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Doda, Norihiro; Igawa, Kenichi*; Iwasaki, Takashi*; Murakami, Satoshi*; Tanaka, Masaaki
Nuclear Engineering and Design, 410, p.112377_1 - 112377_15, 2023/08
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)To enhance the safety of sodium-cooled fast reactors, the decay heat in the core must be removed by natural circulation even if the AC power supply to the forced circulation equipment is lost. Under natural circulation conditions, sodium flow is driven by buoyancy, and flow velocity and temperature distribution influence each other. Thus, it is difficult to evaluate the core hot spot temperature by deterministically considering the uncertainties affecting flow and heat. In this study, a statistical evaluation method is developed for the core hot spot temperature by using Monte Carlo sampling methods. The applicability of the core hotspot evaluation method was confirmed in three representative events during natural circulation decay heat removal operations in loop-type sodium-cooled fast reactors.
Doda, Norihiro; Ohshima, Hiroyuki; Kamide, Hideki; Watanabe, Osamu*
no journal, ,
A safety criterion for the core structural integrity under decay heat removal operations is the hottest cladding temperature, which is evaluated by conservative consideration of various uncertainties. Under natural circulation, the coolant flow rate and temperature distributions in the core change dynamically, and the uncertainty does not always affect in the same way, so it should be treated differently from the situation when under forced convection. We have developed a new core hot spot evaluation method based on the statistical safety evaluation method which can treat the uncertainties under natural circulation conditions in a rational and accountable way. This paper presents the new method and the results applied to the event of loss of external power in a sodium cooled fast reactor.
