributylphosphate diluted to less than 7% by volume with an inert diluent is contacted with the nitric acid solution and backwashed with sulphuric acid.

Abstract: A flexible pipe joint comprising a cylindrical tie member for tieing the ends of pipes together and a flexible envelope for fluid flow conduction between the pipes. The tie member comprises a plurality of annular series of parallel tie bars arranged co-axially and there is adjustable mounting means for the tie member in the envelope for enabling the tie member to accommodate misalignment of the pipes on installation. Further misalignment produced by thermal expansion of the pipes is accommodated by the tie member by uniform flexing of the tie bars.

Abstract: A catalyst suitable, for example, for treatment of cat exhaust emissions is prepared by providing a substrate with a continuous adherent, surface layer of a carrier material for catalytic material by providing on the substrate a layer of carrier material, at least part of which comprises a gel, and firing; and sputtering catalytic material onto the surface layer by bombarding a source of the catalytic material in the neighbourhood of the surface layer with energetic ions, the conditions of atmosphere and selectivity of ions permitted to bombard the catalytic material being such that co-deposition upon the surface layer of unwanted material is avoided.

Abstract: An electrically conducting artefact is produced by heating a silicon nitride artefact to a temperature high enough to decompose part of the silicon nitride to silicon but not high enough to evaporate the silicon which is formed, the heating taking place either in an environment which is inert to silicon or in a carbon containing environment which reacts with the silicon formed to give silicon carbide. Such an artefact has electrical conductivity properties which may, for example, be retained after heating at about 600.degree.C in air for several hours.

Abstract: A fast reactor core is submerged in a pool of liquid metal coolant and there is a catchment tray for falling fuel debris disposed beneath the core. The catchment tray comprises a complex of open top collecting vessels arranged on lattice pitches in layers, the lattice pitches of the layers being off-set to provide a complete catchment area.

Abstract: Inner and outer cylinders are mounted for rotation about a common horizontal axis. Powder is fed into one end of the inner cylinder to produce granules by coagulation as the cylinder rotates. The inner cylinder is open at the other end to provide an outlet for the granules, and has a perforated (mesh) wall portion towards its outlet end through which uncoagulated powder falls into the outer cylinder. The diameter of the latter increases towards the inlet end of the inner cylinder so that the uncoagulated powder travels back down the surface of the outer cylinder as it rotates. On reaching the end thereof adjacent the inlet end of the inner cylinder, the powder is lifted by scoops on the inner surface of the outer cylinder to fall into an open-topped duct by which powder is fed into the inner cylinder.

Abstract: Fluid heating arrangements and methods are provided wherein liquid is caused to flow through a fluid permeable electrical resistance heater body. Prior to the heater body, the liquid passes through a fluid permeable flow control member which offers a uniform resistance to the entire flow of the liquid. Static pressure head of the fluid varies over the entry surface of the flow control member, and the permeability of the combination of the heater body and the flow control member are such as to cause a pressure drop in the fluid greater than the variations in static pressure head of the fluid at the entry surface of the flow control member. This promotes a uniform flow of the fluid through the heater body even in the presence of significant differences in static pressure head over the fluid entry surface of the flow control member.

Abstract: Porous material particularly suitable for selective sorption and retention of macromolecules are manufactured by mixing a finely divided inorganic material with a fugitive additive, forming into discrete particles and heat treating to remove fugitive additive. The fugitive additive is a solid which is preferably mixed with the inorganic material after dissolving the additive in a solvent which is not a solvent for the inorganic material.

Abstract: Bearings including a layer of a bearing metal, e.g. a lead/tin alloy, in which continuous or discontinuous carbon fibres are incorporated and are concentrated at or near the bearing surface. The proportion of carbon fibres at or near the bearing surface is from 2 to 60 .sup.v /o.A method of making shell bearings of this type comprises providing a trough of a backing material for the bearing carrying a continuous longitudinal tow of carbon fibres, pouring into the trough a molten bearing metal at a temperature at which it wets the carbon fibres, and cooling and solidifying the bearing metal with the carbon fibres incorporated therein. The carbon fibres may be coated, e.g. with copper, to enable them to be more readily wetted by the molten bearing metal.

Abstract: A sieve unit, particularly for spherical nuclear fuel particles, in which the particles are fed to a bed of spheres disposed in layers on a mesh screen to provide, when efficiently packed, an effective pore path of a diameter not greater than that of the mesh screen and means are provided for vibrating the unit so that the spheres are efficiently packed.

Abstract: In conventional processes for separating metals by selective precipitation, the precipitate is frequently in an amorphous form, eg a slime, which is difficult to filter, wash and handle generally. In the present process mixed solutions and/or sols of the metals are mixed with a suitable soluble organic polymer to form a viscous mixture. The latter is formed into discrete entities, e.g. drops, which are contacted with a reagent which converts each drop to a gelled entity containing at least one of the metals as a precipitate.In one form of the process, the same chemical reagent also serves to dissolve the other metal present in the initial drops. The metals are then easily separated by separating the gelled drops from the reagent. In another form, the reagent includes two different chemical reagents which contact the drop simultaneously, one to precipitate one metal in the gelled drops and the other to dissolve the other metal.

Abstract: A cylindrical pressure vessel is provided with means to prevent dispersal of fragments of the vessel wall in the event of the vessel bursting. The vessel is wrapped in two layers of chains, one, the underlayer, lying circumferentially around the barrel of the vessel, the other extending axially. The ends of the axial chains are connected to domed covers which embrace the ends of the vessel.

Abstract: A nuclear reactor core comprises an array of closely packed components which include fuel elements and may include control rod guide tubes. The components are arranged with their longitudinal axes vertical and in groups. The components of each group are urged laterally into firm engagement with one another by tilting at least some of them towards the centre of the group. The fuel elements of the group have interlocking bearing pads to resist relative lateral movement of fuel elements.