March 18th, 2011 – Nuclear Events Web-based System (NEWS) – Fukushima Daini Unit 1 – Unit 2 – Unit 4 – Loss of the cooling function to the ultimate heat sink due to the big tsunami

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Event Title: Loss of the cooling function to the ultimate heat sink due to the big tsunami
Event Date: 2011-03-11 Date Sent: 2011-03-18 10:11:00 UTC
Location/Facility:FUKUSHIMA-DAINI-t Event Type: Power Reactor
Country: Japan Reactor Type: Boiling Water Reactors
Event Sender: Masahiro Yagi TINES Rating: 3

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. The turbine driven pump became inoperable.

As a result of the efforts by the people on site, some seawater pumps were recovered and restarted. The suppression pools were cooled and the pressure was decreased. And the sea water pumps became to discharge the heat to the ultimate heat sink through the residual heat removal system.

Finally, the temperature of the reactors was decreased below 100 degree C and the reactors became cold shut down condition.

Event Title: Loss of the cooling function to the ultimate heat sink due to the big tsunami
Event Date: 2011-03-11 Date Sent: 2011-03-18 10:13:00 UTC
Location/Facility:FUKUSHIMA-DAINI-2 ‘Event Type: Power Reactor
Country: Japan Reactor Type: Boiling Water Reactors
Event Sender: Masahiro Yagi INES Rating: 3

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. The turbine driven pump became inoperable.

As a result of the efforts by the people on site, some seawater pumps were recovered and restarted. The suppression pools were cooled and the pressure was decreased. And the sea water pumps became to discharge the heat to the ultimate heat sink through the residual heat removal system.

Finally, the temperature of the reactors was decreased below 100 degree C and the reactors became cold shut down condition.

Event Title: Loss of the cooling function to the ultimate heat sink due to the big tsunami
Event Date: 2011-03-11 Date Sent: 2011-03-18 10:17:0 0UTTC
Location/Facility:FUKUSHIMA-DAINI-4
Country: Japan
Event Sender: Masahiro Yagi
Event Type: P,
Reactor Type: B
INES Rating: 3

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. The turbine driven pump became inoperable.

As a result of the efforts by the people on site, some seawater pumps were recovered and restarted. The suppression pools were cooled and the pressure was decreased. And the sea water pumps became to discharge the heat to the ultimate heat sink through the residual heat removal system.

Finally, the temperature of the reactors was decreased below 100 degree C and the reactors became cold shut down condition.

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March 11th, 2011 – If units 1, 2 and 3 have all lost emergency diesel generators, it would seem that this is more than coincidence

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