Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[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.

 

[83729780]

2.9 trillion becquerels I-134 per liter! => assuming the fission stopped on the 14th that would be some thing in the range of 2.9*10^9= N *(0.5)^((27-14)*24))
2,419*10^103 atom of I-134 just for this liter (some one clever should be able to calculate the weight of that)

well that's 4.14*10^81 kg

which is about 13 orders of magnitude heavier than the entire universe

perhaps you miscalculated?

 

[AntonL]

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.

Bit off topic - you forgetting http://en.wikipedia.org/wiki/Mount_St._Helens" 0.7 cubic miles got shifted in 1980.

and what about a repeat of the http://en.wikipedia.org/wiki/Tunguska_event"

 

[Gilles]

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?

seen on this report :
Te-132 (3 days) : 2.2E-01 Bq/cm^3
I-232 (2hours) : 3.3 +00 Bq/cm^3

correct me if I'm wrong, but if I-232 is a https://www.physicsforums.com/showpost.php?p=3212764&postcount=1491", with a much shorter lifetime, shouldn't the activities be equal ? (because each Te-132 decay is quickly followed by the corresponding I-232 decay ?)

that's all so messy ...

 

[PietKuip]

http://www.tepco.co.jp/cc/press/betu11_j/images/110327o.pdf

Tepco's new numbers. On a different forum, TH1960 writes: "The first column is "ayamari" - mistaken. "

 

[KateB]

Are they solely relying on gamma spectroscopy? Co-56 decays through positron emissions, while I-134 decays through traditional beta decay... It seems it would hard to confuse the two, though I am no physicist.

 

[Astronuc]

Bit off topic - you forgetting http://en.wikipedia.org/wiki/Mount_St._Helens" 0.7 cubic miles got shifted in 1980.

and what about a repeat of the http://en.wikipedia.org/wiki/Tunguska_event"

Mt. St. Helens is inland, to there would be no consequence of tsunami. The Tunguska event was also overland, but it probably would have produced some king of tsunami if it had happened over the ocean.

The point is such catastrophic events that would cause massive destruction or mega-tsunami are exceedingly rare. However, we do need to have a realistic assessment of likely events - and the recent earthquake and tsunami - are more likely than Krakatoa and Tunguska. Most nuclear power plants are not sited where they might be affected by volcanoes or large tsunamis, or perhaps large earthquakes.

 

[Astronuc]

Are they solely relying on gamma spectroscopy? Co-56 decays through positron emissions, while I-134 decays through traditional beta decay... It seems it would hard to confuse the two, though I am no physicist.

The chart of nuclides indicates that electron capture is the predominant mode of decay for Co-56. Nevertheless, I expect they are looking for characteristic gammas (gamma spectroscopy) with which to identify the radionuclides.

Decay gammas are generally discrete, as opposed to beta decay which represents a continuum of beta (and antineutrino) energies.

 

[rmattila]

seen on this report :
Te-132 (3 days) : 2.2E-01 Bq/cm^3
I-232 (2hours) : 3.3 +00 Bq/cm^3

correct me if I'm wrong, but if I-232 is a https://www.physicsforums.com/showpost.php?p=3212764&postcount=1491", with a much shorter lifetime, shouldn't the activities be equal ? (because each Te-132 decay is quickly followed by the corresponding I-232 decay ?)

Only if you assume that both isotopes get transported from the fuel to the location of measurement in an identical manner.

 

[Astronuc]

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?

Mo-98 (n,γ) Mo-99 (ß) Tc-99

Mo-99 is a low yield fission product, and Tc-99 is even lower probability.

 

[turbo]

Most nuclear power plants are not sited where they might be affected by volcanoes or large tsunamis, or perhaps large earthquakes.

I understand that Diablo Canyon is due for a review next month re: a 20-year extension, but that's now on hold.

 

[jlduh]

Most nuclear power plants are not sited where they might be affected by volcanoes or large tsunamis, or perhaps large earthquakes.

Here is a simulation of the Sanriku tsunami earthquake of 1896 i was talking about (height 36m), the wave is simulated 10 minutes after the earthquake:

http://www.netimago.com/image_183025.html

source
http://drh.edm.bosai.go.jp/database/item/26ae4c7ae7dfe46a0527e0dfb3cc3fcd4abf7a9f

And this is a map of the same area with current nuke plants in red:
http://www.netimago.com/image_183027.html

The two bottom ones are Fukushima Daichi and Daini (6 reactor and 4 reactors)

The one at the North is Onagawa Power Plant (3 reactors)

A nice picture a Onagawa NPP, hummm looks quite close from the sea level from this point of view...

http://www.netimago.com/image_183029.html

Wonder if the highest possible tsunami here has also been designed with similar hypothesis than at Fukushima, no?

For information, it can be of interest because of the proximity of the two plants to read what is on the wiki for the Daini plant situation hit also by the 14m tsunami (the plant is 12 miles south from Daïchi):

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

The Fukushima II Nuclear Power Plant (福島第二原子力発電所 Fukushima Dai-N

The March 11, 2011 Tōhoku earthquake resulted in ground accelerations of 0.19 g (1.86 m/s2) to 0.28 (2.77 m/s2) at the plant site, which is well below the design basis. [5] All four units were automatically shut down immediately after the earthquake, according to Nuclear Engineering International,[2] and the diesel engines were started to power the reactor cooling.[7] TEPCO estimated that the tsunami that followed the earthquake and inundated the plant was 14 meters high which is more than twice the designed height.[5] This flooded the pump rooms used for heat transfer to the sea, the ultimate heat sink of the reactors.[7] While the cooling system for unit 3 was undamaged, the other reactors were affected. The cooling systems remained operational, but heated up due to the lack of a heat sink. The high pressure coolant injection (HPCI) system (powered by reactor steam) was used as additional cooling.[7] On March 12, the cooling system for three reactors (numbers 1, 2 and 4) at the torus had topped 100 °C between 05:30 and 06:10 JST,[8][9][10] rendering all cooling systems (depending on temperature difference between the torus and the reactor) ineffective.[7] The coolant systems in the pump room were repaired and activated in Units 1, 2 and 4 in the days following the emergency shutdown after cooling could recommence[8] Coolant temperatures below 100 °C (cold shutdown) were reached in reactor 2 about 34 hours after the emergency shut down (SCRAM).[8] Reactors 1 and 3 followed at 1:24 and 3:52 on March 14 and Reactor 4 at 7:00 on March 15.[11] The loss of cooling water at reactors 1, 2 and 4 was classified a level 3 on the International Nuclear Event Scale (serious incident) by Japanese authorities as of March 18.[12][13][14]

Officials made preparations for release of pressure from the plant on March 12.[15][16] As of March 20, however, no pressure release had been reported.[8][17]
An evacuation order was issued to people living within 3 kilometres (1.9 mi) of the plant,[18] subsequently expanded to 10 km (6.2 mi).[19] Air traffic was restricted in a 10 km (6.2 mi) radius around the plant, according to a NOTAM.[20] These zone were superseded by the 20 km evacuation and 30 km no-fly zones around Fukushima I on March 12 and 15, respectively.

TEPCO announced that a worker who had been seriously injured by the earthquake, and trapped in the crane operating console of the exhaust stack was transported to the ground at 5:13 p.m. and confirmed dead at 5:17 p.m.[19][21][22][23][24]

I wonder also where the generators were on Daini plant, and what made the significant differences between the two plants concerning the consequences of the tsunami on the nuclear process.

 

[TCups]

Mt. St. Helens is inland, to there would be no consequence of tsunami. The Tunguska event was also overland, but it probably would have produced some king of tsunami if it had happened over the ocean.

The point is such catastrophic events that would cause massive destruction or mega-tsunami are exceedingly rare. However, we do need to have a realistic assessment of likely events - and the recent earthquake and tsunami - are more likely than Krakatoa and Tunguska. Most nuclear power plants are not sited where they might be affected by volcanoes or large tsunamis, or perhaps large earthquakes.

It seems to me significant that the diesel generators were located in the turbine buildings. In looking at a retroactive correction to a fundamental design flaw made 40 years ago, it might be understandable that the reasoning was that should a tsunami hit that is big enough to wipe out the generator, then it will be big enough to cause enough more collateral damage that the loss of the generator probably would not matter anyway -- who knows? Idle speculation.

By their nature, though natural disasters are unpredictable. Generators relocated up the back slopes of the site after a 9.0 quake might have just tumbled down the hill like Jack and Jill, for all our ability to predict the "what if's".

Anecdotally, I do have a friend who makes his living servicing large generators and bringing in temporary generators in emergency situations. I haven't spoken to him recently, but I believe I remember him complaining about all the different interface types that were involved in "hooking up" an emergency generator if power were needed quickly. Not always an easy task.

One prudent design criteria or retrofit for power plants everywhere that might be worth considering: A helicopter pad big enough to accommodate a military style, heavy lift helicopter and a standardized connection interface such that an emergency generator could be flown in, hooked up and made operational in a matter of hours, and of course, available back up generators with that interface which could be airlifted to a disaster location quickly, if needed.

Forgive my rambling, please.

 

[Astronuc]

I understand that Diablo Canyon is due for a review next month re: a 20-year extension, but that's now on hold.

It's seismic capabilities are up for review. That's one of the sites that happens to be fairly close to a potentially active fault.

http://diablocanyonpge.com/pdf/24_SFZ_Appendix_J_splay_fault_analysis.pdf

However, one would have to determine whether or not an earthquake related that that or nearby faults would result in a seismic event in excess of that for which the plant was designed.

The plant has been operated fairly conservatively. The chose not to uprate the plant, for instance.

 

[divmstr95]

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.

Actually their retraction never states that they did not detect I-134. It merely states the levels stated were for a different isotope, Co-56.

 

[divmstr95]

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!

The methodology used to predict Tsunami considers the geology of segments along a specific seismic zone as well as several other factors (hydrographic profiles, etc.). It also considers paleotsunami information for a given area based upon previous earthquakes. It may be that the tsunami model for that particular area did not generate a run up and inundation model that high.

Tsunami prediction is not perfect but when you're planning for development of coastal areas it is the best you've got to go on.

 

[Astronuc]

Actually their retraction never states that they did not detect I-134. It merely states the levels stated were for a different isotope, Co-56.

Yes - I notice that. The significance depends on the relative activities of I-134 and Co-56, and how they correct the activity from the time of measurement back to the time the sample was taken. The I-134 activity should decrease at a great rate. If they corrected the Co-56 activity using the I-134 decay rate, then they would have determined a much greater activity for I-134 than actually existed.

Ideally, by sampling one hour or so later, they can then do the decay for I-134 and Co-56 and adjust accordingly and correctly.

 

[Borek]

Here is a simulation of the Sanriku tsunami earthquake of 1896 i was talking about (height 36m), the wave is simulated 10 minutes after the earthquake:

This is not entirely just - in general Japan has no earthquake safe places.

 

[epistememe]

Here is an excellent lecture on reactor physics from KITP.

http://online.itp.ucsb.edu/online/plecture/bmonreal11/rm/flashtv.html

 

[|Fred]

2.9 trillion becquerels I-134 per liter! => assuming the fission stopped on the 14th that would be some thing in the range of 2.9*10^9= N *(0.5)^((27-14)*24))
2,419*10^103 atom of I-134 just for this liter (some one clever should be able to calculate the weight of that)
well that's 4.14*10^81 kg
which is about 13 orders of magnitude heavier than the entire universe
perhaps you miscalculated?

You'll find my calculation below , It rather show that there was no way this iodine was original fission product before scram (point I was tring to make but without the final touch calculating the mass )

I-134 has a Half life of 50 minutes I round it up to 60 minutes.. between the scram and the measurement 13 days ( 13*24) =312 Halflife
They said there was 2.9 x 10^9 Becquerels of I-134 in that liter meaning there was 2.9 10^9 atom of I-134

Number of iodine at scram = 2.9 x 10^9 x 2^312

 

[ivars]

http://www.tepco.co.jp/cc/press/betu11_j/images/110327o.pdf

Tepco's new numbers. On a different forum, TH1960 writes: "The first column is "ayamari" - mistaken. "

Tepco's new numbers does not include neither I-134 nor Co-56. However, every isotope below I-131 has increased in activity by 30-50% in last 12 hours.

 

[Joe Neubarth]

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!

Knowing the potential for hundred foot Tsunamis, the engineers for Fukushima placed the Emergency Diesel Generators in a position where they could be flooded with water. There is no excuse for that. All you can do is scratch your head and wonder, "Why?" This entire crisis would not have occurred if the generators were able to provide power to the plant as they were designed to do in an emergency.

Anybody who has ever walked along the sea shore knows that when a wave washes ashore the in rushing water can (because of inertia) go higher up the shore than the initial wave height. With consideration given to the the likelyhood of a Tsunami, the only place to put the Emergency Generators would be high up the hill.

 

[rhody]

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.

RealWing,

Since you a a former Nuclear Power Plant (NPP) manager, do you or did you use virtual simulator(s) which would show various parts of the reactor, where samples would be taken (under normal circumstances) for training purposes, and in this case general knowledge ? Using terms such as http://www.google.com/url?sa=t&sour...q431mjUA&sig2=Jkr2XAn9Jec3DGUZVjZ0MA&cad=rja", "as low as reasonably achieveable", threw me for a second, but with google, not for long. Screen shots of various parts of the structures involved would greatly aid those attempting to prepare and rehearse the difficult tasks that lie ahead. Are these tools available to those closest to the crisis ? I realize you may or may not know but I thought I would put this out there in case someone following this thread can answer the question. The people addressing the crisis need all the tools they can afford themselves of, and to add the pressure of the world watching them, I can't even begin to imagine what they are going through as they analyze and face each new challenge.

Rhody...

 

[M. Bachmeier]

Questions:

1) Does the cooling (power transfer) system for the core of a Mark I have a series of automatic cut-off valves that would stop a leak from (in large quantities) coming from pipes in that system?

2) Assuming (1) does the presences of large quantities of water (that appear to come from core containment) lead to the conclusion that core containment has been breached? (significant cracks)

3) (1), (2) x reactor #1, or 2, or 3, or all?

 

[KateB]

The chart of nuclides indicates that electron capture is the predominant mode of decay for Co-56. Nevertheless, I expect they are looking for characteristic gammas (gamma spectroscopy) with which to identify the radionuclides.

Decay gammas are generally discrete, as opposed to beta decay which represents a continuum of beta (and antineutrino) energies.

Odd. This site reports Co-56 decay as positron:
http://www.periodictable.com/Isotopes/027.56/index2.p.full.dm.prod.html

While the chart of nuclides does indeed report electron capture as mode of decay:
http://www.nndc.bnl.gov/chart/decaysearchdirect.jsp?nuc=56CO&unc=nds

I guess the .gov site wins. But I wonder at the discrepancy...

 

[KateB]

Yes - I notice that. The significance depends on the relative activities of I-134 and Co-56, and how they correct the activity from the time of measurement back to the time the sample was taken. The I-134 activity should decrease at a great rate. If they corrected the Co-56 activity using the I-134 decay rate, then they would have determined a much greater activity for I-134 than actually existed.

Ideally, by sampling one hour or so later, they can then do the decay for I-134 and Co-56 and adjust accordingly and correctly.

So basically, it's possible that the initial readings were a conglomeration of I-134 and Co-56, and only after a second reading when decay energies had transitioned,were they able to discern between the two?

 

[jlduh]

Anecdotally, I do have a friend who makes his living servicing large generators and bringing in temporary generators in emergency situations. I haven't spoken to him recently, but I believe I remember him complaining about all the different interface types that were involved in "hooking up" an emergency generator if power were needed quickly. Not always an easy task.

I read somewhere that at Daichi when they were trying to connect temporary power generators after the accident they got cable problems, should try to find some sources for this info...

 

[Astronuc]

So basically, it's possible that the initial readings were a conglomeration of I-134 and Co-56, and only after a second reading when decay energies had transitioned,were they able to discern between the two?

The longer half-lived decaying Co-56 would not decrease in activity as much. To discern between mixed isotopes, one has to let the shorter-lived isotope to decay over a reasonable time period - e.g., one-half life or several half-lives, depending on how significant the difference in half-lives and how urgently one needs the results.

This is the method to count the set of delayed neutron precursors which have half-lives on the order of seconds up to 55 seconds. There are 6 major groups.

 

[Astronuc]

Odd. This site reports Co-56 decay as positron:
http://www.periodictable.com/Isotopes/027.56/index2.p.full.dm.prod.html

While the chart of nuclides does indeed report electron capture as mode of decay:
http://www.nndc.bnl.gov/chart/decaysearchdirect.jsp?nuc=56CO&unc=nds

I guess the .gov site wins. But I wonder at the discrepancy...

I'd go with the government site (Brookhaven National Lab and the NNDC (which I think is the National Nuclear Data Center)).

See also - http://wwwndc.jaea.go.jp/cgi-bin/nuclinfo2010?27,56

Decay mode     Half-life 
  EC           77.233 D 27

 

[KateB]

I'd go with the government site (Brookhaven National Lab and the NNDC (which I think is the National Nuclear Data Center)).

See also - http://wwwndc.jaea.go.jp/cgi-bin/nuclinfo2010?27,56

Decay mode     Half-life 
  EC           77.233 D 27

I think I figured it out. I am assuming that B+ emission was the forebearer (as they would have the same outcome) I looked and you need a 1.022 or more MeV change between Co-56 and the daughter for positron (which there isn't), any less is electron capture. Thanks for being my sounding board :)

 

[AntonL]

http://www.tepco.co.jp/cc/press/betu11_j/images/110327o.pdf

Tepco's new numbers. On a different forum, TH1960 writes: "The first column is "ayamari" - mistaken. "

So they simply deleted Co-56, Ag-108m & I-134
retested the same sample 18 hours later and
Tc-99m increased from 8.7E04 to 4.8E05 a factor 5
Again a mistaken reading -
give me some time and I will work out the lifetime what they are measuring

The second sample has no trace of Tc-99m

 

[PietKuip]

So they simply deleted Co-56, Ag-108m & I-134
retested the same sample 18 hours later and
Tc-99m increased from 8.7E04 to 4.8E05 a factor 5
Again a mistaken reading -
give me some time and I will work out the lifetime what they are measuring

The second sample has no trace of Tc-99m

The second column is a revised analysis of the same gamma spectrum. Suddenly the total activity is two orders of magnitude lower. It should be impossible to reconcile both analyses with the same total count rate of their sample...

But they measured that spectrum 10 hours after it had been taken. I agree, those levels of I-134 were impossible in a sample that was so old. Maybe they extrapolated small signals back to the time of sampling, multiplying "noise peaks" with 65000 ??

The third columns is from a new spectrum of the same sample. The fourth column is from a new sample.

 

[jlduh]

Joe Neubarth:

Anybody who has ever walked along the sea shore knows that when a wave washes ashore the in rushing water can (because of inertia) go higher up the shore than the initial wave height.

Yep, this leads to the difference between the "run up" and the "wave height", this schematics is self explanatory:

http://www.netimago.com/image_183063.html

Interesting also, it seems the highest run up the 11th March has reached more than 23 meters at Ofunato. And also of interest it has been almost 15 meters at Onagawa port, (don't know at Onagawa nuclear plant). You can see this in the document below, and observe that the variations are large over local configurations on the coast (one can then ask what kind of accuracy limits we can get from the models used to calculate safety risks...).

http://sendai.hmdc.harvard.edu/portal/other_distro/PARI_Field_Survey_02.pdf

 

[83729780]

something to keep an eye on: pressure in RPV #1 is rising once again:

Reactor pressure
(A) 0.374MPaG, (B) 0.416MPaG (27th 09:00)

http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1301226468P.pdf

compare to:

(A) 0.365MPaG, (B) 0.389MPaG (26th 21:00)

(A) 0.351MPaG, (B) 0.380MPaG (26th 13:00)

(A) 0.376MPaG, (B) 0.360MPaG (26th 09:30)

(A) 0.353MPaG, (B) 0.360MPaG (26th 05:00)

(A) 0.338MPaG, (B) 0.338MPaG (25th 18:30)

why?

 

[RealWing]

RealWing,

Since you a a former Nuclear Power Plant (NPP) manager, do you or did you use virtual simulator(s) which would show various parts of the reactor, where samples would be taken (under normal circumstances) for training purposes, and in this case general knowledge ? Using terms such as http://www.google.com/url?sa=t&sour...q431mjUA&sig2=Jkr2XAn9Jec3DGUZVjZ0MA&cad=rja", "as low as reasonably achieveable", threw me for a second, but with google, not for long. Screen shots of various parts of the structures involved would greatly aid those attempting to prepare and rehearse the difficult tasks that lie ahead. Are these tools available to those closest to the crisis ? I realize you may or may not know but I thought I would put this out there in case someone following this thread can answer the question. The people addressing the crisis need all the tools they can afford themselves of, and to add the pressure of the world watching them, I can't even begin to imagine what they are going through as they analyze and face each new challenge.

Rhody...

We didnt have virtual simulators for this. We had pre-designated normal and emergency sampling points and operators and chem techs were obviously trained and qualified on these. This was all assuming events that were "design basis events" and in later years for some analyzed "beyond design basis events". What is occurring in Japan is outside of any analyzed event
Many plants had made virtual plant tour videos of normally inaccessible parts of the plant (eg in a BWR, many areas in the turbine building are inacessible or have restricted access when the plant is operating) for work planning and modification purposes. I do not know if the Japanese utilities had these or not. (It has been many years since I've been in a Japanese reactor!)

 

[Reno Deano]

Spent fuel pools contain things other than intact fuel bundles: damages fuel rods, highly irradiated RPV QC coupons, used incore detectors, irradiated reactor internals, etc., and most plants store their Pu-Be neutron calibration sources on the spent fuel pool deck or the turbine building for ease of calibrating instruments at various distances. All of these (except the Pu-Be shielded source) could be sources of various radionuclides.

 

[AntonL]

OffTopic: Political fallout in Germany

In today's two German by-election the Green Party had huge gains
4.6% --> 15.4%
11.7% --> 24.2%

 

[rmattila]

I apologize for taking up a topic already discussed thoroughly on this thread, but there's one thing I've been trying to find an answer to, thus far with no success:

As far as I understand, the US plants with Mark I containments were at some point of time refitted with what is called a "hardened venting", mentioned e.g. http://www.scribd.com/doc/51291366/Report-BWR-Mark-I-Containment-03192011-2 , page 10). Would anyone have any idea, whether the plants in Fukushima Dai-ichi had anything equivalent, or was the venting of containment steam attempted e.g. through pipe lines designed just for changing the atmosphere from air to nitrogen under normal pressure/temperature conditions?

 

[rhody]

We didnt have virtual simulators for this. We had pre-designated normal and emergency sampling points and operators and chem techs were obviously trained and qualified on these. This was all assuming events that were "design basis events" and in later years for some analyzed "beyond design basis events". What is occurring in Japan is outside of any analyzed event
Many plants had made virtual plant tour videos of normally inaccessible parts of the plant (eg in a BWR, many areas in the turbine building are inacessible or have restricted access when the plant is operating) for work planning and modification purposes. I do not know if the Japanese utilities had these or not. (It has been many years since I've been in a Japanese reactor!)

Thanks RealWing,

As you stated, "outside of any analyzed event" must be really frustrating for you, Astronuc and other experts in this thread. One would hope, but not expect the general public to understand. I never am failed to be amazed at critical moments in history, the Apollo 13 rescue effort comes to mind, how the best minds can improvise solutions to seemingly impossible situations. I hope history repeats itself here. I hope that all necessary expertise will be brought to bear to relieve the short term crisis and to come up with a long term solution.

Rhody...

 

[KateB]

Regarding the TC-99m sample and the apparent practice of extrapolating back to the time of the sampling as indicated in TEPCO explanation

Using a 1/2 live of 6.02 hours
8.7E04 -- 10h --> 5.57E04
4.8E05 -- 28h --> 1.19E04

assuming that 5.57E04 and 1.19E04 are the actual lab readings
then one can calculate a half life of 11.34 hours

1.057E06 --- 10h --> 5.57E04 -- 18h --> 1.19E04

What isotope has an half life of 11.34 hours ?

could it just be variance in the samples? I am also wondering about the Ba-140. It increased in the new testing, and I wonder if the size is within a normal margin of variability? Ba-140 is a direct fission yield, as far as I understand.

 

[|Fred]

Spent fuel pools contain things other than intact fuel bundles: damages fuel rods, highly irradiated RPV QC coupons, used incore detectors, irradiated reactor internals, etc., and most plants store their Pu-Be neutron calibration sources on the spent fuel pool deck or the turbine building for ease of calibration instruments at various distances. All of these (except the Pu-Be shielded source) could be sources of various radionuclides.

Thank you for this input, that gives some insight on non purely theoretical fact