Posted on 03/15/2011 7:32:54 AM PDT by SeekAndFind
TOKYO—Japanese officials appeared to have regained some control of northeast Japan's troubled nuclear power plant Tuesday afternoon, at least for now, after spikes in radiation levels that followed a new explosion at one reactor and a fire at another earlier in the day put the nation on high alert.
Officials stressed it was too early to say the worst has been averted at the Fukushima Daiichi nuclear power plant, which has suffered serious problems in four of its six reactors since Friday's massive earthquake and tsunami. Determining the cause of the earlier radiation leaks and checking what's happening inside the overheating reactors was difficult.
Authorities also signaled a new area of potential worry: temperature at the remaining two reactors, both not operating at the time of the earthquake and so far not the subject of concern, has risen slightly, prompting the need for close monitoring. Officials were also probing a report that boiling water had been spotted near where the fire broke out Tuesday morning, another potential worrying sign.
But the conditions at the plant appeared to have stabilized in some aspects Tuesday afternoon. While radiation levels at the plant remain elevated, they have dropped significantly from earlier in the day, ruling out the continuation of unstoppable large-scale leaks.
Radiation levels in downtown Tokyo—which had also risen earlier Tuesday, though they remained well below levels that could damage human health—also fell sharply later in the day.
Earlier Tuesday, Prime Minister Naoto Kan warned of the possibility of further increase in radiation levels, as he called on the Japanese people to "act calmly." Officials said radiation levels at the plant had surged to levels that would have impact on the human body.
(Excerpt) Read more at online.wsj.com ...
IAEA has been informed by Japanese authorities that a fire in the reactor building of unit 4 could no longer be observed as of 21:15 UTC 15 Mar 2011. The fire was visually observed at the reactor at 20:45 UTC 15 March 2011. The fire had previously been confirmed extinguished at 0200 15 Mar 2011 after burning for two hours.
12:00 UTC 15 Mar 2011: the water level in unit 5 was detected at 201 cm above the top of the fuel (16.6% decrease of immersion level over the previous 5 hours). Officials at the plant exoressed their intent to use an operational diesel generator in unit 6 to supply water to unit 5.
Japanese authorities have reported concerns about the condition of the spent nuclear fuel pool at Fukushima Daiichi Unit 3 and Unit 4. Japanese Defense Minister Toshimi Kitazawa announced Wednesday that Special Defence Forces helicopters planned to drop water onto Unit 3, and officials are also preparing to spray water into Unit 4 from ground positions, and possibly later into Unit 3. Some debris on the ground from the 14 March explosion at Unit 3 may need to be removed before the spraying can begin.
According to IAEA experts, a typical spent fuel pool temperature is kept below 25o C under normal operating conditions. The temperature of a spent fuel pool is maintained by constant cooling. There is suspicion that either power to the spent fuel pool cooling subsystem has not been constant per putative design requirements, or has been compromised in some manner.
Spent fuel assemblies generate intense heat and radiation. Therefore the spent fuel pools must be constantly checked for water level and temperature. If fuel is no longer covered by water or temperatures reach a boiling point, fuel can become exposed and create a risk of radioactive release.
The IAEA can confirm the following information regarding the temperatures of the spent nuclear fuel pools at Units 4, 5 and 6 at Fukushima Daiichi nuclear power plant:
The IAEA can confirm the following information about human injuries or contamination at the Fukushima Daiichi nuclear power plant
DISCLAIMER: the information provided is a snapshot of the latest information made available to the IAEA by Japanese authorities (and is valid at the time-date stamp indicated). Given the fluid situation at the plant, this information is subject to change [at the drop of a hat, for any reason, no reason, for better or worse, concerning either sickness or health (or both), for ever and ever, Amen].
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