[1C01-06] SA Analysis

[1C06] Evaluation of the factors that prevent the reactor building of 1F2 from exploding

*Penghui Chai¹, Kenichirou Nozaki¹, Shouichi Suehiro¹, Takeshi Honda², Masato Mizokami², Shinya Mizokami², Kenji Owada² (1. TEPCO SYSTEMS COOPRATION, 2. Tokyo Electric Power Company Holdings, Inc.)

Keywords:Fukushima Daiichi Nuclear Power Plant Unit2, Hydrogen explosion, GOTHIC, Hydrogen distribution in the reactor building, Blowout panel

It is considered that the explosions that occurred in the reactor buildings (R/Bs) of 1F1, 1F3, and 1F4 were resulted by the hydrogen leak from the containment vessel or the reverse flow of the vent gas. It is considered that the reason that no hydrogen explosion occurred in 1F2 might be the opening of the blowout panel (BOP), which enhanced the ventilation and reduced the hydrogen concentration in the R/B. To verify this hypothesis, R/B’s hydrogen distribution was simulated and discussed using GOTHIC code. The hydrogen inflow was assumed based on the accident scenario that was evaluated according to the on-site data. The simulation results suggested that the opening of the BOP contributed to preventing the 1F2 R/B from exploding.