A Numerical Study of Water Ingression Phenomena in Melt Pool Coolability
Raj Kumar Singh, Arun Kumar Nayaka, Parimal P. Kulkarnib, P. K. Vijayanc and D. Sahad
Reactor Engineering Division, Bhabha Atomic Research Centre Trombay, Mumbai 400 085, India.
aarunths@barc.gov.in
bparimalk@barc.gov.in
cvijayanp@barc.gov.in
ddsaha@barc.gov.in
ABSTRACT
During a postulated severe accident, the core can melt and the melt can fail the reactor vessel. Subsequently, the molten corium can be relocated in the containment cavity forming a melt pool. The melt pool can be flooded with water at the top for quenching it. However, the question that arises is to what extent the quenching is possible in the corium melt pool? It has been known that water ingression plays an important role in quenching of the molten pool. But can water penetrate into the crust all the way to quench it completely? To reveal that, a numerical simulation has been carried out using the computer code MELCOOL. The code considers the heat transfer behaviour in axial and radial directions from the molten pool to the overlaying water, solidification of the molten pool and the growth of the crust. For water ingression, a new approach based on thermal stresses developed in the crust and the disintegration of crust into debris by brittle fracture has been considered. The code has been validated with the experimental data available in literature from experiments carried out on COMECO test facility. The MELCOOL predictions were compared with the test data for the temperature distribution inside the molten pool. The code was found to simulate the quenching behaviour and depth of water ingression quite well.
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