Abstract: Radioactive waste water containing boric acid is concentrated in an evaporator to which an alkali is added to maintain a substantially neutral pH. The boric acid is sedimented out by cooling the solution and an acid is added to the latter to increase the solids recovery by lowering the pH. The solid sediment is vacuum distilled to yield a moist powder.

Abstract: A method of and an apparatus for the treatment of radioactive waste water from a nuclear electricity-generating power plant. The radioactive waste water containing soluble solids, usually boric acid, is concentrated by evaporation according to the invention to a solids concentration above that which will form a saturated solution at room temperature, whereupon the resulting concentrate is introduced into a storage vessel and cooled therein to room temperature. Solids precipitate and sediment in this vessel and water is decanted from the sediment and recycled to the evaporator where the process is repeated. The process allows the amount of waste in terms of the original material treated which must be stored for a given prolonged period, say between one half and three quarters of a year, for radioactive decay prior to packaging of the waste to be significantly reduced by comparison with earlier systems.

Abstract: A waste-water concentrate containing boric acid together with chemical residues and radionuclides, especially from a nuclear power plant, is treated to recovering boric acid which can be recycled to the plant. According to the invention, the practically neutral solution is acidified with an acid selected from the group which consists of sulfuric acid, hydrochloric acid, nitric acid and acetic acid to precipitate the boric acid which is separated from the concentrate and subjected to at least one recrystallization step. The boric acid thus obtained is of comparatively high purity.

Abstract: Nuclear fuel elements or slugs are removed from the nuclear reactor cores and subjected to inspection, according to the invention, by introducing a plurality of such elements into a submerged inspection vessel which is then closed, the liquid driven out by compressed air and deionized water (deionate) circulated through the inspection vessel at a constant rate. A portion of the deionized water is branched from the circulating stream at a constant rate and the activity of at least one fission-product nuclide is determined continuously to plot the activity versus temperature, thereby signaling a possible defect in the shell of a fuel element. In addition, ultrasonic vibration is applied in the inspection vessel to the fuel elements so that deposits on the exterior thereof are released into the deionate whose circulating path includes a filter and an ion-exchange column for removal of such deposits.