Interim MELCOR Simulation of the Fukushima Daiichi Unit 2 Accident Reactor Core Isolation Cooling Operation

Preliminary uncertainty quantification of the core degradation models in predicting the Fukushima Daiichi unit 3 severe accident

“…Contact between hot corium and colder concrete can lead to local formation of a crust by solidification. MCCI has been modelled in agreement with the MACE data (Ross et al, 2014).…”

“…Mean value was set as SOARCA best-practice value of 0.2 kg/m-s, determined by CORA-13 experiment, with uniform distribution and exploratory bounds of 0.1 kg/m-s and 2 kg/m-s, since there is no basis to inform distribution bounds (Ross et al, 2014;Bixler et al, 2016).…”

“…A review of FARO data shows that for fragmented particle sizes on the order of 5 mm, the HTC may be 1000 W/m 2 K (Bixler et al, 2016). SOARCA suggest 2000 W/m 2 K for debris size of 2 mm (Ross et al, 2014). A uniform distribution has been selected with these two values as bounds.…”

“…The Fukushima accident was the first world severe accident in a Boiling Water Reactor (BWR), offering, despite of the consequences, a unique opportunity to deepen the knowledge on core degradation phenomena and to improve abilities of severe accidents codes in modelling complex accident scenario. nodalization and models have been developed following the Best Practice Guidelines given in SOARCA (Ross et al, 2014) to better represent the plant response to the severe accident.…”

Multi-phase model development to assess RCIC system capabilities under severe accident conditions

“…Times of operation are available, for example, but detailed information such as the flow rate through the turbine, or the pumped volumetric flow rate, are not known. Several important boundary conditions for a system simulation, as opposed to those needed at the validation on the turbine and pump component level, are available [Ross et al, 2013].…”