PHENOMENOLOGICAL BEHAVIOUR OF URANIA STAINLESS STEEL DEBRIS BEDS AT HIGH TEMPERATURE UNDER THERMAL GRADIENTS IN ARGON AND SODIUM ATMOSPHERES
In the Post Accident Heat Removal (PAHR) in-pile experiments which are planned by the in-pile European programme, the simplified systems UO2/Na and UO2/AISI 316 L steel/Na have been taken into account. Under those typical non-equilibrium conditions, chemical and physico-chemical interactions which are not only temperature dependent but also functions of the time and of the thermal gradient, are likely to occur. In order to understand these interactions and the consequent evolution of the thermophysical properties of such debris beds, non isothermal out-of-pile experiments have been performed. Mixed particulate beds of urania particles and stainless steel spheroids were heated under argon and sodium atmospheres at a maximum temperature of 2000circC - 2150circC, under a thermal gradient of 160circ - 180circC/cm, for periods of 6 - 50 hours in steady state conditions. The phenomena which are expected to influence the thermal conductivity of such a mixed bed have been studied by means of optical metallography, scanning electron microscopy and electron microprobe analysis. Namely : item - steel melting, coalescence and migration item - urania-steel wettability changes item - sintering of urania item - change of composition of the urania item - chemical reaction between the urania and some steel components and sodiumpar were related to oxygen potential, temperatures and temperature gradients which were achieved in the system.
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 32511 E
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Record Number: 1989126062700 / Last updated on: 1989-05-01
Available languages: en