Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[|Fred]

That is amazing! Something so very obvious as the data from Reactor Two and nobody appears to understand what is happening.
Reactor Two is NOT venting steam.

In fact the top of the reactor is considerably higher than the temperature of steam. Steam can only go to a higher temperature if it is under pressure, which it is not in this case. Reactor two is venting hot radioactive gases.

So,I ask my question in the morning that I asked at night. Does anybody have any theories as to how the water is missing the core which has to be out of containment at this time. Are we going to see a continued release of hot radioactive gases until the BLOB has diluted itself, or will they continue for a generation or so?

Sorry, You'll probably get amassed as I don't get it, you are saying that visually looks like steam/ exiting unit 2 is not steam but Gaz ? Because RCV is not pressurized and the top of the reactor is to hot ?
What do you think happens when the watter enter the hot RCV ? or does it enter at all?


edit: ah... no you are saying that there is no longer steam exiting unit 2... oh well all I was asking is when has it been reported.. nothing more, nothing less

 

[jlduh]

more than 67 000 tons of contaminated water accumulated at the Daichi plant...

http://www3.nhk.or.jp/daily/english/20_30.html

And i don't see how the accumulation of water would stop in the next month as long as they will have to continue to keep cooling down the stuff in open loop! A second ongoing flooding after the tsunami one...

What are the alternatives (if any exists)?

 

[clancy688]

Ich habe mich gefragt, ob es Tepco überhaupt möglich ist, die Reaktoren direkt zu kühlen, oder ob man die Druckbehälter via containment kühlt. Eine sehr wichtige Frage.

Scheinbar ist das noch nicht der Fall. Zumindest wurde in dem TEPCO-6-Monatsplan angegeben, dass in naher Zukunft die Containments der Reaktoren 1 und 3 mit Wasser geflutet werden. Was heißt, dass es jetzt noch nicht der Fall ist.

That's probably not the case. The recently announced TEPCO-6-month-plan stated, that they'll fill the containments of Units 1 and 3 with water in the near future, indicating that they're currently dry and unfilled.

 

[Rive]

Who want explain why core temperature (empty core as tepco say) is 11C bigger than SFP ?
http://www.mod.go.jp/j/approach/defense/saigai/tohokuoki/kanren/230420.pdf

We can't see the SFP directly, so the temperature what the senor see is some mixture of the temperature of the roof and the FHM. The SFP temperature of Unit 4 is close to the boiling point by the direct measurement (some sample were taken by the concrete pump truck along with a direct temperature measurement.)

 

[Joe Neubarth]

Scheinbar ist das noch] nicht der Fall. Zumindest wurde in dem TEPCO-6-Monatsplan angegeben, dass in naher Zukunft die Containments der Reaktoren 1 und 3 mit Wasser geflutet werden. Was heißt, dass es jetzt noch nicht der Fall ist.

There are too many unanswered questions and the Japanese are not in position to answer them.

 

[jlduh]

The emergency generators at the No. 2 [that is Daini] plant were in buildings housing the reactor cores. Because the reactor buildings are much more airtight, the generators at the No. 2 [Daini] plant continued to function after the tsunami struck.
http://www.asahi.com/english/TKY201104060126.html

Tanks tsutsuji, that looks to me a significant difference between the two if this is confirmed. I believe based on one drawing that i saw (but i don't find it again) that the EDG at Daichi were in fact below the ground level in the reactor buiding which is not intended to be waterproof of course... One can imagine the consequences in case of flooding. Pure stupidity. Putting them in the reactor building seems more intelligent, even if maybe they should have put them on the hills around the plant!

 

[Joe Neubarth]

Tanks tsutsuji, that looks to me a significant difference between the two if this is confirmed. I believe based on one drawing that i saw (but i don't find it again) that the EDG at Daichi were in fact below the ground level in the reactor buiding which is not intended to be waterproof of course... One can imagine the consequences in case of flooding. Pure stupidity.

Absolute pure stupidity. They did not design for the run up from a tsunami. Somebody gave the engineers a number for tsunami height, but it looks like they airheaded the engineering.

 

[tsutsuji]

To be precise, the tsunami was only about four meters. The run up from the tsunami reaching land was in excess of 14 meters.

San Onofre in San Diego County is not designed to withstand a run up in excess of 9 meters, which can be caused by a tsunami half that height. And yet, San Onofre is still allowed to operate with over 3 million people living within 50 miles of the site.

Do you have a source for the "about four meters" ?

Looking at the "predicted maximum level caused by tsunami O.P. 5.7 meter" caption leading via the blue arrow to the red dots just above the sea wall at http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110409e9.pdf , I am wondering how tall that sea wall is. If the sea wall is 5.7 m high and the tsunami only "about four meter" high, should not the nuclear plant have been safe then ?

I would be glad to read more basic science on this topic : how tsunami height and tsunami "run up" are related with each other and possibly modelized, and how sea walls are designed to ensure some predicted level of protection.

What is the meaning of the "O.P." acronym ?

 

[|Fred]

Ich habe mich gefragt, ob es Tepco überhaupt möglich ist, die Reaktoren direkt zu kühlen, oder ob man die Druckbehälter via containment kühlt. Eine sehr wichtige Frage.

he ask him self if tepco has to cool the core from the inside or if could be cooled from the outside (I think)

If I understand you right.. by design it is meant to be cooled from the inside of the RCV. In case of an accident cooling from the outside seems to be procedure because it can help a bit . is it a good solution ? that's debatable.

Ob ich Sie verstehe .. von Design ist gemeint, von der Innenseite des Reactor vessel gekühlt werden.Im Falle eines Unfalls Kühlung von außen scheint Verfahren. Es hilft .I st es eine gute Lösung? that's fraglich.

 

[tsutsuji]

Absolute pure stupidity. They did not design for the run up from a tsunami. Somebody gave the engineers a number for tsunami height, but it looks like they airheaded the engineering.

At least "Tsunami assessment for nuclear power plants in Japan" by M.Takao, TEPCO : http://www.jnes.go.jp/seismic-symposium10/presentationdata/3_sessionB/B-11.pdf (1st Kashiwazaki International Symposium on Seismic Safety of Nuclear Installations, November 2010), page 14, seemed confident in the 4.4 + 1.3 = 5.7 m calculation, whatever that might mean.

 

[clancy688]

At least "Tsunami assessment for nuclear power plants in Japan" by M.Takao, TEPCO : http://www.jnes.go.jp/seismic-sympos...sionB/B-11.pdf , page 14, seemed confident in the 4.4 + 1.3 = 5.7 m calculation, whatever that might mean.

Well, in case of Onagawa they didn't stick with those 5.7 metres but went far beyond. http://search.japantimes.co.jp/cgi-bin/nn20110408b3.html

 

[default.user]

Ich habe mich gefragt, ob es Tepco überhaupt möglich ist, die Reaktoren direkt zu kühlen, oder ob man die Druckbehälter via containment kühlt. Eine sehr wichtige Frage.

If I understand you right.. by design it is meant to be cooled from the inside of the RCV. In case of an accident cooling from the outside seems to be procedure because it can help a bit . is it a good solution ? that's debatable.

Ob ich Sie verstehe .. von Design ist gemeint, von der Innenseite des Reactor vessel gekühlt werden.Im Falle eines Unfalls Kühlung von außen scheint Verfahren. Es hilft .I st es eine gute Lösung? that's fraglich.

Das ist fraglich.

Es ist doch auch fraglich, ob man einen in Kernschmelze befindlichen Druckbehälter ohne Problem [Wasserdampfexplosion] direkt kühlen kann.

Wenn man nicht weiß, wie der Zustand der Kerne ist, so wird man doch sicher keine Fehler machen wollen.

About 130 minutes after the first malfunction, the top of the reactor core was exposed and the intense heat caused a reaction to occur between the steam forming in the reactor core and the Zircaloy nuclear fuel rod cladding, yielding zirconium dioxide, hydrogen, and additional heat

http://en.wikipedia.org/wiki/Three_Mile_Island_accident#Consequences_of_stuck_valve

Wie lange war die Kühlung in Daiichi unterbrochen?

 

[tsutsuji]

Well, in case of Onagawa they didn't stick with those 5.7 metres but went far beyond. http://search.japantimes.co.jp/cgi-bin/nn20110408b3.html

[At Onagawa] The recorded tsunami height of about 13 meters far exceeded the plant's anticipated maximum level of 9.1 meters, and wave marks were found at the edges of the plant, indicating the tsunami fell just short of reaching the main buildings, Tohoku Electric said.
http://search.japantimes.co.jp/cgi-bin/nn20110408b3.html

See also IAEA/JNES/NIED Seminar on Nuclear Disaster & General Disaster Management against Tsunami and Earthquake, Tokyo, December 2007, “Safety Assessment and Disaster Management for Tsunami Hazards at Onagawa Nuclear Power Plant”, Y. Matsumoto, (Tohoku Epco, Japan) : http://www.jnes.go.jp/content/000015486.pdf (in Japanese, but pictures , diagrams and mathematical formulas may provide some information even if you don't read Japanese)

In particular the diagram p.10 indicates that the ground floor's height is 14.8 m at Onagawa, which was perhaps enough for the 11 March tsunami at that location.

 

[clancy688]

See also IAEA/JNES/NIED Seminar on Nuclear Disaster & General Disaster Management against Tsunami and Earthquake, Tokyo, December 2007, “Safety Assessment and Disaster Management for Tsunami Hazards at Onagawa Nuclear Power Plant”, Y. Matsumoto, (Tohoku Epco, Japan)

Wow. The tsunami-chart is interesting. They plotted wave heigths along the coast for three major tsunamis (1611, 1896, 1933).
But at the Onagawa location, all of these three tsunamis were around 5 metres. The really big wave heights of 20 metres and more were reached on the shore starting at 100 km north of the plant location.

Warning, highly speculative:
So that's probably one of the reasons, they only build Daiichi 10 metres above sea level and not really water proof - because historic tsunamis didn't reach 15 metres at Fukushima which's between 100 and 200 km south of Onagawa...?

 

[PietKuip]

Wie lange war die Kühlung in Daiichi unterbrochen?

Cooling at Fukushima was interrupted for longer times than at Three Mile Island, but this was several hours after the chain reaction had been stopped. Thermal power was much lower.

 

[Dmytry]

Wow. The tsunami-chart is interesting. They plotted wave heigths along the coast for three major tsunamis (1611, 1896, 1933).
But at the Onagawa location, all of these three tsunamis were around 5 metres. The really big wave heights of 20 metres and more were reached on the shore starting at 100 km north of the plant location.

Warning, highly speculative:
So that's probably one of the reasons, they only build Daiichi 10 metres above sea level and not really water proof - because historic tsunamis didn't reach 15 metres at Fukushima which's between 100 and 200 km south of Onagawa...?

Sounds stupid. Should of been built to at least withstand max historical tsunami height for entire coast there, the crack goes all the way along. They've de-rated lifetime risk of failure for that plant to worse than 1/100 if we assume that max wave height location is approximately random.

 

[clancy688]

Building 4 has already exploded. Two panels have blasted out of the east side and impacted on the west facade of the turbine building for Unit 4, and smoke is pouring out of the east side of Building 4.

One last comment to that idea:

I checked the T-Hawk Video for the two impact spots you mentioned. There's a guard rail or something like this going along the turbine building. But the debris is sticking between the guard rail and the building, indicating it's come from above.

If it has come from the east side of Unit 4, it should have smashed the guard rail. But that's not the case. The impact damage on the west side of the turbine building origins in the blast at Unit 3. The smoke is probably an optical illusion, it's most likely smoke from Unit 3 as well.

 

[Borek]

Das ist fraglich.

Ich habe mich gefragt, ob es Tepco überhaupt möglich ist, die Reaktoren direkt zu kühlen, oder ob man die Druckbehälter via containment kühlt.

Das kann man nicht sicher ausschließen.

Scheinbar ist das noch nicht der Fall.

Please note: per forum rules all posts should be in English and those in other languages should be deleted.

 

[clancy688]

Please note: per forum rules all posts should be in English and those in other languages should be deleted.

Sorry... ^^; :/

 

[Jorge Stolfi]

Can somebody explain me how to interpret the fact that since several weeks know, i see written in the reports (Tepco, AIEA) that the fuel rods are around half length uncovered -so outside of water- in reactors 1 to 3?

The readings from the only sensors that are still working say that water level in the cores of reactors #1--#3 are 1.6 meters, 2.1 meters, and 2.2 meters below the top of the fuel, respectively. The most optimistic interpretation is that the fuel rods are still there, but uncovered by that amount. Pessimistic interpretations are boundless, of course.

Note that water is being continuously pumped into the innermost pressure vessel (RPV) of each reactor at the rate of >100 liter per minute, and yet the water level is not budging. So there must be leaks that can support that much flow out. It is not clear whether the water flowing out of the reactor pressure vessels is going into the second containment vessel (ironically called "drywell") and from there to the donut-like suppression chamber below; or whether the leak is in some pipe outside the drywell, so that the water is trickling down to the basement; or whether there is a return pipe leading outside the building.

As I understand, each water level sensor consists of two pipes that start in the RPV, one above the water and the other below it, and end on pressure meters outside the building. The difference in pressure between the two pipes gives the water level inside the RPV (about 10 kPa for each meter of water).

The water level sensors do seem to be partly damaged. There are two sensors (3 pipes?) in each reactor, and they give different readings. In the #2 reactor, one says the water level is 1.5 meters below the top of the fuel, the other says 2.1 meters. However, from previous comments in this forum, I gather that the plausible failure modes would cause this kind of sensor to err on the plus side. That is: if the readings are wrong, the actual water level is likely to be lower, rather than higher. That is because there is a steel sleeve between the RPV wall and the fuel, and the sensors may be measuring the water in the gap between the sleeve and the RPV, not the water in the core proper. I gather that the fuel could even be completely dry.

 

[clancy688]

The readings from the only sensors that are still working say that water level in the cores of reactors #1--#3 are 1.6 meters, 2.1 meters, and 2.2 meters below the top of the fuel, respectively. The most optimistic interpretation is that the fuel rods are still there, but uncovered by that amount.

Hm, that could be true for the Unit 1 reactor. But in Unit 2 and 3 the core pressure is very low, close to atmosphere level. I have no clue of thermodynamics, but I have heard that high pressurized steam is able to channel heat very well (=cool the fuel rods even if they are out of the water).
But that doesn't apply to steam at normal pressures... so how can they still be cooled?

 

[Samy24]

Please note: per forum rules all posts should be in English and those in other languages should be deleted.

I did the answer in German and also in English. That was the way a senior member of this forum did it before. But no problem, I do not want to brake the rules. The post is deleted now.

 

[Joe Neubarth]

Do you have a source for the "about four meters" ?

Looking at the "predicted maximum level caused by tsunami O.P. 5.7 meter" caption leading via the blue arrow to the red dots just above the sea wall at http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110409e9.pdf , I am wondering how tall that sea wall is. If the sea wall is 5.7 m high and the tsunami only "about four meter" high, should not the nuclear plant have been safe then ?

I would be glad to read more basic science on this topic : how tsunami height and tsunami "run up" are related with each other and possibly modelized, and how sea walls are designed to ensure some predicted level of protection.

What is the meaning of the "O.P." acronym ?

OP stands for Original Poster. The answer to your other questions is contained in the data on this chart. There are historical accounts in Japan of runups well in excess of 40 feet on the Japanese east coast. Why Fukushima was not built to protect against those reports is beyond me. We know that unbelievable errors have been commited by highly intelligent people in life. The Hubbell space telescope problem when it was originally put in orbit comes to mind. The Mars probe that impacted the planet because somebody did not make a conversion from feet to meters. The crash of the KLM 747 into another 747 on the ground in the Azores killing hundreds. The pilot of the KLM 747 was their company safety officer, yet, he violated all of the rules of safety that day.

On the chart note the tidal heights (tsunami height up and down the east coast of 3.3 to 4.2 meters) and the run up heights which were considerably higher in most cases.

 

[HowlerMonkey]

It's possible the "leaks" that are allowing water to be pumped in without level changes are both from damage and purposeful draining of the water to create flow.

If you simply fill containment with water, it will heat up and boil off so flow is needed to slough off the heat.

Just a theory.

I wonder if they can use pumps to recirculate the water from the basements back into the containment in a sort of cooling loop but I'm not sure how much heat that would slough off.

 

[TCups]

One last comment to that idea:

I checked the T-Hawk Video for the two impact spots you mentioned. There's a guard rail or something like this going along the turbine building. But the debris is sticking between the guard rail and the building, indicating it's come from above.

If it has come from the east side of Unit 4, it should have smashed the guard rail. But that's not the case. The impact damage on the west side of the turbine building origins in the blast at Unit 3. The smoke is probably an optical illusion, it's most likely smoke from Unit 3 as well.

Yes, the dark spots are draped debris, probably roofing insulation, and presumably from the explosion at Unit 3, not from an explosion at Unit 4. But, regarding the report of a fire at Unit 4, check this on-line (copyrighted) document:

https://netfiles.uiuc.edu/mragheb/www/NPRE%20402%20ME%20405%20Nuclear%20Power%20Engineering/Fukushima%20Earthquake%20and%20Tsunami%20Station%20Blackout%20Accident.pdf

On page 6, seems to conclude that a fire has started "in the side of the Building 4" and has a different photograph of the smoke, less from Bldg 3 and more from Bldg 4. I still can't separate what smoke is definitely coming from the exhaust tower vs what might be coming from the east side of Bldg 4.

Photo excerpt attached. It would be useful to have the original photo. Resolution is poor and the light is tricky.

 

[clancy688]

The answer to your other questions is contained in the data on this chart.

Not-so-fun-fact:

http://english.kyodonews.jp/news/2011/04/82888.html

Maximum run-up height was 37.9 metres in Taro. The village was featured in an 2005 Discovery Channel documentary about Tsunamis. They talked about their 10 metre tsunami wall and how this wall is offering them only partial protection.
Watching that documentary now is like watching a prophecy... Taro's been totally shattered by the March 11th monster wave.

 

[tsutsuji]

Wow. The tsunami-chart is interesting. They plotted wave heigths along the coast for three major tsunamis (1611, 1896, 1933).
But at the Onagawa location, all of these three tsunamis were around 5 metres. The really big wave heights of 20 metres and more were reached on the shore starting at 100 km north of the plant location.

Yet they don't seem to have paid any attention to the 869 tsunami : http://www.sciencemag.org/content/332/6025/22.summary

I also wonder why they ruled out those 20 m height tsunamis. I know that the shape of the coast can increase the tsunami's height, so that one possibility might be that Onagawa has a good coast shape. Otherwise, to my layman's eyes, it seems intuitively difficult to rule out that future similar earthquakes might have an epicenter located 100 km to the South, even if their probablility is smaller.

Warning, highly speculative:
So that's probably one of the reasons, they only build Daiichi 10 metres above sea level and not really water proof - because historic tsunamis didn't reach 15 metres at Fukushima which's between 100 and 200 km south of Onagawa...?

Or did they rely on those "hazard maps" :

The Japanese authorities publish annual "hazard maps" to highlight parts of the country deemed at risk from major earthquakes, but there is no reliable scientific basis for the technique, the researcher [Robert Geller at the University of Tokyo] said.
http://www.guardian.co.uk/science/2011/apr/13/flawed-earthquake-predictions-fukushima

Note also, per http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110409e9.pdf that 10m is for units 1, 2, 3 & 4, while units 5 & 6 are 13m high.

By the way, a http://blogs-images.forbes.com/oshadavidson/files/2011/04/Tsunami.jpg"

 

[clancy688]

Photo excerpt attached. It would be useful to have the original photo. Resolution is poor and the light is tricky.

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichiov_march14_2011_dg.jpg

That's the original. The version in the pdf has been zoomed and angled. But it's a photo from March 14th, not 15th as stated in the pdf. It's been taken three minutes after the explosion in Unit 3, at least that's what I've been told by other forum users... ^^ (and I remember too DigitalGlobe stating that they took the pictures immediatly after the explosions)

 

[MadderDoc]

At the TEPCO (lowres) webcam I can not see any steam since the last two days
http://www.gyldengrisgaard.dk/tepcowebcam/tepweb20110420.html"

So does that mean that reactor 1-3 and all the SFP's are run dry?

Actually the webcam photos for today show quite a lot of steam coming from SFP4 in the early morning. (According to Tepco, spraying to SFP4 started at 5:08, so the steam seen on the webcam must have been from water already in the pool)

The webcam is sited at the knoll south of the plant and has direct view to the top of the upper floor of the south side of unit 4, and we currently see the outlet of the concrete pump hovering over it.

Unfortunately we have view to little else:

- Unit 1 is blocked completely out of view

- Of unit 3 is so little left in the height that it 's presence cannot be discerned (except for the occasional smoke/steam from it, then originating from a point about center of unit 4.)

The upper profile of unit 2 can be seen in the webcam as a horizontal line, above the unit 4 building. Also a bit of the top of the vertical vent pipe hanging on its western face (to the left) can be discerned. The 'window' to the east however, from which unit 2 has done most of its steaming is out of view, including an eventual steam fan from it. The window is at the bottom top floor, and that's lost behind the trees, so we would not see even a steam fan from it, if there is one.

 

[etudiant]

Has there been any further evaluation of the impact of accumulated salt on the cooling inside the reactors?
It seems entirely possible that dried salt is blocking the water flow to the core, so the reactor might show as much cooler than the actual core conditions really are.
In that case, would it not take considerably longer for the core to cool down?