A process for concentrating plutonium is given in which plutonium is first precipitated with bismuth phosphate and then, after redissolution, precipitated with a different carrier such as lanthanum fluoride, uranium acetate, bismuth hydroxide, or niobic oxide.

A method is given for precipitating alkali metal plutonium fluorides, such as KPuF₅, KPu₂F₉, NaPuF₅, and RbPuF₅, from an aqueous plutonium(IV) solution by adding hydrogen fluoride and alkali-metal-fluoride.

A process is given for separating from each other uranium, plutonium, and fission products in an aqueous nitric acid solution by the so-called Redox process. The plutonium is first oxidized to the hexavalent state, e.g., with a water-soluble dichromate or sodium bismuthate, preferably together with a holding oxidant such as potassium bromate, potassium permanganate, or an excess of the oxidizing agent. The solution is then contacted with a water-immiscible organic solvent, preferably hexone, whereby uranium and plutonium are extracted while the fission products remain in the aqueous solution. The separated organic phase is then contacted with an aqueous solution of a reducing agent, with or without a holding reductant (e.g., with a ferrous salt plus hydrazine or with ferrous sulfamate), whereby plutonium is reduced to the trivalent state and back-extracted into the aqueous solution. The uranium may finally be back-extracted from the organic solvent (e.g., with a 0.1 N nitric acid).

A process is given for isolating plutonium present in the tetravalent state in an aqueous solution together with fission products. First, the plutonium and fission products are coprecipitated on a bismuth phosphate carrier. The precipitate obtained is dissolved, and the plutonium in the solution is oxidized to the hexavalent state (with ceric nitrate, potassium dichromate, Pb₃O₄, sodium bismuthate and/or potassium dichromate). Thereafter a carrier for fission products is added (bismuth phosphate, lanthanum fluoride, ceric phosphate, bismuth oxalate, thorium iodate, or thorium oxalate), and the fission-product precipitation can be repeated with one other of these carriers. After removal of the fission-product-containing precipitate or precipitates. the plutonium in the supernatant is reduced to the tetravalent state (with sulfur dioxide, hydrogen peroxide, or sodium nitrate), and a carrier for tetravalent plutonium is added (lanthanum fluoride, lanthanum hydroxide, lanthanum phosphate, ceric phosphate, thorium iodate, thorium oxalate, bismuth oxalate, or niobium pentoxide). The plutonium-containing precipitate is then dissolved in a relatively small volume of liquid so as to obtain a concentrated solution. Prior to dissolution, the bismuth phosphate precipitates first formed can be metathesized with a mixture of sodium hydroxide and potassium carbonate and plutonium-containing lanthanum fluorides with alkali-metal hydroxide. In the solutions formed from a plutonium-containing lanthanum fluoride carrier the plutonium can be selectively precipitated with a peroxide after the pH was adjusted preferably to a value of between 1 and 2. Various combinations of second, third, and fourth carriers are discussed.

A process of electrodepositing neptunium from solutions is given which comprises conducting the electrodeposition from an absolute alcohol bath containing a neptunium nitrate and lanthanum nitrate at a potential of approximately 50 volts and a current density of between about 1.8 and 4.7 ma/dm₂.

A method for producing U²³³ is outlined in which a body of thorium carbonate is heated to at least 200 deg C until it attains a constant weight and compressing the body into a pellet having a density of at least 2.6 g/cm³. The pellet is enclosed in a sealed container and placed in the blanket of a thermal nuclear reactor having a neutron flux in which the majority of neutrons have an energy of below I Mev. The pellet is removed from the flux before the ratio of U²³³ to Th²³² is about 1:100.

A nuclear conversion apparatus is described which comprises a body of neutron moderator, tubes extending therethrough, uranium in the tubes, a fluid- circulating system associated with the tubes, a thorium-containing fluid coolant in the system and tubes, and means for withdrawing the fluid from the system and replacing it in the system whereby thorium conversion products may be recovered.

A method is described for preparing neptunium hexafluoride by treating the lower fluorides of neptunium, such as neptunium tetrafluoride and trifluoride, with fluorine at elevated temperatures.

A process is described for extracting Pu⁶⁺ from an aqueous ammonium nitrate-containing nitric acid solution with ethyl sulfide.

A process is described for extracting tetravalent plutonium from an aqueous acid solution with methyl ethyl ketone, methyl isobutyl ketone, or acetophenone and with the extraction of either tetravalent or hexavalent plutonium into menthone.

A process of extracting tetnavalent plutonium from aqueous inonganic acid solutions (acidity between 1 N and pH of 2.5) with 2(beta-ethylbutoxy) ethanol is described.

Processes are described for oxidizing plutonium to the hexavalent state with bromate, permanganate, ceric ions, dichromate, or peroxydisulfate plus silver cations, and for reducing hexavalent plutonium with hydrogen peroxide, ferrous ions, sulfite ions, or sulfur dioxide with or without a complexing agent (fluoride, acetate, oxalate or sulfate). The solutions obtained by these processes are also claimed, as are various plutonium compositions.

A process is described for separating neptunium from plutonium in an aqueous solution containing sulfate ions. The process consists of contacting the solution with an alkali metal bromate, digesting the resulting mixture at 15 to 25 deg C for a period of time not more than that required to oxidize the neptunium, adding lanthanum ions and fluoride ions, and separating the plutonium-containing precipitate thus formed from the supernatant solution.