Talk:Fukushima nuclear accident/Archive 8

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There is already a move discussion going on at #Rename to disaster. Please keep the discussion there.

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Fukushima I nuclear accidents → Fukushima disaster – Please move Fukushima 1 nuclear accidents to Fukushima disaster, because it has now officially been rated an Event 7 on the INES, and is the second most serious nuclear disaster in history. This article should be moved, because both the Chernobyl disaster and Kyshtym disaster were of similar magnitudes, and both have the word (disaster) in their names. — Preceding unsigned comment added by Anthony Appleyard (talk • contribs) Page Fukushima disaster is already a disambig page. Anthony Appleyard (talk) 22:30, 17 April 2011 (UTC) A discussion is already going on #Rename to disaster... Rgds! L.tak (talk) 22:38, 17 April 2011 (UTC) Why should the numeral be eliminated from the title? --Cybercobra (talk) 00:22, 18 April 2011 (UTC) Oppose The earthquake and tsunami also affected Fukushima, and are not covered by this article. The proposed title takes no account of the devastation wrought by the tsunami in Fukushima aside from its affecting the powerplant. Fukushima is a prefecture, not a powerplant, and the other powerplant, Dani (II) is also Fukushima, and not covered by this article either, even though it also had an evacuation zone, hence also a "disaster". 65.94.45.160 (talk) 02:57, 18 April 2011 (UTC) Comment why "Fukushima disaster" instead of Fukushima nuclear disaster ? Atleast that clearly separates it from the overall disaster in Fukushima prefecture. 65.94.45.160 (talk) 03:03, 18 April 2011 (UTC)

Criticality in a spent fuel pool

Criticality in a spent fuel pool is not possible, so I corrected the paragraph here, adding of course a source (I have a master in nuclear engineering, but I have anyway to respect the common rules). The fact is that there is not an enrichment level high enough to self-sustain the chain reaction, out of the accurate disposal of the spent fuel; and when the rods get dry, there is also no moderator for that reaction (water). Filippo83 (talk) 23:00, 14 April 2011 (UTC)

Criticality is theoretically possible, but only is the fuel pellets from the FA's fell out of the damage zircalloy cladding, and then clustered in the bottom of the pool. Having said that, while it is theoretically possible, if it occurred we'd still be seeing it now (especially as the pools cooled). MWadwell (talk) 00:39, 15 April 2011 (UTC)

It was TEPCO that raised the possibility of criticality in the spent fuel pool. It seems pretty crazy to me too, but they are the experts for what might be possible in their systems (however unlikely). Dragons flight (talk) 03:45, 15 April 2011 (UTC)

Additional information added - as TEPCO have conducted analysis of the SFP from unit 4 - indicating that a majority of the fuel assemblies were undamaged - Most fuel in Fukushima 4 pool undamaged. MWadwell (talk) 03:56, 15 April 2011 (UTC)

Really. Thats like being nearly a virgin? If any of them are damaged that means they got hot enough to melt sitting in this pool. I queried this point at the time but the company was asked at a press conference and said they could not rule it out. You would have thought that probably having some nuclear engineers of their own they could give a definitive answer.Sandpiper (talk) 09:52, 15 April 2011 (UTC)

VBG - "almost a virgin". Very droll. I don't have the reference here (I'm currently at home), but a I've found an article on how the fuel assemblies are made. A series of fuel pellets are stacked in a zircalloy tube, which is then sealed at both ends and placed with ~200 other tubes in ~15 by 15 array. That is then protected by a shroud, and has a clamping machanism placed on the bottom, and a handle placed on the top. The entire assembly is ~4 meters long. To damage a fuel assembly, you don't need to melt anything - all you need to do is to damage/split one of the zircalloy tubes. The moment the tube is fractured (even if the pellets aren't dislodged), the radionuclides from all of the pellets in that tube are released. (FYI - to cause a criticality accident, you would need enough of the pellets to fall out of the tubes, and collect in a big enough pile in the bottom of the pool to form a critical mass.) As you can see, it is possible for a single tube (of over 200 in a single fuel assembly) to be damaged, in addition to the fuel assembly being physically damaged (although the storage rack should have protected the assembly) - releasing radionuclides, without the fuel assembly getting hot enough to melt. MWadwell 203.213.66.195 (talk) 10:39, 16 April 2011 (UTC)

EDIT - found one of the documents that I've got at work - it was in the BWR External links on wikipedia - Boiling Water Reactor (BWR) Systems. (I'll keep looking for another one I have, as it shows the fuel assemblies in more details.) It's a 3.3 meg pdf which describes the basic systems (including the core cooling systems and emergency DG generators) - and has a picture (on page 5) of a fuel assembly, showing the pellets, zircalloy tube, shroud and control rods. One important point, is that Fukushima I-1 has less tubes then -2 to -4 (which is one reason that they have higher power). MWadwell (talk) 10:48, 16 April 2011 (UTC)

" The moment the tube is fractured (even if the pellets aren't dislodged), the radionuclides from all of the pellets in that tube are released."

That is just plain incorrect. If the rod is fractured, then the pellets are directly exposed to water - which means that, yes, any trapped gasses will be released and radionuclides in the pellet can now start leeching into the water. It does NOT mean a sudden release of all the radionuclides in the rod. I realize that this might be a simple nomenclature mix-up, but still - the word "release" carries very specific connotations in the field of radiation protection. -- Kolbasz (talk) 13:25, 16 April 2011 (UTC)

G'Day Kolbasz. As you pointed out I should have put "over time" after that sentence. At Chernobyl a vast majority of the radiation was released over the first two weeks (due to the massive damage to the fuel assemblies) - whereas here it is possible that the releases may be stretched out over a longer period of time.... MWadwell (talk) 01:34, 17 April 2011 (UTC)

I am sincerely glad of other contributions. As written by MWadwell, criticality is a theoratical possibility: it is more than just it for highly-enriched fuel or for warheads, but it is still to be seen for lowly-enriched fuel, above all when it is spent and thus even less enriched; more, calculations are made in the most conservative way. Answering to Dragons flight, I will not modify the statement if there is an agreement about, but I did not find any Tepco communicate about, just media quotes. Answering to Sandpiper, melting damaged spent fuel is a real chance: but it is for thermal reasons (spent fuel is still "very hot") and not for nuclear ones; criticality is not involved in it. Finally, I have a master in nuclear engineering, if it can counts. Filipp o83 (talk) 10:00, 15 April 2011 (UTC)

I dont believe this is mentioned in any of the series of press releases, but it was a question asked and answered at a press conference. The spokesman probably answered honestly, and he might have been talking about a very remote possibility, but then again, as a company spokesman who was not apparently contradicted afterwards, maybe he did know something we did (do) not. Personally I thought it unlikely, but hey. Yes, the criticality issue is after fuel rods have melted into a lump in the bottom of the concrete ponds. I myself do not know what the state of fuel pond rods actually is. It should be noted that at least unit 4 did contain fresh fuel. There are numbers somewhere about how many new and old rods are in each pool. (article says 200 new and 1300 old). I have seen suggestions this total is more than the pools were originally designed to hold. Personally I am very pleased we have some people contributing here who understand the subject, but as you ave also understood, while we try to write things which are physically sensible, it was TEPCO who started this particular issue. I remember being unhappy about it because I thought it suggested unrealistic dangers, which is why I was much happier also having the quote from the BBC which somewhat plays down what the company had said. Sandpiper (talk) 21:40, 15 April 2011 (UTC)

I think the BBC did a very good work in covering the disaster (also considering the several earthquakes and the great tsunami) and gave a good and balanced view, also interviewing technical experts, on the nuclear accidents; the same for the CNN. You have no idea how Italian media badly reported the news, I think that the only thing they forgot to mention has been Godzilla. Thus I cannot tell you something against BBC, but I cannot trust as well a press communicate without any other evidence. The problem is, not that spokesmen know something we are not aware of, but they do cannot know every aspect of the nuclear industry: they are men as you and me, and they often cannot listen to all the technical voices they would need to. Furthermore, minimizing the events would have put their company, and then them, under fire; while, giving a theoretical minimum possibility could not be properly understood by public opinion and could spread unmotivated panic. It is the same problem of the China Syndrome: it never happened, neither at TMI or Chernobyl, it is likely impossible "in the real world" (because the molten core would form an external solid layer, stopping to penetrate the basement and so on) but that remote theory was put out once more immediately after Fukushima. -- Filippo83 (talk) 23:47, 15 April 2011 (UTC)

The BBC did a better job than most, but still not a very good one - their reporting was also full of unfounded, unwarranted speculation. Like this egregious example in an article about the possibility of a criticality in fuel pool 4:

Or, did technicians at some point take water from the pond for use in reactor 4's cooling system? There is nothing to say they did; but during the chaos of the weekend, with power systems and options disappearing before their eyes, it might have seemed like a good idea.

The journalist is throwing around wild speculations - and worse, wild speculations about blame - without bothering to look up his facts (that reactor 4 didn't hold any fuel at the time of the earthquake). -- Kolbasz (talk) 12:50, 16 April 2011 (UTC)

I see what you mean, but taking water from the ponds in 4 to use in the other reactors might have seemed like a good idea. There was no FRESH water available on site except perhaps inside the buildings already. To use salt apparently was to eliminate any chance of bringing the plant back into operation, and before things started exploding any idea for saving a few billion pounds worth of equipment may have been appealing. It is not clear whether the company deliberately held back from starting to use salt water for this reason, and only did so after a government order. Sandpiper (talk) 00:11, 17 April 2011 (UTC)

Sandpiper - with no electricity, there are no pumps. And therefore there is no way of moving the water from Reactor 4's SFP to another reactor (head pressure alone would not have been enough) - even if the pipes were there to allow it (which I doubt - too high a chance of LOCA). MWadwell (talk) 01:38, 17 April 2011 (UTC)

Pumping of cooling water to save the reactors from further damage has all been by fire engine, as far as I can see. At the start of all this there was no problem of radioactivity everywhere complicating matters because it hadnt happened yet. Emergency procedures called for adding water to fuel pools by fire hose, which did not work out very well in the event, but it was the plan. A fire engine might as well run a hose from the fuel pools as from the sea? Probably closer? Sandpiper (talk) 09:01, 18 April 2011 (UTC)

P.S. I am a nuclear engineer as job, I have a master in nuclear engineering, but of course I cannot know everything as well: I discussed about criticality issue first of all with some colleague, nuclear physician. -- Filippo83 (talk) 23:50, 15 April 2011 (UTC)

G'Day Filippo83 - I'm a shift manager at a research reactor, and so part of my job is calculating such things as excess reactivity/SDM-1 prior to refuellings/fuel movements/startups. Fun stuff..... MWadwell (talk) 11:27, 16 April 2011 (UTC)

Deaths at plant

I haven't seen a discussion section regarding adding the two deaths at the plant to the info box. To me, this clearly counts as deaths attributable to the accident, but it seems controversial enough to justify a discussion section.

(1) Two people died -- ignoring it seems insulting to them and their families. (2) They died working on the Fukushima plant -- not eating lunch or walking on the beach (3) They died of bleeding, presumably from something *at the plant* falling on them, hitting them, or crushing them. That's caused by the plant. (4) It is consistent with any other accident. If a pedestrian dies from blunt force trauma after being hit by a car, I presume one wouldn't argue that it wasn't a car accident that killed him (because the bleeding killed him, or because the definition of a car accident is two cars hitting each other).

I am fine saying the workers "died from the tsunami" if this is the consensus -- although this seems to be a bit of a odd clarification, since the entire accident resulted from the tsunami. But saying no one died is not NPOV to whatsoever. 66.65.191.165 (talk) 22:00, 17 April 2011 (UTC)

The issue is that the deaths were not in any way related to the nuclear accidents - which is what this article ("Fukushima I Nuclear accidents") and the infobox are about. Feel free to mention it in the article, but putting it in the infobox insinuates a causal relationship that does not exist. Tens of thousands of deaths were caused by the same tsunami, but that doesn't mean that they should be counted in this infobox. Going along with your car analogy: if the driver of a car has a heart attack and dies at the wheel, and the car subsequently crashes into and kills a pedestrian, would you say that both men were killed by the car accident? -- Kolbasz (talk) 22:29, 17 April 2011 (UTC)

Yes I would. Had the man with the heart attack been at work in his office probably someone would have called for help, he would now be in hospital recovering from the attack and the other driver unaffected. It is to be expected that people will have heart attacks wherever they are, but the fact of him being in a car at the time caused the deaths. Of course, in this case plant workers might have been significantly safer inside very robust buildings at the plant than had they been in their homes nearby. But again, had the plant been built on high ground so that it did not get flooded, even more lives might have been saved. Sandpiper (talk) 08:20, 18 April 2011 (UTC)

But the deaths were related to the nuclear accident. During the earthquake, these guys were killed by plant stuff falling on them. I'm fine with your changes to my analogy -- if one guy had died from a heart attack (because he ate unhealthy food) then maybe I could see your point -- his mechanism was unrelated to the plant. However, that isn't the case, these guys died directly from the plant, while working at the plant. This is consistent with how other Wikipedia articles work, tthey were both ; all those killed at the Upper Big Branch Mine disaster (even those whose primary causes of death were different than the initial causes of death); and literally hundreds of other accidents.

I'm not sure I even comprehend the other side of this argument (unless the argument is -- the workers were not killed by radiation, but that doesn't make sense. Neither the info box or the article is about the effects of radiation, if the info box or article is only about radiation, we would have to remove 75% of the content here. 66.65.191.165 (talk) 22:58, 17 April 2011 (UTC)

*sigh* It's not about whether they died from radiation or not. It's not about whether they worked at the plant or not. It's about causality.

"This is consistent with how other Wikipedia articles work, they list all those killed at Bhopal (civilians and plant workers); all those killed at the Upper Big Branch Mine disaster (even those whose primary causes of death were different than the initial causes of death); and literally hundreds of other accidents."

That's because those people's deaths, whether directly or indirectly, resulted from the accidents. The two Fukushima workers' deaths, while tragic, did not. If A caused B and C, and B caused D, does that mean that B caused C? No. -- Kolbasz (talk) 23:51, 17 April 2011 (UTC)

I concur with Kolbasz. The deaths, while tragic, were not caused by the titular nuclear accidents; they were caused by the tsunami and just happened to take place at the plant. The 2 tsunami deaths at the plant and the nuclear accidents at the plant are separate, albeit temporally overlapping, incidents that were both share the common cause of the tsunami. Feel free to add the 2 deaths to the tsunami article. --Cybercobra (talk) 00:19, 18 April 2011 (UTC)

While I appreciate formal conditional logic, I don't agree. There are other causations embedded in all accidents. Other articles (and the media) do not say "17 people died directly from the shaking of the Japanese earthquake, while 452 people died from crushing injuries inflicted by the Japanese earthquake, while 8,532 died from drowning from the tsunami, and 282 died from a failure to administer first aid in the days following the 3 previous accidents." They're all one accident, and the numbers are combined. For example, look at our earthquake coverage. Totals are given, then deaths vs. injuries, then in the detail section, primary causes are listed. Furthermore, there is no attempt to say the 282 who died from "post-earthquake-related factors" don't count, or don't go into the lead, all the deaths are accounted for in the info box.

If we did divide accidents into individual "causations" where would it end? Would someone dying tomorrow from fallen debris be attributed to this accident, or would they be a part of the Fukushima Nuclear Plant Cleanup Accident of April 2011?

Maybe, I don't see your point but, to me, the workers were clearly injured when the earthquake hit the facility. The earthquake is the root ("but for" and "proximate cause") of everything that followed, the same way all the deaths totaled on the Earthquake article are all attributed to the earthquake. There is no unforeseeable intervening cause cause here to create new causation for the deaths.

Slicing the accident this thin just doesn't seem NPOV to me because it appears to be bending over backward to avoid having deaths attributed to the accident.

Feel free to respond, but it appears we disagree -- maybe some others will weigh in a give us better than a 50:50 tie. 66.65.191.165 (talk) 01:04, 18 April 2011 (UTC)

I can see your argument being used to justify including deaths due to the nuclear accidents under the earthquake/tsunami article, as the earthquake/tsunami is the root cause, but I don't see how it supports including the 2 deaths in question in this article; the nuclear accidents aren't the root cause of much (yet). And unless I'm missing something, it's 66:33 at the moment. --Cybercobra (talk) 01:45, 18 April 2011 (UTC)

If the accident is purely "the nuclear accident" then this article wouldn't make sense. The plant didn't spontaneously overheat on one fine Friday afternoon. It is tied part and parcel to the earthquake. Why would we define the "start of the accident" after the accident began? It is hopelessly problematic. Did the nuclear accident begin at the end of the shaking, at the start of the reactor SCRAM, at the end of the SCRAM (which unit), at the start of the tsunami, at the end of the tsunami, or when all the water from the tsunami is pumped from the facility? By this logic, we could claim the nuclear accident hasn't even started yet -- because all of the roads and electrical infrastructure leading to the plant haven't yet been repaired -- and any deaths at the facility were likely exasperated by this poor infrastructure.

Even if we say we are only going to "blame" the plant for damage caused by its direct response to earthquake (which I assume is the most narrow definition of accident we can use, otherwise there really is no accident, even now) -- these workers still died as part of the accident, because something in the plant was not properly fastened per earthquake safety rules. Therefore, their deaths resulted directly from the plant not properly responding to the earthquake (just like all the other injuries). If we don't include direct results from the earthquake, then the radioactivity leaks aren't part of the accident. And, oddly enough, since the reactors probably responded to the quake within a second of two of the start of the earthquake, and the workers died about an hour later --> the workers definitely died after the "accident" began (assuming your definition of the accident starts when the plant started began irregular operations). Furthermore, the fact that no one attempted to rescue the workers is also a direct result of the nuclear accident. There is no doubt the reason other workers didn't go look for the missing workers is because of a fear of radiation, US workers interviewed on CNN said the reason they abandoned the plant was because of a fear of leaking radioactive water.

The larger point is: the statement that "the nuclear accidents aren't the root cause of much" is non-NPOV. Without a large digression, the nuclear accidents have lead to minimum US$55B loss to TEPCO ($25B liability limit + 6 reactors @ $5B replacement cost each). Statements that appear to contradict plain visual evidence just don't appear neutral. And this entire argument appears to be bending over backward with formalistic logic to support the contention that "not much happened" or that "no one was killed" in spite of overwhelming contrary evidence.

As to it being 50:50, I have no idea how I missed Cybercobra's vote. After I wrote my post, I saw it above my post. Regardless, Sandpiper weighed in, now making it 50:50. 66.65.191.165 (talk) 10:24, 18 April 2011 (UTC)

I can quite see a committee being formed in japan in the near future to examine the question of designing buildings to be earthquake proof, and one of its findings may be there were failings in how buildings were designed. It may then say that (eg) 500 lives were lost because of bad building practices. These people's deaths would then be blamed on inadequate building regulations. So they could legitimately be marked up as both caused by the earthquake and caused by bad legislation. If the power station had not existed, probably these two would not have drowned. They would have been working somewhere else, safer. But then again, some people working in the plant are probably from the town in question and had the plant not existed, might still have been working on the coast so that they were swept away. Bad plant design may have caused some deaths, good design might have saved some. This is difficult to disentangle. The article ought to say 2 swept away, etc, and leave it to others to judge if this is a net saving or a net loss. Sandpiper (talk) 08:20, 18 April 2011 (UTC)

Indeed, and it isn't even that close, the workers weren't swept away or drowned. They died from blood loss, almost certainly from something in the plant falling on them. http://www.dailymail.co.uk/news/article-1372787/Japan-Fukushima-nuclear-plant-months-control-2-deaths-confirmed.html 66.65.191.165 (talk) 10:24, 18 April 2011 (UTC)

People died in the tsunami. Even though their deaths weren't caused by anything nuclear, I do think the death of employees is a part of the context of the nuclear accidents. Personally, I think it is worth acknowledging that in the infobox. At the same time, I think the reader is intelligent enough to understand that if we say "2 died from the tsunami" then radiation, etc. had nothing to do with it. Just make clear what happened and let the reader draw their own conclusions. Dragons flight (talk) 10:41, 18 April 2011 (UTC)

I feel that since this article is about the nuclear accident related to the quake and tsunami, the deaths that resulted from the quake should not be in the box, but mentioned in the article, of course. Gandydancer (talk) 11:30, 18 April 2011 (UTC)

Reactor status summary

Pressure vessel, pressure: Would somebody check the figures in this section - they don't make a lot of sense (e.,g 0.456 MPa (0.836 MPa absolute)????). Also changing the scale to kPa would make things easier to read. 223.205.204.221 (talk) 05:42, 8 April 2011 (UTC)mja

I believe that they are confusing the two different readings (from different instruments) to absolute/relative pressure. If you have a look at this reference http://www.iaea.org/press/?p=1968 it states "Instrumentation ‘B’ for Reactor Pressure indicates that the pressure in the RPV is increasing and instrumentation ‘A’ indicates that it has stabilized. NISA has indicated that some instruments in the reactor vessel may not be working properly" - indicating that there are at least two independant instrument trains. Unfortunately, people are reading these values wrong. MWadwell (talk) 15:41, 8 April 2011 (UTC)

The reactor status summary table is missing from the displayed page, but the bulk of the content still exists in the edit view. Did the display code get messed up somehow? I'm going to try to figure it out, but I'm not good with table formating. Leopd (talk) 19:27, 10 April 2011 (UTC)

Nevermind. I see the show/hide links now. Leopd (talk) 19:36, 10 April 2011 (UTC)

I wish the cooling status for each reactor and pool was simply stated. If they are having a problem getting active cooling, why can't they just simply de-pressurize the reactors and let them boil? Water could be added as needed. Core temperatures would be only slightly higher than 100 degrees C. Steam could be vented from several points. The low pressure steam could go to water separators and filters, and the purified water could be dumped in the ocean or possibly even returned to the reactors. 151.202.6.223 (talk) 18:48, 11 April 2011 (UTC) BG

It wouldn't work the way you think - the water touching the rods is taking on radiation. Letting it expell as steam would vent radioactive waste everywhere. Not only that, but there isn't enough water to just waste it in this manner. We're talking about several water towers worth of water, most of which had to be flown in from elsewhere. Also, even if water was no option, and the steam was not radioactive enough to cause troubles, if there were a miscalculation in the application of water, and the rods were exposed, they may go into 'meltdown' - possibly starting a fission process and manufactoring even more highly radioactive waste, or even exploding. Maintaining pressure in these vessels is important for now. What they need to do, however is get the turbines working, allowing the water to circulate and expell its heat without releasing any radiation or wasting any water.173.34.246.144 (talk) 22:02, 19 April 2011 (UTC)

There are many news stories about bringing in super size modified concrete pumps, but nothing about how the radioactive waste water is being treated. The radioactive waste water must or should be treated to protect ground water and reduce ocean contamination. And now they are apparently going to widen the evacuation zone. 172.163.49.171 (talk) 01:39, 12 April 2011 (UTC) BG

They are going to treat the contaminated water onsite using Landysh - it's mentioned in the article. MWadwell (talk) 10:59, 16 April 2011 (UTC)

NISA reports

nisa seem to have taken to issuing 'extract' reports instead of full ones. Does anyone know whether the full ones are also available somewhere? The full ones had contained values for plant parameters, water levels, temperatures, etc. Are these now 'secret'? Sandpiper (talk) 21:27, 18 April 2011 (UTC)

In English? I think the reports you are looking for are here: http://www.meti.go.jp/press/ , but in Japanese. Click on the link that is the next sequential release (e.g. there was # 第１００報 , then there was 第１０２報). They appear to coincide with the English versions here http://www.nisa.meti.go.jp/english/ If you meant another NISA report, it may be at the same link, you'll probably just have to link on the Japanese version, but obviously, if you want text -- it isn't here. 12:43, 19 April 2011 (UTC) —Preceding unsigned comment added by 66.65.191.165 (talk)

Did six people really die in the hydrogen explosion in reactor unit 3?

"Six soldiers from the Japanese Central Nuclear Biological Chemical Weapon Defence Unit are reported to have been killed in the explosion."

It seems that this is not reported in the Japanese media at all. In fact several independent sources in the Japanese media report that 6 people were injured. The article that makes this claim has been criticized in the comments sections for providing inaccurate information. To me, it seems like a mistranslation. —Preceding unsigned comment added by 219.36.206.181 (talk) 07:53, 21 April 2011 (UTC)

The report says it is by a telegraph journalist who spoke to workers from the plant on a ship being used as accommodation. As such it does not seem to be reporting other announcements, so not surprising the story is not mirrored elsewhere. One of those comment posts you mention suggests looking instead at the IAEA for better information: My own impression comparing their posts with others from tepco and NISA is that they were sorely lagging behind and only had 'official' information. Certainly this is not officially sanctioned information. I am starting to wonder whether there is a disinformation campaign about real casualty levels. Sandpiper (talk) 10:53, 21 April 2011 (UTC)

Other Power stations

It would seem that there were failures during the crisis at other power stations. In the absence of the real disaster at fukushima, or the aftermath of the eartquake and tsunami generally, these near misses would in themselves have been headline stories. It does not appear that wiki is covering them anywhere. Sandpiper (talk) 08:02, 23 April 2011 (UTC)

Check out 2011 Japanese nuclear accidents - which mentions the following nuclear incidents: Fukushima I, Fukushima II, Onagawa, Higashidori, Tokai and Rokkasho. The nuclear accidents are also mentioned in the general article on the earthquake here. MWadwell (talk) 12:29, 23 April 2011 (UTC)

Reversion at 22:45 23 April

22:45, 23 April 2011 Logan (talk | contribs) m (220,471 bytes) (Reverted edits by 66.65.191.165 (talk) to last revision by MauchoEagle (HG)) (undo)

Why were these revisions reverted? I can't imagine this being controversial. I added new headings to the section (because it was so long), and updated that TEPCO (1) announced the amount of water released and (2) that TEPCO started storing water in the wastewater plant instead of condensate storage. The stuff added is from TEPCO releases. 66.65.191.165 (talk) 23:05, 23 April 2011 (UTC)

So sorry - Huggle was supposed to undo that reversion, but it decided not to. Logan _Talk ^{Contributions} 23:07, 23 April 2011 (UTC)

Thanks for the info. The amount of back and forth on this article is quite insane. 66.65.191.165 (talk) 23:20, 23 April 2011 (UTC)

Reactors 5&6

I think that Sandpiper deserves an answer about them. Reactors 4, 5 and 6 were not working at the day of the earthquake, for maintenance operations, as known. This means that no incident/accident could ever have happened inside them, since the loaded fuel never went critical, even if it was of course enriched, and so there was no need for emergency cooling. The question is different for the pools, annexed to reactors, containing the spent fuel: it is less enriched, but it has also the heat of radioactive decay to be removed, having been involved in a nuclear fission reaction. We know about the incident at the pool of reactor 4. For the pools at reactor 5 and 6, you can check here: by then (27th of March) there was no problem report; so I would record the INES level for those reactors to 0, at most. Filippo83 (talk) 10:15, 15 April 2011 (UTC)

The relevant wiki article defines the ines levels and gives examples. Level 2 says 'Significant failures in safety ­provisions but with no actual ­consequences.'. Level 3 says 'Near accident at a nuclear power plant with no safety provisions remaining'. So i suspect 5 and 6 are actually level 3 incidents themselves? I am not sure if there were no actual consequences from 5 and 6, but unquestionably there was a significant failure of the equipment designed to safeguard the reactor - none of it was working! If you look at the NISA bulletins they list reactor parameters and you can see that whether or not 5 and 6 started in cold shutdown, they did not stay that way. Reactors are always producing heat and it has to be continuosly removed. TEPCO reported when they once again had the reactors under control after restoring power.Sandpiper (talk) 22:02, 15 April 2011 (UTC)

Please, you have to give me the date (and the source): from IAEA bulletins, which take their data from NISA ones and from Tepco infos, reactors 5 and 6 have experienced no harmful incident at all as long as they told us. The only problem you can find after 17th March is: Units 5 and 6 remain in comparatively good condition. Temperatures at both, which had risen when the cooling pumps were briefly shut down in order to switch to off-site power, temperatures have since been restored to lower levels, and both units are still in cold shutdown. For the same reasons, a brief rise in temperature also occurred at the Common Spent Fuel Pool on 24 March. Between 11th and 17th March, the water temperature at spent fuel pools of reactors 5 and 6 rose up to 58-60°C, from usual <25°C, but then was safely put down to normal levels; there was no radiation leak nor other danger. I repeat, reactors 5 and 6 theirselves were not operating on that day and in the weeks before, the fuel inside them was never used before, and so there was no possible problem with them. Also, the IAEA bulletins clearly states on 18th March that Another positive development is that diesel generators are providing power for cooling for both Units 5 and 6. You can then check INES levels here: you can easily see that the situation at units 5 and 6 cannot be worse than INES level 1, since no one was harmed nor there was any release of radioactivity (neither internally to the plant buildings). I would then say that reactors 5 and 6 are 0 level, while spent fuel pools 5 and 6 are 1 level (breach of operating limits, with no consequences). I think that the disaster is serious and big enough even without looking for never-happened incidents to those two reactors; but, we know, for someone even a car hitting outer NPP gate is a "nuclear incident", as a professor of mine once told me. -- Filippo83 (talk) 23:34, 15 April 2011 (UTC)

I cant tell you which reports off hand are relevant because there have now been 80 odd NISA ones and similar tepco. They may be refd in the article in the 5&6 section which records generators being restarted when they were. The article is to be read as a whole and records that ALL mains or generated power was lost after the tsunami. On 17 March one of the genrators belonging to unit 6 was repaired and used to start running the cooling again. Note that is 1 generator for 2 reactors when it sounds like they should have 2 each, and they seems to have had to choose which cooling system was most urgent to run first. Before this there was NO cooling for those reactors or their fuel ponds, and the temperatures of all were rising steadily. 'the cooling pumps were briefly shut down in order to switch to off site power' is a very optimistic gloss on the events as they were reported when they happened. off site power was restored via the grid connection to the transformers behind 5 and 6, but when they switched off the pumps running from the generator, they were unable to restart them from the grid power. Something went wrong. There then followed a short period of no cooling again before whatever was repaired. Befeore any power was restored there were reports of concern about the reactors and that water levels inside were falling. The water level is reported as about 2m above the rods, which sounds pretty good compared to others which were 1.5 m below top of rods, but the other fukushima plant when safely under control was reporting water levels 10m above rods. Also remember, there was no fresh water available to add to the reactors. Sandpiper (talk) 23:08, 16 April 2011 (UTC)

This NISA diagram [1] states that as of 14:00 on 18 mar reactor 5 temperature was 182C and reactor 6 161C. reactor 5 pressure 1.3Mpa. I am not sure what the maximum possible pressure is before venting must take place, but this is pretty high. It might imply venting did take place. Fuel pools at approx 65C. The accompanying text (release 30) [2] says 1 generator is operating. update number 28 of 17:30 march 17 [3] says one unit of generator is operating and that this is new. Report 27 07:30 mar 17 does not mention 5&6. This TEPCO release (amongst others) [4] states that both 5&6 achieved cold shutdown by 20 March. On eg 17 March [5] all they were reporting was that there had been no coolant leak and that 'reactor has been shut down'. Being shutdown is the same as they state for all the reactors, and seems to mean only that the control rods are in. By contrast, 'cold shutdown' means not only control rods in, but actually cold rather than still hot. Note also that these reactors did start from 'cold shutdown' when this all began, so they had risen from room temperature to 181C before cooling was restored. Reckon thats safe?. This IAEA page for 19 march [6] says 2 generators are working at 5&6. The equivalent page for 18 March says diesel generators (plural) are providing cooling at 5&6 but I think this is a mistake, because the second has not yet been started. The entry for 17 March says water levels are dropping in reactors 5&6. The entry for 16 march says water in unit 5 was at 2m and had fallen 40cm in 5 hours. Sandpiper (talk) 23:51, 16 April 2011 (UTC)

They lost there deisel generators. Each reactor must have 3 working deisel generators. They are one of the layers (at ANSTO, they would be the 3rd of 5 layers) of defense in depth. To me, this fall under the "Significant failures in safety ­provisions but with no actual ­consequences" part of the "Impact on defence-in-depth" section of the INES level 2. For comparison, have a look at what happened at Fukushima II - the reactors there were damaged by the Tsunami as well, and that was classed as a INES Level 3. MWadwell (talk) 11:35, 16 April 2011 (UTC)

I think the more relevant critical system is that none of the cooling was working at all. 'No safety systems remaining'. Total failure of all cooling systems. This seems to me to be the level 3 condition. Sandpiper (talk) 23:08, 16 April 2011 (UTC)

Sorry - sometimes I forget to fully state what I am thinking. With no DG's, you have no pumps, no I&C (instrumentation and control), and so you lose control of the systems. That is why backup diesel generators are so important, and why they are the second harshest restrictions placed on me when at work (stack emmissions are the harshest). If I lose a single DG (of two DG's) - OPAL has to shutdown within 7 days, and if I lose both DG's I have 24 hours before shutting OPAL down. I've found an example copy of a BWR's OLC's - and they have it even harsher, as if they lose a single DG they have to be shutdown in 3 days, and 12 hours if they lose 2 DG's (and remember they have 3 standby DG's). MWadwell (talk) 01:50, 17 April 2011 (UTC)

I think the press releases have been designed to say what has to be said but not volunteer information about new things to wory about. Thus they did not mention 5&6 until they had good news. On their own and in ordinary times, what happened there would have been front page news. Reactors out of control and heading for meltdown once all the water had boiled away??? This logic about not providing information seems to cover things like plant layout. So I still dont know how many generators there were, or how they were sited, eg low lying, well protected, in the open, whatever. The info from 5&6 seemed to suggest that 6 had two generators, rather than 3 as you suggest would be mandatory. Might this be a question of Japanese regulations rather than those wherever you are working? I saw a report which said Japanese authorities would introduce a requirement for 2 generators per reactor, which seemed very odd in view of having that many already. Also, I dont know what power rating these generators have, as compared to how much is needed to run a reactor. Clearly 1 was not enough for 2 reactors because they only started further pumps after 2 generators were operational. Another issue is the matter of backup batteries. What exactly might these be expected to power, but also where would they be located - so would they also be in the apparently flooded basements. And with regard to flooding, I have seen no real detail of what happened. Maybe the water simply drained away for the most part after the tsunami receded, or maybe it did not. How high up are the control rooms? Sandpiper (talk) 09:14, 17 April 2011 (UTC)

Regarding the press releases - I agree. TEPCO seems to be quite leary of providing information (especially bad information). Regarding the process numbers (i.e. temperatures/pressures) of reactors, I've found a document from NISA that has all of the maximum temperature/pressures - [7] (on page 8) and it also has the number of emergency diesels (note, the information I had about 3 diesels was based on an emergency diesel for the standby service water (SSW) system - which obviously isn't counted as an emergency diesel by TEPCO (probably because all it can power is the SSW - nothing else). As to the layout, I've found this for Reactor 3 (which, as it was constructed at the same time as the other reactors, probably means that they are the same) [8] - which shows that the two DG's (located on the left edge of the turbine hall basement) are on the north side of the building (the arrow at the top of the page points to the sea). On this, I'll mention diversity. It is a requirement that all equipment is divided up into seperate trains (that way it is impossible for a fault in one train to affect the other train). This also means that it is impossible for a DG of one train to power equipment on another train (impossible that is - unless someone runs some emergency cabling - which is what may have happened at Units 5 and 6). However, the idea of diversity doesn't seem to have been fully implimented here - as diversity also means that the two trains have to be physically seperated from each other - but the floor plan of Unit 3's turbine hall clearly shows the two DG's (and associated emergency power distribution boards) sitting next to each other.... Onto the batteries, normally they are for instrumentation and control ONLY - as the pumps to run this place would be in the hundreds (if not thousands) of kW's - clearly impossible to power using batteries for any length of time. However, emergency cooling was designed into the plant, by the implimentation of the High Pressure Coolant Injection (HPCI) system - but if you look at the basement floorplan, you'll see (on the bottom right of the image) 3 HPCP (High Pressure Condensate Pumps) - which means if they get flooded (as the DG's did) that you lose the only cooling system that will work without electrical supply. As to the flooding, I believe that the majority of the 10000 tons of water discharged into the sea was from the turbine hall basements, as with them flooded you've lost both the emergency DG's, as well as the emergency power distribution boards. And without the power distribution boards, there is no way to use any portable generators (as they must be connected into these boards). Finally, as to the control rooms, the only indication I have managed to find as to their location is from a generic GE document on BWR's - which shows them to be on the top floor of the building bounded by the turbine hall and the reactor building (right next to the building holding the emergency DG's - which would make me think that the Fukushima plants are slightly customised, and so the control room might be anywhere....) MWadwell (talk) 10:28, 22 April 2011 (UTC)

I see the nisa report makes no mention of difficulties at 5&6, simply starting its narrative by reporting cold shutdown at around 20 March, after power had been restored. Huh. I see it does mention that HPCI failed at unit 1 because batteries were soaked in water, which is confirmation of that. Its a shame it does not describe the other units in as much detail. The unit 3 layout is appreciated, though annoyingly written much in japanese! Unit 6 layout will be different because it is a different containment, but unit 1 is also a smaller reactor than 2,3 so may differ too. I wouldnt know if any design changes were incorporated as they went along, but it would seem that during the plants build period the designs did evolve. Sandpiper (talk) 08:40, 24 April 2011 (UTC)

"60 per cent of the [Caesium-137] released from Chernobyl"

Can people please stop posting that figure? It's 1) from an unofficial source (the Austrian meteorological institute), 2) relying on measurements from the US Pacific coast (with all that entails in the form of errors introduced by the meteorological models), 3) that's immensely higher than that of other unofficial estimates (e.g. the IRSN's March 22 estimate at 10%), and 4) from March 24. The official figures, two separate estimations from two separate agencies, from April 12 - almost three weeks later - put the total release at roughly 10 percent of Chernobyl's. -- Kolbasz (talk) 15:34, 19 April 2011 (UTC)

Oops, pasted the wrong IRSN paper. This was the correct reference. -- Kolbasz (talk) 19:21, 19 April 2011 (UTC)

An IP user keeps trying to add in bits of a New Scientist article based on the same source , and selectively quote it to give a misleading impression. In the article, Wotawa from the Austrian institute says that the relatively low radiation levels observed near the plant are "entirely consistent" with their claims of near-Chernobyl emissions - this is quoted out of context to imply that levels outside Japan are "consistent with" the levels inside Japan, or inside Chernobyl, or something.

Also, the user keeps claiming that quotes from the Austrian expert are from the CTBTO.

Amuchmoreexotic (talk) 16:39, 19 April 2011 (UTC)

Ok, so I was incorrect in that the disputed quote is indeed from "Central Institute for Meteorology and Geodynamics" not from the CTBT.

However, glancing over the article again, it appears (1) the CIMG is using the CTBT raw data. (2) And the CIMG data is 24 March -- newer than the IRSN 22 March numbers. (3) The CIMG is "the national meteorological and geophysical service of Austria" and "was founded in 1851 and is the oldest weather service in the world.". So, they are not any more "unofficial" than the EPA. Clearly -- *any* worldwide numbers will have to come from a non-Japan source (which could be construed as unofficial, but otherwise there is no data). (5) Both New Scientist and USA Today felt the numbers were reliable enough to quote (6) The later 12 April numbers are from NISA & NSC (which are not really independent) -- which are Japan-only (no world-wide network); (6) the infinitesimal gamma radiation numbers reported by RadNet are not meaningful in this context.

I read the quote to be saying that the amount measured worldwide (by CTBT and interpreted by CIMG) is what is to be expected from (consistent with) the (NISA) numbers in Japan. E.g. much lower, due to dispersion and decay.

Finally, simply deleting the quote repeatedly, without re-wording it, without citing a new source, or without referencing the talk page makes it look like you are editing with an agenda. While I acknowledge my error above, others taking a whole paragraph out cited to 4 independent sources that are quoting the oldest weather service in the world and replacing it with (paraphrasing) 'The levels are very tiny' didn't strike me as good editing.

So, what non-NISA, worldwide, non-Gamma-only, post 24 March, radioisotope numbers would you two consider appropriate? Same Anon Editor 66.65.191.165 (talk) 18:42, 19 April 2011 (UTC)

1) Correct. But all of it is based on the measurements from just two CTBTO stations - one in Takasaki and one in Sacramento, CA. Stations which only measure the ¹³¹
I
; the caesium figures are pure guesswork. By comparison, the IRSN and, one would assume NISA/NSC, estimates use actual on-site nuclide ratios, as well as the actual core configurations. 2) While the ZAMG paper is dated March 24, if you read it carefully, you'll find that the latest data it uses is from March 21. The IRSN paper uses data up to March 22. But one day still makes very little difference compared to the three weeks worth of additional data for the NISA/NSC estimates. 3) When ZAMG was founded is irrelevant. If you want relevancy, you could consider that it's a meteorological institute in a country without domestic nuclear power (a country officially opposed to it, even), rather than a dedicated radiation protection/nuclear safety organization. 4?) I'm afraid I don't understand why sources stating the total release of radioactivity must be non-Japanese. Could you explain? 5) If they had been peer-reviewed journals, the number of times it had been cited would've mattered. Not so for news reporting. 6) The total amount of radioactivity released is what it's all about. Whether it eventually ends up in Japan or abroad has no bearing on it.

And again: one source says 60% (well, actually, it says 20-60%, and only quoting the upper bound without as much as an "up to" qualifier is rather disingenuous), while three say 10%. -- Kolbasz (talk) 21:12, 19 April 2011 (UTC)

There is already specific information about the levels observed outside Japan lower down the section. The article you've added is about one institute's estimate of the total radiation released by the reactor, using detectors outside Japan, but not specifically aiming to estimate the levels outside Japan. So I don't think it really belongs in this section. If it does belong, you should put it into context by mentioning the other, lower estimates.

As you admit, you misunderstood the source of the quote, so why have you restored what you wrote with the same wrong attributions? That's just adding misinformation, so I am going to remove it all for now.

"[T]he infinitesimal gamma radiation numbers reported by RadNet are not meaningful in this context" - the RadNet figures do list isotope levels, not just "gamma radiation". Why do you think they aren't meaningful? They are direct evidence about the radiation levels outside Japan.

I don't think it's clear without any context what exactly the amounts being "entirely consistent" means. I think we should either reword it to make it clear (ie the Austrian institute thinks that the low amounts observed outside Japan are consistent with its estimate of emissions from the reactor), or just remove it.

I don't see how putting one (misattributed) outlier estimate of the total emission levels at the top of this section adds anything to the article if there are direct measurements about the radiation outside Japan. I don't think it's necessary to reword it or find a new source if simply deleting it makes the article more accurate.

Amuchmoreexotic (talk) 00:03, 20 April 2011 (UTC)

Why have you restored what you wrote -->

I didn't restore the edit, another editor did (not that I disagree with him/her as the scientist being from CTBT or ZAMG doesn't appear to make or break this reporting to me).

Why non-Japanese reporting agency? -->

Because we are editing the "Radiation in other countries" section, Japanese numbers belong in the Japanese section (because the Japanese don't have monitors in the US/Europe/etc).

There is already specific info about the levels outside Japan -->

Not really "the fallout" section contextualizes into a uSv/hr context, as opposed to Bq or % of another accident. I believe uSv/hr is somewhat misleading for most readers, it doesn't translate to food / land contamination limits. Further, it makes assumptions about concentration, internal/external exposure, and nominal dissipation. An average user would find 10^5x TMI or 25% of Chernobyl far more valuable, even if there is a chance they could misinterpret its actual meaning.

RadNet are not meaningful in this context -->

The RadNet reporting I have seen (until just recently) has been gross gamma counts, which suffer from all the same assumptions about concentration, internal/external exposure, and nominal dissipation (except worse) -- plus suffer from the fact that it is only gamma, not beta, which further underestimates the importance of the decay modes. The isotope measurements are also extremely limited. E.g. for NYC (the largest city in the US), there appears to be only a single test for I-131 in one sample of drinking water on one occasion since the accident. Further, testing the drinking water "at the tap" ignores that there are literally millions of acre-feet between a raindrop and a consumer's tap. What am I to surmise from a reading of 0 pCi/l, that it takes a long time for rainwater to reach a tap?

I don't think it's necessary to reword ... if simply deleting it makes the article more accurate -->

If every one of 10k to 50k daily viewers erased a sentence they considered inaccurate, this article would be perennially empty.

ZAMG [is] a meteorological institute in a country ... officially opposed to nuclear power -->

And this is a more compelling reason for them to distort their reporting than NISA / NSC / TEPCO who have been endlessly criticized for a lack of independence and inaccurate reporting? I'm not going to accuse NISA of being biased, but I don't see an argument that an independent country with nothing to lose, 10,000 miles away has more incentive to be biased than a regulatory agency long accused of trusting a utility facing US$12B in clean costs + cost for displacing residents from more than 1000 square miles. Same Anon 66.65.191.165 (talk) 03:40, 20 April 2011 (UTC)

I see no new posts, so I rewrote it adding the new data for comparison. I believe this corrects any issues and is good to go in the article.

A widely cited Austrian Meteorological Service report estimated the total amount of I-131 radiation released as of 19 March based on extrapolating data from several days of ideal observation at a handful of worldwide CTBTO radionuclide measuring facilities (Freiburg, Germany; Stockholm, Sweden; Takasaki, Japan and Sacramento, USA) during the first 10 days of the accident. The report's estimates of total I-131 emissions based on these worldwide measuring stations ranged from 10 PBq to 700 PBq. This estimate was 1% to 40% of the 1760 PBq of I-131 estimated to be release at Chernobyl. This report may not have been updated, but for comparison, a 12 April NISA report estimated the total I-131 release (based upon Japanese measurement equipment) at 130 to 150 PBq total release for the longer period of time. This would be approximately 7% to 9% of the I-131 Chernobyl release. An UC Berkeley professor of nuclear engineering who is measuring radionuclide detected in California, but not estimating the total release, asserted "that the fallout poses no significant health threat." The expert who prepared the Austrian Meteorological Service report asserted that the "Chernobyl accident emitted much more radioactivity and a wider diversity of radioactive elements than Fukushima Daiichi has so far, but it was iodine and caesium that caused most of the health risk – especially outside the immediate area of the Chernobyl plant."

Same Anon 66.65.191.165 (talk) 05:55, 21 April 2011 (UTC)

Much better! I still can't find anything in the actual paper about data from any other stations than Takasaki and Sacramento being involved in the actual extrapolation, but this is good enough for me. So good work, 66.65.191.165! -- Kolbasz (talk) 17:04, 23 April 2011 (UTC)

Thanks. From memory, the news article mentions the other testing sites, but it is not mentioned in the report, I assumed it was supplemental information given to the reporter that wasn't available at the time of the preparation of the report.

Likewise, I think your edits over at "Radiation effects from Fukushima I nuclear accidents" are for the better. Parts of that article definitely need pruning. Same Anon 66.65.191.165 (talk) 21:47, 24 April 2011 (UTC)

13 generators

Article currently says there were 13 emergency generators operating before the tsunmi. Anyone have any information about how many generators there actually were/are in the plant? Sandpiper (talk) 08:39, 20 April 2011 (UTC)

I believe the article (when I last read it) incorrectly treats the citation. Here are the two quotes:

[reactors] automatically shutdown due to the Miyagiken-oki Earthquake. For the above 3 units, off-site power was lost due to malfunction of one out of two off-site power systems, leading to automatic startup of emergency diesel generators. Subsequently, at 3:41PM, emergency diesel generators shutdown due to malfunction resulting in the complete loss of alternating current for all three units. http://www.tepco.co.jp/en/press/corp-com/release/11031103-e.html

(and)

The Prime Minister's Office, the nuclear safety agency and even Tokyo Electric Power Co., the operator of the Fukushima plant, were filled with relief immediately after the earthquake. They had been told backup diesel generators would provide sufficient support to stabilize the Nos. 1 to 3 reactors, which were in operation when the quake hit. However, subsequent tsunami destroyed 12 of the 13 emergency generators. http://www.yomiuri.co.jp/dy/national/T110411004567.htm

I read that to mean

(1) grid power was lost

(2) some amount of generators turned on (unknown)

(3) there were 13 total generators

(4) Something (presumably the tsnumai, but not from these sources)

(5) 12 of the 13 generators fail (#13 was actually built into the unit 6 reactor building, that's why it survived, but not explained here)

So, I originally wrote something like "an unknown number of generators were started after the [grid power was lost], subsequently 12 of the 13 generators available were destroyed and could not provide power." 66.65.191.165 (talk) 06:07, 21 April 2011 (UTC)

But that was changed (actually I just saw, by you). This was removed too:

"The tsunami also destroyed all of the No. 1 plant's pumps, which were also not located within a sealed structure."[65]"

which I think should remain in this article as well. As it is particularly germane to a valid debate about the engineering cause of the accident (1) loss of electricity or (2) the tsunami. 66.65.191.165 (talk) 06:22, 21 April 2011 (UTC)

See the refs I posted above discussing this which imply that the generator at 6 was repaired on 17 March, so presumably not functioning before that, and no mention i have found anywhere else of any other functioning generator except its twin at 6 which was repaired a bit later. It seems to me that this report of a functioning generators at this date plus no reports of failed generators before this (despite nearly all being failed), have been conflated into implying one generator did survive the tsunami. The yomiuru ref also mentions trying to find cables to connect mobile generators, which in light of the fact it is now a month later and although mains power is restored, still little is operating, sounds like it was purely an excuse at the time. Obviously it might be the first problem they had to overcome, but the plain fact is having a long enough lead is not the main difficulty. The problem with restoring equipment is not simply functioning generators. There is an additional difficulty in that the cited ref talks about power for 1-3, not 5&6, which effectively seem to be electrically completely separate. This [9] for example says all generators failed.

As to the pumps, obviously it did not destroy all the plants pumps because most of them are, as best i can gather, internal to the buildings. It remains an interesting point whether they are 'destroyed' or merely inaccessible right now. It would appear sea water pumps were outside without protection and I do not know if these were 'destroyed' or merely damaged. Sandpiper (talk) 09:33, 21 April 2011 (UTC)

I give greater weight to the Yomiuri reporting because it is a full month later than the Asahi reporting. Given the lack of power, the number of times the plant was evacuated, and the general confusion that existed, I think there is a high probably of confusion in informal TEPCO reporting to the media in the days after the accident. So, I think the report on April 11 is more likely to be accurate than a March 13th report. I haven't read about repair of the unit 6 generators on 17 March (and couldn't find your link in the discussion page). If two generators were repaired, that might be inconsistent with one surviving the tsunami, but not necessarily.

The article is quite clear that the plant's pumps were destroyed. I don't find this incredible at all: (1) Unit 1 was first to overheat, implying it had been cooled less (otherwise it is odd that the smallest unit overheated first) (because even with battery power, something wasn't working correctly); (2a) functional diagrams of BWRs frequently show the feedwater pumps in turbine buildings (http://www.nucleartourist.com/type/bwr.htm) NRC basic docs show the same (http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf) (feedwater pumps in the turbine building); coupled with the fact that (3) turbine buildings are less robust than reactor buildings (not really available online, probably due to 9/11 concerns, but see pg 170 of this book http://books.google.com/books?id=5M2mVU_9fqAC&lpg=PP1&dq=Earthquake%20Hazards%20and%20Mitigation&pg=PA170#v=onepage&q&f=false which puts turbine buildings as category III safety buildings, below waste water treatment).

Interestingly, this presentation (http://www.ne.doe.gov/np2010/pdfs/8%20%20US-APWR%20Layout%20presentation.pdf) shows that gen III reactors have a power supply building which is required to be seismic category I (the highest category), potentially something that would have prevented this accident.

I think we should start trusting new high-quality reporting, over the original reporting. Until official reports are prepared (probably years away), I think that will yield the best article.

Finally, I think we should consider breaking each unit/reactor into its own article. Each of these events/accidents/meltdowns is a complex, multi-billion dollar event, and would justify its own page if it occurred alone. Trying to keep them on one page limits what details we can include and keeps pushing the article length up to ~100k, which is really long for the reader. But given the debate about everything in this article, I assume such a task is nearly impossible. 66.65.191.165 (talk) 05:44, 22 April 2011 (UTC)

I cant agree that simply because the report is later, it is necessarily more accurate. Clearly it is a semi-dramatisation of events, including what thoughts politicians were having. As such it draws upon a suggestion in the IAEA report of an operating generator, but frankly at that time IAEA reports were making mistakes. I have not seen anything definitive except multiple news reports saying ALL power was lost after the tsunami. Nothing about everyone hudddling in reactor 5/6 because there the lights were still on. If you read the TEPCO bulletins they state that there was varying levels of cooling still operating after the tsunami in 1-3, before it all failed. Fundamentally, it failed because the heat exchangers were not working to remove heat from the core cooling, so however much recycling of water was still working internally, the heat had nowhere to go. External pumps bringing in sea water for cooling to the heat exchangers had no power, but possibly no longer exist as you say. Some pumps were supposedly directly diesel driven rather than electric. What excatly has happened to them, I have not seen reported. Tepco reports definitely state that some pumps DID work initially after the tsunami (I presume the ones powered directly by steam rather than electricity), so cannot ALL have been destroyed. Although the TEPCO reports are terse, I think they have proved to accurately state things as they were. They confine themselves to headlines and leave things out rather than state inaccurately. I'd love to have some new high quality reporting, but I havnt seen any yet. Sandpiper (talk) 08:20, 22 April 2011 (UTC)

IAEA on march 14 stated all external and generated power at the plant had been lost. They are also reported to have complained about lack of information and its reliability coming from Japan in the early days. Sandpiper (talk) 07:55, 23 April 2011 (UTC)

I think it is hard to know. I would separate a couple facts though, its possible that a generator remained functional, but couldn't power cooling systems (especially if some of the switching equipment was flooded or destroyed). It is also possible that a generator was functional, but failed after some amount of operation - given the condition of the facility and the fact that fuel and/or cooling water (for the EDG) needed to be provided, its possible the EDG failed shortly after the event (hence the later talk about repair).

Regarding if the fundamental failure was the lack of residual heat removal systems, I'm think we are going to find out that the RCIC and recirc pumps were damaged in the earthquake. TEPCO / IAEA haven't even hinted at this yet, but the description of the building from those working inside during the earthquake (pipes breaking, equipment falling) didn't make it sound like the only issue was the RHR system. Since no one has been inside yet, this hasn't been commented on, but it seems likely to me.

I think all your proposed mechanisms make sense, but that there are others that are viable as well, we won't know until more information comes out. 66.65.191.165 (talk) 22:26, 24 April 2011 (UTC)

RCIC worked in 2. I guess it failed as it must when the wetwell boiled. The steam turbine runs on differential pressure between them. NISA have said high pressure injection's batteries were soaked in 1. There have been no comments on 5 and 6 so who knows if batteries were ok to run it, but it wasnt needed initially since they started from cold. These reactors got to 160/180C and were loosing water...shutdown and from cold. Yes, its possible a generator survived at 6 and the switching/pumps did not, or that one survived and then failed from something else, but nothing says this. The statements say that initially all generated power failed. Then they say as something new that a generator will be used to run a pump. From the limited info available, 5&6 rose steadily in temp through the incident and were only brought back under control by some sort of repair. Sandpiper (talk) 09:51, 25 April 2011 (UTC)

venting via fuel ponds

I have seen discussion that in the early design of this type of reactor venting from the reactor to atmosphere was something of an afterthought as it was never meant to happen. Later designs were altered to vent via the vent stacks outside the buildings and some reactors were retrofitted to do this. However, at Fukushima I venting was directly into the reactor building - hence the buildup inside of hydrogen. Furthermore, by design vented steam was fed through the fuel ponds, so that it would condense back to water and be retained. Except that if the pond cooling wasn't working, all this would do would be to heat up the fuel ponds until they too started boiling. Hence emptying them of water and exposing the fuel there. If this is correct, then in effect the system was set up to cause a fuel pond crisis if a reactor one happened first. This would somewhat explain why the fuel ponds ran out of water. Does anyone have any further information? Sandpiper (talk) 08:29, 22 April 2011 (UTC)

It is a known fact that reactors require venting, and that the vented gases contain radionuclides. If you have a look at this link BWR/6 General Description of a Boiling Water Reactor (warning - it's a 7.7 MB file) you'll see on page 5-2 a description of the Standby Gas Treatment System (SGST). A simplified image is available from the Nuclear Tourist here. "

That document describes a mark 6 reactor. Unit 1 is mark 3 and units 2,3 mark 4. Units 1-4 are mark 1 containment, and I imagine a mark 6 reactor would use later mark containment? Sandpiper (talk)

I can think of two reason why it may have been vented into the building: 1) Dose reduction - by trapping the radionuclides in the building, you allow them to decay away in a safe place before they are (eventually) vented to the atmosphere. For the isotopes of iodine (which have a half life measured in days), this can significantly reduce the amount of radiation released; 2) due to the pressure losses over the filters, an air extraction fan is required to "pull" the air out of the building - and with a station blackout, this wasn't working (similarly, neither would the recombiner/cooler-condensor worked - which is what normally gets rid of the hydrogen).

As to venting through the fuel pond, this is a design feature of some of the newer Gen III reactors, and to the best of my knowledge is not used in BWR's. MWadwell (talk) 10:53, 22 April 2011 (UTC)

The item I read suggested that this form of internal venting was an original feature subsequenly dropped. Fukushima I is, I think one of the earlist reactors built and was done to original american blueprints, whereas later builds had imporvements added. ? Sandpiper (talk) 18:12, 22 April 2011 (UTC)

The venting issues are somewhat complicated, this document discusses some of them: http://www.nei.org/filefolder/Report_-_BWR_Mark_I_Containment_03192011_2.pdf Generally speaking, the NRC required Mark I BWR reactors to retrofit "Torus Hardened Vent"s to their designs (see page 20 of 21 (of the PDF numbering) for a description of the THV). Last I heard, it was unclear if the Japanese regulatory authority required this modification of their Mark I plants - it was very expensive. That question might even be answered in this document, as I haven't read it all. 66.65.191.165 (talk) 00:36, 23 April 2011 (UTC)

I see it says there is no nuclear generator in the world designed to withstand total loss of power for an extended period (as here). It says the containment system worked beyond its design pressure. Generally the reactor performed as expected in design studies. So this outcome was entirely predictable given the tsunami. It says that when they designed the mark III containment they discovered more about how Mark I (as here) would work in a coolant loss accident, and discovered water hammer effects (I think, 'oscillatory hydrodynamic loads') from sudden pressure changes which they had not anticipated, which might cause reactor failure. In short, a serious design fault even with the kind of accident it was designed to cope with (rather than this one, which it was designed not to cope with). All this happened in 1975, just 5 years after the plant began operating, but in fact before unit 4 began operating. It says that all US reactors of this type 'added a containment venting capability', ie have had retrofitted venting systems to discharge from primary containment to outside the plant. By implication, this was not included in the original design, as I read elsewhere. It followed concerns in the 80s and 90s over what would happen in the event of a station blackout, as here. Again, it says that US reactors have had additional measures installed from 2001 to add water to reactors in case of damage to the buildings (eg, by terrorist, but flooding or hydrogen explosion as here might have caused the sort of damage they had in mind?) It says that design testing in operation was carried out on this design in 1972-74 leading to modifications, all of which was after building of units 1-3 had commenced, so its fair to say they were somewhat prototypes.

No, the document says nothing about whether vents were fitted to japanese reactors or about how venting takes place in the absence of this designed system for doing it. I presume the reactors had some sort of safety valve, But as I said what I read before said this vented into the fuel pool. At one point during the failure cascade it was impossible to operate vent valves due to battery failure, but I dont know what that implies about what these valves were or where situated. Sandpiper (talk) 07:22, 23 April 2011 (UTC)

A couple of (hopefully quick points): 1) The document referenced by 66.65.191.165 mentions two groups - the BWR's Owners Group (BWROG) and the Mark I Owners Group. First point - I can confirm here that TEPCO is a member of the BWROG, and is almost certainly aware of the modifications required by the NRC to be made to the torus venting system and the stack venting system. Next point, is that the NRC is the "Gold Standard" that is used globally (for example, here at OPAL we use the NRC guidelines - even though they are not legally applicable to Australia) - and so I consider it unlikely that neither TEPCO nor NISA insisted on the plant modifications. The third point (specifically on the hardened venting system to the stack), a review of the photo's taken after the earthquake show that there is a LOT of damage sustained to the ventilation pipework between the reactor buildings and the stacks - and so a vent to the stacks probably wasn't possible. The last point (specifically addressing Sandpipers comments about venting through the fuel pool) - ALL of the literature I have read (both generic information from GE as well as specific information on the Fukushima units) states that the RPV is vented through the wetwell - NOT the fuel pools. If you are going to continue to state this, then I'm going to insist on references....

The facts of the matter is that the Fukushima units were hit with a number of Beyond Design Basis events (the size of the earthquake, the size of the Tsunami, and the extent of the "Station Blackout") - and I think that considering all of this, the plants have stood up reasonably well. Not as good as a Gen III reactor would (which, after all, is designed for increased plant safety based on the Gen II reactors like at Fukushima), but reasonably well regardless. MWadwell (talk) 12:18, 23 April 2011 (UTC)

To the extent you trust a redacted document on the US government's websites: Fukushima was retrofitted with the THV. (http://markey.house.gov/docs/4-6-11markey_e-mail_2_-nrc_question_regarding_fukushima_unit_2.pdf). This is new since the last time I searched for an answer on this question.

I ran across this quite by accident just now: http://www.asahi.com/english/TKY201103140243.html

Vents were installed at the boiling-water reactors (BWRs) operated by Tokyo Electric Power Co. from the mid-1990s. The design was revised to allow gas to be released into the atmosphere through a filter located at the bottom of the containment vessel.

I'm going to post it (a second time) lower in this section, due to the amount of text. 66.65.191.165 (talk) 22:32, 24 April 2011 (UTC)

We arent going to answer this, are we? Plainly, the vents did not prevent an explosion. The asahi link says containment had vents installed, but what containment? Secondary containment? I don't see the 'major risks' they suggest from venting direct from primary containment to the top of the vent stacks, and certainly dont see it blowing off the top of secondary containment. Perhaps if the pipes had burst. That still leaves us with the explanation by gas leaks from primary containment seals under the very high pressures around the time venting was performed, so that the explosions were linked but not directly caused by venting. They vented too late? Sandpiper (talk) 09:34, 25 April 2011 (UTC)

MWadwell, I had been told (by someone I trust) that some of the accident reconstruction chemical analysis of the notable 1986 accident discovered (despite the obvious many differences between a BWR and the RBMK-1000) that an unexpectedly quick buildup of high pressure gases via unpredicted chemical pathways was possible. This person believed that this analysis may have played a role in NRCs eventual decision to enforce the THV mods in the US. Have you ever heard this? I've never seen a report, and the chemistry is many leagues beyond me. 66.65.191.165 (talk) 21:21, 23 April 2011 (UTC)

G'Day 66.65.191.165 - thanks for confirming that the Fukushima units were fitted with THV's (even though the source is a little suspect - it's the best one I've found so far). Onto the evaluation of the 1986 accident, I'm suspicious that Chernobyl had anything to do with the THV's, as the Report on BWR containment states that the NRC presented the conclusions of the Long Term Program (LTP) of the Mark 1 Owners Group in July 1980 (NUREG-0661) and August 1982 (NUREG 0661 Supplement 1) - which occurred before Chernobyl. Having said that, the report then goes on to state that in the late 1980's and early 1990's, procedural changes and modifications were made to handle station blackouts - but I'm unsure if this is in response to Chernobyl or as a result of the issuing of NRC Regulatory Guide 1.155- Station Blackout (which was issued in August 1988). As to the unpredicted chemical pathways, I haven't heard anything about this, but I'll try and catch a Reactor Chemist who works on shift tomorrow morning (during handover) to see if he has heard more about it. MWadwell (talk) 02:56, 24 April 2011 (UTC)

Thanks. 66.65.191.165 (talk) 21:36, 24 April 2011 (UTC)

Hate to be picky, but the posted response just says the plant had hardened vents. Vents for what? On all reactors? I know nothing about the history of coverups by tepco, but apparently it has a terrible reputation for failing to report problems or implement safety measures. Sandpiper (talk) 08:50, 24 April 2011 (UTC)

I agree, but that is the most (by far) detailed answer I've found. I think it very likely refers to "the" torus hardened vent "retrofit," as that is how the terminology is used. However, there is a chance that whoever answered this email didn't know for sure. I'm going to treat it as "conditionally proven" that the reactors were retrofitted, but subject to new information.

Also, to echo MWadwell a bit, I think the existence (or non-existence) of this vent probably won't turn out to be critical. The units simply were not designed to be without power for this long, and vent or not, they were going to be in trouble. As far as coverup or non-implementation, given the some of the things we've learned about TEPCO, I guess there is a chance they were able to avoid installing the THVs through political influence, but I doubt there is any chance of a coverup. This was a big modification. Opining more than that is well beyond my knowledge. 66.65.191.165 (talk) 21:36, 24 April 2011 (UTC)

I ran across this quite by accident just now: http://www.asahi.com/english/TKY201103140243.html

Vents were installed at the boiling-water reactors (BWRs) operated by Tokyo Electric Power Co. from the mid-1990s. The design was revised to allow gas to be released into the atmosphere through a filter located at the bottom of the containment vessel. 66.65.191.165 (talk) 22:32, 24 April 2011 (UTC)

I will try to minimize my comments on the "design-basis accident" discussion, but I will say that flooding of the EDGs appears to be a single-point failure (it appears that it also flooded the switch gear) that could lead to a SBO, that everyone (in the industry) knew was very, very bad. 66.65.191.165 (talk) 21:21, 23 April 2011 (UTC)

I agree - as I've stated before, I believe that locating the two EDG's in the same room fails the diversity criteria that all essential services must meet. MWadwell (talk) 02:56, 24 April 2011 (UTC)

Nisa report posted above says batteries in unit 1 were 'soaked' too. Anyone able to say if these were stacked next to the generators? Sandpiper (talk) 08:50, 24 April 2011 (UTC)

Its safe to say there will be fundamental design changes for emergency cooling and emergency venting in the future. Its good what happened can't be swept under the rug or blamed on the operators. I still think unpressurized boiling (=venting) is the way to go in this type of emergency. You don't need high pressure water injection pumps, a good steam dryer is already above the core, and you can vent and filter reactor water. A mediocre condenser above the pressure vessel would do wonders or the regular condensers would do. 172.164.148.35 (talk) 12:37, 22 April 2011 (UTC) BG 172.163.57.161 (talk) 17:07, 22 April 2011 (UTC)BG

But once they released pressure they knew the water would all boil away unless it no water, could be replaced, and they had no means to do this. If by condensers, you mean some working via cooling water from the sea, there wasnt any of this either. Sandpiper (talk) 18:16, 22 April 2011 (UTC)

After depressurizing you don't need a high pressure pump to inject water. A fire truck, portable pump, municipal water supply, or other source would work fine. They didn't have it, but even a cheap air-cooled condenser above the pressure vessel would have been effective enough. 172.162.170.162 (talk) 22:44, 22 April 2011 (UTC) BG

So where would you get a 50-100MW air cooled condenser in a hurry, and where would you site it? You mean, an alternative better design would have had one already for emergency use? The next problem is no water supply. No available fresh water, just the alternative of using salt water. Even sea water is not a sustainable option because the reactor would become choked with precipitated salt. I have not seen a detailed calculation of how much salt would be dumped inside by the amount of water boiled off from these reactors. It is possible that someone did do this calculation and showed it could not work. Sandpiper (talk) 06:01, 23 April 2011 (UTC)

Yes, they couldn't do much with what they had, and I agreed with you from the beginning that saltwater was a problem. Hindsight is 20/20. But having a passive cooling system is better, the fuel pools becoming uncovered and the hydrogen explosions did not have to happen, and there's a lot to be said for unpressurized long term emergency cooling. They simply were not prepared for this.172.129.9.32 (talk) 14:18, 23 April 2011 (UTC) BG *** BTW, now they're talking about building a long underground wall to isolate the water table near the plant. This has merit, but its better and might be easier to drill several small wells near the plant and continuously run them so the water table flow goes towards the sea. They could dump the water in the ocean or use it to hose down or flush out the facilities. Also makes it easy to test the ground water. 172.162.140.160 (talk) 23:13, 23 April 2011 (UTC) BG

Tsunami hit

I find this sentence wrong:

The plant was protected by a seawall designed to withstand a 5.7 metres (19 ft) tsunami, but not the 14-metre (46 ft) wave which arrived 15 minutes after the earthquake.

I'm going to correct the bolded words of this sentence because:

1. in the citation provided it is not stated that the wave hit only 15 minutes after the quake,
2. in this article by the BBC there is a paragraph where one can read that the tsunami hit one hour after the quake:

Mains electric power to the pumps providing this cooling water was lost in the earthquake, so back-up diesel generators kicked in, again as designed, and all looked good. But an hour later the tsunami hit, taking out the diesel generators and the oil storage tanks. Fukushima Daiichi was designed to withstand a six-metre tsunami - 15 metres was just too much.

--Vitaltrust (talk) 13:45, 22 April 2011 (UTC)

I agree that it has been widely reported that the tsunami hit 1 hour after the earthquake. But if you look at the time line, I'm not sure:

On 11 March at 14:46 JST, unit 1 scrammed in response to an earthquake seconds earlier. http://www.tepco.co.jp/en/press/corp-com/release/11031103-e.html

Then at approximately, 14:52 JST, the *city* of Fukushima was hit by a tsunami. http://www.jma.go.jp/en/tsunami/observation_04_20110313180559.html

At 15:41 emergency diesel generators shutdown. http://www.tepco.co.jp/en/press/corp-com/release/11031103-e.html

At 15:42, TEPCO declared a "Nuclear Emergency Situation" for units 1 and 2. http://www.tepco.co.jp/en/press/corp-com/release/11031103-e.html

Perhaps there is a large difference between the tsunami arrival time for the plant and the city, but otherwise it seems odd. Does anyone know if the tsunami hit the plant and the city of Fukushima at the same time? Could there be some sort of difference in the plant's time and the JMA's reporting time? The difference in times is almost exactly 1 hour. 66.65.191.165 (talk) 00:48, 23 April 2011 (UTC)

I dont know what is happening here. The tsunami does not appear to have behaved as predicted. It might be that it did not radiate out from the epicentre because there seem to have been major changes in land/sea bed height over a very big area. The reported wave height at the power plant seems to be greater than its general height, perhaps because of local topography. The wiki tsunami article gives some arrival times at certain places but I dont know any japanese geography and all those mentioned seemed to be too far north. Sandpiper (talk) 07:35, 23 April 2011 (UTC)

According to the Yomiuri Shimbun, the first tsunami hit the plant at 3:27 p.m.--41 minutes after the earthquake. [10] Oda Mari (talk) 08:51, 23 April 2011 (UTC)

It is not possible for the tsunami to hit the city of Fukushima, since it is located inland in a mountain valley. The tsunami hit the coastal region of Fukushima Prefecture, but not the city proper. Regarding the timeline, I suppose the plant was striken by different subsequent waves of tsunami, as in http://www.jma.go.jp/en/tsunami/observation_04_20110313180559.html it is reported that a first wave of just 0.3m hit the town of Soma, some 40km north of Fukushima I Nuclear Power Plant, at 14.55 JST but the tallest wave (more than 7.3m) arrived at 15.50 JST, one hour later than the earthquake. The fact that, around this time, the backup diesel generators at the plant went off seems to confirm that it was the wave at 15.50 JST that made the most damages, not the previous ones. However, I must admit that the timeline of events is not very clear, since some sources are a bit conflicting. --Vitaltrust (talk) 16:49, 23 April 2011 (UTC)

Oh, so is Soma the closest JMA tsunami reporting-site to the nuclear facility? If you do a Google maps route, Soma shows 450km away (http://maps.google.com/maps?f=d&source=s_d&saddr=soma,+japan&daddr=fukushima+nuclear+power+plant,+japan&hl=en&geocode=FU5FawIdiEdeCCkBAFQs-P6aXzFonE5Ifn15JA%3BFeH9OgIdav9nCCkZlJkJON0gYDEU4gYhdWDE7A&mra=ltm&dirflg=d&sll=39.00252,140.714782&sspn=4.080736,13.480225&ie=UTF8&ll=36.914764,141.921387&spn=8.394122,26.960449&z=6). Are there two somas? If so, then it does bring the timeline into closer alignment with commonly reported "1 hour after the earthquake." It would make something more like this:

I wasn't sure what the JMA's "Fukushima Onahama-oki" was, I assumed it was Fukushima city.

11 March 14:46 JST (05:46 UTC) a 9.0-magnitude undersea megathrust earthquake off the coast of Japan that occurred at on Friday, 11 March 2011. http://www.webcitation.org/5xgjBRle0

11 March 14:46 JST, unit 1 scrammed in response to an earthquake seconds earlier. http://www.tepco.co.jp/en/press/corp-com/release/11031103-e.html

11 March 14:52 JST, Fukushima Onahama-oki was hit by a small tsunami 0.7m (estimated by sea buoy?). http://www.jma.go.jp/en/tsunami/observation_04_20110313180559.html

11 March 14:55 JST, Soma was hit by a small tsunami, 0.7m. http://www.jma.go.jp/en/tsunami/observation_04_20110313180559.html

11 March 15:04 JST, Fukushima Onahama-oki was hit by the reported maximum tsunami, 1m - 4m (estimated by sea buoy?) http://www.jma.go.jp/en/tsunami/observation_04_20110313180559.html

11 March 15:41 JST, Emergency diesel generators shutdown. http://www.tepco.co.jp/en/press/corp-com/release/11031103-e.html

11 March 15:42 JST, TEPCO declared a "Nuclear Emergency Situation" for units 1 and 2. http://www.tepco.co.jp/en/press/corp-com/release/11031103-e.html

11 March 15:50 JST, Soma was hit by a large tsunami, 7.3m, or more http://www.jma.go.jp/en/tsunami/observation_04_20110313180559.html

Both these two stories show the waves hitting the plant, but don't mention the time. http://www.the9billion.com/2011/04/10/moment-japan-tsunami-hit-fukushima-nuclear-plant/ http://photoblog.msnbc.msn.com/_news/2011/03/25/6341698-new-images-show-immediate-aftermath-of-tsunami-striking-fukushima-nuclear-plant I checked three cites used by Wikipedia and none of them specify the time. Which is odd, given that it clearly must be recorded somewhere. I think we should just use "after the earthquake, a tsunami struck."

Sandpiper, I think you might be right, there may be some inconsistency between the general tsunami observations and whatever happened at the plant. 66.65.191.165 (talk) 20:40, 23 April 2011 (UTC)

There is a town called "Soma" also in Fukushima Prefecture, roughly 40km north of the plant: look at this article. When you say that a place called Soma is 450km far from the plant, maybe it's because Google Earth used another place for the mapping. I have tried by myself with Google Maps, and the "wrong" Soma couldn't be hit by a tsunami wave since it is located inland, in a mountainous area. --Vitaltrust (talk) 09:27, 24 April 2011 (UTC)

Thanks for the clarification. Also, FYI, I updated an error in the the "order of events" table above. 66.65.191.165 (talk) 22:36, 24 April 2011 (UTC)

It sounds as though there was more than one wave, which may have messed up official timekeeping and reporting generally. Do we reckon it is the case there was more than one wave, so we might say that? I read one eye witness report of a black wall approaching the plant and then flooding it, so there was one specific incident but it didnt give times (naturally).Sandpiper (talk) 08:40, 24 April 2011 (UTC)

I changed the wording to "the 14-metre (46 ft) maximum wave which arrived 41 - 60 minutes after the earthquake", and used a better source. This seems the safest wording, but anyone can change it if they have better info. The original sources were inadequate and the initial BBC report was apparently just an estimate. Whether it was a 14 or 15 meter peak wave can be rectified later. The new source is certainly not perfect, and won't satisfy everyone (including me), but its better than the sources before. The arrival time of the peak wave is of great interest and maybe someone can find a definitive source; if not eventually there will be an official report that should state it. I read someone had a video. 172.162.21.114 (talk) 14:34, 24 April 2011 (UTC) BG