It’s Wednesday evening in Japan, mid-morning in US east coast.
We’ve had a lot of information on the Japanese nuclear disaster. Given that there were three operating reactors at the time of the earthquake and there have been problems with four (three of them with the reactors themselves and on at Unit 4 regarding the rods in the storage pool) I thought it would be worth while to start a time line of events to help everyone keep it all straight in their minds.
Since this has been rather chaotic and there is concern that there has been some holding back of information from TEPCO (Tokyo Electric Power Company) officials I am going to only use information that I can get in more than one place.
A note on times; all times are going to be Japan Standard Time, so they will be a day ahead. Also for some events we don’t have a time stamp so I will just give them in approximate order, based on when they were reported.
- Three reactors active at Daiichi Nuclear Power Station, Units 1, 2 and 3. Unit 4-6 are in active. Unit 4 has fuel rods removed from maintenance. Units 5 and 6 are in cold shut down mode.
-9.0 earthquake strikes off of coast of Honshu prefecture.
-Reactors in affected area begin emergency shutdown procedures. Control rods are automatically inserted into the reactor cores to curtail fission. Shut down is successful, fission stops.
-Heat production by the cores falls to 6% of that during operation.
-Massive tsunami waves strike the Japanese coast. Wide spread devastation occurs. Power grid is knocked out in the area around Daiichi and much of the north eastern coast of Japan.
-Tsunami strikes Daiichi plant. Generators and fuel storage on ocean side of plant. All diesel storage washed away.
-Power fails at Daiichi, coolant stops circulating in Units 1-3. Diesel back ups for the pumps fail due to tsunami damage and lack of fuel. Switching system also wiped out by tsunami.
-Circulation of water in cooling ponds stops.
- Temperatures in the cores begin to rise, increasing the amount of steam inside the reactors. Pressure increases, water level around the core fall.
-Fail safe, battery operated, cooling systems begins operation. Battery life estimated at 8 hours
5pm – Approximately
-Japanese officials call press conference and announce that there is a state of emergency for the area around the plant. They state that here is a problem with the cooling system in Unit 1 but that there has not been any release of radioactivity.
-2,000 residents nearest power plant advised to evacuate, but not ordered to do so.
-Technicians at the plants attempt to bring in new batteries and diesel generators to keep fail safe pumps going, and to start emergency back up cooling system.
-Kyodo News reports that radiation at Unit 1 control room is 1,000 times normal. Indications that the core is either uncovered or close to it.
- Operators vent steam from Unit 1 to lower pressure
10pm – Approximately
– Mandatory evacuation orders go out to 45,000 people within 6 miles of the Daiichi NPS.
– Sec. State Clinton announces that US Air Force brought coolant to the plant. This is most likely boric acid which is used as coolant and moderates nuclear reactions better than purified water.
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