Nuclear Expert's Step-By-Step Assessment of the Fukushima Disaster & What You Need to Know

In this detailed interview, Chris talks with longtime member Dogs_In_A_Pile, an expert on nuclear energy who has been posting frequent updates to this site covering the developments at the Fukushima reactor in Japan as they have unfolded.

Based on his decades of experience, Dogs provides a detailed overview of how nuclear reactors work and then speculates as best he can (as the world is still dealing with imperfect information on the situation) how the technical situation at Fukushima likely degraded since the 9.0-magnitude earthquake hit on March 11.

This is an excellent discussion that addresses in depth many of the questions asked on this site over the past week: How does nuclear energy work? What caused the explosion of several of Fukushima's reactors? What is 'decay heat' and why is it so important here? What's the likelihood the situation will be brought under control soon? What dangers should - and shouldn't - we worry about?

Many thanks to Dogs for bringing a knowledgeable and rational voice that helps demystify the haze of incomplete (and often erroneous) information that has been circulating in the media around this tragedy.

Click the play button below to listen to Chris' interview with Dogs_In_A_Pile (runtime 1h:14m:56s):

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In this podcast, Dogs addresses: 

  • How nuclear energy works
  • What type of reactors are at Fukushima
  • The different between 'core' and 'spent' fuel and the importance of 'decay heat'
  • The likely progression of the breakdown of events following the 9.0 earthquake
  • The difference between radioactivity and contamination
  • How events at Fukushima are likely to progress from here
  • How concerned people should be (both in Japan and elsewhere) about the effects of this disaster
  • What preparations are prudent at this point

Click here to read the transcript 

Dogs_In_A_Pile is an expert in the nuclear field: he is a retired navy officer with over 20 years experience, most of that on nuclear-powered submarines. He is a certified nuclear engineer, which means he is certified to operate, maintain and oversee nuclear facilities. He also has extensive expertise on nuclear weaponry. He is a longtime and highly-appreciated member of the community.



Our series of podcast interviews with notable minds includes:


This is a companion discussion topic for the original entry at

Chris, Dogs: Thanks for the info.

"FUKUSHIMA, Japan (AP) -- More foods are showing traces of contamination in Japan, where radiation has been leaking from a damaged nuclear plant.

Japan’s Health Ministry says tests have found excess amounts of radioactive cesium (SEE’-zee-um) on canola and chrysanthemum greens. And some of the produce came from areas where contamination hadn’t previously been recorded.

The government previously halted shipments of spinach from one area near the nuclear plant and raw milk from another after tests found excessive levels of radioactive iodine.

And Tokyo’s tap water, where iodine turned up Friday, now has cesium as well."

The transcript is now posted above.

[quote=saxplayer00o1]Chris, Dogs: Thanks for the info.
“FUKUSHIMA, Japan (AP) – More foods are showing traces of contamination in Japan, where radiation has been leaking from a damaged nuclear plant.
Japan’s Health Ministry says tests have found excess amounts of radioactive cesium (SEE’-zee-um) on canola and chrysanthemum greens. And some of the produce came from areas where contamination hadn’t previously been recorded.
The government previously halted shipments of spinach from one area near the nuclear plant and raw milk from another after tests found excessive levels of radioactive iodine.
And Tokyo’s tap water, where iodine turned up Friday, now has cesium as well.”
sax - It was my pleasure to help…
Everyone should understand that this is going to be a major issue going forward.  What is being detected is particulate radioactive contaminantion spread by the steam venting, explosions and possibly the fires at the site that settled out on to the greens.  Much of this contamination has also settled on the ground where growing plants will pick it up in their root complexes and distribute it within the plant. 
Animals that graze on these plants will also deposit these radionuclides within their bodies and/or pass along in their milk.  This is going to have significant repercussions for at least 5-6 generations.

Thanks for that interesting discussion - still many puzzling aspects with too little information to sort it all out. They are going to use some SDF tanks with special radiation protection as buldozers to clear rubble from around 3 and 4 - still pretty hot in the area it seems. They also say that the pressure rise in unit 3 has stopped short of requiring them to vent again -for the moment.
This is the best clip of the explosion at #3 I found - shows the initial flash right at the beginning of the clip and then the massive plume accompanied by three explosive reports:

Whatever happened at #4 was pretty violent - maybe even more than one event as I recall reports initially of "a hole in the roof and a hole in the wall ’ that were too small to get much water into, but recent pictures show the roof in ruins. Can’t believe oil fires or even gas bottles could come close to causing that kind of damage.

The IAEA reported that holes were made in the roofs of units 5 & 6 to prevent the buildup of hydrogen as a precautionary measure:

The fact that contamination has already affected tap water, green vegetables, and possibly milk I find worrying.

Latest IAEA report:

Says that contamination is from iodine, no mention of caesium.Also says that  they still have no direct way to measure temperatures or water levels in units 1-4 fuel storage pools (radiation levels too high still is my guess). White smoke present but diminishing, continued seawater spraying, and core pressure stabilized or falling at unit 3 so no need to vent. NHK is also reporting this:

I’m half way through this excellent interview and pausing for a break.  My knowledge of reactors is basic, but I’d like to share some thoughts that others may find helpful.  A major reason for the confusion many feel is that terms are not defined in various reports, and they are used interchangeably and incorrectly.  I will try to clarify a few basics, and I welcome corrections as needed.  Look at the illustration at the top of this thread.
Reactor vessel – This is the red cylinder in the center.  It contains the fuel and control rods, and is made of very strong and thick steel.  It is the “pressure cooker” where the nuclear reaction takes place.  Super hot water is piped out to provide power and cool water is piped back in.

Containment structure – This is the thick reinforced concrete structure, shaped like an upside down light bulb, surrounding the reactor vessel.  I think the torus (donut) below it is included in this structure.  This is for safety in case the reactor vessel is breached.

Reactor building – This is the square building that surrounds them.  It includes the storage pool for spent fuel, pipes, pumps, sensor, controls, etc.  It appears to be designed so the top portion can blow off without damage to the containment structure, the reactor vessel, and essential systems.  However it does expose any spent fuel in the storage pool surrounding the top of the containment structure.  This type of explosion can be clearly seen in photos of reactor building 1, with the steel framework exposed and a neat line of intact walls lower down.  This is entirely different from the damage to the other reactor buildings with massive damage to the lower parts of the building. 

The confusion – Try to keep the above in mind regarding any reports you receive.

*   I have seen” the containment” refer to the metal tubes containing the fuel pellets, the reactor vessel, the containment structure, and the building.  All of these have a containment function, but only one is the containment structure.

*   “Primary containment” has been used to refer to all of the first three.

*   “The reactor” has been used to refer to the building.  An explosion of the top of the building is very different from an explosion of the reactor vessel containing the nuclear reaction, even if it is “shut down” and slowly going dormant.

*   Many of the reporters plainly don’t know what they are talking about and loosely parrot terms that give the most dramatic effect to their story.  In many cases we simply can’t assign even a tentative definition to their terms, so we can’t have any confidence in understanding what is happening.

Having a clear idea of the three structural elements above is essential to understanding.  For some people I’m just restating the obvious, but I think there are others who will find this helpful.  Now back to the interview.


Not sure if this is the place for this questionsto mods feel free to move this.I did a brief google search for a list of imports from Japan to the US and all I could find was a short list of…
electronics (tv’s, components, etc.)
I think that’s about it.  So my question is, can some of you internet savy information sleuths find a more detailed list of what we import here in the USA from Japan?  Being that some people coming off of recent flights from Japan have set off the radiation detection systems as well as radiation contamination in Tokyo water, I thought it might be a  good idea to start thinking about imports in general.  I have a feeling this will be information MSM or our .gov will not be sharing with us for a good long while :wink:
Thanks in advance

Thanks for the interview guys.  It was very helpful to hear information directly from a real expert that we can trust.

Arguably no one has more data and experience with nuclear testing and the effects of radiation fallout than the United States, much of it right here at home – in Nevada. Perhaps an inclusion of this data in the discussion, for relevancy, would be useful.
Also, if anyone happens to find themselves in Las Vegas and tires of the neon and debauchery, a few miles off the Strip buried in an unobtrusive shopping mall, is the Atomic Testing Museum (in association with the Smithsonian) and is well worth the diversion. The story of nuclear testing in Nevada is an important story, and it helps place current events in context.



Between 16 July 1945 and 23 September 1992 the United States of America conducted (by official count) 1054 nuclear tests, and two nuclear attacks. The number of actual nuclear devices (aka “bombs”) tested, and nuclear explosions is larger than this, but harder to establish precisely. Some devices that were tested failed to produce any noticeable explosion (some by design, some not), other “tests” (by official definition) were actually multiple device detonations. It is not clear whether all multiple device tests have yet been identified, and enumerated.

These pages focus principally (although not exclusively) on the period from 16 July 1945 to 4 November 1962, the era of atmospheric testing*. There are a number of reasons for this. These early years marked the height of the Cold War, when the U.S. nuclear weapons establishment came into being, when the major breakthroughs in weapon design occurred, and when the most severe effects of nuclear testing were felt around the world. During this period test series were grand operations, involving huge numbers of people, and each often with a set of clear objectives. The era of atmospheric testing is also the period for which the most information is available. When tests were exploded in the open, everyone could collect data on what was being tested. When the tests went underground, testing became routine, and information about what was being tested went underground too. And of course, we can’t have a gallery without pictures- and atmospheric tests are the only ones for which pictures exist.

  • There were actually a few surface tests included in the official test count conducted after 4 November 1962. These were a series of zero yield tests of plutonium dispersal conducted in 1963, known as Operation Roller Coaster.

Nuclear Testing and Health

Ever since nuclear testing began it has been very difficult to get a useful accounting of human exposures to the fallout from these tests. Partly this was motivated by military secrecy, partly by a desire to allay public fears (i.e public relations reasons), and partly by a fear of possible legal action by actual of potential victims. Some exposure related incidents have been revealed due to the impossibility of hiding them: namely the high radiation exposures of the Marshallese and the Japanese aboard the Fifth Lucky Dragon after the Castle Bravo disaster. But most information on this subject has been withheld, deliberated buried in obscure reports, or never collected (this is the principle of being careful not to learn what you don't want to know). This information has slowly come to light in bits and pieces over the last 20 years.

What is probably the most important study of the health effects of testing were announced by the National Cancer Institute in August of 1997, and released in October. The study report is now available on line: National Cancer Institute Study Estimating Thyroid Doses of I-131 Received by Americans From Nevada Atmospheric Nuclear Bomb Test.

The basic finding of the report is that internal exposures to radioiodine (I-131) in fallout from continental nucelar testing was the most serious health consequence. Radioiodine concentrates in milk when consumed by cows when grazing, and then concentrates in human thyroid glands when contaminated milk is ingested. This concentration effect is especially strong in children. The NCI study estimates that the average American alive at the time received a thyroid radiation exposure of 2 rads, with some people receiving up to 300 rads. The effect of these exposures is to boost the chance of contracting thyroid cancer some time during a lifetime. This cancer is normally not very rare, and is highly treatable (as cancers go). It is possible to estimate the overall effect of the total radiation exposure of the American population. From the 380 million person-rads of total exposure roughly 120,000 extra cases of thyroid cancer can be expected to develop, resulting in some 6,000 deaths [See note]. For comparison, the worst industrial disaster in history (Bhopal, India; 3 December 1984) killed about 3000 people and injured 150,000.

No effort was made to systematically study the nationwide effects of atmospheric nuclear testing until congress ordered the study – which was finally released 15 years later. In hearing held in September 1998, Bruce Wachholz, chief of the radiation effects branch of the National Cancer Institute, told a Senate hearing that the basic results were known as early as 1989 and a final draft report was completed in 1992 yet none of the information was made public for five more years.






Trinity 1945 Alamagordo New Mexico 1

The Post War Test Series





Crossroads 1946 Bikini Atoll 2
Sandstone 1948 Enewetak Atoll 3
Ranger 1951 Nevada Test Site 5
Greenhouse 1951 Enewetak Atoll 4
Buster-Jangle 1951 Nevada Test Site 7
Tumbler-Snapper 1951 Nevada Test Site 7
Ivy 1952 Enewetak Atoll 2
Upshot-Knothole 1953 Nevada Test Site 11
Castle 1954 Bikini Atoll Enewetak Atoll 6
Teapot 1955 Nevada Test Site 14
Wigwam 1955 Pacific Ocean 1
Project 56 1955 Nevada Test Site 4
Redwing 1956 Bikini Atoll Enewetak Atoll 17
Plumbbob 1957 Nevada Test Site 30
Project 58 1957 Nevada Test Site 2
Project 58 A 1958 Nevada Test Site 2
Hardtack I 1958 Bikini Atoll Enewetak Atoll Johnston Island 35
Argus 1958 South Atlantic 3
Hardtack II 1958 Nevada Test Site 37
Nougat 1961-1962 Nevada Test Site 32
Dominic (with Fishbowl) 1962 Christmas Island Johnston Island Central Pacific 36
Storax (with Sunbeam and Roller Coaster) 1962-1963 Nevada Test Site Nellis Air Force Range 56




Subsurface Cratering Shots

Test Series 

Test Name 

Time and Date (GMT) 


Test Type 

Height (m) 

Yield (kt) 




Nougat Danny Boy 18:15 5-Mar-62 (GMT) NTS Area Area 18a Shaft -34 m 0.42 DOD Weapons Effects (Non-plowshare) Explore cratering mechanics in hard, dry rock (basalt); 81 m (265 ft) wide crater, 26 m (84 ft) deep
Whetstone Sulky 19:35 18-Dec-64 (GMT) NTS Area 18d Shaft -27.1 m 0.092 LLNL 11th Plowshare Explore cratering mechanics in hard, dry rock (granite) and study dispersal pattern of airborne radionuclides; produced a permanent "retarc" (inverted crater); released 13 kilocuries of I-131
Whetstone Palanquin 13:14.00.11 14-Apr-65 (GMT) NTS Area 20k Crater -85.7 m 4.3 LLNL 12th Plowshare Explore cratering mechanics in hard, dry rock (rhyolite) and study dispersal pattern of airborne radionuclides; crater produced was 240 feet by 70 feet; released 910 kilocuries of I-131
Crosstie Cabriolet 16:00.00.11 1-Jan-68 (GMT) NTS Area 20l Crater -20 m 2.3 LLNL 20th Plowshare Study effects and phenomenology of cratering in hard rock (rhyolite); optimum depth of burial for cratering; crater produced was 360 feet by 120 feet; released 6 kilocuries of I-131
Crosstie Buggy 17:04.00.11 12-Mar-68 (GMT) NTS Area 30 Shaft -40 m 5.4 LLNL 21st Plowshare Trench cratering experiment, five 1.1 kt charges detonated 150 feet apart, produced crater 850 ft long, 250 ft wide, and 65 ft deep; released 40 kilocuries of I-131
Bowline Schooner 16:00.00.14 8-Dec-68 (GMT) NTS Area 20u Crater -100 m 30 LLNL 23rd Plowshare Study effects and phenomenology of cratering in hard rock (tuff); crater produced was 800 feet by 270 feet; probably used tungsten-rhenium alloy fission tamper, U-235 core (based on radioisotope releases), released 15 kilocuries of I-131


I’d like to add a little more information I am privy to. My chosen field is also Nuclear power and my specialization of the past 15 years is in Radiation Protection (with an additional 5-year stint in Operations)
The Earhquake/Tsunami:

My understanding is the intial plant response to the Earthquake was as expected.  A complete loss of offsite power is anticipated since the distribution system is not siemically qualified (not earth quake proof).  All or most of the Deisel generators fired up and provided ample power for shut down equipment. 

The sea wall surrounding Daichii was ~7 meters.  The wave that hit the facility is reported to have been 8-9 Meters high.  So not only did the water spill over and take out the deisel generators (which were working post quake), but also some above ground fuel tanks are reported to have been swept away (I’d guess it was the DG Day tanks).

I suspect the wave, which continued to flow several miles inland, subsequently created a veritable swimming pool around the site where by the entire site sits in meteres of standing water.  If the site is like many here in the US, (including mine) then most of the Emergency Core Cooling pumps, some buses, critical valves etc sit at levels near or below the site ground level.  So when I envision what the scenario the plant operators had to contend with I’m thinking they would have to deal with water intrusion and outright submersion of anything at ground level (plus 15’) and below.  Many plants (but not all) have water tight doors around critical equipment but i cannot imagine any systems that would remain operable under these conditions. When i think of all the contingency equipment that would be affected by a site submerged in this much water i can only gasp.

If you had submerge pumps you’d have essentially a compromised flow path (your not going to get much past an idle impeller) even if you were to restore power. An electrical pump is not going to fire up after being submerged. I’m wondering if the choice to go to seawater was as much a flow path issue as it was a water source issue.  Sea water injection is the last chance option and in many cases involves the used of portable deisel pumps aligned to direct flowpaths into the core.  We will know soon enough but I suspect this might be why.

My background is in PWR’s and we have steam driven turbines that can assist in a compltete loss of power.  I suspect a BWR would have the same and I’m wondering what happened to this alternative.


The explosions:

The explosions in #1 and #3 were due to venting of the gas mixture from the core containment.  The explosive mixture is largly due to Hydrogen produced from the steam/oxygen reaction withe the hot zirc rods.   Zr + 2(H2O) (steam)  + heat —-> ZrO2 + 2H2.  A simpler explanation is Steam + High Temps + Zirconium = Hydrogen.

The fire at the Spent Fuel pool in #4 , as I have been told, was due to oil from a pump being used in that area.  It was not a Zirconium reaction, or at least what I understand.

I am told the Pool at #4 lost inventory due to the debris that fell into it due to the exterior walls being damaged and dropped into the pool as a result of the explosion at #3.  This lost inventory shortened time to boil and the debris i suspect blocked make-up flow paths so that the pool could not be filled and recirculated/cooled using normal means.


The Fallout

The fallout hazard is a big questionmark.  As Dogs in a Pile mentione iodine is a hazard since it concentrates in the thyroid.  However it has a short “half life” and will cease to be an appreciable hazard after 60 -100 days.  If you have fuel damage and a breached core containment so that there is nothing to inhibit it’s release into the atmosphere then you could get a deadly combination of airborne an airborne release of fission products eminating from the fuel. So the feared combination that produces an un mitigated release is where you have degrading fuel and a breached core containment.  If you have one without the other the situation is much less severe.

I think releases to date have been to alleviate pressure in the core containment structure.  These releases probably would have went into a secondary vessel (the reactor building??) and then through filtration.  Recall the explosions at #1 and #3 happened as a result of this vent into the secondary vessel where the Hydrogen formed an explosive atmosphere.  In my mind that calls into question any filtration ability of the  #1or #3 core containments.  Again this could still be a relatively less severe issue if the core containment remains in tact and fuel degradation is not an issue.  There is a third possibilty that there exists a filtration flowpath is not connected to the secondary pressure vessel flowpath which remains viable.  Such design characteristics are likely but whether they are operable is another question.

The information I have received only leaves Fukushima #2’s core containment in question.  I actually heard it is feared to be ruptured.

Reports I have heard put the airborne contamination from the site at very low levels as they relate to immediate health effects.  I have yet to hear actual numbers but my impression is that the contamination is a combination of nuisance contamination and perhaps also short unfiltered concentrated “puff” releases that should dilute quickly (still not good, but far from worst case ).  The best case scenario is where core material is largely contained and subsequent releases are filtered and pose little contamination hazards.  My gut feeling is that the actual levels experienced will be closer to the best case scenario described above, versus the extreme other end of the spectrum which is what we saw from Chernobyl.


The severity

Time will tell on this one. One thing to keep in mind; radiation is VERY easy to detect with instrumentation.  Therefore when you hear reports such as “iodine found in Tokyo drinking water” we should not automatically assume the worst is upon us. We are able to detect Cesium, Iodine and a host of other radio-nuclides as extremely trace levels.  Their presence alone tells us little as to the severity of the accident.  Their concentation, however, would tell us much more.  We would then be able to postulate such things as unihabitable zones, delayed health effects, viable food and water supplies, etc. I will update the site with this information if and when I get it.

At this stage the governmental authorities WILL advise the public to take preventative measures.  They have not advised taking Potassium Iodide (used to prevent iodine uptake in a severe accident release) which leads me to believe the worst case has been averted so far.  As each day passes decay heat diminishes.  Hopefully we are entering a recovery phase and are no longer contending with degrading conditions at Diachii.

Caveat : There is an information vacuum.  Nothing I’ve said above is absolute and some of it may turn out to have been inaccurate.  i’m just sharing what i know.


Thanks for the informative post.  I hope we hear more from you.


As I posted elsewhere on the site, regarding reactor #4, there’s just no way at all that I can believe that a lubricating oil fire did this damage:

Give the bent rebar, the pulverized concrete, twisted metal, and the general rubble level, this has every earmark of a relatively high-energy explosion, not an oil-based fire.

In fact, this is so blindingly obvious, that I hesitate to even pretend that I think there’s any sort of reasonable disagreement that can be had as to whether the outer containment building blew up or is suffering the effects of a couple of fires that “spontaneously put themselves out” as I keep reading in the news.

Given that this reactor was in full maintenance shut down prior to the quake, all that we are left with is the spent fuel as the source of the explosion.   Once we arrive at this conclusion, then things get a little bit trickier for the authorities because it means that the most likely explanation is that the spent fuel rods got heated to such a degree that they liberated sufficient hydrogen to create an explosion.

Once we assume that, then we have to face the idea that the spent fuel rods themselves are scattered hither and yon.

And once we go there, then we are faced with the implications centered on contamination, clean-up and the possibility that re-criticality of the pile is among the things that need to be definitively ruled out, not assumed away. 

All in all, the damage in all the photos speaks of far greater damage and the liklihood of more profound contamination than we have yet been told about.  Of course, some solid data, say the orginal scans and thermal imaging photos from the RQ-4 Global Hawk drone flyovers that the US has been conducting since the 12th (we have now learned) would be a great start.  

For some reason the US government, which has analysed all the photos and data, is deferring to the Japanese government which has steadfastly refused to release the data, so far.  

Which means we must simply scrutinize low-resolution photos for what information we can.  To me, everything about reactors #3 and #4 looks to be in far worse shape than official proclamations would suggest. 

Thanks Chris, Dogs, and all the others who have put so much energy into these strings… it is absolutely the best and most informative ongoing conversation about this disaster.  Although I don’t have much to add… I have a great interest in this and have been reading every word… and I am praying for a safe outcome… My own industry (Semiconductor manufacturing) is reeling from Japan being on it’s knees like this.  One of the main Silicon wafer suppliers (SEH) has a big plant in Fukushima prefecture that produced something like 22% of all silicon wafer demand last year… not sure when/if it will operate again.  Keep up the great work!  Never stop seeking the truth!         

Just to let you know that after 25 years Chernobyl disaster is still spreading radiation.
In Southern Germany we have some migrating  radiation disasters running arround. Radioactive BOARS coming from chernobyl after 1986 disaster.

The boars became radioactive due to their hunger of all kind of wild mushrooms and truffels which are absorbing these radioactive substances.,1518,709345,00.html



Some other recent podcasts on the Fukushima Reactors and related issues:

The Economist, released March 18

Financial Times, released March 18, released March 19



Thanks Rick and Chris for the podcast. I’ve learned more about nuclear technology/meltdowns/radiation/contamination in the past 10 days than I ever really wanted to know. And most of what I learned came from this great website!
Let’s all hope the situation in Japan resolves itself in the best way possible, and soon. Fingers crossed.

Thanks Dogs and Chris for the in depth and reasoned discussion; I think your general assessment based on what limited knowledge we have now is pretty good. 
I had the pleasure of working with naval nuclear officers like Dogs in my former career.  Their extensive training and committment is the one of the primary reasons for the strength of the US nuclear navy, not just the technology.  My sense is human interaction remains important in nuclear safety even in an age of increasing automation.

The Navy trains operators to not only interpret reactor instrumentation and status to diagnosis a casuality and make the right response, but also to deal with others who might try to persuade one to do the wrong thing or ignore potential dangers.  That’s a mindset I try to use for navigating the challenging economic and energy issues ahead. 


I have not seen any official explanation for the hydrogen explosion at unit 4 and the implications assuming the source was the fuel stored in the pool. There is only mention of the fires and the possibility of lubricating oil as a source. I believe there must have been two explosions as initially it was reported that there was a hole in the roof and in a side wall, however the recent pictures show the roof destroyed. It apparently remains too hot to inspect the unit directly and mitigation efforts have been to spray water on it.
The damage to unit 3 seems very severe and how the spent fuel pool could have survived the explosion isn’t clear. It has been reported that the pressure was rising in the reactor yesterday , but later stabilized, and now is rising again. There was a spike in radiationlevels after 3am yesterday at Ibaraki monitoring station consistent with the release of radioactive steam, but no such release was reported. Levels monitored in Tokyo have been rising slightly over the past 12 hours after remaining steady for the previous 12, also consistent with some kind of release.

Radiation and precip at Ibaraki:

A point in Tokyo:

Smoke and steam has been noted today causing workers to withdraw temporarily. Electrical malfunctions were a possible cause.

The situation remains very serious, but information is drying up in my opinion.

Thank you for the very helpful information and explanations.  You filled in a lot of holes for me in my understanding of this very complex situation.

I just read that there is damage to the “nuclear fuel rods.”

I have confirmed the translation of this article with a Japanese colleague of mine.

So here’s my question.  If one or more of the reactors is damaged such that cooling cannot be stabilized, is their only option to entomb the whole four reactor complex?  If so, can you talk a bit about how this mitigates heat decay that will continue to occur?  I am guessing that the sand and concrete provides a good enough shield to contain the radiation.  Am I correct?

Thanks again for your willingness to enlighten us.