Friday, March 25, 2011

"Breach" Feared at Fukushima Daiichi Based on Large Amounts of Radiation Detected in Turbine Room Water

I sent the following email to a friend of mine last night as a possible explanation for the high radioactivity of the Reactor 3 turbine room water:

The news coming out of Japan is still very meager. After the explosion of reactor building 2, two workers were said to be missing. Were they found? Are they dead? Who knows? The Japanese media is too polite to ask.

Two workers were in a turbine room today with 12 inches of standing water on the floor. They only had on regular boots, which were soaked. After several hours, they developed large sores through to the muscle. Supposedly the radiation levels were measuring fairly low, but most radiation detectors do not detect beta particles because they can be stopped by a sheet of paper.

And indeed, the wounds have been said to be beta burns. What puts out beta? Tritium. But what produces tritium in a nuclear plant that runs with regular water? Well some tritium is produced by neutron bombardment of the water in the reactor, but it is supposed to be a small amount. A hydrogen atom has to pick up two neutrons, which doesn’t happen often. Tritium production is slow even in heavy water reactors.

But Boron, when hit with a high energy neutron, will produce quite a bit of tritium. (When hit with a low energy neutron, it generally goes to lithium.) This would imply that the boron-treated water that they have been putting into the pools and reactors has been boiling away, leaving encrustations of boron behind (and literally tons salt from the sea water, but that is another story). The water, which would act as a neutron moderator, is gone, so the high energy neutrons are converting the boron to tritium.

I bet they are releasing gobs and gobs of tritium, and don’t even know it, since many of their detectors won't see it.

There are two possibilities: 1) The water is coming directly from the core through a breach.  2) The spent fuel pool has become critical and is producing high energy neutrons like a reactor.

Thursday, March 24, 2011

Total radioactive emissions at Fukushima are in the same order of magnitude as Chernobyl

The Austrian "Zentralanstalt für Meteorologie und Geodynamik (ZAMG) (the official meteorological and geophysical service of Austria), has produced an analysis estimating the total emissions of Iodine-131 and Cesium-137 since the beginning of the crisis at Fukushima Daiichi, finding them of the same order of magnitude as the emissions at Chernobyl.  The radiation load is measured in Becquerels (Bq). Each Bq is the disintegration of a single atomic nucleus, so the values become quite large. They are expressed in scientific notation.
"In the phase of March 12 to 13, the Fukushima emissions were mostly transported to the Pacific, eventually hitting the CTBTO station in Sacramento/California. In the phase March 14 to 15, on the other hand, most of the emissions were transported inland, hitting the CTBTO station in Takasaki, Japan. Based on simulated dilution factors and measurements, we were able to have a first rough source estimate.

"Regarding Iodine-131, the picture is relatively homogeneous. A source term [total release] of 1017 Bq per day would explain the measurements in Takasaki as well as Sacramento. The total 4-day emission of 4x1017 Bq is on the order of  20% of the total emissions of Iodine-131 that occurred during the Chernobyl accident. Regarding Cesium-137, the situation is a bit different. In the cloud eventually propagating to the United States, the ratio of Iodine-131 to Cesium-137 was about 30. This is similar to the Chernobyl accident. In Takasaki, however, this ratio was four. This would indicate a much larger Cesium-137 release in the second two-day period after the accident. Taking this together, the source term [total release] would be about 3x1015 Bq during the first two days, and 3x1016 during the second two-day period. In sum, this could amount to about 50% of the Chernobyl source term of Cesium-137.

For more, click here for the English pdf download.

So far, I believe Japan has been very lucky that the winds have been primarily out to sea (toward the east).  I also note that their evacuation/shelter zone is the exact same size as the one that was initially specified for Chernobyl: 30 km (approx. 19 miles). However, the American government has advised their citizens to evacuate out to 50 miles from the plant.  The outskirts of Tokyo are only 130 miles away, with fairly large population centers in the 100 mile range.

It is important to note that the total quantity of fuel involved in the Fukushima Daiichi disaster is  much more than that at Chernobyl -- perhaps by a factor of 30 times.  There are at least 3 fueled reactors with very serious damage, and an exceptionally large amount of fuel was being stored in each of the spent fuel pools.  Plus some concern exists about the fifth and sixth reactors and pools.

This is still an exceptionally serious situation.

Wednesday, March 23, 2011

Deshaked, Sharpened Fukushima Daiichi Helicopter Videos

He used VirtualDub+Deshaker


Fukushima Daiichi Reactor Number 3 and 4 Damage Analyses

Reactor Building 3 at the Fukushima Daiichi Nuclear Power Plant has sustained significant damage from a hydrogen explosion that was much larger than the explosions that damaged the other buildings.  The question that we would like to answer is whether or not the top of the reactor vessel or any of the various levels of containment have been damaged, and whether or not the spent fuel pool has been damaged.

First, we need to understand the configuration of the spent fuel pool and the top of the reactor.  Here is the schematic of the power plant:

During refueling or inspection, the top cap of the concrete shell, the steel containment vessel, and the top of the reactor vessel can be removed by the building crane to access the fuel rods in the reactor.  Before this operation, the spent fuel pool and the top of the reactor area are all flooded with water.  This enables the fuel to be removed and placed into the spent fuel pool while still being submerged at all times.  The way the design allows this to be done can be seen more easily in the next figures.

The whole top area is flooded when transferring fuel.  Seals around the reactor keep the water from flowing into the dry well.  Gates with inflatable seals keep the water in the spent fuel pool after the operation is complete.  Except for the gates, the fuel pool is surrounded by fairly thick concrete.

The source of these diagrams is at "All Things Nuclear":  They also have a more detailed discussion about seal integrity, and the fact that leakage has occurred in other plants when the air pressure is lost and the seals deflate.  It is likely that the seals are at least leaking, or may even be blown away completely in some cases.

The following is an overhead view (also from the previous link) "of an irradiated spent fuel bundle being transferred from the reactor core (lower right) to the spent fuel pool (upper left) through what is called the 'cattle chute' at the Browns Ferry Nuclear Plant in Alabama. The spent fuel pool gate has been removed to connect the spent fuel pool water with the water in the reactor well area above the open reactor pressure vessel."

To further understand what this looks like at Fukushima, we can peer into the ruins of Reactor Building 4:

We are looking here at the SE corner of the building.  I am fairly sure that the top two "stories" of number 4 are the open area at the top of the reactor where the crane runs.  The floor of the second floor from the top, where the steam is coming from, is the top of the spent fuel pool.  In the following closeup, you can see the green building crane dolly, about the size of a Greyhound bus, which appears to have fallen from its rails and is laying on top of the spent fuel pool.  The thick and largely intact gray beam above the crane is one of the rails, I believe.

For number 4, the spent fuel pool may be intact, but the holes in the building on the right side, third floor from the top make me wonder.  Also, the gates with their inflatable seals, are probably leaking badly.  The Japanese apparently have been successful in spraying large quantities of water into this area.

In looking at the photos of the Reactor Building 3 damage, my concern is that the top of the remaining ruins are so low that the reactor top may be missing, and the spent fuel pool largely destroyed.

First let's look at the Number 1 building for some perspective on the problem.  A hydrogen explosion destroyed the top crane attic of this building too, but much less damage to the rest of the building occurred.  It appears that Number 1 had a different design, with a more fragile upper two stories.  This weakness allowed the explosion (which may have been smaller to begin with) to exit the building without building up damaging pressure in the lower floors.  The remaining top structure beams are the equivalent height as the top two stories in Buildings 3 and 4, I believe, even though the top of Number 1 has three repeating structures, i.e. three "stories".

We do not see all the way to the ground around the building, but it appears that the top one-quarter is damaged.  It also appears that a central structure exists -- perhaps the top cover to the reactor, perhaps not.  I would expect that the top of the spent fuel pool is right at the top of the undamaged section.

Reactor Building 3 sustained severe damage from a very large explosion.  The damage to the facing side of Number 4 was caused by the explosion of Number 3.  In the following video, note the large structural components falling after being blown thousands of feet into the air.

Here are views of the damage to 3:

Reactor Building 3 in foreground left.  North side of Reactor Building 4 in middle of image.

The west side of 3

The northeast corner of 3 (left upper part of the frame), looking mostly east

The southeast corner of 3

Looking down onto the west side of 3

The northwest corner of 3.  West side of 2 on left, north side of 4 on right.  Intervening materials and structures do not allow us to see the base of the buildings, making the buildings seem shorter than they are.

West side of 3. The damage on this side is extensive down to a level below that seen on the east side.  The building is basically destroyed to the tops of the support buildings nearby.

I believe that the top of the free standing skeleton wall on the east side is at the original top of the building.  The spent fuel pool at the SE corner, with the steam coming out, appears to have some damage to its concrete walls and structure, but may be largely intact.  I would suspect that the gates and seals are gone -- blown away by the explosion.  This would mean, based on the diagrams above, that the tops of the rod assemblies in the pool are at the top of the maximum possible water level with no gates.  It is likely impossible to fully cover the rods.

There is no evidence of the building crane dolly.  Not sure where it went.

The following thermal IR image shows the spent fuel pool in 3 glowing at 62 deg C.  The center of the building, around the reactor cap, is glowing at 128 deg C.  This likely represents steam leaking from the primary containment through a damaged reactor dry well top cap -- or perhaps scattered fuel assemblies.

The spent fuel pools were pretty much at or above capacity.  Those in Building 3 contained MOX, a mixture of plutonium and uranium.  Not good.  Probably worse than is being reported, if my analysis is correct.

And I am really concerned about what is happening under that hot roof of Building 2.

click for hi-res

Monday, March 21, 2011

Infrared (IR) Thermal Heat Map Images of Fukushima Daiichi

Japanese NHK TV showed these images today (22 March in Japan). Some areas are supposedly 128 degrees C. They also mentioned a core temperature, but I must have heard it wrong. I thought I heard 300-some degrees C. Can't be right.  Black smoke has been coming out of reactor 3.

NHK TV image

Fukushima Reactors 1 through 4 in false-color IR.  Blue and green are cool, orange and red are hot, white is very hot

Closeup of Reactor 3

Reactor 3.  The building appears to have been almost totally destroyed.  I can't imagine that the spent fuel pool is intact.  It is located fairly high in the structure -- and there is nothing left much higher than the surrounding low buildings.  I wonder if the reactor vessel top has been crushed or broken off.


Sunday, March 20, 2011

Japanese Response Slow -- Finally Start to Issue Potassium Iodide

From yahoo news:

"Amid concerns of wider contamination, a nuclear safety official said the government was caught off-guard by the accident's severity and only belatedly realized the need to give potassium iodide to those living within 12 miles (20 kilometers) of the Fukushima Dai-ichi nuclear complex.

"The pills help reduce the chances of thyroid cancer, one of the diseases that may develop from radiation exposure. The official, Kazuma Yokota, said an explosion at the plant's Unit 3 reactor last Sunday should have triggered the distribution. But the order only came three days later.

"'We should have made this decision and announced it sooner,' Yokota told reporters at the emergency command center in the city of Fukushima. "'t is true that we had not foreseen a disaster of these proportions. We had not practiced or trained for something this bad. We must admit that we were not fully prepared.'"

Saturday, March 19, 2011

Fukushima nuclear reactor 3 being cooled with firehoses (Video)



Radiation Detected in Japanese Food and Tap Water

TOKYO, March 20, Kyodo

Radioactive iodine beyond Japan's regulated standard was detected in tap water in a town in Fukushima Prefecture on Thursday, apparently due to the nuclear crisis at the Fukushima Daiichi nuclear power plant, the government said Saturday.

The health ministry said levels on Friday and Saturday in the town of Kawamata were below the limit but milk there has been found to contain radioactive iodine above the country's standard, raising concern about radioactive contamination in the region.

Kawamata is located around 45 kilometers northwest of the nuclear power plant.

Meanwhile, slight amounts of radioactive iodine have been detected in tap water in Tokyo, its vicinity and most prefectures neighboring Fukushima, the government said the same day.

While the substance was found in Tochigi, Gunma, Niigata, Chiba and Saitama prefectures as well as Tokyo, traces of cesium have been also found in tap water in Tochigi and Gunma, the Ministry of Education, Culture, Sports, Science and Technology said, adding the levels would not affect human health even if ingested.

Tochigi, Gunma and Niigata prefectures border Fukushima Prefecture.

The Gunma prefectural government said it had detected the substances for the first time since it began testing tap water for radioactive materials in 1990.

Full story:

Swedish government advises their nationals in Tokyo to take potassium iodide

The Swedish government, as reported on the government Radiation Protection Agency website, is advising all Swedes in the Tokyo area to begin taking potassium iodine tablets based on an expected wind change that will bring radiation into the city.

Any Swedes who do not have tablets can pick them up at the Swedish Embassy in Tokyo.

Here is a Google translation of the website.

Everything you need to know about medical protection against radiation

The radiation released in Japan is fairly small compared to, say, Chernobyl, and should not cause much of a concern for the US.  But the whole situation has raised awareness of nuclear radiation and the potential for future nuclear disasters.

Since the mid-1990s, I have maintained a personal stock of potassium iodate medication, which protects the thyroid from radioactive iodine-131. I chose potassium iodate (KIO3) (from a company called Medical Corps) because of its longer storage life when compared with potassium iodide (KI).  Additionally, some studies show that large doses of KI may cause thyroid cancer.

Either medication is only to be taken in an acute emergency, and certainly is not recommended for general everyday use or for low levels of radiation such as what we expect to see wafting in from Japan.

But radioactive iodine-131 is only one part of the problem, and I have been wondering what to do about the other radioactive elements that are produced in nuclear disasters of various sorts. The most concerning products of nuclear fission in addition to iodine-131 are strontium-90, cesium-137, and cesium-134.  You would see these in any nuclear plant meltdown or following a nuclear explosion.  But in a "dirty bomb" situation, all bets are off, and you could see just about any radioactive element from radium to cobalt-60 to polonium.

Noodling around on the web, I found all kinds of information and disinformation, including so-called holistic cures of very dubious efficacy.

Then I stumbled onto the US Department of Health and Human Services' excellent web site called "Radiation Emergency Medical Management - Guidance on Diagnosis and Treatment for Health Care Providers", located here.  You can download the whole site as a zip file (569 MB) to your computer here, or an abridged version onto your mobile device here.  I would suggest that everyone download the whole site.  On the internet, you never know when something may disappear.

The site is vast, and includes information on every medical aspect of radiation contamination with full descriptions of what to do in almost any eventuality.  One page shows a table of radioactive isotopes and their effects on the body, along with another table listing the various countermeasure medications to be used for each isotope.  Unfortunately, several of these medications are prescription only, which means of course that in a real disaster, by the time the medications get to people, it will likely be too late.

But to protect against strontium-90 and cesium-137/134, it might be a good idea to get some Prussian Blue, and some sodium alginate (made from kelp), both of which appear to be readily available (although the medical-grade Prussian Blue, aka Radiogardase, is apparently prescription only).

Medical Corps is currently trying to get caught up on their orders for KIO3, and has suspended new orders temporarily, but they apparently still have a very large stock.

Of course, keeping radioactive isotopes out of your body as much as possible to begin with is the best thing to do.  Contamination on the skin can be washed off, but the effects get much worse when radioactive particles are ingested or inhaled.  The first line of defense is a good mask.  Even now, you can pick up surplus nuclear/biological/chemical masks, with a bunch of extra filters, for less than $50 on eBay.

Cold War era radiation survey meters (geiger counters and the like) are also available on eBay, but are not very sensitive.  A good modern alternative is The Inspector, for about $500.  These all measure dose rate -- how much radiation you are exposed to per hour.  Cold War era pen-shaped dosimeters are also available that measure your accumulated dose.  Again, they are not very sensitive and are more suited to a nuclear war situation, where you are trying to determine if you will be 1) not sick, 2) a little sick, 3) not going to make it.

In other words, most of the Cold War items are intended mostly for triage and deciding when you might be able to leave a shelter, not for trying to determine if you are getting a small dose that may increase your cancer risk.

JP Laboratories makes some postage stamp-sized RADsticker dosimeters that are cheap ($4), but only start to change color at 25 rads.  A friend gave me one, but I really want to know well before I get that much radiation.

They also have the credit card-sized RADTriage-FIT that starts to change color at 1 or 2 rads, which is probably about right since the allowed yearly occupational dose is 5 rads, and it is generally accepted that cancer risk begins to increase around 10-20 rads.  These dosimeters have limited life (a year or two), but can be frozen to increase life to 5 years or so.  A good site for some of these items is KI4U, Inc.

Stay safe out there.

Friday, March 18, 2011

Latest Satellite Photo of Fukushima Daiichi from DigitalGlobe Friday 18 March

Click on the image below for a high resolution version.  Be sure to click a second time if your browser defaults to a version that autofits to your window.

I would suggest that the cessation of steam coming from the reactors is concerning.  There may be no water in them anymore.

Radiation Plot at Main Gate of Fukushima Daiichi

Here is a partial plot of radiation rates at the main gate and other locations around the nuclear plant at Fukushima Daiichi.

Click image for larger version
The peaks at 12,000 microsieverts/hour corresponds to 1.2 rem per hour.  Less than two hour's exposure at this rate would be equivalent to the maximum occupational exposure limit for an entire year (2 rem).  A day's exposure would be quite unhealthy.  Several days could cause acute radiation sickness.

(The occupational exposure limit for emergencies is 10 rem.  This has been increased to 25 rem for Fukushima.  After workers reach this limit, they cannot return to the plant.)

Note that these peaks were measured at the main gate -- a long way from the reactors themselves.

CNN is reporting tonight that a radiation exposure rate of 20,000 microsieverts/hour has now been recorded.  The highest peak so far.  Things don't seem to be getting better.

The original data on the chart is from the plant operator Tokyo Electric Power Company (TEPCO), and was plotted and analyzed by the German organization Gesellschaft fuer Anlangen- und Reaktorsicherheit (GRS) mbH.

Fukushima Daiichi Reactor Status 18 March 1000 JST (0100 UTC)

The website of the Japan Atomic Industrial Forum (JAIF) has the latest detailed status of the damage and the efforts being taken to regain control of the situation.  Here is their website:

The latest report is dated 18 March, 1000 JST (17 March 2100 United States EDT) and is shown below:

Click image for larger version
The complete pdf report from the JAIF website also contains additional information

Thursday, March 17, 2011

Miniature NHK Model of Fukushima Daiichi Nuclear Facility

NHK TV has built a model of the whole Fukushima Daiichi Nuclear Power Plant.

Here is a closeup of their models for reactors 3 and 4:


Fukushima Daiichi Spent Fuel Storage Pools and Current Status

17 March 1200 JST.

The storage pools for spent nuclear fuel are located in the top parts of the reactor buildings, so that fuel normally removed from the reactors can quickly be placed into the pool.

Diagram showing the location of the pool in each reactor

The pool in reactor building 4 has caught fire twice and it was originally thought that there was no water left in the pool. Today it was discovered that there was still water in the pool.

As you can see below, the pool in reactor building 3 appears to be gone -- scattered perhaps by the hydrogen explosion that destroyed the exterior building

The remnants of the reactor building 3 is on the left.  Reactor building 4 is in the middle of the photo.

Reference photo of the plant, showing reactors 2, 3, and 4 (l to r).  This was taken from an angle similar to that of the previous photo.  Note that the reactor building 3 has now collapsed almost down to the level of the low buildings.

Another photo of the damaged reactor building 3

Satellite photo of the four reactors on 16 March

"Plutonium-uranium mixed oxide (MOX) fuel rods are placed in a storage pool at the No. 3 reactor of the Fukushima Daiichi nuclear power plant in Fukushima Prefecture, northern Japan, in this picture taken August 21, 2010. Operators of the earthquake-crippled nuclear plant in Japan again deployed military helicopters on March 17, 2011, in a bid to douse overheating reactors, as U.S. officials warned of the rising risk of a catastrophic radiation leak from spent fuel rods." REUTERS/Kyodo

It is obvious to me that the spent fuel pool in reactor building 3 has been destroyed.

An attempt was made this morning (JST) to dump sea water on reactor 3 using helicopters, but it appeared to be highly unsuccessful.  The four dumps were made at fairly high altitude (1000 meters), and most of the water appeared to be taken away from the reactors by the wind.  Each pool holds around 2000 tons of water.  Each helicopter drops about 7.5 tons.

CNN is only showing video of the one drop that managed to get significant water on the reactor.  Here is a more realistic video:

Reactor 3 is a priority because it uses a combination uranium and plutonium fuel (MOX fuel), and appears to be heavily damaged, producing large quantities of steam from the reactor.  It is believed that this steam is escaping from the reactor vessel itself.

Groups of police officers are planning to use 11 riot water cannons this afternoon to shoot water through holes in the reactor 4 building in an attempt to cool the fuel rods in its pool.

TEPCO is bringing in a new power line so that pumps can be run, but acknowledged that the the existing cooling pumps have been ruined by sea water, and temporary pumps will be required.  I would suspect that the lines to the reactors have been destroyed, and I don't think reactors 2 and 3 will hold water.

The Japan Nuclear Industrial Safety Agency reported in a press conference on NHK TV today that the pools in reactors 5 and 6 are now in trouble, and may have only a little water left.  Pressures and temperatures are rising.

Reactors 1 and 2 are being cooled by sea water, according to the Defense Minister, but if that were true, I would expect to see some steam escaping.

It is just me or does the whole response seem rather amateurish, with little or no long term planning?


Wednesday, March 16, 2011

Satellite Photo of Damage to Fukushima Daiichi Reactor on Wednesday March 16th

This satellite image is from the DigitalGlobe Flickr Photostream, and was collected mid-morning on March 16th local time.  Four reactors are shown with #1 on the right.  #1 had a hydrogen explosion early in the disaster, which removed the upper-floor walls and roof.  #3 had a very large hydrogen explosion, and is emitting the most steam.  It is the only reactor that contains a special plutonium mixture called MOX.  #4 on the left had been shut down before the earthquake occurred, and had no fuel in the reactor, but contained a spent fuel pool on one of the upper floors, which had a hydrogen explosion and caught fire.  #2 had a hydrogen explosion in the pressure suppression toroid beneath the reactor, which is releasing a large amount of radiation.

Click for larger image

Fukushima Daiichi Reactor Status

As of 16 March 0247 UTC, large quantities of steam are coming from Fukushima Daiichi Reactor #3. Chief Cabinet Secretary Yukiyo Edamo stated that the radiation around the plant has reached as high as 1000 millisieverts/hour which is the same as 100 rems/hour. This is sufficient to cause serious radiation sickness in one hour.  All workers have been evacuated, so the reactors are on their own.  He mentioned that plans are in work to attempt the cooling of the reactor #4 spent fuel pool, which contains over 500 nuclear fuel rods, but that right now the work has been suspended.

Recent photo of Reactors #3 and #4 (l to r)
Click for larger image

UPDATE:  Now (0316 UTC) TEPCO is saying 6.4 millisieverts/hour, and that the 1000 millisievert/hour number quoted by Edamo is incorrect. That would only be 0.64 rem/hour.  It would therefore take about 8 hours to get to the 5 rem annual occupational exposure limit.

UPDATE 2:  But the Associated Press is still quoting the 1000 millisievert/hour number

Tuesday, March 15, 2011

Best Japan Nuclear Crisis News Tracking Sites


CNN is absolutely terrible, first reporting on events sometimes 12 hours after they have occurred.  They still have not reported that a hydrogen explosion occurred in Unit #4, which has been widely reported in Japanese media since last night. is a real time site that includes links to breaking stories, posted both by Reuters staff and by readers.  The stories are up-to-the-minute fresh.  It is really the only site you need.  As stories and links come in here, you can build up a list of other sites to track. is NHK World TV Live, in English.  Another mirror is here shows radiation readings in Tokyo, recorded by an amateur (since no official readings are available).

Monday, March 14, 2011

New, Larger Explosion at Fukushima Nuclear Plant

This explosion at Reactor #3 looks to be much worse than the previous one at Reactor #1. Close-up at 0:57 in the video:

Note large parts of the building being blown high into the air and falling down.

The explosion occurred at 1101 Monday 14 March JST (0201 Monday UTC, 2201 Sunday EDT)  See for live blog.

Saturday, March 12, 2011

Radiation Effects in Humans


Note: For most purposes of radiation protection in humans, Roentgen (R), radiation absorbed dose (rad) and radiation equivalent man (rem) are considered roughly equivalent. The SI unit of radiation is the sievert. One sievert equals 100 rem. Radiation dose rate at the Fukushima reactor briefly reached a high of 1557 microseiverts/hour, then dropped. This would correspond to a total dose of about one rad if you were exposed for 10 hours. Not a big deal.

Here is a table showing radiation effects on humans for various acute doses:

0 to 25 rads:
  • No easily detectable clinical effect in humans
  • However, at about 15 rads there could be temporary sterility in males
  • Some epidemiological studies suggest an increased risk of cancer in this dose range, but the data suggest that risks in the 15‐20 rad dose range are very small and difficult to measure
  • Above 10 rad there appears to be a significant risk of thyroid cancer due to radioactive iodine exposure in children 15 years of age and younger
  • Some studies have shown a link between low dose radiation exposure and childhood leukemia and non-Hodgkins lymphoma, but other studies of children exposed to radiation at Chernobyl and Hiroshima, show no link.
25 to 100 rads:
  • Slight short‐term reduction in blood cells
  • Disabling sickness not common
100 to 200 rads:
  • Nausea and fatigue
  • Vomiting if dose is greater than 125 rads
  • Longer‐term reduction in number of some types of blood cells
200 to 300 rads:
  • Nausea and vomiting on the first day of exposure
  • Up to a two‐week latent period followed by appetite loss, general malaise, sore throat, pallor, diarrhea, and moderate emaciation
  • Recovery in about three months unless complicated by infection or injury
300 to 600 rads:
  • Nausea, vomiting, and diarrhea in first few hours
  • Up to a one‐week latent period followed by loss of appetite, fever, and general malaise in the second week, followed by bleeding, inflammation of mouth and throat, diarrhea, and emaciation
  • Some deaths in two to six weeks
  • Eventual death for 50% if exposure is above 450 rads
  • Others recover in about six months
Over 600 rads:
  • Nausea, vomiting, and diarrhea in the first few hours, followed by rapid emaciation and death in 2nd week
  • Eventual death of nearly 100%

Information from JP Laboratories,, and Steve Quayle's Radiation Measurement Conversion Tables.

Officials Claim Positive Signs on Japanese Reactor


The following is reprinted on The Big Dustup by permission of STRATFOR.  Additional images have been added.

New developments at Japan’s earthquake-damaged Fukushima Daiichi nuclear reactor No. 1 may suggest positive signs for authorities’ efforts to contain the problem. But many dangers and risks remain.

Japanese Chief Cabinet Secretary Yukio Edano said that while an explosion did occur at the plant, it did not damage the steel container around reactor No.1, where emergency workers are still struggling to cool down the reactor core after nuclear fuel rods were damaged following the failure of cooling systems due to the earthquake damage and short power supply. Edano said the explosion did not occur within the reactor container and thus did not lead to a large leak of radioactive material. The Nuclear and Industrial Safety Agency claims that radiation levels support the view that there has been no breach of the container around the reactor, though they have risen as a result of actions taken to relieve pressure in the container by releasing radioactive steam.

Explosion blows the roof off of one of the reactor buildings

If accurate, these would be positive developments for the attempt to avert a meltdown in the reactor core. A number of nuclear engineers and experts interviewed in the press have also suggested that the explosion at the nuclear plant was not caused by a breach of the reactor itself, but rather involved the sudden release of hydrogen, which Edano confirmed, saying the hydrogen had been trapped between the reactor core and the surrounding containment structure, and exploded when released and mixed with oxygen. The government did not call for an expansion of the evacuation area of 20 kilometers (about 12 miles) around the two plants, and the fact that the evacuation zone has not been expanded is a positive sign.

click for larger image

It is too early to say, however, that a catastrophe has been averted. The nuclear safety agency said the Tokyo Electric Power Co. (TEPCO), which operates the nuclear plant, had succeeded in relieving pressure, but confirmed that some of the nuclear fuel had melted and that further depressurizing was necessary to continue to contain the reactor heat and pressure. TEPCO claims it is continuing to pump sea water and boric acid into the reactor container in order to substitute for the failed cooling process. Edano estimated it would take five to 10 hours to fill the container and 10 days to complete the process of cooling.

A number of questions remain. For instance, Edano claimed radiation levels were decreasing around the area, whereas the nuclear safety agency pointed to the fact that the release of steam to depressurize the reactor resulted in increased radiation levels. Other questions include the nature of the earlier explosion and whether it is true that the container was not damaged; whether radiation levels are as negligible as the government says; whether pressure in the reactor is indeed dropping; the sustainability of the cooling effort which is using batteries due to the lack of electricity; and the status of the Fukushima Daini reactors that were also reported to have had cooling malfunctions (water levels and radiation levels there last appeared to show no cause for worry). Thus while the official statements suggest some progress, potentially making this incident more similar to Three Mile Island than Chernobyl, nevertheless details are sparse and the situation remains precarious.

Reprinted on The Big Dustup by permission of STRATFOR.

Related Special Topic Page:  The Japanese Disaster: Full Coverage