Japan
 INES 2 |
Failure of the reactor component cooling water system and others by tsunami |
Unit 2 of the Onagawa Nuclear Power Station started operation since 14:00 on March 11, and the Tohoku District – Off the Pacific Ocean Earthquake occurred at 14:46 on the same day. The reactor was automatically stopped and emergency diesel generator A (EDG (A)), emergency diesel generator B (EDG (B)), and high-pressure core-spray diesel generator (EDG (H)) automatically started.
INES 7 |
Re-evaluation of INES rating; Effect to the Nuclear Facilities from the earthquake on east area of Japan |
In March 18, rating of the INES on the events in Fukushima Dai-ichi Nuclear Power Station, by the Tohoku Regional Pacific Ocean Offshore Earthquake is temporary estimated Rating 5. However, Nuclear and Industrial Safety Agency (NISA) estimated total amount of discharge from Fukushima Dai-ichi NPS, using the analytical result of the state of nuclear reactor under the cooperation of Japan Nuclear Energy Safety Organization (JNES). As a result of re-evaluation, total amount of discharged I131 is estimated at 1.3E17Bq, and Cs137 is estimated at 6.1E15Bq.
INES 3 |
Loss of the cooling function to the ultimate heat sink due to the big tsunami |
Fukushima Dai-ni Nuclear Power Station Units 1, 2 and 4, which is in rated power operation, have automatically shut down around 14:46(JST) on March 11, 2011, because of the Tohoku regional Pacific Ocean Offshore Earthquake. Following the earthquake, the big tsunami attacked the power station and the seawater pump rooms were flooded. The licensee lost the function operability of sea water pumps for last heat removal. The turbine driven pump started operation and the exhausted steam increased the pressure of the suppression pool.
INES 3 |
Loss of the cooling function to the ultimate heat sink due to the big tsunami |
Fukushima Dai-ni Nuclear Power Station Units 1, 2 and 4, which is in rated power operation, have automatically shut down around 14:46(JST) on March 11, 2011, because of the Tohoku regional Pacific Ocean Offshore Earthquake. Following the earthquake, the big tsunami attacked the power station and the seawater pump rooms were flooded. The licensee lost the function operability of sea water pumps for last heat removal. The turbine driven pump started operation and the exhausted steam increased the pressure of the suppression pool.
INES 3 |
Loss of the cooling function to the ultimate heat sink due to the big tsunami |
Fukushima Dai-ni Nuclear Power Station Units 1, 2 and 4, which is in rated power operation, have automatically shut down around 14:46(JST) on March 11, 2011, because of the Tohoku regional Pacific Ocean Offshore Earthquake. Following the earthquake, the big tsunami attacked the power station and the seawater pump rooms were flooded. The licensee lost the function operability of sea water pumps for last heat removal. The turbine driven pump started operation and the exhausted steam increased the pressure of the suppression pool.
INES 3 |
Loss of cooling function and water supplying function on the spent fuel pool due to the big tsunami. |
Fukushima Dai-ichi Nuclear Power Station Unit 4, which was in shutdown mode, was attacked by the Tohoku regional Pacific Ocean Offshore Earthquake around 14:46 (JST) in March 11, 2011.
After that, the power station was attacked by a tsunami.
Electricity rooms and seawater pump rooms were flooded, and the cooling function and water supplying function on the spent fuel pool became inoperable.
INES 5 |
The core damage by loss of all cooling function due to the big tsunami. |
In March 18, rating of the INES on the events in Fukushima Dai-ichi Nuclear Power Station, by the Tohoku Regional Pacific Ocean Offshore Earthquake is temporary estimated Rating 5. However, Nuclear and Industrial Safety Agency (NISA) estimated total amount of discharge from Fukushima Dai-ichi NPS, using the analytical result of the state of nuclear reactor under the cooperation of Japan Nuclear Energy Safety Organization (JNES). As a result of re-evaluation, total amount of discharged I131 is estimated at 1.3*10^17Bq, and Cs137 is estimated at 6.1*10^15 Bq.
INES 5 |
The core damage by loss of all cooling function due to the big tsunami. |
Fukushima Dai-ichi Nuclear Power Station Unit 1, 2 and 3, which is in rated power operation, have automatically shut down around 14:46 (JST) in March 11, 2011 because of the Tohoku regional Pacific Ocean Offshore Earthquake.
After that, the power station was attacked by tsunami.
Electricity rooms and seawater pump rooms were flooded, and the cooling function became only the coolant injection of the turbine driven pump.
INES 5 |
Abnormal rise of radioactive dosage value at site boundary (INES Level 4) |
The core damage by loss of all cooling function due to the big tsunami.-Provisional 2
Fukushima Dai-ichi Nuclear Power Station Unit 1, 2 and 3, which is in rated power operation, have automatically shut down around 14:46 (JST) in March 11, 2011 because of the Tohoku regional Pacific Ocean Offshore Earthquake.
After that, the power station was attacked by tsunami.
Electricity rooms and seawater pump rooms were flooded, and the cooling function became only the coolant injection of the turbine driven pump.
INES 3 |
Effect to the Nuclear Facilities from the earthquake on east area of Japan |
14:46 (UTC 5:46) March 11, an earthquake hit east area of Japan. Summary of earthquake and current status of each nuclear facility is as follows;
1. Summary of Earthquake
(1) Time of Occurrence: 14:46 (UTC 5:46) March 11, 2011, Friday
(2) Epicenter: Off-Coast of Sanriku (North Latitude: 38; East Longitude: 142.9), 10km deep, M8.8
2. The status of operation at Power Stations(Number of automatic shutdown(units): 10 (as of 00:30(UTC:11:46), March12)
a.
