Fukushima 1 Nuclear Accident Day 4: Monday, 14 March 2011

11:15
The outer building surrounding Unit 3 of Fukushima I explodes, presumably due to the ignition of built up hydrogen gas. No health risk reported, though 600 people have been ordered to stay indoors. Chief Cabinet Secretary Yukio Edano reported that "The vessel containing the No. 3 reactor’s radioactive core is intact after yesterday’s blast", and while that the outer reactor building of Unit 3 at Fukushima I was blown apart, the inner containment vessel was not breached. TEPCO also stated that one worker was injured and seven missing. TEPCO later said at least four employees and two contractors were injured in the blast.
11:44
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 20 μSv/hour.
12:30
Status of the Fukushima I station at 12:30 March 14

Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity Damaged Not damaged Damaged Not damaged Not damaged Not damaged
Containment integrity Not damaged Not damaged Not damaged Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional RCIC working Not functional Not necessary Not necessary Not necessary
Building integrity Damaged Not damaged Damaged Not damaged Not damaged Not damaged
Pressure vessel, water level Unknown Above core Unknown Safe Safe Safe
Pressure vessel, pressure Stable Stable Stable Safe Safe Safe
Containment pressure Stable Stable Stable Safe Safe Safe
Seawater injection Suspended To be decided Performed Not necessary Not necessary Not necessary
Containment venting Performed Preparing Performed Not necessary Not necessary Not necessary
Environmental effect (NPS border) 20 μSv/hour at 11:44
Evacuation radius 20 km
INES Level 4 (estimated by NISA)
13:15
Fukushima II Unit 1 cooling system has been restored, work continues on units 2 and 4.
13:55
Radiation reading at the Fukushima I Nuclear Power Station (NPS) border is 15 μSv/hour.
20:30
Status of the Fukushima I station at 20:30 March 14

Unit 1 Unit 2 Unit 3 Unit 4 Unit 5 Unit 6
Power output (MWe) 460 784 784 784 784 1100
Type of reactor BWR-3 BWR-4 BWR-4 BWR-4 BWR-4 BWR-5
Status at earthquake In service In service In service Defueled Outage (scheduled) Outage (scheduled)
Fuel integrity Damaged Unknown Damaged Not damaged Not damaged Not damaged
Containment integrity Not damaged Not damaged Not damaged Not damaged Not damaged Not damaged
Core cooling system 1 (ECCS/RHR) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Core cooling system 2 (RCIC/MUWC) Not functional Not functional Not functional Not necessary Not necessary Not necessary
Building integrity Damaged Not damaged Damaged Not damaged Not damaged Not damaged
Pressure vessel, water level Unknown Low (recovering) Unknown Safe Safe Safe
Pressure vessel, pressure Low Unknown Stable Safe Safe Safe
Containment pressure Stable Increasing Stable Safe Safe Safe
Seawater injection Suspended Performed Performed Not necessary Not necessary Not necessary
Containment venting Performed Preparing Performed Not necessary Not necessary Not necessary
Environmental effect (NPS border) 15 μSv/hour at 13:55
Evacuation radius 20 km
INES Level 4 (estimated by NISA)
21:00 (approximate)
Fuel rods within Reactor #2 of the Fukushima I nuclear plant were fully exposed to air (but were still within the intact containment vessel and therefore not exposed to the outer atmosphere). TEPCO earlier said the cooling system had been lost and began injecting seawater into the reactor to cool it down.
21:08
The IAEA announce the temperature in the spent fuel pond of reactor 4 are at 84 °C
21:16
Yukio Edano affirms that Reactor number 2 of Fukushima I is unlikely to explode. In addition, he stated that there is ongoing work to cool down the reactor.
23:20 (approximate)
Fuel rods at Reactor #2 of Fukushima I became fully exposed once again. TEPCO says that pressure inside the reactor rose again because the unit's air flow gauge was accidentally turned off. With the gauge turned off, flow of water into the reactor was blocked, leading to full exposure of the rods.

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