science-review.ru
Scientific journal
Scientific Review. Technical science
ISSN 2500-0799
ПИ №ФС77-57440
ISSN 2500-0799
ПИ №ФС77-57440
ABOUT THE NATURE OF THE COURSE OF ACCIDENTS WITH CORE MATERIALS MELTING OF FAST REACTOR WITH SODIUM COOLANT
257 KB
The existing concept of safety includes consideration in the project of nuclear power plant beyond design accidents with severe core damage. The article is devoted to the phenomenology of heavy beyond design accidents in fast reactors with sodium coolant (of BN), accompanied by melting and movement of core materials. The analysis is based on the test results of experimental programs and the accompanying computational modeling of emergency physical processes. In the safety analysis of BN reactor accepted division of beyond design accident into four stages: initial, transitional, post-accident material relocation and post-accident heat removal. As a result of relocation and solidification of the cladding melt in transition stage steel blockages of channels are formed ‑ solid foundation for the pool. Under melt-through of blockage the melt will be flow into the channels between the yet solid parts of the fuel rods at some length, it hardens there and again forms a layer of blockages. The process of heat-generating mass moving will be the intermittent nature: melt-through of blockages layer, leaking of melt at some length and solidification, the melting of the next layer, etc. Research is required of processes under post-accident material relocation stage and residual heat removal from the heat-generating mass at the last stage of the accident.