TEPCO says temperature of No. 2 reactor has dropped below 100 degrees C

Nice to read some good news from Fukushima Daiichi.

Some relief, if true.

TEPCO says.........

Well with most of the fuel melted trough the reactor vessel and into the basement or ground below. It is natural for the reactor to cool down. Does not mean that things are under control.

By definition it is not "cold shutdown" if the fuel has melted through the bottom of the containment vessel.

@Squidbert - are you sure that's right?

My understanding is that the fuel melted through the reactor vessel and has been pooled at the bottom of the containment vessel, so it's still contained and covered with water and is not in the basement or the ground. In other words, it's still totally covered and being cooled.

This can only be good news.

i guess i can start eating the rice and veggies from this area then...NOT!

I would not hold my breath on any of this, one big cover up after another IMHO.

Well it (melting through) would be the natural progression of things, so I tend to believe that over what TEPCO is telling us. The loss of pressure in the containment vessel also indicates this I think.

But even if the corium is still in the containment vessel, they are measuring the temperature of the reactor vessel, which does not have any fuel in it any more so measurements are moot.

The following quote (although regarding reactor 1 and not 2 ) from wikipedia also points towards this direction.

TEPCO estimates the nuclear fuel was exposed to the air less than five hours after the earthquake struck. Fuel rods melted away rapidly as the temperature inside the core reached 2,800 C within six hours. In less than 16 hours, the reactor core melted and dropped to the bottom of the pressure vessel, burning a hole through the vessel. By that time, water was pumped into the reactor in an effort to prevent the worst-case scenario overheating fuel melting its way through the containment and discharging large amounts of radionuclides in the environment.[156] In June the Japanese government confirmed that Unit 1 reactor vessel containment was breached, and pumped cooling water continues to leak months after the disaster.[13]

Reactor 2 is the reactor where TEPCO originally reported 1000mSv/h in the basement, only to retract the statement a couple of hours later. It has however (as I understand it) later been found out that the 1000mSv/h number was correct, and the only wrong part of the statement was that the dose was 10 million times larger than normal, it was supposed to say 100 thousand times larger.

Either way, the fuel is not were it is supposed to be

I guess my point is that "Cold shutdown" are just words. But it's definition is intended for a working reactor not for the pile of junk that is at the TEPCO site in Fukushima.

Ok then, maybe better luck with this?

http://www.infiniteunknown.net/2011/09/21/japanese-msm-finally-questions-cold-shutdown-possibility/ (Originally in Mainichi)

If the cooling system with a total extension of four kilometers develops trouble, the temperatures of the reactor cores could rise again. Since it remains unclear where the melted fuel is situated in the troubled reactors, the temperatures of the pressure vessels alone are far from convincing.

Under these circumstances, the phrase, “cold shutdown,” should not be used in a casual manner without clearly defining it. It is important to grasp the actual conditions of the reactors and fuel as accurately as possible and take appropriate countermeasures in a well-organized manner.

@Zichi

There can be no cold shut down of reactors 1-3 unless TEPCO have redefined its meaning?

Nail, on the head, with hammer you hit.

More FALSE HOPE. They played this games before. It is irrelevant at this point the temperature. Why ? Because if the fuel melted through (a very real possibility), that would mean lower temperatures.

Two things: measure the amount of radiation still coming out and check for iodine. If there is still fission is all nonsense; if he levels of radiation don't decrease a lot, it's all nonsense. Lastly physical verification of the fuel's location is needed. If it's outside of the reactor, best pray REAL HARD nothing goes wrong Caiden the damn thing could explode, making march look like child's play.

I hate these liars at TEPCO, the j govtand mostly reputable media giving false hope. This should be written by a nuear engineer, not an English major.

In case you were wondering, what I refer to is a very possible scenario, related to SquidBerts comment. Michio kako, physicist, says pretty much the same.,

Michio kako, physicist, says pretty much the same.

What the heck is up with everyone citing Michio Kaku as an authority? He's not a nuclear physicist or engineer, his only qualifications are liking to be on TV a lot and being a anti-nuclear activist.

Listening to what he says is as bad as listening to what a TEPCO exec says!

More FALSE HOPE.

And Beangry, you NEVER have anything positive to say, always tearing things down. This is GOOD news, and the only reason you see it as bad news is you want to see it as bad news. Try taking off the doom and gloom spectacles and be objective for once!

@Pawatan,

I know your comment was directed at beangry, but I would like to take the opportunity to say: I am glad that they are making progress at the Fukushima plant, thanks to all the workers there doing hard work. If this message sometimes becomes lost in my criticism of how TEPCO and the government is handling this I am sorry.

My main concern here is that they seem to be taking this so called "Cold shutdown" as a reason to lift restrictions in the security zones, which I think will turn out to be a big mistake.

Japan has promised to achieve a cold shutdown of the plant by the year-end.

Actually they said January but I'll take year end .

My main concern here is that they seem to be taking this so called "Cold shutdown" as a reason to lift restrictions in the security zones, which I think will turn out to be a big mistake.

SquidBert, I agree we as citizens and residents should be vigilant and make sure that excuses are not made to justify putting more people in harm's way than have already been. We need transparent, agenda-free, objective sources for information and the people making the decisions need to consult those independent voices, not those with vested interests on any side of the issue. Almost 7 months on, we all deserve this.

It just makes me mad to see some constantly criticising and never acknowledging that while the situation remains very dangerous and unstable it's far better than it was in March. Announcements such as this one reflect that.

the site slowly recovers from the March 11 tsunami.

Recovers? How dare they use this word? Is this a word for what is going on there? All the stuff has melt down, heavy tons of radioactive fuel and is still there glowing and emitting death. It's just cooling very slowly and the whole thing is a death trap. Nothing is recovering there and will not until they recycle the killer stuff and decommission the NPP and then recovery might begin.

Now speak about where you pour the used radioactive coolant.

You guys are all talking like you know what is going on there. When I read how pessimistic you guys and not trust the system, I wonder why some of you are still in Japan. Tepco will always be here with the Japanese system. Get used to!

High hydrogen levels in pipes at No.1 reactor

http://www3.nhk.or.jp/daily/english/29_01.html

Excerpt: It found that the density of hydrogen was high, at between 61 to 63 percent.

3 Fukushima reactors cooled below 100 degrees

http://www3.nhk.or.jp/daily/english/28_31.html

Excerpt: Tokyo Electric Power Company or TEPCO says the temperature in the lower area of the Number 2 reactor stood at 99.4 degrees at 5 PM on Wednesday. Temperatures at the Number 1 and 3 reactors have been maintained below 100 degrees Celsius since August.

Squidbert:

" Well with most of the fuel melted trough the reactor vessel and into the basement or ground below. It is natural for the reactor to cool down "

That is not what the intl. experts are saying. They are saying very small amounts have melted through the control rod openings at the bottom, but almost all of the fuel is in the containment vessel, and at this temperature it is going to stay there.

Do you have any reliable information that says otherwise? And by "reliable" I don´t mean activist websites.

WilliB,

Sources are only what I already stated in my, 29, 2011 - 10:08AM JST and Sep. 29, 2011 - 10:35AM JST post.

Point being, that more reliable sources does are difficult to find. But the extremely high temperatures (2800 C), that even the government admits to being reached during the period 6 to 16 hours after the initial hydrogen explosions, would be enough to melt its way trough the containment vessel.

Where are your international sources saying that "only a small amount have melted through"? And by "reliable" I don't mean the goons of Big Nuke. See, I can play that game to. ;-)

If proper international inspection of the site was allowed, and if the workers at the plant were allowed to speak out in media (which has been prevented numerous times) then no one would have to make guesses.

But when making guesses in the field of nuclear safety, guesses should always err on the side of caution, should they not?

In fact we have seen for the last 7 months what happens when you allow guesses or estimation of i.e. tsunami height to err on the side profit instead of safety, and I do not like what I see one bit.

SquidBert, agree with every single word of yours! Cold shutdown could be performed only if the fuel is in place. Itself it is a long period of waiting for further temperature drop that will allow for the fuel to be removed to storage pull and after even longer time to be transported for reprocessing, etc.

What we are told again is misleading despite the good news for the lower temperatures. Agree also that this can trick the affected that they can return "as planned". The truth is that government is keeping on purpose those people's hopes alive so they don't pay for relocating. From the beginning this is a game of money and interests - the state against the private company - who will trick the other side to pay the compensations.

What is the temperature under the reactor?

As of mid- to late August, officially reported measurements were still showing radioactive iodine 131 in Tokyo, Iwate, Nagano and Niigata. The half-life is only 8 days, so this means fission was ongoing at that point. This is re-criticality, right?

http://enenews.com/fukushima-in-recriticality-iodine-131-detected-in-4-locations-tokyo-iwate-nagano-niigata

@Zichi

In fact the link provided by badmigraine has two further links, that goes into explaining the sources somewhat. I agree that the information is sketchy, but I think there is a chance they are onto something real here. Not enough information to tell for sure.

http://enenews.com/breaking-iodine-131-detected-large-amounts-almost-200-km-fukushima-meltdowns

and

http://fukushima-diary.com/2011/09/breaking-news-fukushima-in-recriticality/

which in turn links to: http://iii4iii.posterous.com/69211695

@Pawatan,

Using Kako as a citation is the responsible thing to do, even if you don't agree with his pov. It is far more transparent than the AFP article written by someone who apparently knows very little about science. Btw, as a scientist k do not follow your ideology of positive thinking. I call it what it is, even if I is negative. I don't sugar coat nothing, and I don't give false hope. Many other physicists and nuclear engineers agree with the things I've written, I dint RELY on Kako. I'm not anti-nuc, but zichi is. So what?

"tear down"? I'm nott the one prentending a lower temperature is a major breakthrough. We don't even know where the fuel is. This is not good news at all, just mote TEPCO nonsense. Or why the radiation output still 1/4 of march levels to this very day? No improvement there means NO improvement.

And the point is I cited SOMEBODY you're likely to know. Afp cited TEPCO. That is an impeccable source! TEPCO says... Officials said....

@Pawaan

"What the heck is up with everyone citing Michio Kaku as an authority? He's not a nuclear physicist or engineer, his only qualifications are liking to be on TV a lot and being a anti-nuclear activist.

Listening to what he says is as bad as listening to what a TEPCO exec"

According to CUNY Kaku is a PHYSICIST and chair of the dept; a Harvard and Princeton educated Phd with 70+ articles and books. http://www1.ccny.cuny.edu/prospective/science/profiles/Kaku-Profile.cfm

Yes he likes the limelight and cash but you misrepresent the facts saying he's not a physcist. So why does CUNY advertise him as one?

beangry

According to CUNY Kaku is a PHYSICIST

So am I, beangry, but much like Michio Kaku I am not a NUCLEAR physicist so I won't claim to be an authority, unlike him. I never said he wasn't a physicist, I said he's not a nuclear physicist nor is he a nuclear engineer. So what exactly does he know about NPPs? That's right, pretty much nothing. He's an anti-nuclear activist - what exactly would you expect him to say? Something positive about nuclear power?

And beangry, if you think an astrophysicist knows anything about geophysics or a researcher in optics knows anything about nuclear physics then you are mistaken. Like most scientific fields it's highly, highly specialized.

It's not for you to say what he's studied or done research in. I too put more emphasis on what nuclear experts say, but I do no discount kaku's work because he's successful on tv. I evaluate what he says and if I see a problem with it I check it and ask why. Whilst I'm no fan of his, he's more accurate than TEPCO. Btw, he's not as ignorant of nuc work as you mint think.

Kaku claimed on CNN that there wasn't a single textbook in the world that said you should pump sea water into a nuclear reactor to prevent a catastrophe. He laughed when he said it.

And that was the point he lost all credibility in my eyes. Being wrong is one thing. Being so very badly wrong is another.

It's not for you to say what he's studied or done research in.

It's well known except seemingly in activist circles that he has no idea what he's talking about. Now I know you said:

Whilst I'm no fan of his, he's more accurate than TEPCO.

It's really not saying much, is it? In this case, though, with the managers out of the picture, yes, I am going to trust the nuclear engineers' technical opinions of the site status over a non-nuclear physicist who hasn't even visited the site. Really, how is he going to have any special insight into Fukushima Daiichi if he's not a nuclear physicist or engineer and hasn't studied the site? He was on TV right after the disaster began making ludicrously wild claims about what would happen. Why would you listen to someone like that? Would you want to listen to an actual expert with a reasonable voice?

Reactor one currently is radiating 34 Sv/ Hr (34,000 mSv) in the dry well (DW), spiked at 300+ Sv/ hr on 27th September, and around 675 mSv/ Hr in the suppression chamber (SC), unlike reactors two and three, where the corresponding figures are 8.9 Sv/ hr (DW) and 6.9 Sv/ hr (SC), and reactor three 3.39 Sv/ hr (DW) and 0.3 Sv/ hr (SC). Source //atmc.jp.

That would suggest that the situation in reactor one is quite different to the others, with a lot of the melted fuel rods outside of the reactor vessel. Radiation is too intense to allow inspection by both silicon-based robots or carbon-based workers. Whether it has leaked further outside of the dry well is not known, but it could account for the high levels of radiation in the cooling water. All 'educated guesswork' of course!

Kaku claimed on CNN that there wasn't a single textbook in the world that said you should pump sea water into a nuclear reactor to prevent a catastrophe. He laughed when he said it.

I don't know this Kaku-guy very well, except for having seen him briefly on some National Geographics show. But I am curious if the feeling that was conveyed in that CNN interview was along the lines of:

Improvised problem solving in emergency situations is rarely a skill that can be taught from books.

Or:

OMG, what were these stupid people thinking poring sea water on a nuclear reactor?

In fact, some U.S nuclear scientists were stating (and I'm not saying they are right) in the early days of this accident that the best thing for the Japanese to do is just let corium drop out the bottom of the reactor, without adding water. Their point being, that even if you get a high criticallity reaction, it is mainly the water vapor and hydrogen explosions that facilitate the spreading of radio-active particles. Take away the water, and your problem will be much more localized. Again I am not saying they were right.

According to CUNY Kaku is a PHYSICIST and chair of the dept; a Harvard and Princeton educated Phd with 70+ articles and books.

The number of things someone's written is not evidence of authority. Kaku, who has also been interviewed about the threat of an alien invasion, has a background in theoretical physics but really works towards public understanding of science, i.e. he writes popular science books and goes on TV. I have just checked his technical research papers at Cornell University Library (I can't find a full list on his website) and found 6 papers, the latest of which was published 11 years ago. So he wouldn't be your first port of call for a fully-informed assessment of the latest cutting-edge research even in his own field. If anyone can find more recent peer-reviewed technical work, I will concede that he has up-to-date expertise in that area - but it's not nuclear physics or reactor operation experience.

I evaluate what he says and if I see a problem with it I check it and ask why.

I wonder how you go about seeing a problem when presumably you're not a nuclear physicist. I would hazard a guess that none of us here are. The Dunning-Kruger effect strikes again. The only thing we can do is look at the backgrounds of these people making public pronouncements on Fukushima and ask whether their qualifications and peer-reviewed research output (if they exist at all) are relevant to the subject.

The only thing we can do is look at the backgrounds of these people making public pronouncements on Fukushima and ask whether their qualifications and peer-reviewed research output (if they exist at all) are relevant to the subject.

That is EXACTLY what people need to be doing. What good is an 'expert' if they don't have any relevant expertise?

IHe claimed that the only reason we didn't lose Northern Japan was because they dumped sea water into the reactor. He laughed as he said it to highlight the fact that it was such an out there concept that they did that. That no textbook would tell you to dump seawater to stop a meltdown.

He also stated in the same interview that it prevented 3 chernobyls.

To be a supposed leading scientist and to make a claim like that is reprehensible.

Well I don't know anything about 'alien invasion' interviews; I know he does a science for 'dummies' type show and works on other material to help the public (and his wallet) much like Sagan. I'm no fan of his, and would be the first to distance myself from his statements if they are wrong. The CNN interview: I think he was saying putting sea water in a reactor is not standard practice (we now know the j- govt had no plan b because they claimed disasters couldn't happen). That wouldn't discredit him, for his point was (as I understood it) was the situation was so bad they had to invent or use non-standard ways to deal with the meltdowns.

But that's my point: whether adding water or not was correct, it seems TEPCO knew there were 3 full meltdowns, and he's not the only one saying it. One other thing, I encourage you to read his work and determine if you think his expertise is relevant enough to make comments. But 'losing northern japan' or having '3 chernobyls' is a reference he made to nuclear fallout if the 3 reactors released more radiation, which could still occur (earthquakes do happen).

Now Kaku specifically referenced scientific studies HE was involved in with other physicists at the time, checking tepco's statements. I'd like to see the data, but either HE is lying or there is more to the story. As chair he has a lot to lose by misrepresenting the facts, so I'm not so sure you all have been fair to him. Btw, I likewise hate the the pro vs con nuclear arguments, they distort the facts.

He didn't say it wasn't standard practice. He indicated it was an absurd idea. Hence the reason he giggled as a child when he said it.

I can understand your assesment because you're not claiming to be an expert and therefore you can be wrong.

But to put it in simple terms. All of the nuclear power plants in the UK are situated on the coast for one reason. And one reason alone. ANd that is that if it all goes t!ts up that there is an endless supply of water which can cool the reactor. And ANYONE who claims to have any knowledge on the subject and is on television as an expert should know that.

"ANd that is that if it all goes t!ts up that there is an endless supply of water which can cool the reactor."

Something I didnt question. I know why they're there, but I do not agree with poisoning the seas for some idiotic way of generating steam (which is an Einstein quote, btw). Destroying our oceans with oil spills or nuclear wastes is not a viable option, and tepco did something unprecedented. It's a complete disaster, and now with the water table affected, we can only imagine the problems we'll have. My whole point is rebuilding Fukushima is a pr stunt, not something we can take seriously. They'll never fix it, and more talk of a "cold shutdown" is irrelevant. It means nothing. And NO scientist can state with certainty where the fuel is since nothing on the planet can get close enough to check. Rather than be angry with Kaku for his fame or lack of understanding (as you claim it), look at the real problems.

Why do we have to hang onto every syllable uttered from the tepco freaks? Why do we even listen to what they say? You guys give me minus thumbs but all I'm saying is tepco is engaging in another PR stunt and you guys are falling for it.

Zichi,

When TEPCO decided to pump water into the reactors, no one had the forethought that it would also create hydrogen which led to the three explosions plus a possible steam explosion inside No3 reactor.

Exactly, I think YongYang knew though.

Zichi

TEPCO has been pumping nitrogen into the No.1 reactor since April. The temperature between nitrogen freezing and boiling is very small.

I don't think TEPCO is pumping enough nitrogen into reactor 1, hence the hydrogen in the pipes which NHK reported

Fumiya Tanabe, former head of the research at Japan Atomic Energy Agency, stated at the beginning of August that the melted fuel in reactor No3 is now in the basement having gone through the base of the pressure vessel and the containment vessel because the amount of cooling water Mar21-24 was only about 11-32% of what was needed to remove the decay heat. Because of this he stated there was a spike in the air radiation released.

Hawaii news daily, had an artice reporting a number of spikes coming from Daiichi and the poor buggers at the monitoring station had fallout from those spikes.

http://hawaiinewsdaily.com/2011/07/kauai-station-suspects-new-traces-of-fukushima-radiation/

http://hawaiinewsdaily.com/2011/06/hawaii-monitoring-stations-detect-spike-in-fukushima-radiation/

http://hawaiinewsdaily.com/2011/06/fukushima-spews-los-alamos-burns-vermont-rages-we-almost-lost-nebraska/

Utrack, I think the hydrogen in the pipe story belongs to No2 reactor not No1?

I just went to NHK to make sure and their saying reactor 1 but hey all the reactor probably could use more nitrogen.

High hydrogen levels in pipes at No.1 reactor

http://www3.nhk.or.jp/daily/english/29_01.html

Exactly, I think YongYang knew though.

BURY IT! Hey, where is that fella? I kind of miss the guy.

beangry

You guys give me minus thumbs but all I'm saying is tepco is engaging in another PR stunt and you guys are falling for it.

So you know this isn't true...why? Because you don't want to believe it, that's why. There's no other reason. That's why you are getting thumbs down - people complain about a lack of facts, you get facts, and then some scream "all lies!" if it's positive and "the horrible truth!" if it's negative.

Why do you even bother reading/posting if you only listen to that which just reinforces your beliefs?

My understanding some months ago was that "cold" shutdown to TEPCO means under 100 degrees, which means the hundreds of tons of water they are pouring onto the corium daily will no longer be boiling, ie, no longer bubbling and releasing huge quantities of radioactive steam.

Yesterday and today the temperature in No.2 dipped temporarily to 99.4 and after going above 100 again, to 99.7, which is much lower since they started this new spraying system, and an important step towards preventing radioactive releases to the environment.

Rather than be angry with Kaku for his fame or lack of understanding (as you claim it), look at the real problems.

I am not angry with him. I was just highlighting the fact that he made a statement that was grossly inaccurate. That he did so was either due to ignorance or to intentionally mislead the viewers but either way he has no credibility as an expert.

Selfishly, I'm just glad I don't have to worry about any of this anymore and feel very sorry for those of you that do. Hope this is a sign of real progress for you all.

zichi:

" until the plant is under control, that is, all nuclear fuel is removed from the plant, which could take 30 years, it will remain highly dangerous and a concern for the whole world. "

Nonsense. Take a look at decay heat curves. Even without doing anything, the danger is getting less every day. And the the cooling systems and shielding are being improved every day, so the situation is rapidly getting better. Of course, the location will be a nasty piece of property for a long time. But "concern for the whole world"? Really now, that is hype.

If you want to see a "concern for the whole world", take a look Iran´s nuclear bomb program. That is a whole different ballpark.

tl;dr(comments)

is there any significance in this 100 degree mark? nuclear fuel doesn't have the same boiling point as water right? Doesn't really say much that it has gone below 100 degree, what was it 3 months ago? 1 month ago?

thanks,

This would be a bit of good news for a change - if we could believe a single word uttered by the lying incompetent cover-my-arse execs at TEPCO.

Sadly, trust, once broken, doesn't get fixed. Fire them all and let IAEA sort it out.

"Cold Shutdown" doesn't mean the fuel is at room temperature. From Wiki:

A reactor is in cold shutdown when, in addition, its coolant system is at atmospheric pressure and at a temperature below 200 degrees Fahrenheit (approx. 95 degrees Celsius).[1] This temperature is low enough that the water cooling the fuel in a light water reactor does not boil even when the reactor coolant system is de-pressurized.

Extending that to the situation at Daiichi, the temperature of the water actually covering the fuel (wherever it currently is) is the temperature that should be used to determine "cold shutdown" status, not the temperature of the water in the containment vessel (unless it's all the same body of water)

It would be nice if they actually knew where the fuel was. Then they could measure the temperature. Then they could confirm whether it is under 100 degrees or not.

@ushosh123,

is there any significance in this 100 degree mark? nuclear fuel doesn't have the same boiling point as water right? Doesn't really say much that it has gone below 100 degree, what was it 3 months ago? 1 month ago?

If the water's not boiling (100C), then it's not creating steam pressure that could further damage the reactor building. It also is ONE of the requirements for "cold shutdown" status.

They estimate the core temperature in the reactors in March reached 2,800C about 6 hours after the tsunami hit, so things have dropped considerably.

Pawatan@

"So you know this isn't true...why? Because you don't want to believe it, that's why. There's no other reason. That's why you are getting thumbs down - people complain about a lack of facts, you get facts, and then some scream "all lies!" if it's positive and "the horrible truth!" if it's negative.

Why do you even bother reading/posting if you only listen to that which just reinforces your beliefs?"

You didn't present any evidence, only argued your pov. I'm not against listening, but I do not listen to TEPCO. They are liars and only a fool would want to disappoint himself by repeating the same error over and over. I didn't present any "beliefs", rather if you go back and READ my comments (instead of just spewing hate) you would realise I asked a simple question any person involved in nuclear work would ask: is the iodine being released and how much radiation is coming out? This tells more than the temp because we don't know where the fuel is. YOU refuse to deal with the fact the fuel might be in the reactor and might not be; experts can believe what they will, but some disagree with what you wrote. The only way to know the stats of the fuel is to inspect ti, but thar is impossible.

That leaves radiation measurements, which will tell you IF the temperature being lowered is because some leaked out or it is really cooling. Many on here doubt what TEPCO says, is that a a crime or antiscientific? No. You just dislike me so much you can't objectively look at what I say.

@HedaMadness

"the fact that he made a statement that was grossly inaccurate. That he did so was either due to ignorance or to intentionally mislead the viewers but either way he has no credibility as an expert."

Says YOU. But that is your interpretation of his statement which may or may not be correct. As to his being qualified to speak on the subject that depends on the research he's been involved in, and he claimed to have been working on tests (along with other scientists) to reconstruct he accident based on the released Dara by TEPCO. As I said before, unless you can demonsrate he is lying, I prefer to give him the benefit of a doubt before looking at some guy - and a patronising one at that - and putting faith in it.

Kaku, right or wrong, is not an anonymous blogge like you. He puts his reputation on the line. I welcome a chLlenge by his colleagues, but YOU are not one of them.

Please tone down your rhetoric and keep the discussion civil.

You're right, I'm not one of his colleagues. But then again I AM qualified to say that there are textbooks that state that nuclear reactors are sited next to oceans so that in a worst case scenario there is an endless supply of water. So to reiterate my point. Again. He made a claim. Which is false. A claim that was intentionally or accidentally false but neither explanation makes him credible.

@ushosh123,

I think it would be better( as in safer, clearer) if cold shutdown would have been defined as: "the point where you can turn of all cooling systems, without causing any increase in pressure, temperature of the vessel" Basically, the point where you can walk a way and leave the reactor with no power without having come back and bite you on your behind

And I think a large part of the public believe that is what "cold shutdown" means.

@Heda

there are textbooks that state that nuclear reactors are sited next to oceans so that in a worst case scenario there is an endless supply of water.

I would agree with you. I have however not seen any references to taking said sea water and dumping atop the reactor using a helicopter.

They use helicopters to dump water on wildfires to try and bring them under control. Why is it so remarkable that they would do it here?

The ONLY question with regards to the sea water is why did TEPCO take so long to decide that the plant was unsalvageable and the worst case scenario had been reached? It's obviously a cost issue but I would hope that at some point in the future there will be a public enquiry as to why they waited till they did and whether they thought that they were justified to wait till then.

Kaku, right or wrong, is not an anonymous blogge like you. He puts his reputation on the line. I welcome a chLlenge by his colleagues, but YOU are not one of them.

Kaku doesn't have colleagues or reputation to put on the line. This is just not his field at all. It's as if I make comments on automotive design - I can have an opinion for sure but it's as an uninformed outsider, just like Kaku on nuclear physics.

Sorry, but I just do not beleive a single word that either TEPCO or the Japanese Government say on the matter of the Nuclear problems of Fukushima.