Michele Kearney's Nuclear Wire

Major News and Commentary Military and Civilian Nuclear Activities

Wednesday, March 16, 2011

Blog Post: Japan Nuclear Emergency Update With Reactor Status List

Blog Post: Japan Nuclear Emergency Update With Reactor Status List

Workers at the Fukushima Daiichi nuclear plant were evacuated briefly late Tuesday night after radiation levels at the gate of the power plant peaked at 6.4 millisieverts per hour.
They returned after radiation levels fell again. Tuesday also saw the Japanese government increase the legal radiation exposure for nuclear workers to 250 millisieverts.
Tepco had cut the number of workers at the plant to just 50 following a fire Monday in unit 4 and subsequent increased radiation readings.
Crews continue to try vent steam and pump seawater into units 1, 2 and 3 to prevent containment damage from excess pressure and heat. Explosions have ripped through the outer buildings of all three reactors in the last few days, indicating a buildup of hydrogen that could be caused by water contacting damaged fuel cladding.
The New York Times reported Tuesday that the U.S. military has helped put out fires at the plant, and other news agencies indicated U.S. forces may be asked to increase their assistance at the plant.
Below is a status report for each reactor at Fukushima Daiichi as of 11:00 p.m., Tuesday, based on reports from Tepco, Japanese government officials and international media (unless noted, times and days of the week are EST):
Unit 1
As much as 70 percent of the fuel within the reactor may be damaged, according to a report Tuesday from Kyodo news.
Unit 2
Tepco officials said they were not sure if increases in radiation observed at the plant Tuesday originated from a breach reported in unit 2’s suppression chamber.
As much as 33 percent of the fuel within the reactor may be damaged according to Kyodo news.
Unit 3
Tepco told Government officials Tuesday night that smoke or vapor visible from an NHK TV helicopter might be coming from unit 3.
Unit 3 had been using mixed-oxide (MOX) fuel made from spent uranium and plutonium. The fuel’s lower melting point and added toxicity would make vapor in contact with the spent fuel potentially more harmful.
Unit 4
Firefighters extinguished a fire in the outer building Monday, and a second sighting of flames reported Tuesday were no longer visible after about 30 minutes.
Water temperature in its spent fuel tank reached 84 C Tuesday, twice the normal reading, and reports indicate the water level was below normal.
All of the non-spent reactors fuel had been transferred from the reactor core to the pool before the earthquake, making it more prone to heating. Plans were forming to add water and boric acid to the tank, although elevated radiation levels were preventing access.
Unit 5
Nikkei news said Tuesday spent fuel tank water temperature was reported at 58.7 C, compared to 24 C normally.
Additionally, news reports indicated Tepco also was working to bring down the temperature inside the reactor and the spent fuel tank.
Unit 6
Nikkei news said Tuesday spent fuel tank water temperature has been reported at 57 C, compared to 24 C normally.
Additional reports indicate Tepco was working to bring down the temperature inside the reactor and the spent fuel tank Tuesday.
Fukushima Daini
Tepco reported Monday that all four reactors at its Fukushima Daini plant nearby have achieved cold shutdown.
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