[en] The purpose of any technique for solidification of high-level liquid wastes is transformation of a solution of fission products of known type into a solid product which has been studied in the laboratory. The process used must therefore permit fabrication of the desired product. The author discusses the techniques used in the fabrication of: calcinates, glass-metal composites, modified-calcinate-metal composites, and glasses or products of strong glassy phase. (Auth.)

[en] Converting fission product solutions into a solid, vitrified product for safe ultimate storage is the approach pursued by France in the treatment of this type of waste. The continuous vitrification technique developed by the CEA for the conversion of fission product solutions at the same time helps to greatly reduce the volume of such solutions. The equipment used for this purpose, i.e., a rotary calciner for calcination of the solution and a melting furnace for vitrification of the calcination product, is described in the article. The results of experiments conducted on the equipment in a prototype system built at the Marcoule Nuclear Research Center for a total of approximately 7,400 hours are reported and discussed. Also a new vitrification furnace is described which operates by direct induction in the molten glass. Thanks to the satisfactory results achieved with respect to performance and reliability of the equipment, the development of this line has been extended up to the industrial scale. A system employing this principle has been set up on the Marcoule site. (orig./HPH)

[en] Glass shows interesting technical and economical properties for long term storage of solidified radioactive wastes by vitrification or embedding. Glass composition, vitrification processes, stability under irradiation, thermal stability and aqueous corrosion are studied

No abstract available

[en] Research and development carried out in France for a long time about solidification of high level radioactive wastes have been mainly directed toward the glassy state. Investigations about borosilicates lead up to choose glass as a final form for the fission products solutions stored in both reprocessing plants. Works related to various techniques to make use of this type of material started also a long time ago. A two steps continuous process was selected owing to satisfactory results rised from a long term prototype running with respects to the glass manufacturing as well as the remotely handling ability. AVM, the Marcoule Vitrification Plant has been running since 1978. Further Vitrification Plants related to the La Hague reprocessing plant are under design

[en] A brief historical background of the research and development work conducted in France over 25 years is first presented. Then, the papers deals with the vitrification at (1) the UP1 reprocessing plant (Marcoule) and (2) the UP2 and UP3 reprocessing plants (La Hague). 1) The properties of glass required for high-level radioactive waste vitrification are recalled. The vitrification process and facility of Marcoule are presented. (2) The average characteristics (chemical composition, activity) of LWR fission product solution are given. The glass formulations developed to solidify LWR waste solution must meet the same requirements as those used in the UP1 facility at Marcoule. Three important aspects must be considered with respect to the glass fabrication process: corrosiveness of the molten glass with regard to metals, viscosity of the molten glass, and, volatization during glass fabrication. The glass properties required in view of interim storage and long-term disposal are then largely developed. Two identical vitrification facilities are planned for the site: T7, to process the UP2 throughput, and T7 for the UP3 plant. A prototype unit was built and operated at Marcoule

[en] High level radioactive wastes generated by the reprocessing of spent fuels is an important concern in the conditioning of radioactive wastes. This paper deals with the status of the knowledge about glasses used for the treatment of these liquids

No abstract available

[en] To meet waste acceptance specifications, it is necessary to demonstrate that the glass produced at the site is suitable for long-term disposal. The experimental studies carried out in France for such a demonstration have been performed according to the following strategy: (1) selection, definition, and characterization of a reference glass; (2) performance of sensitivity tests to quality a sufficiently broad compositional region that covers all credible compositions to be produced; (3) demonstration that the inevitable process disturbances taking place in the glass-making process can be detected and corrected in time to avoid any additional modification of glass formulations from those obtained in the range tested during the sensitivity test; and (4) implementation of a quality control plan guaranteeing the control of the process parameters under normal and degraded operating conditions

[en] The conversion of high level radioactive liquid wastes into glass is now considered in every nuclear country. The glass composition must take into account the components of the solutions and be formulated in order to meet certain requirements, mainly those necessary for safe further disposal. The compositions of these glasses, all borosilicates, are consequently unusual. Heat due to β γ decay generates some devitrification but it has not yet been demonstrated that this is detrimental. β irradiation has minor effects on the glass structure but the effect of α emitters is not presently totally investigated. If stored energy consequenses are negligible, further experiments must be carried out to ascertain the effect of helium build up or the behaviour of the mechanical properties. Processes of industrial interest have been developped and a plant has already produced radioactive glass blocks for 5 years