Patent Number: 039705170
Section: summary

BACKGROUND OF THE INVENTION The invention relates to a process of safely compacting a radio-active material into a solid body, said material being presented in a container which is enclosed in a vacuum chamber beforehand, as disclosed in applicant's co-pending U.S. application, having Ser. No. 370,513, filed June 15, 1973. It is known that the temperature of radio-active materials, emitting radiation energy, increases and that consequently they can be used as isotopic heat sources. Such an isotope is separated, as a rule, from fission products by means of chemical separation processes. The isotope to be separated is then bonded in a specific chemical compound, permitting the practical application of the radio-active isotope. As a rule the final product of the chemical separation processes applied, will be a product of average density, which however, is lower than the theoretical density of the chemical compound. Beginning with a radio-active material in the form of a granulated or pulverous chemical mass, such mass will be densified for practical purposes to the highest possible degree, by cold and/or hot compacting, and as the case may be, by a subsequent sintering process into bodies which can be easily handled and displaced. It is a well-known fact that the energy-output per unit of volume is in proportion to the number of radio-active atoms per unit of volume. Consequently, in order to realize optimum energy-output, the density of the solid body should approximate as closely as possible, the theoretical density of the selected chemical compound. SUMMARY OF THE INVENTION The present improvement provides a process, by which the aforementioned aim can be realized in a safe and economically advantageous manner. For this purpose and as described in the above-mentioned co-pending application within "hot cell", the evacuated compressible container is placed within a second safety-container, whereafter the entire arrangement of containers is compacted. Due to such process the density of the radio-active granulated or pulverous mass will be increased to a density, amounting to more than 95% of the chemical compound's theoretical density. According to the improvement, the second container constitutes a safety-buffer-element, preventing the spreading of the radio-active material during compacting. It is advantageous to fill up the second container with a high-pressure transmitting medium, preferably composed of a liquid metal; satisfactory results were obtained with liquid lead. It is also preferably to carry out the compacting of the container-arrangement under a pressure of at least 1000 bar and at a temperature above 1200.degree.C for certain period of time.