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Abstract

Under non-isothermal conditions as those which are obtained in out-of-pile and in-pile experiments, the consequent non-equilibrium states imply, in particular, transport phenomena from the hottest zones to the colder parts. The same mixtures of urania and steel particles which were used for crucible qualification studies have been employed to investigate the redistribution of the elements and the interactions between the urania and the steel under the thermal gradient. To this end, the mixed beds were heated in vacuum at a maximum temperature of 2000circC (bottom of the mixed bed), in a thermal gradient of sim 160circC/cm, for steady-state- periods of one hour and 24 hours. The main results of the post-test analysis can be summarized as follows: item - the oxygen redistributes in the urania, with the consequent formation of hypostoichiometric urania (UO"2-x") and metallic uranium in the hottest zones. The metallic uranium is extracted by the molten steel, which solidifies upon cooling in form of a uranium-rich phase. In the coldest parts on the other hand, hyperstoichiometric urania (UO"2+x") are formed. item - The metallic elements of the steel also redistribute by fractional evaporation of the most volatile elements Si, Mn and Cr, which are found to be enriched in the coldest parts.par

Additional information

Authors: CAMBINI M, JRC-ISPRA;TOCI T, JRC-ISPRA;BOTTELIER P, JRC-ISPRA;BUSCAGLIA G JRC-ISPRA, JRC-ISPRA
Bibliographic Reference: CONFERENCE ON THE SCIENCE AND TECHNOLOGY OF FAST REACTOR SAFETY, GUERNSEY, CHANNEL ISLANDS/UK, MAY 12-16, 1986, AVAILABILITY: CEC-LUXEMBOURG, DG XIII/A2, BP 1907, MENTIONING PAPER ORA 32513 E
Availability: Can be ordered online
Record Number: 1989126069800 / Last updated on: 1989-05-01
Category: PUBLICATION
Available languages: en