TEPCO image of reactor 4

Possibility of major releases from reactor #3, wind currently blowing inland

Pressure inside the reactor’s steel containment is still rising. Tepco increased cooling efforts but has been unable to stop the increasing pressure which unabated threatens to breach the containment structure. In such an event, given the destruction of the reactor building, radioactive steam and air would be released directly into the atmosphere.

Tepco claims says containment pressure could be stabilising, but situation is still dangerous. Any decrease in pressure could mean good news or bad news.

Possible events that could result in a decrease:

  1. improved cooling
  2. a leak in the reactor containment, which is suspected to be damaged
  3. pressure rising so high that emergency valves are activated


Radiation levels

Radiation levels in Daini, south of Daiichi, doubled when the wind turned south, further recorded increases can be expected when new data comes in. Monitoring this data will be a priority for us and we will keep you informed as we find out more.

The fuel rods in the reactor have been out of water for days, releasing radioactive substances into the reactor pressure vessel (“steel casing”). The hot fuel rods turn water into steam which is then vented to from the pressure vessel into the containment.

Fuel pool progress

Fuel pool #4: critical, major spraying scheduled for tonight

80 tons of water was sprayed into the pool this morning. Military said water made it into the pool, but no further confirmation is available. Holes were made to the roof to allow water to pass through.

The government agencies refuse to disclose the information they obtained on water level and temperature yesterday morning by remote sensing from a helicopter, indicating that the situation is critical. Nuclear safety agency NISA admits that a hydrogen explosion took place in #4, but finds it hard to explain. NISA says there is immediate threat of radioactive release from the fuel pool of Unit 4.

Electricity connection progress slow

Electricity has been connected into reactors 1 & 2 and Tepco operators are working to inspect if the power source and electric equipment in the reactor are operable.

Cables should be connected to units 3 & 4 today, but Tepco says inspections and repairs will take until Monday or Tuesday.

Progress on the electrical connnection up until now has been slowed by radioactive releases from spraying, forcing the workers to leave the site.

Fuel pools #3, 5, 6: condition improving

The Tokyo Fire Department shot water into a spent-fuel pool of the No. 3 reactor in an operation that lasted more than 13 hours. More than 2,000 tons of water is believed to entered into the No. 3 reactor's pool so far, exceeding the pool's capacity of 1,400 tons.

At Units 5 and 6, restored emergency power supply is working and the cooling system has begun to cool down the spent fuel pond, bringing temperatures down to much less alarming levels.

Further information: To help you decipher the complex information around radiation and health we have created a radiation guide covering effects, safety and basics of the Fukushima 1 radiation releases.

Additional resources

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Main Fukushima nuclear crisis page.