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Fission product and Actinide release from the Debris bed test Phebus FPT4: synthesis of the Post Test Analyses and of the Revaporisation testing of the Plenum samples

ICAPP05, Séoul, COREE, 15-19 May 05

P.D.W. Bottomley (1) , A-C. Gregoire, P. Carbol (1), J-P. Glatz (1), D. Knoche (1), D. Papaioannou (1), D. Solatie (1), S. Van Winckel (1), G. Grégoire, D. Jacquemain.


The Phébus FP FPT4 test was performed with a fuel debris bed geometry, to look at late phase core degradation and the releases of low volatile fission products and actinides. Post Test Analyses results indicate that releases of noble gases (Xe, Kr) and high-volatile fission products (Cs, I) were nearly complete and comparable to those obtained during Phébus tests performed with a fuel bundle geometry (FPT1, FPT2). Volatile fission products such as Mo, Te, Rb, Sb were released significantly as in previous tests. Ba integral release was greater than that observed during FPT1. The similar release fraction for all lanthanides and fuel elements suggests the released fuel particles deposited onto the plenum surfaces. A blockage by molten material induced a steam by-pass which may explain some of the low releases.
The revaporisation testing under different atmospheres (pure steam, H2/N2 and steam /H2) and up to 1000°C was performed on samples from the first upper plenum. These showed high releases of Cs for all the atmospheres tested. However, different kinetics of revaporisation were observed depending on the gas composition and temperature. Besides Cs, significant revaporisation of other elements were observed: e.g. Ag under reducing conditions, Cd and Sn in steam-containing atmospheres.


(1) : ITU


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