Abstract Molten fuel–coolant interactions in postulated severe accident scenario of nuclear reactors lead to the formation of a porous debris bed. Substantial heat generation takes place within such debris beds as a result of radioactive decay, and this needs to be continuously removed in order to maintain the temperature of the debris material within acceptable limits. This is achieved by boiling heat transfer using cooling water. Any failure in this regard can lead to re-melting of the material in an extreme situation and lead to further catastrophic consequences. In this context, it becomes imperative to have an assessment of the limit beyond which the debris cannot be maintained in a coolable condition. This limit is typically identified by the occurrence of dryout, i.e. water vapour accumulation within the debris bed. This chapter attempts to highlight the underlying mechanism and the pertinent factors contributing to dryout occurrence in typical debris beds. Various experimental studies and numerical modelling carried out in this regard are thoroughly reviewed. Augmentation of the dryout limit using available techniques is discussed in detail. A numerical model that has been developed for analysing multiphase flow and the associated heat and mass transfer in such porous debris beds are also presented in this chapter along with some salient results.
Coolability of Heat-Generating Porous Debris Beds in Severe Accident Situations
04.11.2018
32 pages
Aufsatz/Kapitel (Buch)
Elektronische Ressource
Englisch
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