GB873171A - Production of u - Google Patents

Abstract

873,171. Nuclear reactors. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Nov. 15, 1945 [Nov. 3, 1944], No. 30680/45. Class 39(4). Uranium 233 is produced by subjecting thorium to the action of neutrons the majority of which have an energy of below 1 mev. and by terminating this reaction before the ratio of uranium 233 to thorium is about 1 to 100. Preferably the reaction is terminated when the ratio of uranium 233 plus protoactinium 233 to thorium is between 1 to 1 million and 1 to ten thousand. The thorium is bombarded with 10<SP>15</SP> neutrons per second for a period of at least one month. The neutrons may be obtained from a fast neutron source using . moderator materials containing carbon, deuterium or hydrogen; such as graphite, paraffin, water or heavy water. The reason for terminating the reaction at the specified stage is to prevent excessive wastage of uranium 233 by fission. It is preferred that the thorium should not contain more than sufficient natural uranium to dilute the uranium 233 by more than 20%. The uranium may be extracted by dissolving the thorium compound in nitric or hydrochloric acid, adjusting to pH of about 3 and precipitating both uranium and thorium with an excess of hydrogen peroxide. After removal of the supernatant liquid the precipitate is treated with alkali such as sodium hydroxide and a solution containing the uranium peroxide but not the thorium peroxide results. The uranium may then be separated by acidifying with nitric or hydrochloric acid. The fission products precipitated with the uranium at this stage may be separated by dissolving and precipitating several times. Alternatively the fission products may be removed by crystallizing out uranyl nitrate hexahydrate and dissolving this compound in ether. In an alternative process the thorium is precipitated as a fluoride, iodate, oxylate or phosphate. In the foregoing process the protoactinium is removed with the thorium but it may be separately processed by means of manganese dioxide precipitates dissolved in a mixture of hydrogen peroxide and hydrochloric acid, adding zirconium oxychloride and precipitating the zirconium as zirconium phosphate. Further details of the process are described -in Specification 30681/45.