Experimental study on the coolability of molten core materials discharged into a depth- and volume-limited sodium plenum

Matsuba, Kenichi  ; Kato, Shinya  ; Kamiyama, Kenji  ; Akaev, A. S.*; Vurim, A. D.*; Baklanov, V. V.*

During a severe accident in sodium-cooled fast reactors, molten core materials could be discharged from the core region toward the lower sodium region of the reactor vessel through coolant channels, such as control rod guide tubes. Typical SFRs have a sodium plenum with limited depth and volume, such as the core inlet plenum located under the core region. Therefore, it is important to evaluate the coolability of molten core materials discharged into a depth- and volume-limited sodium plenum. In the present study, to deepen the understanding on the coolability of molten core materials discharged into such a sodium plenum, conditions under which molten core materials form solidified fragments were discussed based on an experiment discharging a molten fuel simulant (molten Al2O3) into a test vessel filled with liquid sodium.