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This is another clearinghouse diary for discussion and commentary about the ongoing nuclear disaster(s) in Japan. Previous diaries can be found listed in the Mothership.
More Below the Fold...
Here is a series of resources highlighted on the mothership and other ROVs to assist you in finding a variety of information regarding the crisis.
3/21 Radiation levels at the front gate have gone down to 261.6 microsieverts. Work has resumed on power restoration.
NHK (Japanese) - h/t spideymike
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3/21 According to TEPCO, radioactive iodine-131 was detected Monday in the seawater samples at levels 126.7 times higher than the legal concentration limit. Levels of cesium-134 were 24.8 times higher and those of cesium-137 16.5 times higher while a trace amount of cobalt 58 was detected in a sample of seawater taken from near the plant.
Kyodo
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3/21 IAEA reports radiation 1600 times normal 20 kilometers away
Kyoda h/t politik
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3/21 - There were steam releases at reactors #2 and #3 in the afternoon. All 700 workers were evacuated and the work to restore the engines, pumps and electrical power to the plant has been suspended until further notice. Radiation spiked one kilometer west of the facility, rising from 494 microsieverts at 5:40 p.m. to 1,932 at 6:30 p.m. The level dropped to 442 at 8:30 p.m.
[most recent earthquake and tsunami casualty numbers] - 8,649 people have died and another 13,262 are missing - WaPo
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While workers at the plant work to stablize the situation, cesium has turned up in Tokyo water and some crops:
But the contamination spread to spinach in three other prefectures and to more vegetables — canola and chrysanthemum greens. Tokyo's tap water, where iodine turned up Friday, now has cesium. Rain and dust are also tainted.
NY Post and from the
AP
The announcement by Japan's Health Ministry late Sunday that tests had detected excess amounts of radioactive elements on canola and chrysanthemum greens
h/t Siri
This is a bad development as cesium has a 30 year half life and is harder to clean up than radioactive iodine.
Because of the chemical nature of cesium, it moves easily through the environment. This makes the cleanup of cesium-137 difficult.
EPA h/t mahakali overdrive
The situation at the Daiichi power plant remains very serious.
International Atomic Energy Agency chief Yukiya Amano, who returned to Vienna after a two-day visit to Japan, indicated to reporters on Saturday that it was premature to be optimistic about the future of the troubled plant.
''I hope that safety, stability will be recovered as soon as possible...But I still don't think it is time to say that I think they are going in a good direction or not.'' Kyodo News
Spent fuel is proving to be the biggest threat in this crisis. 1814 tons of spent fuel are stored at the plant, 647 tons of this in the spent fuel pools at the 6 reactors (h/t to politik and Into the Woods). For perspective, the Chernobyl accident involved ~200 tons of nuclear fuel.
The spent fuel pools are a main priority as the water levels in several of them have become dangerously low. Reactor 4's pool poses special problems as its fuel was just changed in Dec. 2010, thus is relatively new. Reactor 3 is problematic in another way, as it uses MOX fuel which contains both uranium and plutonium. TEPCO has been dropping water from helicopters and shooting water with water cannons at the reactors for the last four days in hopes of hitting the spent fuel pools and re-covering the spent fuel currently in the pools. Although such efforts have produced steam from the damaged reactors, thus indicating some water must have hit the marks, such measures are hardly a sustainable solution to the problem, and can do little more than buy time.
Yesterday, it was reported that
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 until 3:40 a.m., while the Defense Ministry plans to shoot water into a similar pool of the No. 4 reactor shortly.
More than 2,000 tons of water is believed to have been put into the No. 3 reactor's pool so far, exceeding the pool's capacity of 1,400 tons.
We are all crossing our fingers that the water hit its mark, and will do so for spent fuel pool 4 as well. (h/t to woolie)
Radiation levels at the plant remain high.
NHK (link) reported yesterday evening (US time) that radiation levels near reactors 1 and 2 are ~10-15 mSv/hr.
Kyodo News reports that
As of 11:00 a.m., Tokyo Electric said the radiation level about 0.5 kilometer northwest from the No. 2 reactor dropped to 2,579 microsievert per hour, compared to 3,443 microsievert per hour at 2 p.m. Saturday.
Allowable radiation exposure levels recently increased Kyodo News reports that high radiation levels have been hampering workers' abilities to get much done while on site.
Six workers at the crisis-hit Fukushima Daiichi nuclear power plant have been exposed to radiation levels beyond the limit applied to an emergency operation, Tokyo Electric Power Co. said Saturday, without elaborating on the work that they were engaged in. They are continuing to work on different tasks because they have not shown any abnormal signs since being exposed to over 100 millisieverts of radiation, the utility said.
In response,
The limit has been raised to 250 millisieverts for the ongoing crisis, the worst in Japan's history, by the Health, Labor and Welfare Ministry.
(h/t to politik)
In addition to raising the exposure limit, unmanned operations are being performed where possible
(Kyodo News).
Radiation in water and some foods, specifically milk and spinach from Fukushima prefecture have been detected. Only traces at allowable levels have been found in tap water. The levels found on spinach and in milk from Fukushima exceeded the allowable limits, prompting Japan to ban the sale of food products from Fukushima. Guardian UK and Kyodo News have more information.
In 1 kilogram of spinach grown in open air in the city, 54,000 becquerels of iodine was detected, exceeding the 2,000 becquerel limit preliminarily set by the government under the food sanitation law, the Ibaraki prefectural government said.
The level of cesium in the spinach grown in the city was also higher at 1,931 becquerels, compared to the limit of 500 becquerels.
--snip-- On the Consumer Agency website, Renho, state minister in charge of consumer affairs and food safety, said the reported radiation levels in spinach and raw milk are ''not expected to immediately affect human health,'' and called on the public to ''act calmly. (from Kyodo News).
This article contains much more information on the presence and levels of radioactive iodine and Cs in tap water, milk and other green leafy vegetables in various prefectures.
The disaster has been upgraded on the International Nuclear and Radiological Event Scale (INES) from a level 4 to a level 5 event on its 1-7 scale. What does this mean? gchaucer2 provided us with the following from INES:
Events are classified on the scale at seven levels: Levels 1–3 are called "incidents" and Levels 4–7 "accidents". The scale is designed so that the severity of an event is about ten times greater for each increase in level on the scale. Events without safety significance are called “deviations”and are classified Below Scale / Level 0.
Chaucer gives, in her
comment, INES examples of accidents at each level:
7. Chernobyl, 1986 -- effect on people and environment;
6. Kyshtym, Russia, 1957 -- effect on people and environment -- significant release due to exploding radioactive waste tank;
5. Windscale Pile, UK, 1957 -- effect on people and environment --fire in reactor core;
5. Three Mile Island, 1979 -- Radiological Barriers and Control;
4. Toakaimura, Japan 1999 -- effect on people and environment -- fatal exposures to workers after failure at nuke plant.
For more on INES, see discussion in this
thread.
It was reported that electrical cables had been laid to try to get power to the cooling systems at the reactors, although it is unknown what state either the electrical or cooling systems are in the reactors. According to Kyodo News
external power was restored at 3:46 p.m. to the No. 2 reactor's unit. The company has said it will start trying to restore the system to monitor radiation and other data, light the control room and cool down the reactor and the reactor's spent-fuel storage pool.
Note: this article is an excellent summary of events at the plant on Sunday.
Ultimate Plans for the Plant: TEPCO hopes to have enough power restored to the plant soon to begin running the cooling systems at all the damaged reactors. Should such efforts fail, there has recently been talk of burying the plant in cement as a last resort. More on the logistics of such a prospect can be found this Telegraph UK article. (h/t to mahakali overdrive)
When asked whether it will ever be brought back on line,
Japan’s top government spokesman says the country’s tsunami-ravaged nuclear plant must eventually be scrapped. Chief Cabinet Secretary Yukio Edano’s comment Sunday was the first word from the government that the Fukushima Dai-ichi nuclear complex will have to be closed once its overheating reactors are brought under control. Washington Post
(h/t to Just Bob)
Reactor status update:The IAEA issued the following briefing on Mar 19, 2011 at 4:30 UTC:
Unit 1
Coolant within Unit 1 is covering about half of the fuel rods in the reactor, leading to fuel damage. High pressure within the reactor's containment led operators to vent gas from the containment. Later, an explosion destroyed the outer shell of the reactor building above the containment on 12 March. There are no indications of problems with either the reactor pressure vessel or the primary containment vessel. Efforts to pump seawater into the reactor core are continuing.
On 18 March, Japan assigned an INES rating of 5 to this unit.
Unit 2
Coolant within Unit 2 is covering about half of the fuel rods in the reactor, leading to fuel damage. Following an explosion on 15 March, Japanese officials expressed concerns that the reactor's containment may not be fully intact. NISA officials reported on 18 March that white smoke continues to emerge from the building. Efforts to pump seawater into the reactor core are continuing.
On 18 March, Japan assigned an INES rating of 5 to this unit.
Unit 3
Coolant within Unit 3 is covering about half of the fuel rods in the reactor, leading to fuel damage. High pressure within the reactor's containment led operators to vent gas from the containment. Later, an explosion destroyed the outer shell of the reactor building above the containment on 14 March. Following the explosion, Japanese officials expressed concerns that the reactor's containment may not be fully intact. NISA officials reported on 18 March that white smoke continues to emerge from the building. Efforts to pump seawater into the reactor core are continuing.
Of additional concern at Unit 3 is the condition of the spent fuel pool in the building. There are indications that there is an inadequate cooling water level in the pool, and Japanese authorities have addressed the problem by dropping water from helicopters into the building and spraying water from trucks. On 18 March, Japanese Self Defence Forces used seven fire trucks to continue spraying efforts. There is no data on the temperature of the water in the pool.
On 18 March, Japan assigned an INES rating of 5 to this unit.
Unit 4
All fuel had been removed from the reactor core for routine maintenance before the earthquake and placed into the spent fuel pool. A portion of the building's outer shell was damaged by the explosion at Unit 3 on 14 March, and there have been two reported fires - possibly including one in the spent fuel pool on 15 March -- that extinguished spontaneously, although smoke remained visible on 18 March. Authorities remain concerned about the condition of the spent fuel pool.
On 18 March, Japan assigned an INES rating of 4 to this site.
Unit 5 and 6
Shut down before the earthquake, there are no immediate concerns about these reactors' cores or containment. Instrumentation from both spent fuel pools, however, has shown gradually increasing temperatures. Officials have configured two diesel generators at Unit 6 to power water circulation in the spent fuel pools and cores of Units 5 and 6. Workers have opened holes in the roofs of both buildings to prevent the possible accumulation of hydrogen, which is suspected of causing explosions at other units.
Restoration of Grid
Progress has been achieved in restoring external power to the nuclear power plant, although it remains uncertain when full power will be available.
Spent Fuel Pool Temperatures: In a positive development, it was
confirmed that power has been restored to unit 6, and cooling is functioning effectively.
The most recent reports indicate that units 5 and 6 are relatively stable.
The No. 5 and No. 6 reactors at the quake-hit Fukushima Daiichi nuclear plant went into stable condition on Sunday, after a successful cold shutdown, authorities said.
The reactors at the power plant, whose nuclear reactor buildings were crippled after being hit by the catastrophic quake and ensuing tsunami on March 11, went into cold shutdown following restoration of cooling functions late Saturday. Kyodo News
As for the the other 4,
Kyodo News has confirmed that temperatures in their spent fuel pools are below 100 degrees C:
In a sign that the ongoing operation to cool down the spent-fuel tanks is working, Defense Minister Toshimi Kitazawa said that the temperatures of the pools at all six reactor units were below 100 C. But a temporary rise in pressure in the No. 3 reactor's containment vessel highlighted that authorities are still walking on thin ice in dealing with the disaster
(h/t to peraspera)
Much more information on evacuation, radiation levels, etc can be found in the IAEA link above. These reports are updated regularly.
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