Tuesday, March 15, 2011

No.2 reactor chronology in Japan

No.2 reactor chronology in Japan

Three of the 6 nuclear reactors at the Fukushima Number One nuclear power plant automatically halted operations at 2:46 PM on Friday after the earthquake struck.

But the emergency power generator to cool the reactors failed to work.

Tokyo Electric Power Company notified the government that a state of emergency existed based on laws governing nuclear issues. The government then instructed nearby residents to evacuate.

At the No.2 reactor, the cooling water had partially evaporated, considerably reducing the water level inside the nuclear containment vessel.

Two days after the earthquake, on Sunday, the pressure rose.

To prevent the container from being damaged, work began to release the inside air which includes radioactive substances.

But on Monday, the pressure increased further, and the water level also dropped.

TEPCO began to pump in sea water on Monday afternoon. But the pump ran out of fuel and the water level remained low. The 4 meter tall fuel rods are believed to have been fully exposed for 2 hours and 20 minutes.

Shortly after 9:30 PM, high levels of radiation measuring 3,130 microsieverts per hour were recorded near the plant gates. It is believed that the fuel rods were likely damaged and melted.

At around 6:10 Tuesday morning, an explosion was heard near a facility known as the suppression pool, which adjusts the pressure of the No.2 reactor.

At one point immediately after the explosion, radiation levels near the power plant reached 965.5 microsieverts.

The facility is believed to have sustained damage, and radioactive substances are unlikely to have been sufficiently contained.

Tuesday, March 15, 2011 16:05 +0900 (JST)