Boiling heat transfer phenomenon base on the event of loca and severe accident

Research and development base on TMI-2 NPP accident mostly directed to vessel and core performance. The majority of research was conducted which aimed on boiling heat transfer phenomenon, begin by loss of coolant accident (LOCA) until severe accident, in which core meltdown. Study on boiling heat transfer has been done by simulation on core bottom re-flooding process and a narrow gap cooling. The results of experimental research which was conducted by BATAN concerning LOCA and severe accident are giving a clearly picture, in how boiling heat transfer phenomenon was occurs during sequent of nuclear reactors accident, especially TMI-2 accident. The mapping of heat transfer base on transient temperature data was created in boiling curve form which was shown the differences of heat flux in three boiling regimes, both in pool boiling and flow boiling. The experimental simulation of LOCA shown that the CHF value (67.31 kW/m² ) is small than the CHF value of severe accident (262 kW/m²). (author)