Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[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

 

[rhody]

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?!"

From Washington Post, today...

Perhaps this http://www.chron.com/disp/story.mpl/ap/top/all/7493328.html" explains it:

Tepco said it miscalculated the radioactivity measurement in the unit 2 turbine building because it mistook the data for iodine-134 for the data of cobalt-56, which has a longer half-life

Does this make more sense Astronuc, AntonL ?

Rhody...

 

[M. Bachmeier]

From Washington Post, today...

Perhaps this http://www.chron.com/disp/story.mpl/ap/top/all/7493328.html" explains it:


Does this make more sense Astronuc ?

Rhody...

According to what was said at the press conference (NHK) http://www3.nhk.or.jp/daily/english/27_24.html?play

They were not making a certain claim that iodine-134 was not what was detected, but would take another sample. Note: unless translation was incorrect.

 

[PietKuip]

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?

There is a huge difference in activity and dilution of course.

One would bring such dilute samples off site. It should be difficult to measure seawater with the backgrounds at the accident site.

So they had a sample of half a litre and they measured it for 1000 seconds. Probably in a Marinelli beaker with a germanium detector.

On-site they seem to have a car with monitoring instruments. They should have portable spectrometers with them too.

 

[jlduh]

Actually, the Tepco study designed the highest possible tsunami at + 5,7m above "OP" (don't know what "O.P." means), confirmed by this study, and the platform on which the plant is built is 10 to 13m above "OP". So it was presented almost as a 2X safety factor in comparison with the "highest possible designed tsunami"!

I didn't even mention, in addition to "earthquake tsunamis", megatsunamis which can have various origins but one of the main being big landslides for example due to explosions on a volcano...

http://en.wikipedia.org/wiki/Megatsunami

But some may say that with waves bigger than 100 meters, anyway the catastroph would be terrible even without any nuclear plant...

 

[rhody]

According to what was said at the press conference (NHK) http://www3.nhk.or.jp/daily/english/27_24.html?play

They were not making a certain claim that iodine-134 was not what was detected, but would take another sample. Note: unless translation was incorrect.

M Bachmeier,

If I understand what you said, if it is cobalt-56, then it needs to be confirmed with a new set of measurements, no ? Another problem here is you are reporting on information from a press conference (real time I assume) whereas the WP article must be older, and as such the information is older as well. When I reported it, google news said it was about 10 minutes old. If that is correct it may have been reported in the press conference, which I did not watch, and am hoping you can confirm or refute. I don't know how long the WP takes to review and post breaking news, but can't imagine it could take too long.

Rhody...

 

[AntonL]

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?!"

Here is the explanation, basically they extrapolate the measurement back to the time of sampling, and because of short life time of I-134 the value sky-rockets. Apparently they mistook Cobolt-56 but there seems to be confusion about that as well.

http://www.asahi.com/national/update/0327/TKY201103270213.html][/URL]
TEPCO, 27, announced that after 10 million times the radiation detected in normal water reactor turbine building entrapment in Fukushima Daiichi Unit 2 nuclear power plant, and at night, "mistaken for a different matter, " an interview with , re-corrected the early morning of July 28 further correction. Substantially revised and the number measured in the turbine building where even the 26th. Not share information, office workers exposure to high radiation-related locations (nuked) the accident happened. The lack of communication, has spurred the confusion.

Entrapment when the water is examined in Unit 2, calculated back to the time taken for the radioactivity of a substance called iodine-134 decreased very quickly, better, 1cc were around 2.9 billion becquerels. 1 million times the normal. Once found in large quantities so, could even have occurred in a fission reactor. TEPCO Nuclear Safety Commission will be asked to re-evaluate.

TEPCO and measured again, but should decrease rapidly if the radioactive iodine-134 was not much less. TEPCO 27 night, "could be mistaken for those slower decrease of cobalt 56, " said. However, in the early morning of July 28 meeting was "instead of cesium 134 Cobalt 56" was corrected again. The morning briefing "was detected" two different substances was announced, in fact, had not come out.

Mutou Sakai, vice president is "(the analysis) There was not enough in the process of examining the contents, " he said.

TEPCO spokesman said, "despite the possibility that measurement uncertainty, and make public, was hidden after [and] criticism, " to worry about. Nuclear and Industrial Safety Agency, METI also have to give priority to public for the same reason.

 

[M. Bachmeier]

M Bachmeier,

If I understand what you said, if it is cobalt-56, then it needs to be confirmed with a new set of measurements, no ? Another problem here is you are reporting on information from a press conference (real time I assume) whereas the WP article must be older, and as such the information is older as well. When I reported it, google news said it was about 10 minutes old. If that is correct it may have been reported in the press conference, which I did not watch, and am hoping you can confirm or refute. I don't know how long the WP takes to review and post breaking news, but can't imagine it could take too long.

Rhody...

My intention was only to clarify, not to be critical of any effort to increase the level of information. Accurate information is hard to come by and is often distorted as it passes through communication channels, so please don't take offense.

Please note link... and am relying on translation as reported...

 

[jlduh]

Again...

http://www.chron.com/disp/story.mpl/ap/top/all/7493328.html

Officials acknowledged there was radioactive water in all four of the Fukushima Dai-ichi complex's most troubled reactors, and that airborne radiation in Unit 2 measured 1,000 millisieverts per hour, four times the limit deemed safe by the government.

An other example of "mistake" in the way it is presented.

1,000 millisieverts per hour, Four times the ANNUAL limit deemed safe by the government FOR WORKERS IN THE NUCLEAR INDUSTRY IN CASE OF NECESSITY (which is currently the case!).

Mistake of the press or in the declaration of the autorities, how hell can the normal citizen who reads this can have a clear view of what is safe or unsafe?

 

[PietKuip]

Here is the explanation, basically they extrapolate the measurement back to the time of sampling, and because of short life time of I-134 the value sky-rockets.

That is no good reason. Just take a spectrum of the sample every half hour. It will show what the half-life of the peaks are.

 

[Astronuc]

From Washington Post, today...

Perhaps this http://www.chron.com/disp/story.mpl/ap/top/all/7493328.html" explains it:


Does this make more sense Astronuc, AntonL ?

Rhody...

Yes - that's plausible to a degree.

The decay of Co-56 does produce a gamma ray of 846.771 keV, with a relative intensity of 99.94. It could be mistaken for the 847 and 885 keV gammas from I-134. But those two gammas have relatively low intensity to lower energy gammas or X-rays.

Normally, one would not expect a high rate of Co-56 (from neutron activation of Fe-56) to be present in a sample. On the other hand, this is not a normal situation, and there is probably a lot of activated corrosion products in the wate with the fission products. Normally, the corrosion products would be captured on filters, while iodine would remain in the cooling water.

 

[Astronuc]

That is no good reason. Just take a spectrum of the sample every half hour. It will show what the half-life of the peaks are.

Yes - they would need to take a second count on the same sample and allow for decay of different isotopes. However, I would imagine that the lab procedure would allow for one sample - because it assumes normal conditions, not abnormal conditions. Normally, they would be sampling reactor coolant from the primary system - not seawater or samples from the torus, or wherever.

I hope they improve their sampling techniques.

 

[M. Bachmeier]

Yes - that's plausible to a degree.

The decay of Co-56 does produce a gamma ray of 846.771 keV, with a relative intensity of 99.94. It could be mistaken for the 847 and 885 keV gammas from I-134. But those two gammas have relatively low intensity to lower energy gammas or X-rays.

Normally, one would not expect a high rate of Co-56 (from neutron activation of Fe-56) to be present in a sample. On the other hand, this is not a normal situation, and there is probably a lot of activated corrosion products in the wate with the fission products. Normally, the corrosion products would be captured on filters, while iodine would remain in the cooling water.

Does this have any relation to the Co-56 question?

"Upper limits for yields of certain isotopes of argon from fission of 235U by thermal neutrons were determined radiochemically as follows: 37Ar, ≤1×10-7%; 39Ar, ≤4×10-7%; 41Ar, ≤3×10-9%; 42Ar, ≤3×10-11%. The upper limit for the fission yield of 56Co (daughter of 56Ni) was determined as ≤8×10-8%. The yields of these isotopes are three to seven orders of magnitude lower than those expected from thermal-neutron-induced ternary fission of 235U as described by Muga."

From: http://prola.aps.org/abstract/PR/v142/i3/p716_1

 

[rhody]

please don't take offense.

M Bachmeier,

None taken...

AntonL,

After your last post, thus the reason for new measurements. I believe that clarifies the issue.

Edit: Astronuc

I hope they improve their sampling techniques.

Rhody...

 

[PietKuip]

Yes - they would need to take a second count on the same sample and allow for decay of different isotopes. However, I would imagine that the lab procedure would allow for one sample - because it assumes normal conditions, not abnormal conditions. Normally, they would be sampling reactor coolant from the primary system - not seawater or samples from the torus, or wherever.

I hope they improve their sampling techniques.

Indeed. It is irresponsible to send back some person into that basement just for reasons of lab protocol.

 

[Astronuc]

Actually, the Tepco study designed the highest possible tsunami at + 5,7m above "OP" (don't know what "O.P." means), confirmed by this study, and the platform on which the plant is built is 10 to 13m above "OP". So it was presented almost as a 2X safety factor in comparison with the "highest possible designed tsunami"!

I didn't even mention, in addition to "earthquake tsunamis", megatsunamis which can have various origins but one of the main being big landslides for example due to explosions on a volcano...

http://en.wikipedia.org/wiki/Megatsunami

But some may say that with waves bigger than 100 meters, anyway the catastroph would be terrible even without any nuclear plant...

The 535 eruption of Krakatoa (Krakatau) apparently blew up many cubic miles of earth!
http://en.wikipedia.org/wiki/Krakatoa

While it was an island for many centuries ~535 to 1883, it has been posited that there was continuous land between what is now Sumatra and Java.
http://en.wikipedia.org/wiki/Krakatoa#535_AD_event

Yet - we have not experienced such events since.

 

[PietKuip]

http://www.ustream.tv/channel/cnic-news is a technical seminar about the accident with English translation. Live, I think.

Sorry, that was yesterday.

 

[ivars]

So its Co-56 that has activity around 10^6 Bq/cm^3? Is that better news? Where did it came from? Its not in the table...But I read it can be created from Fe-56 by neutron activation. Where do neutrons come from? Why it is in the water?

 

[RealWing]

Indeed. It is irresponsible to send back some person into that basement just for reasons of lab protocol.

As a former NPP manager, I've been closely following this event from the beginning, but just found this forum yesterday. I've been trying to put myself in their shoes to better understand what they are dealing with.
I would fully expect that they are doing their best to limit doses to workers ALARA - even in these very stressful circumstances. They would not be irresponsibly simply ordering someone to go and get a sample. They would do their best to use long handled sampling, different routes etc and HP briefings to minimize dose.

 

[TCups]

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

Reference: http://www.bnl.gov/bnlweb/history/tc-99m.asp

I do not know if it is pertinent to nuclear reactors, but in the hot labs of radiology departments everywhere, technetium-99m is generated from elution of molybdenum-99, which has a half-life of 66 hours, allowing it to be transported over fairly long distances. Could the presence of a longer half-lived molybdenum-99 be the source of the technetium?

 

[Astronuc]

Yes - that's plausible to a degree.

The decay of Co-56 does produce a gamma ray of 846.771 keV, with a relative intensity of 99.94. It could be mistaken for the 847 and 885 keV gammas from I-134. But those two gammas have relatively low intensity to lower energy gammas or X-rays.

Normally, one would not expect a high rate of Co-56 (from neutron activation of Fe-56) to be present in a sample. On the other hand, this is not a normal situation, and there is probably a lot of activated corrosion products in the wate with the fission products. Normally, the corrosion products would be captured on filters, while iodine would remain in the cooling water.

I have to correct myself on this. Co-56 undergoes electron capture to Fe-56. Co-56 would come from electron capture by Ni-56.