Calculation of the reverse air flow rate to cells from the vessel ventilation system

Kosaka, Ichiro; Yamanouchi, Takamichi; not registered

At 11th, March, 97, the fire incident happened, and after the fire incident, the explosion happened in the Bitiminization Demonstration Facility. It has been suspected that the reverse air flow to filling room(R152) from the vessel ventilation system made the explosive atmosphere after the fire incident. The calculation of the reverse flow rate to the cell was therfore carried out, using FIRAC computer code. The FIRAC is designed for the calculation of a fluid temperature, pressure and flow rate, using lumped-parameter method. In the FIRAC, the network system is modeled as nodes and branches. As the results of calculation, the reverse air flow rate to R152 from vessel ventilation system is about 94 m/h and the reverse air flow rate to the other cells are slight, assuming that the leak rate from R152 is 650 m/h and others are 1 vol%/h when the pressure difference is 40 mmAq. On the other hand, the reverse air flow rate to R152 is about 34m/h, the reverse air flow rate to the cells in the underground stairs is about 39 m/h and to the others are from 5 to 10 m/h, assuming that the leak rate from all cells are 1 vol%/h when the pressure difference is 40 mmAq.