TEPCO has released a comprehensive video (13 minutes) that shows damage from the tsunami and the ongoing work activities to decontaminate and stabilize the Fukushima Daiichi Nuclear Power Plant.
On May 12, TEPCO announced that Fukushima Daiichi Unit 1 is in a state of core “meltdown” because the majority of the fuel rods in the core had melted and fallen to the bottom of the reactor pressure vessel. TEPCO was trying to determine why water levels in the reactor were falling and discovered coolant water in the reactor had dropped low enough to completely expose the nuclear fuel rods. TEPCO also stated that holes were created in the reactor pressure vessel as a result of the meltdown and that the primary containment vessel was damaged. A large quantity of highly radioactive water is believed to be leaking into the basement of the reactor building.
On May 15, new analysis of data by TEPCO staff was released that suggests the damage to the Unit 1 reactor occurred within 16 hours of the March 11 earthquake. Furthermore, their analysis indicates that the water level in the reactor pressure vessel fell below active fuel 4.5 hours after the earthquake, which would initiate fuel melting. At this stage, the fuel reached 2800°C and the melting of the core advanced rapidly such that all the fuel rods had melted and dropped to the bottom of the RPV by 0650 (JST) March 12.
As a result of this recent analysis, TEPCO has suspended the implementation of their long-term cooling plan while they re-evaluate their countermeasures for Unit 1. In the meantime, TEPCO has increased the water injection rate into Unit 1 to between 8-10 tonnes of water per hour. This has lowered temperatures to 110°C in the upper portion of the reactor pressure vessel and 84°C in the lower part of the reactor pressure vessel.
TEPCO is working to fix gauges in Fukushima Daiichi Units 2 and 3 so they can determine exact water levels in the reactors. The company believes the gauges may not be providing accurate water levels, similar to the situation they experienced last week with Unit 1. The worst case would be that the nuclear fuel rods are exposed in Units 2 and 3 and have melted down.
TEPCO has revealed that an operation to transfer highly radioactive water pooled in Daiichi’s Unit 3 turbine building caused radioactive contamination of the sea nearby. Water containing high concentrations of caesium 134 and 137 many thousand times state limits was detected leaking from a pit into the sea near Unit 3’s water intake on May 11. TEPCO said the leak from an underground pipe connected to the pit has been stopped.
TEPCO is reporting that it believes the March 15 explosion at Unit 4 may have been caused by hydrogen from the Unit 3 reactor. The two reactors share a common exhaust pipe joined through ducts. TEPCO believes that when it vented gas from Unit 3 through the duct, hydrogen may have leaked into the Unit 4 reactor building. This belief is based on an analysis of photographs taken in April of the Unit 4 fuel pool, which revealed no damage to the fuel rods.
Chubu Electric Power Company, operator of the Hamaoka nuclear power station, shut down Hamaoka Unit 4 on May 13 and Unit 5 on May 15 in response to a Japanese government request. All five reactors at Hamaoka will remain in safe shutdown state while work to protect the nuclear power station from a high magnitude earthquake is undertaken over the next two years.
Japan Atomic Industrial Forum reports that Japan is shutting down so many reactors because of the earthquake and other reasons that only about one-third of the country’s 54 nuclear power reactors will be operational by the end of May. The March 11 earthquake and tsunami led to the shutdown of 14 reactors, including those at Fukushima Daiichi NPS. Nineteen other reactors are currently offline, either undergoing regular inspection or scheduled to be inspected in the near future. Another five reactors will be shut down over the next few months in advance of scheduled inspections. If Japanese utilities keep these 40 reactors offline, almost three-quarters of Japan’s reactors will be shut down this summer.
Update from CNSC
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My, this does look rather scary. Glad I have a good supply of seaweed, it's the only known way to safely escort radioactive fallout from your body.
Gratitude to the water of Fukushima, I'm sorry we've poisoned you.
Is there any audio or is this just B-roll?
Terry, sorry TEPCO did not provide an audio track.