Community Research and Development Information Service - CORDIS

Abstract

Gegenstand der vorliegenden Arbeit sind Untersuchungen zur Herstellung und Charakterisierung von keramischen Produkten mit echten TRU-elementhaltigen Rueckstaenden sowie die Erstellung des technischen Konzeptes fuer eine inaktive Pilotanlage, deren Montage im Anschluss daran durchgefuehrt werden soll. Das Verfahren eignet sich fuer die Verfestigung der meisten in der Kerntechnik anfallenden anorganischen Abfaelle und insbesondere fuer folgende TRU-Abfaelle: item - Aufloeserrueckstaende (Klaerschlamm der Brennstoffloesung von Wiederaufarbeitungsanlagen fuer bestrahlte Kernbrennstoffe); item - MAW-Faellschlamm (Faellschlamm aus der Auftrennung von mittelaktiven Abfall-loesungen); item - Alphakonzentrate (aus fluessingen Abfaellen der Fertigung von MOX-Brennelementen); item - Rueckstaende aus der trockenen und nassen Verbrennung von TRU-Abfaellen.par Die Abfaelle enthalten je nach Abfallart neben Aktiniden gegebenenfalls Spaltprodukte (Zirconium, Ruthenium, Molybdaen usw.) und Prozess chemikalien (Sulfate, Phosphate, Fluoride). ti The consolidation of alpha-containing residue in a ceramic matrix ab This report covers the research work concerning the embedding of TRU-waste in a sintered alumosilicate based ceramic matrix carried out from 1983-1985. The aim of this work was to complete the experimental demonstration on the feasibility of incorporating original TRU-waste in a ceramic matrix as well as the prosecution of the evaluation of a technical process producing TRU-waste bearing ceramic pellets. The following kinds of original TRU-waste had been incorporated in ceramics: item - dissolver residues from the reprocessing of fast breeder reactor fuel elements (KNK II at KfK), item - residues from the acid digestion of burnable TRU- wastes produced in the ALONA-facility/Mol, Belgium, item - TRU-element bearing sludges, precipitated from original MAW-solutions, according to the waste splitting method.par The final products were characterized by determinating their destiny, open porosity, mechanical strength, homogeneity, phase composition, microstructure as well as leachability. No deterioration with regard to the product-properties required for the final disposal of radioactive waste could be detected by investigating these TRU-waste ceramic pellets. According to the requirements of a technical process it was necessary to find out the dependence of the product quality from producing parameters. Therefore the most convenient composition of the matrix raw material had been determined with 66 wt% reactive corundum, 17 wt% kaolinite, 17 wt% bentonite. The optimum predensification of the ceramic green ware is 35 pm 5 bars. The minimum time needed for drying the green pellets had been found to be ten minutes using 260circC as drying temperature and 10 mm as the diameter of the pellets. During the heat treatment of the green pellets 10-15 minutes of holding time at maximum temperature (1320 pm 70circC) will be sufficient. Using simulated dissolver residues it was possible to increase the waste loading degree from 20 to 40 wt% without a significant decreasing of the product properties. The evaluation of a technical process for the production of TRU-waste bearing ceramics had been prosecuted by investigations with emphasis to the suitability of the components foreseen (possibility of adaptation for remote operation). Therefore a self- cleaning twin-screw-extruder was selected for the process steps mixing'', homogenization'' and forming''. Objectives of further work were the evaluation of the process steps, dosage of feed and raw materials'', drying'' and sintering''.

Additional information

Authors: LOIDA A, INSTITUT FUER NUKLEARE ENTSORGUNGSTECHNIK, KERNFORSCHUNGSZENTRUM KARLSRUHE (GERMANY);SCHUBERT G INSTITUT FUER NUKLEARE ENTSORGUNGSTECHNIK, KERNFORSCHUNGSZENTRUM KARLSRUHE (GERMANY), INSTITUT FUER NUKLEARE ENTSORGUNGSTECHNIK, KERNFORSCHUNGSZENTRUM KARLSRUHE (GERMANY)
Bibliographic Reference: EUR 11030 DE (1988) FS, 147 PP., ECU 11-25, AVAILABILITY: EUROFFICE, LUXEMBOURG, POB 1003
Availability: Can be ordered online
Record Number: 1989126106100 / Last updated on: 1989-06-01
Category: PUBLICATION
Available languages: de