Abstract: A boiler for vaporizing liquid hydrogen fluoride has a heat transfer surface arranged to be covered increasingly by the liquid as the liquid level rises so that the heat supplied to the boiler can be adjusted to maintain a constant level of liquid in the boiler and thereby equate the feed rate of liquid hydrogen fluoride to that vaporized. Thus by metering and controlling the feed rate of the liquid the feed rate of the vapor can be metered and controlled.

Abstract: A pelleting press in which the die has at least a part which is fluid-permeable so that powder in the die can be compressed simultaneously by fluid permeating the die and mechanically from at least one end of the die. It has a particular application in the pelleting of nuclear fuel powders.The die may be of reaction - sintered silicon carbide rendered fluid-permeable by removal of silicon.

Abstract: A method and apparatus for separating particles suspended in a liquid from the liquid. A flow of the liquid is passed through a filter bed of ferromagnetic bodies which acts as a coarse filter to trap the larger particles in the flow. The filter bed is arranged within a truncated cone between the poles of an electromagnet. To cleanse the bed and flush out the trapped particles a wash liquid is passed through the bed and the electromagnet is energized to levitate the bed to thereby allow the wash liquid to remove the particles. The liquid flow from the coarse filter can be passed to a high gradient magnetic separator at which remaining small particles in the flow are filtered magnetically.

Abstract: A spacer grid for fuel assemblies in a water reactor is provided. The grid shell is shaped so that a pressing in Zircaloy can be made. Cross members in a lattice in the shell provide spacing for the fuel pins of the fuel assembly. Each fuel pin has its own cell in the lattice, and at least some of the joints between the members comprise two attachment points spaced along one of the members at a single intersection.

Abstract: A bellows-type valve includes several additional safeguards in the form of back-up seals which are effective to prevent in- or out-leakage should the bellows fail. Some of the seals can be changed while the valve remains closed. There is provision for testing the integrity of the seals while the valve remains operative.

Abstract: A boiler for vaporizing liquid hydrogen fluoride has a heat transfer surface arranged to be covered increasingly by the liquid as the liquid level rises so that the heat supplied to the boiler can be adjusted to maintain a constant level of liquid in the boiler and thereby equate the feed rate of liquid hydrogen fluoride to that vaporized. Thus by metering and controlling the feed rate of the liquid the feed rate of the vapor can be metered and controlled.

Abstract: In the production of nuclear fuel pellets consisting essentially of oxides of uranium, or mixtures of these oxides with oxides of thorium or plutonium, by granulating the oxide powder, pressing the granulated powder into compacts and sintering the compacts, niobium pentoxide is added to the oxide power in sufficient quantity to encourage grain growth in the oxide compact during sintering and the sintering and other process parameters are adjusted so that no impurities are trapped in the sintering pellets which would prevent a high matrix density and grain size being obtained.Adjustment and control of the oxygen potential of the sintering atmosphere is proposed.

Abstract: A shear machine for irradiated nuclear fuel elements has a replaceable shear assembly comprising a fuel element support block, a shear blade support and two clamp members which hold the fuel element to be sheared in contact with the support block. A first clamp member contacts the fuel element remote from the shear blade and a second clamp member contacts the fuel element adjacent the shear blade and is advanced towards the support block during shearing to compensate for any compression of the fuel element caused by the shear blade.

Abstract: During the reprocessing of irradiated nuclear fuel by solvent extraction techniques a primary separation to give a uranium containing product stream and a plutonium containing product stream occurs. The plutonium in the plutonium containing stream is separated from neptunium and uranium by bringing a solution containing plutonium, neptunium and uranium in an organic solvent into contact first with an aqueous solution of a hydroxylamine and/or a hydrazine salt at 30.degree. to 35.degree. C. to preferentially reduce the neptunium and to extract it into the aqueous phase and then bringing the organic solution containing plutonium and uranium into contact with an aqueous phase containing a hydroxylamine and a hydrazine salt at about 50.degree. C. to preferentially reduce the plutonium and to extract it into the aqueous phase leaving the uranium in the organic solvent.

Abstract: In a filter assembly for particle-in-gas filtration, filter units are supported on a horizontal partition in the filtering position and are raised from the partition and moved horizontally to enable the filter units to be replaced. The invention may be used in nuclear installations.

Abstract: A ferrule type nuclear-reactor fuel grid has the two adjacent cells for the respective fuel rods from a single piece of metal strip. A dividing partition between the two cells may be a part of the single piece or a separate piece of strip. In either case the partition carries a resilient member extending into the cell opening to urge a fuel rod inserted therein against fixed stops pressed out of the ferrule wall. By this design a large number of fuel rods may be located in a compact array with a smaller amount of parasitic structural material in the grid.

Abstract: The shutting down of a gas cooled nuclear reactor is effected by causing boron or other neutron poisons to deposit upon and adhere to reactor core surfaces. The introduction of the poison and other necessary substances into the core is achieved by spilling numerous coherent pellets into the core vessel; the pellets containing a substance which changes state at a predetermined temperature resulting in disintegration of the pellets and deposition of their constituents.

Abstract: A device for indicating the direction of rotation of a rotating body forming part of or associated with rotating electrical machine comprises the combination of a probe unit positioned to interrupt magnetic lines of force generated by the electrical machine, a detector for interpreting signals from the probe unit, and an indicator, which can be a center zero current meter or an oscilloscope, for displaying direction of rotation.

Abstract: Low density nuclear fuel pellets are produced by mixing uranium dioxide powder and/or plutonium dioxide powder with ammonium oxalate, forming the mixture into pellets and sintering the pellets.

Abstract: A vessel for receiving material from an area of total containment, such as a glove box, provided with an integral filling tube through which the material is transferred, the filling tube being capable of passing through a sphincter valve and of being constricted to the point of severance to obtain simultaneous sealing at both ends of the disjunction.

Abstract: Sintered nuclear fuel pellets of improved dimensional stability under irradiation are produced by controlling the production of voidage in the pellets during manufacture of the pellets.

Abstract: A nuclear fuel assembly has a plurality nuclear fuel pins which are extremely long and slender thin walled tubes containing heavy nuclear fuel pellets supported in exceedingly close pitch as a cluster. The end support for supporting these pins vertically locates each pin by a spigot and socket connection of special design. By other connection the pin is positioned and retained in the cluster whilst it can execute limited changes in length, and can when necessary be detached from its support by a force which may distort the connection but will not put the integrity of the fuel can as a fuel container at risk.