Characteristics of conjugate free convection in a corium pool formed during a severe reactor accident

Conjugate natural convection flow in a thick walled semi-circular cavity co ntaining molten core material has been analysed numerically. The lower plen um debris bed represents decay heating, heat conduction, and heat convectio n within the debris. The internal heat generation resulting from the radioa ctive decay of fission products ensures that most of the pool remains molte n and also causes natural convection in the pool. Bottom circular wall of t he cavity is taken to be thick with finite conductive properties, while top wall is considered to be isothermal. In carrying out the analysis, various constituents of the core material are assumed to be mixed homogenously. Th us a homogeneous fluid, for which Pr number is 0.45, has been considered wh ile Ra number range from 3.2 x 10(7) to 3.2 x 10(12) has been investigated. Present results for non-conjugate semi-circular cavity compare very well w ith previously published experimental studies. (C) 2001 Elsevier Science Lt d. All rights reserved.