Here's a series of radiation dose rates at 1 meter height, as inferred by US airplane and helicopter overflights. It reveals the general shape of the fallout plume.
[US Department of Energy] The Situation in Japan (Updated 03/29/11)
Here's a couple of them.
Folloiwing up on I-131 and Cs-137 fallout, a new assessment from the IAEA:
[IAEA] Fukushima Nuclear Accident Update Log | Updates of 30 March 2011
Based on measurements of I-131 and Cs-137 in soil, sampled from 18 to 26 March in 9 municipalities at distances of 25 to 58 km from the Fukushima Nuclear Power Plant, the total deposition of iodine-131 and cesium-137 has been calculated. The results indicate a pronounced spatial variability of the total deposition of iodine-131 and cesium-137. The average total deposition determined at these locations for iodine-131 range from 0.2 to 25 Megabecquerel per square metre and for cesium-137 from 0.02-3.7 Megabecquerel per square metre. The highest values were found in a relatively small area in the Northwest from the Fukushima Nuclear Power Plant. First assessment indicates that one of the IAEA operational criteria for evacuation is exceeded in Iitate village. We advised the counterpart to carefully access the situation. They indicated that they are already assessing.
I posted a similar conclusion 3 days ago. This subject was already in the news 5 days ago, and the original data was available to the Japanese ministry MEXT 10 days ago (although they delayed its public release).
IAEA links to a copy of their "Criteria for Use in Preparedness and Response for a Nuclear or Radiological Emergency". My guess is that the criterion is in table 3, effective dose (E) of 100 mSv per annum, suggesting "temporary relocation".
AFP is reporting on this:
[AFP] IAEA worried about radiation in Japan village
The International Atomic Energy Agency said safe limits had been exceeded at Iitate village, 40 kilometres (25 miles) northwest of Fukushima, well outside the government-imposed 20 kilometre exclusion zone and the 30-kilometre "stay indoors" zone.
Tokyo Electric Power Co. stock (Tokyo 9501) -- the utility which just lost four of its commercial reactors -- has had quite a month:
To date, shares of Japan's largest electric utility have lost 78% of their value since the March 11 earthquake, or $32 billion. Debt is also seen as at risk; ratings agencies have downgraded TEPCO [1], its debt is trading at "extremely discounted" prices [2], and the price of credit default swaps (insurance against default on debt) has gone up tenfold [2-3].
Besides the enormous losses and liabilities, one reason for shareholder fear is the serious possibility of nationalization [4-5]. Both sources suggest this would only hurt shareholders as opposed to bondholders (creditors), except in the scenario of a form of bankruptcy [5].
Liability is unclear. Nuclear operators are liable for full damages in accidents, but the Japanese government is liable for accidents caused by certain natural distasters [6]; it hasn't been determined which category this falls under. (Suppliers, e.g. General Electric, have no liability [6]). Legal experts suggest the GoJ will in fact shoulder the cost [6], although GoJ chief cabinet secretary Yukio Edano thinks this is "impossible" under the "social circumstances" [4]. At any rate, TEPCO is seeking $25 billion in (private sector) loans following the catastrophe, which it appears likely to get [7].
[1] [AFP] Ratings agencies downgrade Japanese nuclear plant operator
[2] [WSJ] Tepco Debt Worries Hit Financial Firms
[3] [WSJ MarketBeat] Yikes. Check out CDS on Tokyo Electric
[4] [WSJ] Speculation Grows on Tepco Takeover
[5] [FT Alphaville] Tepco and those nationalisation rumours
[6] [WSJ] Japanese Taxpayers Likely to Shoulder Nuclear Liability
One of the most significant components of fallout is the gamma emitter Cesium-137 (137Cs). As a comparatively volatile, high-yield fission product, it is one of the things you are most likely to detect after a major radiological release. Unlike noble gases (such as xenon and krypton), it does not diffuse away but settles down in soil, where it can be absorbed by plants. Unlike very-short-lived volatile FPs like Iodine-131, 137Cs is stable enough (t_1/2 = 30.17 years) to be a long-term hazard (it is still sufficiently short-lived to be highly radioactive). 137Cs contamination is one of the big reasons for post-Chernobyl exclusion zones still in effect today.
Oxford physicist Wade Allison, writing an opinion in the BBC, makes an assertion about Fukushima Daiichi 137Cs fallout (whose accuracy I am disputing):
[BBC] Viewpoint: We should stop running away from radiation [Wade Allison]
So what of the radioactivity released at Fukushima? How does it compare with that at Chernobyl? Let's look at the measured count rates. The highest rate reported, at 1900 on 22 March, for any Japanese prefecture was 12 kBq per sq m (for the radioactive isotope of caesium, caesium-137).
A map of Chernobyl in the UN report shows regions shaded according to rate, up to 3,700 kBq per sq m - areas with less than 37 kBq per sq m are not shaded at all. In round terms, this suggests that the radioactive fallout at Fukushima is less than 1% of that at Chernobyl.
The measurements in the linked source are of (individually measured) 131I and 137Cs deposition levels, measured in mega-Becquerels of activity per square kilometer of area (MBq/km2). The problem with Professor Allison's claim is that the figure he cites is from the Ibaraki prefecture, at a great distance from Fukushima Daiichi. According to the source, these Bq/km2 measurements are not being performed in Fukushima prefecture (where Fukushima Daiichi plant, and the entire evacuation zone around it, is located). The prefecture-level fallout summaries exclude the prefecture where the fallout levels are certainly the highest, as well as the neighboring Miyagi prefecture (here's a map of Japanese prefectures).
I stress that I have no clue about the accuracy of the following reports, or if I understand them correctly, or what the reasonable implications are; I am in no way an expert on this subject, and it is certainly not my intention to contribute to the (already overwhelming) volume of poorly-informed panic-raising. But; at least two credible sources, the major newspaper the Asahi Shimbun and the American journal Science, estimate there are substantially higher 137Cs fallout levels in Fukushima prefecture -- including outside of the mandatory evacuation zone. (Particularly in the village Iitate in the Fukushima prefecture, about 40 km from Fukushima Daiichi). These are measurements of soil samples, expressed in Bq/kg 137Cs as opposed to Bq/m2 (reflecting, I assume, a different measurement technique). You could only approximate the Bq/m2 deposition rate from this figure, but the values being reported (3.26 MBq/m2 and 8 MBq/m2) are amazingly high, and would constitute a long-term health hazard if accurate.
[Asahi Shimbun] Radiation from Fukushima exceeds Three Mile Island
Cesium-137 levels of 163,000 becquerels per kilogram of soil was detected in Iitate, Fukushima Prefecture, about 40 kilometers northwest of the Fukushima plant, on March 20. That was the highest figure in the prefecture.
According to Tetsuji Imanaka, an associate professor of nuclear engineering at the Kyoto University Research Reactor Institute, if the Iitate figure was converted to one square meter, the figure would be 3.26 million becquerels.
[Science] Japan Soil Measurements Surprisingly High
Based on a rough estimate, a person standing on soil with 163,000 Bq/kg of cesium-137 would receive about 150 millisieverts per year of radiation, says [Shih-Yew Chen of Argonne National Laboratory]. This is well above the U.S. Environmental Protection Agency standard of 50 millisieverts per year for an evacuation. (Per day, it's 0.41 millisieverts, which is equivalent to four chest x-rays.) But Chen adds, "one point [of data] doesn't mean that much."
The hot spot is similar to levels found in some areas affected by the 1986 Chernobyl nuclear reactor accident in the former Soviet Union. Assuming the radiation is no more than 2 centimeters deep, Chen calculates that 163,000 Bq/kg is roughly equivalent to 8 million Bq/m2. The highest cesium-137 levels in some villages near Chernobyl were 5 million Bq/m2.
The primary source is the Japanese ministry MEXT: Reading of environmental radioactivity level（English version)
I do not think that 150 mSv/year is an immediately hazardous dose rate, or that it is actually what Iitate residents are exposed to (dose levels indoors should be rather lower). But it is a chronically hazardous dose rate. 150 mSv/year is beyond linear no-threshold debates about "low level" radiation; it is (I understand) uncontroversially dangerous, that prolonged exposure would result in significantly increased cancer risk. For example the threshold described in the Health Physics Society position paper is 50 mSv in one year, or 100 mSv in a lifetime. According to a radiobiology textbook suggested by Google, the excess risk cancer mortality risk (which is lower than total cancer risk) would be, according to ICRP recommendations, around 0.5-1.0% from 150 mSv total dose (that is, one year of 150 mSv/year). Longer exposures would carry proportionally higher risks.
[Google Books excerpt] Radiobiology for the radiologist By Eric J. Hall, Amato J. Giaccia
For this reason, this level of 137Cs fallout would (I understand) force a permanent evacuation, if it covered a large area. For example, it compares with Chernobyl closed zones: 3.26 MBq/m2 and 8 MBq/m2 are respectively 88 and 216 Ci/km2, falling into the "Confiscated/Closed zone" on this map (of 137Cs levels in 1996):
Notably, parts of Iitate are outside of the 30-km mandatory evacuation zone, although many residents appear to be spontaneously evacuating of their own accord.
Any experts care to comment?
Google Map shows location of Iitate village (A) relative to Fukushima Daiichi NPP (B). Dotted lines are prefectural borders; (A) and (B) are in Fukushima prefecture.
The IAEA site (which I've linked before) has become a lot more informative and detailed:
http://www.iaea.org/newscenter/news/tsunamiupdate01.html
This seems to be the best English-language summary currently available.
Here's a clarification possible due to IAEA's precise language. Seawater is, in fact, being injected into the reactor pressure vessels (i.e. the core, where the fuel is). Some other reporting was ambiguous as to whether it was the RPVs or the secondary containments.
(Update: actually the JAIF site clarifies that the water injection is in both the RPVs and the containment vessels, in units #1 and #3. No containment-vessel injection in #2 (maybe because of the suspected hole?))
[Telegraph] Japan earthquake: panic in Tokyo as radiation spreads
But it also reported that radiation levels in Saitama, just outside Tokyo, were 40 times usual levels, although still not harmful to health.
Winds from the stricken Fukushima Daiichi nuclear plant were travelling in a south-westerly direction towards Tokyo, 155 miles away, at two to three metres per second.
[NYT] Japan Faces Potential Nuclear Disaster as Radiation Levels Rise
Tokyo Electric Power said Tuesday that after the explosion at the No. 2 reactor, pressure had dropped in the “suppression pool” — a section at the bottom of the reactor that converts steam to water and is part of the critical function of keeping the nuclear fuel protected. After that occurred, radiation levels outside No. 2 were reported to have risen sharply.
“We are on the brink. We are now facing the worst-case scenario,” said Hiroaki Koide, a senior reactor engineering specialist at the Research Reactor Institute of Kyoto University. “We can assume that the containment vessel at Reactor No. 2 is already breached. If there is heavy melting inside the reactor, large amounts of radiation will most definitely be released.”
Another executive said the chain of events at Daiichi suggested that it would be difficult to maintain emergency seawater cooling operations for an extended period if the containment vessel at one reactor had been compromised because radiation levels could threaten the health of workers nearby.
Unclear what the contents of the radioisotope plume are -- noble gases only, or iodine and cesium as well? I cannot find monitoring data on this (common Geiger counters do not distinguish them). (update: At least trace amounts of both detected).
Separately, a spent fuel pond exposed to the atmopshere caught fire -- but this has been put out:
http://www.iaea.org/newscenter/news/tsunamiupdate01.html
Japanese authorities also today informed the IAEA at 04:50 CET that the spent fuel storage pond at the Unit 4 reactor of the Fukushima Daiichi nuclear power plant is on fire and radioactivity is being released directly into the atmosphere.
Latest JAIF status report says 400 mSv/hr (milliSieverts) dose rate immediately adjacent to reactors; 8.2 milliSieverts/hr (8,200 μSv/hr) at site boundary. Most nuclear workers evacuated from the site.
http://www.jaif.or.jp/english/
(Update) But they've fallen since then:http://www.reuters.com/article/2011/03/15/japan-quake-radiation-idUSTFD00668420110315Chief Cabinet Secretary Yukio Edano told reporters that radiation levels at the Fukushima Daiichi complex, more than 200 km north of Tokyo, had fallen dramatically to 596.4 microsieverts per hour as of 0630 GMT.
Wind shifting inland, first from NE towards Tokyo, then from E:
[Reuters] Wind near quake-hit Japan nuke plant to blow inland on Tuesday
A third reactor has gone south:
The plant’s operator, Tokyo Electric Power, said late Monday that repeated efforts to inject seawater into the reactor had failed, causing water levels inside the reactor’s containment vessel to fall and exposing its fuel rods. After what at first appeared to be a successful bid to refill the vessel, water levels again dwindled, this time to critical levels, exposing the rods almost completely, company executives said.
Workers were having difficulty injecting seawater into the reactor because its vents — necessary to release pressure in the containment vessel by allowing radioactive steam to escape — had stopped working properly, they said.
The more time that passes with fuel rods uncovered by water and the pressure inside the containment vessel unvented, the greater the risk that the containment vessel will crack or explode, creating a potentially catastrophic release of radioactive material into the atmosphere...
[NYT] Emergency Cooling Effort Failing at Japanese Reactor, Deepening Crisis
Video of new explosion:
[YouTube] Fukushima I Nuclear Power Plant Reactor 3 explosion on March 14, 2011
Photo from a Japanese-language magazine (?) called "Gigazine" (click to enlarge):
[Gigazine] 福島第一原発3号機で水素爆発が発生、半径20km圏内の住民は屋内待避を
Photos from Google / DigitalGlobe / GeoEye, published by ABC (Australian news):
[ABC] Japan Earthquake: before and after
| Fukushuima-Daiichi #1 after explosion: [1] | GE Mark I BWR containment [2] |
 |
 |
Here's the labeled cutaway again:
GE Mark I BWR containment [Magdi Ragheb, U. Illinois at Urbana-Champaign]
[1] [NYT] Japan Floods Nuclear Reactor Crippled by Quake in Effort to Avert Meltdown
[2] [NRC] Reactor Concepts Manual | Boiling Water Reactor (BWR) Systems
The spent fuel pool is on the top floor of the reactor building (assuming this is the same layout):
GE Mark I BWR containment [Magdi Ragheb, U. Illinois at Urbana-Champaign]
(Newer photo!) Fukushuima-Daiichi #1, after: [NYT]
Fukushuima-Daiichi #1, before and after [NYT]
Has it collapsed with the rest of the building? Is it exposed? I haven't seen any official comment about this.
(News sources seem contradictory on what exactly collapsed: NY Times at one point says "destroyed the concrete structure surrounding the reactor", at another "destroyed the exterior walls of a crippled reactor". Which is it? (But then, they also say that GoJ and TEPCO "gave confusing accounts of the causes of the explosion and the damage it caused"...))
"We've confirmed that the reactor container was not damaged. The explosion didn't occur inside the reactor container. As such there was no large amount of radiation leakage outside"
--Japan Chief Cabinet Secretary Yukio Edano [5]
[Russia Today/YouTube] Video of blast at Fukushima nuke plant, radiation leak reported
Developing news:
[1] [Guardian] Japan nuclear alert and earthquake - live coverage
[2] [WSJ] Japan Officials Probe Nuclear Plant Collapse
[3] [BBC] Huge blast at Japan nuclear power plant
[4] [Guardian] Fukushima nuclear plant blast puts Japan on high alert
[5] [Reuters] Japan to fill leaking nuke reactor with sea water
[6] [WSJ] Japan Fills Damaged Reactor With Seawater
[7] [IAEA] Japan Earthquake Update (2030 CET)
[8] [WSJ]Japan Tries Using Seawater to Cool Damaged Reactor
[9] [WNA] Battle to stabilise earthquake reactors
[10] [NHK/Wikipedia] Before and after image of Fukushima I Nuclear Power Plant Unit 1
[11] [NHK] 3 patients exposed to radiation in Fukushima
[12] [Reuters] Health risk from Japan reactor seems quite low-WHO
(This post is being updated without warning)
Very developing news:
(earlier content follows)
The biggest crisis supposedly involves Fukushima-Daiichi unit #1 [ref 1]. According to IAEA's CNPP database [ref 2], this is a General Electric BWR/3 reactor [table, ref 3] (refuting wikipedia [ref 4], which incorrectly thinks it is a BWR/4). Nuclear Tourist [ref 5] says this reactor uses a Mark I containment (pictured below). An NRC introduction I found, "Reactor Concepts Manual | Boiling Water Reactor (BWR) Systems" [ref 6], gives a basic overview of the coolant systems which are in the news (RCIC, ECCS). Some more information is in an article by Madgi Ragheb (UIUC) [ref. 7]
There are ongoing press releases from TEPCO with details [11].
Brave New Climate has a very active discussion thread [17]
Developing news:
GE Mark I BWR containment [Magdi Ragheb, U. Illinois at Urbana-Champaign]
GE Mark I BWR containment [NRC]
[1] [WSJ] Nuclear Plants Release Radiation
[2] [IAEA] Country Nuclear Power Profiles 2010
[3] [IAEA CNPP] Reactors in Operation, 31 Dec. 2009
[4] [Wikipedia] List of boiling water reactors
[5] [Nuclear Tourist] Containment
[6] [NRC] Reactor Concepts Manual | Boiling Water Reactor (BWR) Systems
[7] [M. Ragheb] Containment Structures
[8] [BusinessWeek] Japan Reactor Rods May Have Started to Melt, Agency Says
[9] [Mainichi Shimbun] Meltdown feared at Fukushima nuclear plant after quake
[10] [Nikkei] Possible Meltdown At Tepco Reactor
[12] [TEPCO] Plant Status of Fukushima Daini Nuclear Power Station (as of 1PM March 12th)
[13] [TEPCO] Plant Status of Fukushima Daiichi Nuclear Power Station (as of 1PM March 12th)
[14] [Washington Post] Japanese nuclear reactors in peril, radiation surges after earthquake, tsunami
[15] [ANS] Radiation Dose Chart
[16] [MSNBC] Japan braces for meltdown at nuclear plant
[17] [Brave New Climate] Discussion Thread – Japanese nuclear reactors and the 11 March 2011 earthquake
[18] [NYT] Radioactive Element Detected Near Nuclear Plant
[19] [CNN] Report: Explosion near Japanese nuclear plant
[20] [LA Times] Meltdown fears rise as walls crumble at Japan nuclear site
[21] [Telegraph] Japan earthquake: nuclear disaster feared after power plant 'explosion'
This post is obsolete. It was a developing live-blog of events and is no longer accurate.
A compilation from various sources:
The NPP has 10 reactors: Fukushima Daiichi (Fukushima 1) has six units, and Fukushima Daini (Fukushima 2) has four. According to TEPCO, Fukushima Daiichi #4,5,6 were in an outage, and the other seven were shut down in the earthquake [11].
[1] [Guardian] Japan declares 'nuclear emergency' after quake
[2] [NEI Magazine] Japan initiates emergency protocol after earthquake
[3] [AFP/Kyodo] Fire breaks out at Japanese nuclear plant: Kyodo
[4] [AP] Japan to evacuate residents near nuke plant
[5] [Reuters] Japan trying to fix nuclear plant cooling problem
[6] [Washington Post] Japan issues emergency at nuke plant; no leak
[10] [IAEA] Japan: Nuclear Power Reactors - Alphabetic
[11] [TEPCO] Impact to TEPCO's Facilities due to Miyagiken-Oki Earthquake (as of 10PM)
[12] [Bloomberg] Japan Orders Evacuation From Near Nuclear Plant After Quake
[Mainichi Shimbun] 10-meter tsunami observed in area near Sendai in Miyagi Pref.
TOKYO (Kyodo) -- A 10-meter tsunami was observed at Sendai port in Sendai, Miyagi Prefecture, in northeastern Japan, at around 3:55 p.m. after a powerful earthquake with a magnitude of 8.4 [upgraded to 8.9] rocked the region Friday, local police said.
[...]
A 7.3-meter tsunami was also observed in Soma port in Sendai and elsewhere, the [Japan Meteorological Agency] said, adding a 4.1-meter tsunami was observed in Kamaishi port in Iwate Prefecture in northern Japan, the agency said.
Anyone know the status of the nuclear reactors on this coast? My rough reading is that they must have seen a direct strike. In particular Onagawa NPP is extremely close to the epicenter.
(Update) To answer my own question:
[Reuters] Fire at Tohoku Elec Onagawa nuclear plant -Kyodo
(Reuters) - A fire broke out at Tohoku Electric Power Co's (9506.T) Onagawa nuclear plant in northeastern Japan following Friday's major earthquake, Kyodo news agency said.
Also, at another NPP (!!!)
[Reuters] Japan: trying to fix nuclear plant cooling problem
(Reuters) - Japan said on Friday a cooling function at Tokyo Electric Power's (9501.T) Fukushima Daiichi nuclear plant was not working after a major earthquake but that it was trying to get backup power for cooling.
The government has declared an emergency situation as a precaution but there was no radioactive leakage and no damage from the cooling problem was expected at this stage, Chief Cabinet Secretary Yukio Edano told a news conference.
(Note that the first article contradicts the second; the second was published an hour later so I assume the first was in fact wrong?)
Emergency diesel generators not working, reports NEI magazine (Nuclear Engineering International, not the lobby group Nuclear Energy Institute):
[NEI Magazine] Japan initiates emergency protocol after earthquake
-Utility TEPCO has requested the establishment of a nuclear emergency response programme for Fukushima Daiichi 1&3 and Fukushima Daini 1.
JAIF reported that Fukushima Daiichi 1, 2 and 3 automatically shut down; units 4, 5 and 6 were in maintenance outages. Fukushima Daini 1, 2, 3 and 4 automatically shut down.
JAIF has reported that TEPCO sent the emergency report because emergency diesel generators at the two sites are out of order. It said that there is no report that the radiation was detected out of the site. It said that an emergency headquarters has been set up and will issue information hourly.
One of the emergency coolant systems has been activated (not elaborated which):
[AFP] Fire breaks out at Japanese nuclear plant: Kyodo
Kyodo also reported that an emergency core-cooling unit had been activated at Fukushima nuclear plant, without giving further details.
![[NHK/Wikipedia] Before and after image of Fukushima I Nuclear Power Plant Unit 1](http://en.wikipedia.org/wiki/File:2011-03-12_1800_NHK_S%C5%8Dg%C5%8D_channel_news_program_screen_shot.jpg){kind=link}