Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Astronuc]

Gross stupidity from an engineering standpoint. Who in his right mind is going to design a plant with the Emergency Diesel Generators placed where they can get douched by the ocean?? ? ? ? ?

Fourty+ years ago, they anticipated a tsunami (something like 6 m). However, fourty+ later, the tsunami that struck was greater (14 m). Ideally, the fuel tanks would have been buried or placed on the other side of the plant (same with EDGs), or hardened such as not to be vulnerable to a tsunami.

 

[Astronuc]

When the Japanese announced that they were feeding sea water into the plants, I was wondering if they knew they could be diluting the boron inside the plant, but figured that the engineers there knew what they were doing. Now, I think they did not consider what they were doing after the explosions.

The seawater was borated. Soluble boron is not normally used in the cooling system in a BWR. It is added in the case of an emergency, but the complement of control rods is designed to shutdown the reactor (core) without the introduction of soluble boron. The reactors were shutdown normally - before the tsunami hit - at least according to what I read. The operators started normal shutdown procedures in response to the seismic activity.

When the connection to the grid was lost, the EDGs came on-line, ran for about one hour, then they were knock out by the tsunami.

 

[Joe Neubarth]

The seawater was borated. Soluble boron is not normally used in the cooling system in a BWR. It is added in the case of an emergency, but the complement of control rods is designed to shutdown the reactor (core) without the introduction of soluble boron. The reactors were shutdown normally - before the tsunami hit - at least according to what I read. The operators started normal shutdown procedures in response to the seismic activity.

When the connection to the grid was lost, the EDGs came on-line, ran for about one hour, then they were knock out by the tsunami.

You are not following me. The BORON from the rods (if they melted) is GONE!

 

[AntonL]

When the Japanese announced that they were feeding sea water into the plants, I was wondering if they knew they could be diluting the boron inside the plant, but figured that the engineers there knew what they were d
oing. Now, I think they did not consider what they were doing after the explosions.

Pure speculation and false accusations!
With a destroyed plant they took the right decisions at the right time otherwise we would have seen a complete meltdown by now.

The only mistake in my opinion is why there is not a huge team of international expertise working in Japan as a think tank, checking the decisions and predicting outcome from the action taken to save the situation.

 

[Astronuc]

The real consideration is self sustaining criticality. Any time you have a Uranium atom split from a neutron strike and it releases its 2+ Neutrons and at least one of them causes another Uranium atom to split and that goes on for a few seconds, you have a continuing chain reaction..

In the present state it can not be sustained even if they are flushing all of the BoricAcid out of the reactor and creating an ideal situation for a hot box for a hundred years.

Not necessarily - there are isotopes of Pu (Pu-240 and 242), Cm and Am that undergo spontaneous fission - as a low level. Those neutrons are then available to activate other elements or cause a fission of a nearby U-235 or Pu-239 atom.

Again, the seawater was borated, and the control blades were inserted.

 

[rmattila]

What I would like to know is whether they have added extra boron after switching to the freshwater injection. One explanation for flooding the turbine hall basement is flow of water through steam/feedwater/emergency feedwater pipelines through an untight isolation valve. The presence of Ce-144 in the water found in turbine hall of unit 1 (the containment of which is said to be intact) might be an indication that the flow has been in the form of water rather than steam. Since you probably can't trust the level gauges any more due to salt deposits in their impulse pipes, it could be that they have overfilled the reactor, and thus possibly driven some of the boron initially added out of the reactor.

 

[Astronuc]

You are not following me. The BORON from the rods (if they melted) is GONE!

Does one know they melted?

There certainly would be a concern of boron leaching out of the control rods - if they cracked or melted.

But then the seawater was borated.

 

[Joe Neubarth]

When I went through Naval Nuclear Power School I asked about the rods melting in a reactor accident and was assured that they would melt at the same time the fuel plates melted.

No study of that had been conducted and put in our physics classes or in our books, so I was always a cynic. (That was way back in 1968 - 1969). To date I have not seen that in the Reactor Lava any substantive Boron is found. The answer, of course, is that it goes into solution as Boric Acid. By flooding the reactor with sea water the Japanese were flushing their poison away from the Reactor Lava that was eating through the bottom of the vessel. (If a melt down occured.)

 

[Angry Citizen]

The BORON from the rods (if they melted) is GONE!

Just because a substance is soluble doesn't necessarily mean it's going to violate conservation of mass. It's in there somewhere.

 

[Astronuc]

What I would like to know is whether they have added extra boron after switching to the freshwater injection. One explanation for flooding the turbine hall basement is flow of water through steam/feedwater/emergency feedwater pipelines through an untight isolation valve. The presence of Ce-144 in the water found in turbine hall of unit 1 (the containment of which is said to be intact) might be an indication that the flow has been in the form of water rather than steam. Since you probably can't trust the level gauges any more due to salt deposits in their impulse pipes, it could be that they have overfilled the reactor, and thus possibly driven some of the boron initially added out of the reactor.

The presence of solid fission products like Ce-144, and isotopes of Y, Zr, La, Ba, . . . would indicate fuel washout, which could simply mean breached cladding, but not necessarily melting of the cladding. I would like to know if they detect Np-239.

I would hope that the fresh water is borated.

 

[rmattila]

When I went through Naval Nuclear Power School I asked about the rods melting in a reactor accident and was assured that they would melt at the same time the fuel plates melted.

Boiling water reactor has different control rod design from that of the naval PWRs. The BWR CRs are in the form of a cruciform blade that is inserted in between the assemblies. Different designs and materials have been used, and I'm not sure which is the one used in Japan. One typical material is stainless steel, which melts at around 1700 C, whereas the UO2 in the fuel rods remains solid until 2800 C. Therefore, recriticality in a severe BWR accident is a well known risk, and thus boron injection is one countermeasure used when preparing for an eventual core meltdown.

 

[Joe Neubarth]

Not necessarily - there are isotopes of Pu (Pu-240 and 242), Cm and Am that undergo spontaneous fission - as a low level. Those neutrons are then available to activate other elements or cause a fission of a nearby U-235 or Pu-239 atom.

Again, the seawater was borated, and the control blades were inserted.

I can not find where they say the sea water was being borated. Do you have a link?

I understand that the control rods were inserted when they scrammed. That is not the issue that I am talking about. Remember, I have been trained to operate nuclear reactor plants.

The questions raised on this board about why in the heck we are finding fission products that have a short term half life in the adjoining buildings. As I have posted, my conjecture is based upon the possibility of a Reactor melt down. Conjecture only as I understand this forum does not want to say that that is the only possible explanation to all of the recent findings. I am convinced that we had a full reactor melt down two weeks ago, but as I have stated to be politically correct, that is just my opinion and is not stated as known fact.

 

[Astronuc]

When I went through Naval Nuclear Power School I asked about the rods melting in a reactor accident and was assured that they would melt at the same time the fuel plates melted.

No study of that had been conducted and put in our physics classes or in our books, so I was always a cynic. (That was way back in 1968 - 1969). To date I have not seen that in the Reactor Lava any substantive Boron is found. The answer, of course, is that it goes into solution as Boric Acid. By flooding the reactor with sea water the Japanese were flushing their poison away from the Reactor Lava that was eating through the bottom of the vessel. (If a melt down occured.)

Um - we have to wait for the evidence that the CRBs and fuel melted. SS304 has a melting point of 1400 - 1455 °C, and Zircaloy-2 has a slightly higher melting point of about 1800°C. It's not clear yet that those temperatures were realized. The control rods are not strongly heated (there is some gamma heating related to decay products in the core), and they sit between fuel assemblies and their Zircaloy channels. The steam between the channels might have been somewhat superheated, but it's not clear that the steam would superheat to > 1000°C.

Nevertheless, the seawater was reportedly borated.

 

[RealWing]

The presence of solid fission products like Ce-144, and isotopes of Y, Zr, La, Ba, . . . would indicate fuel washout, which could simply mean breached cladding, but not necessarily melting of the cladding. I would like to know if they detect Np-239.

I would hope that the fresh water is borated.

The latest TEPCO update for Unit 2 states: -"From 10:10 am on March 26th, freshwater (with boric acid) injection was initiated. (switched from the seawater injection)"

No mention of borating in the other 2 units.

http://www.tepco.co.jp/en/press/corp-com/release/11032708-e.html

 

[PietKuip]

This is from the Tepco retraction. What are they writing on the blackboard?

Identification of iodine-134 should be unambiguous from the gamma spectrum. Tepco should publish their data.

 

[Joe Neubarth]

Boiling water reactor has different control rod design from that of the naval PWRs. The BWR CRs are in the form of a cruciform blade that is inserted in between the assemblies. Different designs and materials have been used, and I'm not sure which is the one used in Japan. One typical material is stainless steel, which melts at around 1700 C, whereas the UO2 in the fuel rods remains solid until 2800 C. Therefore, recriticality in a severe BWR accident is a well known risk, and thus boron injection is one countermeasure used when preparing for an eventual core meltdown.

The Uranium Pellets go wherever the Zirconium flows.

 

[rmattila]

The Uranium Pellets go wherever the Zirconium flows.

I agree that's the most probable course of action, but in principle in might be possible that some kind of "heap" of UO2 would remain higher than the already-molten cladding. (Not very probable, though.)

 

[Astronuc]

I can not find where they say the sea water was being borated. Do you have a link?

I understand that the control rods were inserted when they scrammed. That is not the issue that I am talking about. Remember, I have been trained to operate nuclear reactor plants.

The questions raised on this board about why in the heck we are finding fission products that have a short term half life in the adjoining buildings. As I have posted, my conjecture is based upon the possibility of a Reactor melt down. Conjecture only as I understand this forum does not want to say that that is the only possible explanation to all of the recent findings. I am convinced that we had a full reactor melt down two weeks ago, but as I have stated to be politically correct, that is just my opinion and is not stated as known fact.

The addition of borated seawater was mentioned numerous times in this thread starting with post 13. That was a reference to a video, but a link was not cited.

However, Fukushima Nuclear Accident Update (14 March 2011, 00:30 UTC) - Clarified
http://www.iaea.org/newscenter/news/2011/fukushima140311.html

Unit 1 is being powered by mobile power generators on site, and work continues to restore power to the plant. There is currently no power via off-site power supply or backup diesel generators being provided to the plant. Seawater and boron are being injected into the reactor vessel to cool the reactor. Due to the explosion on 12 March, the outer shell of the containment building has been lost.

Unit 2 is being powered by mobile power generators on site, and work continues to restore power to the plant. There is currently neither off-site power supply nor backup diesel generators providing power to the plant. The reactor core is being cooled through reactor core isolation cooling, a procedure used to remove heat from the core. The current reactor water level is lower than normal but remains steady. The outer shell of the containment building is intact at Unit 2.

Unit 3 does not have off-site power supply nor backup diesel generators providing power to the plant. As the high pressure injection system and other attempts to cool the reactor core have failed, injection of water and boron into the reactor vessel has commenced. . . . .

I bolded for reference. How many references/citations does one wish before accepting the seawater was added with boron?

Fukushima Nuclear Accident Update Log
http://www.iaea.org/newscenter/news/tsunamiupdate01.html

 

[PietKuip]

At higher resolution. Is there anything interesting on the whiteboard?

 

[Astronuc]

Two more references one referring to borated freshwater, and the older one referring to borated seawater:

http://www.tepco.co.jp/en/press/corp-com/release/11032706-e.html
-We have been injecting sea water into the reactor, but from 10:10 am on March 26th, we started injecting fresh water (with boric acid) into it.

Back on March 13 -
http://www.tepco.co.jp/en/press/corp-com/release/11031312-e.html

Unit 1(Shut down)
- Reactor has been shut down. However, the unit is under inspection due to the explosive sound and white smoke that was confirmed after the big quake occurred at 3:36PM.
- We have been injecting sea water and boric acid which absorbs neutron into the reactor pressure vessel.

Unit 2(Shut down)
- Reactor has been shut down and Reactor Core Isolation Cooling System has been injecting water to the reactor. Current reactor water level is lower than normal level, but the water level is steady. After fully securing safety, measures to lowering the pressure of reactor containment vessel has been taken, under the instruction of the national government.

Unit 3(Shut down)
- Reactor has been shut down. However, as High Pressure Core Injection System has been automatically shut down and water injection to the reactor was interrupted, following the instruction by the government and with fully securing safety, steps to lowering the pressure of reactor containment vessel has been taken. Spraying in order to lower pressure level within the reactor containment vessel has been cancelled.
- After that, safety relief valve has been opened manually, lowering the pressure level of the reactor, which was immediately followed by injection of boric acid water which absorbs neutron, into the reactor pressure vessel.

I bolded for emphasis.

 

[seasponges]

If one of the reactors at Fukushima underwent a full meltdown, how devastating an effect would it have on the region?

 

[rhody]

The only mistake in my opinion is why there is not a huge team of international expertise working in Japan as a think tank, checking the decisions and predicting outcome from the action taken to save the situation.

Anton,

I agree, however, given the sensitive nature of the situation, how can you be sure that it is not happening. I will say this, I would feel much better knowing that it is in fact happening without being privy to the details. Fair enough ? When I asked Astronuc who I have a great deal of respect for a question like this and do not get a yes or no answer, it may be that he cannot discuss even the existence of what I am asking about. That in and of itself is telling, interpret it as you wish, but I feel better even with a "silent" response knowing of its potential positive implications. Enough said.

Rhody...

 

[dtaipei]

Tepco press conference now live on uStream - began 4 minutes ago. Japanese no subtitles though.

 

[AntonL]

This is from the Tepco retraction. What are they writing on the blackboard?

Identification of iodine-134 should be unambiguous from the gamma spectrum. Tepco should publish their data.

Spot On - here is the NHK report

TEPCO retracts radioactivity test result
Tokyo Electric Power Company has retracted its announcement that 10 million times the
normal density of radioactive materials had been detected in water at the Number 2 reactor
of the Fukushima Daiichi nuclear plant.

The utility says it will conduct another test of the leaked water at the reactor's turbine
building.

The company said on Sunday evening that the data for iodine-134 announced earlier in the
day was actually for another substance that has a longer half-life.

The plant operator said earlier on Sunday that 2.9 billion becquerels per cubic centimeter
had been detected in the leaked water.

It said although the initial figure was wrong, the water still has a high level of radioactivity
of 1,000 millisieverts per hour.

Sunday, March 27, 2011 22:02 +0900 (JST)

 

[Astronuc]

If one of the reactors at Fukushima underwent a full meltdown, how devastating an effect would it have on the region?

If a core meltdown, it should be confined to containment. The immediate effect is a highly contaminated containment and loss of generation. Currently, TEPCO has lost 4 units, with 3 units have some degree of core damaged (any melting is undetermined at this time).

Now, if there is severe core damage, which appears to be the case, the matter becomes one of how much of the fission products are released to the environment. The containment of Units 1,2,3 are heavily contaminated. Some of that contamination (fission products) has been released to the environment. The short and long term effects depend on which and how much of those radioisotopes have been released.

Unit 4 may have damaged fuel in the SFP. Fission products, primarily Xe and Kr, and volatiles, I and Cs, have been released to the atmosphere. Again it is a matter of determining how much fuel has been damaged, and how much of the inventory of fission products has been released to the environment.

There is clearly a significant release of fission products from the core of Units 1, 2 and 3, and likely the SFP of Unit 4. There may be some damage to fuel in SFPs of U 1, 2, and 3, but the focus has been on the cores and contaminate water in the respective containments.

We do not know the extent of the damage to the cores of U 1, 2 and 3, or the extent of damage to the fuel in the SFPs. We are waiting for TEPCO to stabilize the units, so that they can start clearing out the debris and damaged structures, and then they can start thinking about how inspect the SFPs and cores. Removing the damaged fuel will be a challenge, since the eight of the fuel rods form the structure (connection between upper and lower tie plates), and it is the upper tie plate that is used to lift the fuel assembly as a unit. The channels are not mechanically connected to the bottom tie plate (although one design not used at Fukushima does use the channel as a structural element).

 

[Astronuc]

A general note:

Please refrain from unfounded speculation and personal attacks/slights/comments.

Please address the technical nature of the matter at hand, and when making claims about the event, please cite the sources. References or citations from crackpot sites, or those of dubious scientific or technical merit, may be deleted.

 

[jlduh]

Concerning the tsunami assessment problem relative to nuclear installations AND their safety devices like EDG, I would like to know more about how was designed the tsunami model made by TEPCO "according to JSCE method published in 2002"? They are saying they are modelling the "highest possible tsunami" but this doesn't sounds easily understandable taking account some basic facts...

http://www.netimago.com/image_182963.html
http://www.jnes.go.jp/seismic-symposium10/presentationdata/3_sessionB/B-11.pdf

In particular, are they taking into account the fact that a specific type of tsunamis, called "Tsunamis earthquakes", can happen and create huge waves even if the magnitude of the source earthquake is not that big, because of some specific conditions (with slow rupture at the fault and many other complex parameters)?

http://www.scidev.net/fr/latin-america-and-caribbean/news/un-mod-le-simple-pourrait-pr-voir-les-rares-s-ismes-provoquant-des-tsunamis-.html
http://www.eri.u-tokyo.ac.jp/seno/Papers/2002GL014868.pdf

The record 36m high tsunami at Sanriku (1896) is believed to be a tsunami of that type (tsunami earthquake), and Sanriku have been a place of huge tsunamis even if earthquakes were not so big than the current one:

1896 (magnitude 7,2 / wave height 36m): http://en.wikipedia.org/wiki/1896_Meiji-Sanriku_earthquake

At 7:30 pm on June 15, families were celebrating the return of soldiers from the Sino Japanese War and a Shinto holiday when they felt a small earthquake. There was little concern because it was so weak and there had been many small tremors in the previous few months. About 35 minutes later the Sanriku coast was struck by the first wave of the tsunami, followed by a second a few minutes later.[2] The tsunami damage was particularly severe because it coincided with high tide. Wave heights of up to 38.2 meters (125 ft) were measured.

1933 (magnitude 8,4 / wave height 28m): http://en.wikipedia.org/wiki/1933_Sanriku_earthquake

If some people on the forum are knowledgeable on these subjects and methods please don't hesitate to bring some infos. Putting the EDG at a certain height which is safe seems good sense but what has to be this certain height? How all this stuff is really elaborated? Should be reviewed quickly as i feel many nuke plants are not so far from the ocean... and not so far from Sanriku either!

 

[Dancewithbear]

Astronuc, 



Would you be able to render an opinion on the Ukrainian proposal to cool the reactors with liquid metal (Tin). I find this idea very intriguing and would like to hear others thoughts on the matter.

On 17 March, KyivPost reported that a Ukrainian group of specialists who were involved in the aftermath of the Chernobyl nuclear disaster proposed low-melting and chemically neutral metal, such as tin, to cool the fuel rods even if molten or damaged.
Chopped tin can be injected in the reactor through the existing cooling water pipes with compressed inert gas, helium or argon. Melted tin creates a crust (low vapor pressure), cools the reactor and delays the decay products recovery. Liquid metal cooled reactors need no pump and due to no pressure and a wider temperature-range are less likely to a Loss-of-coolant accident.

This solution has similarities with the 2400 metric tonnes of lead (see also Lead-cooled fast reactor) used to successfully cooling and covering the Chernobyl nuclear plant but avoids the toxic lead.[4] Liquid metal cooled reactors were used in several Soviet submarines which shows additional basic feasibility.
It also avoids the danger of additional explosions caused by water breaking down to hydrogen and oxygen starting at temperatures around 800 °C due to Thermolysis.
A team of Ukrainian nuclear specialists is ready to fly out for realizing this in practice. The Japanese Embassy was informed.
http://www.itri.co.uk/pooled/articles/BF_NEWSART/view.asp?Q=BF_NEWSART_322665

Furthering that idea I was also wondering if Gallium or Boron-Gallium could be used in the spent pools. Gallium melts at ~29.76C (85.57F) and boiling point at 2204C/3999F.
I think you could easily add a heat exchanger to the spent pool.

Your and others opinions would be greatly appreciated.

TIA, DWB

 

[Astronuc]

Spot On - here is the NHK report

TEPCO retracts radioactivity test result
Tokyo Electric Power Company has retracted its announcement that 10 million times the
normal density of radioactive materials had been detected in water at the Number 2 reactor
of the Fukushima Daiichi nuclear plant.

The utility says it will conduct another test of the leaked water at the reactor's turbine
building.

The company said on Sunday evening that the data for iodine-134 announced earlier in the
day was actually for another substance that has a longer half-life.

I take that to mean they were reporting activity for another radionuclide, possibly one with a gamma-ray (or beta) of similar energy. The precursor to I-134 (t_1/2 = 52.5 min) is Te-134 (t_1/2 = 41.8 min).

Now I'm curious as to what they think they were measuring.

 

[PietKuip]

I take that to mean they were reporting activity for another radionuclide, possibly one with a gamma-ray (or beta) of similar energy. The precursor to I-134 (t_1/2 = 52.5 min) is Te-134 (t_1/2 = 41.8 min).

Now I'm curious as to what they think they were measuring.

Assuming that Tepco uses detectors with better than amateur resolution, there is no way of mistaking the gamma spectrum of I-134 for something else.

They should publish the spectrum.

 

[Astronuc]

Astronuc, 



Would you be able to render an opinion on the Ukrainian proposal to cool the reactors with liquid metal (Tin). I find this idea very intriguing and would like to hear others thoughts on the matter.

On 17 March, KyivPost reported that a Ukrainian group of specialists who were involved in the aftermath of the Chernobyl nuclear disaster proposed low-melting and chemically neutral metal, such as tin, to cool the fuel rods even if molten or damaged.
Chopped tin can be injected in the reactor through the existing cooling water pipes with compressed inert gas, helium or argon. Melted tin creates a crust (low vapor pressure), cools the reactor and delays the decay products recovery. Liquid metal cooled reactors need no pump and due to no pressure and a wider temperature-range are less likely to a Loss-of-coolant accident.

This solution has similarities with the 2400 metric tonnes of lead (see also Lead-cooled fast reactor) used to successfully cooling and covering the Chernobyl nuclear plant but avoids the toxic lead.[4] Liquid metal cooled reactors were used in several Soviet submarines which shows additional basic feasibility.
It also avoids the danger of additional explosions caused by water breaking down to hydrogen and oxygen starting at temperatures around 800 °C due to Thermolysis.
A team of Ukrainian nuclear specialists is ready to fly out for realizing this in practice. The Japanese Embassy was informed.
http://www.itri.co.uk/pooled/articles/BF_NEWSART/view.asp?Q=BF_NEWSART_322665

Furthering that idea I was also wondering if Gallium or Boron-Gallium could be used in the spent pools. Gallium melts at ~29.76C (85.57F) and boiling point at 2204C/3999F.
I think you could easily add a heat exchanger to the spent pool.

Your and others opinions would be greatly appreciated.

TIA, DWB

I'd have to think about it.

I believe that some Russian marine reactors have use Pb or Pb-Bi.

The idea of Sn (Tmelt = 231.93 °C) is intriguing. However consideration must be given to the possible chemical reactions with Zr (Sn is a substitutional alloying element in Zircaloy, i.e. Zr and Sn can form a solid solution) and other elements, to the displacement of heavily contaminated coolant, whether or not it would actually get to where one want to place it, the mass (density ~7.3 times that of water it displaces). Is there sufficient mass of Sn available.

Same concerns for Ga.

Another concern for the Sn would be in the longer term with respect to dismantling the core, which would be necessary to decommission the plant. Otherwise, U1, 2, and 3, and possibly 4, would have to be entombed in place.

 

[Astronuc]

Assuming that Tepco uses detectors with better than amateur resolution, there is no way of mistaking the gamma spectrum of I-134 for something else.

They should publish the spectrum.

I would simply prefer an explanation of why the I-134 activity is incorrect, if it is, rather than just a statement to the effect that "the data for iodine-134 announced earlier in the day was actually for another substance that has a longer half-life." My response - "What other substance?!"

 

[AntonL]

I take that to mean they were reporting activity for another radionuclide, possibly one with a gamma-ray (or beta) of similar energy. The precursor to I-134 (t_1/2 = 52.5 min) is Te-134 (t_1/2 = 41.8 min).

Now I'm curious as to what they think they were measuring.

Why are they retracting the data in such a public way.
a) Is it because of high dosage 2.9 x 10^9 , or
b) Because of the short 1/2-life of 53 minutes and thus should not be present 16 or 17 days later

if b) then how will they explain Tc-99p 6hr 1/2-life, that should also not be present

 

[Astronuc]

Concerning the tsunami assessment problem relative to nuclear installations AND their safety devices like EDG, I would like to know more about how was designed the tsunami model made by TEPCO "according to JSCE method published in 2002"? They are saying they are modelling the "highest possible tsunami" but this doesn't sounds easily understandable taking account some basic facts...

http://www.netimago.com/image_182963.html
http://www.jnes.go.jp/seismic-symposium10/presentationdata/3_sessionB/B-11.pdf

In particular, are they taking into account the fact that a specific type of tsunamis, called "Tsunamis earthquakes", can happen and create huge waves even if the magnitude of the source earthquake is not that big, because of some specific conditions (with slow rupture at the fault and many other complex parameters)?

http://www.scidev.net/fr/latin-america-and-caribbean/news/un-mod-le-simple-pourrait-pr-voir-les-rares-s-ismes-provoquant-des-tsunamis-.html
http://www.eri.u-tokyo.ac.jp/seno/Papers/2002GL014868.pdf

The record 36m high tsunami at Sanriku (1896) is believed to be a tsunami of that type (tsunami earthquake), and Sanriku have been a place of huge tsunamis even if earthquakes were not so big than the current one:

1896 (magnitude 7,2 / wave height 36m): http://en.wikipedia.org/wiki/1896_Meiji-Sanriku_earthquake



1933 (magnitude 8,4 / wave height 28m): http://en.wikipedia.org/wiki/1933_Sanriku_earthquake

If some people on the forum are knowledgeable on these subjects and methods please don't hesitate to bring some infos. Putting the EDG at a certain height which is safe seems good sense but what has to be this certain height? How all this stuff is really elaborated? Should be reviewed quickly as i feel many nuke plants are not so far from the ocean... and not so far from Sanriku either!

That's very interesting. Also consider the 1964 Alaska earthquake - mag 9.2 and a 27-foot (8.2 m) tsunami nearby in the village of Chenega.

From the diagram, it appears the site could have handled a 10 m tsunami, but the site apparently experience a 14 m (46 ft) tsunami.

One has to go back to the analysis done by Ebasco to determine the rationale used in determining the limiting tsunami.

The other factor to be considered is the 'combined effects' of natural phenomena. Did the combined effects include 'massive earthquake + tsunami' with the consequences of 'loss of offsite power' (LOOP) + 'loss of EDGs or ECCS'? I doubt the LOOP and loss of ECCS were considered, i.e., they expected to have one or the other.

 

[AntonL]

Assuming that Tepco uses detectors with better than amateur resolution, there is no way of mistaking the gamma spectrum of I-134 for something else.

They should publish the spectrum.

extracted from attached report for sea-water analysis - basement water would have have been done very similar. Any clues in this statement regarding their near-site measuring capabilities?

Bringing 500ml of the sample to Fukushima Daini Nuclear Power Station and measuring with the Germanium semi-conductor detector