Heat and fluid flow in accident of Fukushima Daiichi Nuclear Power Plant, Unit 1. When the isolation condenser was working

An accident scenario of Fukushima Daiichi Nuclear Power Plant, Unit 1 is analyzed from the data open to the public. The author assumed that the isolation condensers were partially functional at the initial stage of the accident. The estimation describes that the rupture time of the pressure containment vessel was at 4:00 12/3/2011 and the rupture area was approximately 8 cm in equivalent diameter. The estimation show that the rupture time of the reactor pressure vessel was at approximately 6:00 12/3/2011 and the diameter was approximately 5 cm. These estimations are different from the ones by TEPCO, and have some discrepancy between measurements. However many measured evidences show good accordance with the present scenario. (author)