Examination of melted fuel rods and released core material from the first Phebus-FP reactor accident experiment

摘要

In the first Phebus test, 20, one meter long, lightly irradiated UO2 fuel rods and a central Ag-In-Cd control rod were heated by fission power to an estimated 3000 degrees C. In this paper results are reported for the composition of the molten cerium pool in the lower part of the test assembly and deposits of released core material in the vertical line. The examination techniques used comprised optical microscopy, scanning electron microscopy, X-ray microbeam analysis, inductively coupled plasma mass spectroscopy, X-ray diffraction and gamma-spectroscopy. The matrix of the cerium pool was a single phase of composition (U0.50Zr0.47Fe0.02Y0.01)O2 +/- x. Inclusions in the solidified pool were ReIr alloys, W with minor concentrations of Fe and Ni and spinels of Cr, Fe and Ni. The main constituents of the deposit in the vertical line were Re, Ag, In and Sn. Tin formed a thin layer on the steel surface. Droplets of the cerium matrix phase were embedded in the deposit. Traces of Cs-137 were mainly responsible for the gamma-activity of the deposit. (C) 2000 Elsevier Science B.V. All rights reserved. [References: 22]