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Abstract

The investigation of the early behaviour of debris beds in high pressure water and the heating of the bottom plate on which the debris rests are important aspects of the FARO-LWR out-of-pile tests. In the first two tests 18 and 44 kg of UO(2)/ZrO(2) fell through the water and 2/3 of the melt fragmented in both tests. The remainder of the melt ended up as frozen cakes on the bottom plate and heated it very little in comparison with the heating of the overlying water by the debris bed. The heat fluxes from these transient debris beds to the water were evaluated to be between 8 and 10.5 MW/m2 during the first 10 seconds and about 3.5 MW/m2 from 10 to 24 s. In particular, the first value is considerably higher than dryout heat fluxes measured in experiments with steady state debris beds. This implies that the shallow and initially hot FARO debris beds must have cooled down rapidly and that they did not dry out significantly. Some fluidisation probably occurred in the early life of these beds. The simplified modelling of the debris beds in both the COMETA and TEXAS-II codes are shown to give reasonable results for these tests.

Additional information

Authors: WIDER H U, JRC Ispra (IT);ANNUNZIATO A, JRC Ispra (IT);HOHMANN H, JRC Ispra (IT);MAGALLON D, JRC Ispra (IT);YERKESS A, JRC Ispra (IT)
Bibliographic Reference: Paper presented: SMIRT Seminar on Containment of Nuclear Reactors, Karlsruhe (DE), August 23-24, 1993
Availability: Available from (1) as Paper EN 37779 ORA
Record Number: 199410228 / Last updated on: 1994-11-28
Category: PUBLICATION
Original language: en
Available languages: en
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