Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[rhody]

To all,

What degree of confidence could a plant operator or engineer put on identification of a blurred white dot appearing for a couple of seconds in a helicopter flyby as being an adequate level of water in an SPF?

With that helicopter pilot risking and more than likely shortening his life, I have one question, WHERE ARE OUR PREDATOR UNMANNED DRONES WITH THEIR HIGH RESOLUTION 3 MILLION DOLLAR CAMERA'S. This is a no-brainer, at least for me, if ever they needed the technology, it was YESTERDAY ! There I feel better, having vented. Back to normal. Just had to vent, sorry.

Rhody...

 

[Reno Deano]

Sacramento, CA news reported today that an EPA area monitor (beta/gamma) reading in cpm had elevated readings and they associated it with the Japanese problems! They even said it was due to Cs-137 or Iodine. However, there have been no reports of increase activity of monitors from facilities further West: Livermore Labs, Vallecitos Labs, or any of the DOE or California State monitoring sites or the Nuclear Plants about similar readings.

More than likely it is a faulty monitor or just at transient spike from something else in the area.

I would rather believe almost anyone else's results before those of the EPA.

 

[Reno Deano]

To all,


With that helicopter pilot risking and more than likely shortening his life, I have one question, WHERE ARE OUR PREDATOR UNMANNED DRONES WITH THEIR HIGH RESOLUTION 3 MILLION DOLLAR CAMERA'S. This is a no-brainer, at least for me, if ever they needed the technology, it was YESTERDAY ! There I feel better, having vented. Back to normal. Just had to vent, sorry.

Rhody...

I don't think he was in any great danger (especially from radiation) other than that is normally associated with flying an apparatus that drops like a boiled egg when the rotors stop. You didn't see him flying directly over the units or through a steam cloud did you?

 

[AtomicWombat]

BOTE calculation. See here:
http://www.asianewsnet.net/home/news.php?sec=1&id=17975"

"The radiation level at the scene before the operation was 4.13 millisieverts per hour at an altitude of about 300 meters and 87.7 millisieverts per hour about 100 metres above ground."

The inverse square law would imply a 9 fold increase in radiation from 300 metres to 100 metres. Instead we see a 87.7/4.13 = 21.2 fold increase. (I am still looking for data on gamma ray attenuation in air.)

Now the inverse square law strictly only applies to a point source. We can only extrapolate to the effective cross sectional area of the source from the angle of the helicopter. Let's extrapolate to 2 metres from the source (4 square metre cross section).

If we assume 4.13 millisieverts per hour at 300 metres and no attenuation, we would estimate 4.13*(300/2)^2 = 93000 millisieverts per hour = 93 sieverts per hour = 9300 REM/hr.

If we assume 87.7 millisieverts per hour at 100 metres and no attenuation, we would estimate 87.7 *(100/2)^2 ~ 220,000 millisieverts per hour = 220 sieverts per hour = 22,000 REM/hr ~ 22,000 Roentgens/hr.

These are Chernobyl-like estimates, but they are BOTE calculations and they ignore atmospheric attenuation.

Please check my calculations. I realize these are non-trivial conclusions. I'm hoping to find an error.

More BOTE calculations, which I'll do on the fly...

http://en.wikibooks.org/wiki/Basic_Physics_of_Nuclear_Medicine/Attenuation_of_Gamma-Rays"

I'll adapt the linear attenuation model to the spherical case. Intensity is power per unit area, so the linear intensity law [URL]http://upload.wikimedia.org/math/a/0/9/a0940ee8f846fa377f8d6dc4452a4ab3.png[/URL] becomes -dP ~ P.dx.

This leads to the equation Pd = Po*exp(-mu*x), where Po is power near the source, Pd is power at a distance xd, xd - xo is distance from the source and mu is the attenuation constant in air. Dividing by area we get (Id/Io) = (xd/xo)^2*exp(-mu*(xd - x0)) and
xd - x0 ~ xd for our purposes.

Assume mu is 0.00016 cm^-1 for 200 keV gamma = 0.016 m^-1.
http://en.wikibooks.org/wiki/Basic_...Attenuation_of_Gamma-Rays#Mathematical_Model"
We want Io assuming the above info :
Io = Id* (xd/xo)^2/(exp(-mu*xd))
We already have calculation above for Ix* (xd/xo)^2: 93 sieverts per hour based on the 300 metre measuremnt and 220 sieverts per hour based on the 100 metre measurement.

So Io = 93/exp(-0.016*300) = 11,300 Sv/hr based on 300 metres metres extrapolated to 2 metres.

Io = 220/exp(-0.016*100) = 1090 Sv/hr based on 100 metres extrapolated to 2 metres.

There may be an error in my maths (done on the fly) or the assumptions about extrapolations to point sources may be way off (there are multiple sources). Also I'm not convinced I've correctly dealt with spherical attenuation and the effective cross sectional area of the source may be greater than 4 square metres.

Comments please?

 

[swimmer]

Live stream on http://www3.nhk.or.jp/nhkworld/" just reported there's TEPCO Fukushima Daiichi workers who have now received maximum radiation dose of 100mSv and that they would not be sent back in.

 

[Astronuc]

This thought has been with me all afternoon, from the summary of the Chernobyl incident post #450 above from the quote in the article:

In fact, the reactor had serious design faults: when run at low power it was dangerously unstable and difficult to control; additionally, for the first four seconds after being inserted, the control rods would do the opposite of what they were supposed to - instead of slowing reaction, they would cause a sudden power surge. Under normal conditions these faults were not regarded as dangerous; but were the reactor ever to be pushed beyond its normal limits, they could prove catastrophic.

This is an academic question probably best for Astronuc,

"What design flaw and phenomenon is this ? and what could be done (if anything) today to prevent it ?"

Basically, the responsible engineer and staff disabled the protection systems. They performed an experiment, but the parameters of the core were not in accordance with the plan (I need to go back and review the sequence). They removed a control element, and then got a + reactivity feedback due to an unanticipated source (the part I for which I need to refresh my memory). When that happened, they naturally reinserted the control elements. Now, in a graphite-moderated core, water (which is normally a moderator in an LWR) is actually a neutron poison. When the tip (not an absorber) of the control rod was inserted, it displaced the water, which removed the -reactivity, or otherwise inserted more + reactivity - and boom - the neutron multiplication took off - very quickly. In fact, IIRC, they went prompt critical, which is a BIG NO-NO!

The other effect in play with respect to cooling water in the RBMK, when the water gets hot, particularly when it boils (becomes vapor), it also absorbs less neutrons, and so that has positive reactivity coefficient. Generally, LWRs are designed for negative reactivity coefficients for moderator density and fuel temperature (Doppler) effects.

Second concerning gamma ray radiation, scroll down to health effects, same article:

The most biological damaging forms of gamma radiation occur in the gamma ray window, between 3 and 10 MeV, with higher energy gamma rays being less harmful because the body is relatively transparent to them.

Why is the range from 3 to 10 million electron volts so damaging to human cells? The higher the energy the more penetrating the gamma. 3-10 MeV just happen to have the right energy range to be penetrating, but not so penetrating that they pass through. In other words, they will penetrate and produce secondary radiation via the photoelectric and Compton effects, and even pair prodcution.

Finally, a little further down, same article, under Body Response, can someone address this issue please ?

When gamma radiation breaks DNA molecules, a cell may be able to repair the damaged genetic material, within limits. However, a study of Rothkamm and Lobrich has shown that this repair process works well after high-dose exposure but is much slower in the case of a low-dose exposure.

I'll leave that for a biophysicist.


BTW - http://news.nationalgeographic.com/news/energy/2011/03/1103165-japan-nuclear-chernobyl-three-mile-island/

 

[swimmer]

Could be a local spike, and it could be transient. Either side 31 and 33 are lower, but higher than locations further S and W.

Thank you, Astronuc. Your expertise is much appreciated.

More monitoring info can be accessed from this http://ht.ly/4exnv"

 

[Reno Deano]

Dr. Michio Kaku is a theoretical physicist, best-selling author, and popularizer of science. He’s the co-founder of string field theory (a branch of string theory), and continues Einstein’s search to unite the four fundamental forces of nature into one unified theory.

Is currently speaking on CNN live. If you can get a later video replay of it, it is a must see...especially as he speaks about the Japanese leaders (Gov't and TEPCO) being out of touch with reality. One point he makes is that that they categorized the seriousness of the reactor accidents as a "5" when that was what 3 mile island was, and it was only 1 reactor and they have at least 3 to 4 reactors in similar trouble...all at once! He recommends entombing the problem reactors now...?

Dr. Kaku may have his interview on his site soon: http://mkaku.org/home/"

 

[javadave]

Dr. Michio Kaku is a theoretical physicist, best-selling author, and popularizer of science. He’s the co-founder of string field theory (a branch of string theory), and continues Einstein’s search to unite the four fundamental forces of nature into one unified theory.

Is currently speaking on CNN live. If you can get a later video replay of it, it is a must see...especially as he speaks about the Japanese leaders (Gov't and TEPCO) being out of touch with reality. One point he makes is that that the categorized the seriousness of the reactor accidents as a "5" when that was what 3 mile island was, and it was only 1 reactor and they have at least 3 to 4 reactors in similar trouble...all at once! He recommends entombing the problem reactors now...?

Dr. Kaku may have his interview on his site soon: http://mkaku.org/home/"

Kaku is also peddling his new book right now, so who knows if he is being sensational due to other motives.

 

[Astronuc]

Kaku is also peddling his new book right now, so who knows if he is being sensational due to other motives.

I have to wonder how many non-experts are going to write books about this event.


FYI - Sequence of Events
http://www.jaif.or.jp/english/aij/member/2011/2011-03-18c.pdf


How Is Japan's Nuclear Disaster Different?
According to the author, Josie Garthwaite, Fukushima Daiichi may be no Chernobyl, but it has overshadowed Three Mile Island..
http://news.nationalgeographic.com/news/energy/2011/03/1103165-japan-nuclear-chernobyl-three-mile-island/

We await a comprehensive analysis of the activity release and exposures.

 

[rhody]

I don't think he was in any great danger (especially from radiation) other than that is normally associated with flying an apparatus that drops like a boiled egg when the rotors stop. You didn't see him flying directly over the units or through a steam cloud did you?

Reno,

No, pilot safety was only part of my concern, of course he made the flyby as quick as possible and not directly in a vapor stream. From the looks of it, he used a hand held (not HD camera to take that video). The http://en.wikipedia.org/wiki/General_Atomics_MQ-1_Predator" is capable of staying aloft for 40 hours and has a cruise speed of over 70kt.

The surveillance and reconnaissance payload capacity is 450lb and the vehicle carries electro-optical and infrared cameras and a synthetic aperture radar. The two-color DLTV television is equipped with a variable zoom and 955mm Spotter. The high resolution FLIR has six fields of view, 19mm to 560mm.

This platform can provide superior visual and thermal imagery that would be invaluable to teams on the ground assessing the situation. I would not be surprised to learn sometime in the distant future that one or more of our Keyhole spy satellite's had been directed to use it's precious maneuvering gases to overfly, sense and record the crippled reactor's in Japan. Only time will tell what if any information was gathered, analyzed and then provided to our president in his daily security brief.

Rhody...

 

[Angry Citizen]

The predator is capable of staying aloft for 40 hours and has a cruise speed of over 70kt.

You'd think the military would have hardened it against ionizing radiation to combat the effectiveness of tactical nuclear weapons, but the Predator may not have been built with that in mind. After all, the engineers who designed Fukushima's EDG system didn't consider the possibility of a tsunami. Boneheads.

 

[rhody]

Basically, the responsible engineer and staff disabled the protection systems. They performed an experiment, but the parameters of the core were not in accordance with the plan (I need to go back and review the sequence). They removed a control element, and then got a + reactivity feedback due to an unanticipated source (the part I for which I need to refresh my memory). When that happened, they naturally reinserted the control elements. Now, in a graphite-moderated core, water (which is normally a moderator in an LWR) is actually a neutron poison. When the tip (not an absorber) of the control rod was inserted, it displaced the water, which removed the -reactivity, or otherwise inserted more + reactivity - and boom - the neutron multiplication took off - very quickly. In fact, IIRC, they went prompt critical, which is a BIG NO-NO!

The other effect in play with respect to cooling water in the RBMK, when the water gets hot, particularly when it boils (becomes vapor), it also absorbs less neutrons, and so that has positive reactivity coefficient. Generally, LWRs are designed for negative reactivity coefficients for moderator density and fuel temperature (Doppler) effects.

Why is the range from 3 to 10 million electron volts so damaging to human cells? The higher the energy the more penetrating the gamma. 3-10 MeV just happen to have the right energy range to be penetrating, but not so penetrating that they pass through. In other words, they will penetrate and produce secondary radiation via the photoelectric and Compton effects, and even pair prodcution.

I'll leave that for a biophysicist.


BTW - http://news.nationalgeographic.com/news/energy/2011/03/1103165-japan-nuclear-chernobyl-three-mile-island/

Thanks Astronuc,

You are providing insight that would not possible to obtain otherwise, and since you are a mentor on here, we reap the benefit, a win, win.

Rhody...

 

[rhody]

You'd think the military would have hardened it against ionizing radiation to combat the effectiveness of tactical nuclear weapons, but the Predator may not have been built with that in mind. After all, the engineers who designed Fukushima's EDG system didn't consider the possibility of a tsunami. Boneheads.

Angry,

How can you be so sure it wasn't ?

Rhody...

 

[Reno Deano]

Live stream on http://www3.nhk.or.jp/nhkworld/" just reported there's TEPCO Fukushima Daiichi workers who have now received maximum radiation dose of 100mSv and that they would not be sent back in.

TEPCO's actions are in keeping with responsible health physics practices for emergency workers and the current situations.

Dean Chaney, CHP

 

[Reno Deano]

Has anyone seen any offsite radionuclide specific measurement data? Hand held gamma specs are dime a dozen in Japan! Every measurement team should have one. They also should have analyzed insitu air samples, by now.

 

[Astronuc]

Has anyone seen any offsite radionuclide specific measurement data? Hand held gamma specs are dime a dozen in Japan! Every measurement team should have one. They also should have analyzed insitu air samples, by now.

That's what I really want to see - the Cis of various nuclides.

 

[Angry Citizen]

Angry,

How can you be so sure it wasn't ?

Rhody...

I'm as uncertain as you are. I simply wanted to offer a possible explanation. We know a few facts. 1) Predators are dependent on a dense network of sophisticated electronics. 2) Any significant electronic interference would disrupt unshielded electronics. 3) Predators are designed to be lightweight, meaning it's possible that some engineer decided to nix shielding on account of weight or cost or some combination of the two. 4) Predators aren't necessarily designed for a nuclear-armed opponent. AFAIK, they were developed to combat guerrillas and insurgents whose technological capabilities are low, or to observe enemy positions before engagement. Radiation shielding would fall far outside necessity for such missions, since guerrillas don't tend to carry Fukushima nuclear plants on their backs, and modern warfare doesn't tend to include the risk of tactical nuclear weapons.

But I would take this analysis with a grain of salt. For all I know, the American military decided to be greedy and didn't want to risk a multi-million dollar plane. Or it's like someone else said: maybe we've got a satellite up there with sufficient imaging capabilities, but it's not being released to the public in order to keep our spy satellites' capabilities unknown (this possibility also applying to the lack of Predators).

 

[rhody]

Angry,

Look at it this way, a more perfect environment could not be had to probe your areas of concern, radiation hardness, no ?

Rhody...

 

[PoC83]

So, I was hoping someone could give me a clear answer on this because I've been unable to do so. How fast does this radiation dilute in air? Over the course of several kms what type of concentration loss occurs?

 

[Astronuc]

So, I was hoping someone could give me a clear answer on this because I've been unable to do so. How fast does this radiation dilute in air? Over the course of several kms what type of concentration loss occurs?

It depends on a number of factors such as temperature (molecular diffusion), wind speed and turbulence (mixing), among various meterological conditions. Rain can wash nuclides out of the air, but then deposit on land, where they enter the soil, plant life or animal life, or diluted in water and transported by flow water.

This is in addition to the decay of the particular nuclides being transported.

I'll see if I can dig up a reference on plume dispersal.

 

[OmCheeto]

That's what I really want to see - the Cis of various nuclides.

Thank you for keeping up with all this Astro.

 

[Angry Citizen]

Angry,

Look at it this way, a more perfect environment could not be had to probe your areas of concern, radiation hardness, no ?

Rhody...

Believe me, I'm on your side in this. I'd love some more information. Much of the hysteria surrounding this incident is based on lack of knowledge. And I mean that both maliciously and non-maliciously. There is terrible ignorance of the dangers (much of which is invented) of nuclear power in the vast majority of individuals (maliciously), and those who could interpret details with their vast knowledge lack the information to do so (non-maliciously). An example of the latter is Astronuc here: Just imagine what he could tell us if he knew the details inside the plant right now. All this speculation about corium would go away quick, fast, and in a hurry.

 

[rhody]

Believe me, I'm on your side in this. I'd love some more information. Much of the hysteria surrounding this incident is based on lack of knowledge. And I mean that both maliciously and non-maliciously. There is terrible ignorance of the dangers (much of which is invented) of nuclear power in the vast majority of individuals (maliciously), and those who could interpret details with their vast knowledge lack the information to do so (non-maliciously). An example of the latter is Astronuc here: Just imagine what he could tell us if he knew the details inside the plant right now. All this speculation about corium would go away quick, fast, and in a hurry.

Angry,

If you haven't already done so I recommend you take the time to read the link on Chernobyl https://www.physicsforums.com/showpost.php?p=3195716&postcount=450".
It paints a sobering picture of what mistakes were made, and action taken to control the radiation after the event. As to your last comment, I agree, accurate information regarding the reactor's state is critical (no pun intended, well maybe just a little) to assess what steps need to be taken. The hard part is time is not on our side, nor is there any room for error.

Rhody...

 

[Angry Citizen]

I've read about Chernobyl extensively. Nothing in this disaster seems to approach Chernobyl's magnitude. I'm not a nuclear engineer, but I can tell you that the dispersal of contaminants is much different in this situation. For one, it doesn't appear as though anything from within the core has caught fire. I believe any smoke (note: not steam) rising from the destroyed buildings has been from a building fire. This released some contaminants from the gas venting that would otherwise have stayed within the units, but again, nothing like Chernobyl.

For another, all but one of the containment units appear intact, and the other one is either intact as well, or merely cracked. This last one is bad, but again, it's nothing like the explosive destructive power seen in Chernobyl which released solid contaminants into aerosol form. The key here is where the hydrogen explosion occurred. At Chernobyl, it occurred within the core, which as you know would send contaminants airborne. At Fukushima, it occurred outside the core, which would tend to compact the contaminants, though dispersal into aerosol form is still an obvious fact. The difference again is that the only source of these contaminants is from the gas venting, which would contain a certain level of caesium and other solid contaminants, but nothing on the level of a full core breach.

Finally, there was a release of corium at Chernobyl. No such corium is known to be outside the reactors at Fukushima. Inside the core we can only speculate, but it seems likely that there's corium in all three damaged reactors, even if it's only a small amount (EDIT: I made a terrible mistake and put 'at the bottom of' -- please disregard that).

The wildcard here is the spent fuel ponds. From what Astronuc has been telling us, a spent fuel meltdown hasn't been studied extensively. This is the only possible way Fukushima could become another Chernobyl. Sadly, what I know about spent fuel ponds pales in comparison to what I know about nuclear reactors. Again I'll stress that I'm not Astronuc. I'm not a nuclear engineer. This is simply what I can glean from his testimony, from my own (layman's) knowledge of nuclear reactors, and from what I know about aerodynamics and particle dispersal patterns (my knowledge of which will probably increase exponentially in the next couple years -- I'm an aerospace engineering student). So please, take my statements with a grain of salt -- or a pillar of it.

Edit: I've never heard of Cherenkov radiation. At least I got something new from the article. God it's beautiful.

 

[Reno Deano]

From NEI today:

No Radiation Levels of Concern in Western U.S.

The U.S. Department of Energy and Environmental Protection Agency on Friday issued a joint statement to confirm that the nationwide network of sensitive radiation monitoring equipment has detected no radiation levels of concern to U.S. citizens.

The EPA's RadNet system notifies scientists in near real-time of elevated levels of radiation to enable them to determine whether protective actions are required. DOE's IMS (International Monitoring System) operates as part of the Comprehensive Nuclear Test Ban Treaty and detects tiny quantities of radiation that may indicate an underground nuclear explosion anywhere in the world.

One of the DOE monitors in Sacramento, Calif., detected tiny quantities of a radioisotope (xenon-133). The level of the isotope detected would result in one-millionth of the dose rate that a person would normally receive from natural background sources.

More information is available at www.epa.gov/radiation[/url] or http://nei.cachefly.net/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region/

[I]Authors Note: I think this is bad info on Xe-133, even though they did not directly associate it with the Japanese reactor crisis. Xe-133 shorter half-life than I-131, and is used in and around most major cities in hospitals and industrial complexes. Whomever wrote the last paragraph was not very knowledgeable in communicating radiation dose facts.[/I]

 

[Astronuc]

The wildcard here is the spent fuel ponds. From what Astronuc has been telling us, a spent fuel meltdown hasn't been studied extensively. This is the only possible way Fukushima could become another Chernobyl. Sadly, what I know about spent fuel ponds pales in comparison to what I know about nuclear reactors. Again I'll stress that I'm not Astronuc. I'm not a nuclear engineer. This is simply what I can glean from his testimony, from my own (layman's) knowledge of nuclear reactors, and from what I know about aerodynamics and particle dispersal patterns (my knowledge of which will probably increase exponentially in the next couple years -- I'm an aerospace engineering student). So please, take my statements with a grain of salt -- or a pillar of it.

I'll have to try to dig up research on corium and severe accidents.

Having hot Zr-2 and Zr-4 in air is common practice in the manufacturing process. Red hot ingots are hot worked into logs and subsequently billets. It oxidizes, but it doesn't burn.

http://www.wahchang.com/pages/products/data/pdf/Zirconium Production Flow Chart.pdf (use 'save target as')

 

[BHamilton]

More BOTE calculations, which I'll do on the fly...

Comments please?

You seem to have mixed up the measurements and your model's predictions in your last post...

With a model of I ~ I0 (x0/x)^2 exp(-mu*(x-x0)) and two points (100 meters, 4.13 mSv/hr, 300 meters, 87.7 mSv/hr) and one degree of freedom (mu), one can directly find the mu that fits the data (mu = ln(I1*x1*x1/I0*x0*x0)/(x1-x0) and you find mu = 0.0043 m^-1.

Going back and using this to find the value at 20 meters, we find on the order of 3 Sv/hr. Closer than that I wouldn't trust the model, since even at that distance we're already likely outside the region of validity of the model (which assumes the source is small compared to the distance we're measuring at, once we hit sizes of the same order of magnitude as the reactor buildings bets are off here). A safer prediction would be the value we find at 50m, which is like 430 mSv/hr

Dr. Michio Kaku ...

Is currently speaking on CNN live. If you can get a later video replay of it, it is a must see...especially as he speaks about the Japanese leaders (Gov't and TEPCO) being out of touch with reality.

This is a very serious situation of course, but I find the idea of Michio Kaku accusing anyone else of being out of touch with reality hilarious

 

[vanesch]

Basically, the responsible engineer and staff disabled the protection systems. They performed an experiment, but the parameters of the core were not in accordance with the plan (I need to go back and review the sequence). They removed a control element, and then got a + reactivity feedback due to an unanticipated source (the part I for which I need to refresh my memory). When that happened, they naturally reinserted the control elements. Now, in a graphite-moderated core, water (which is normally a moderator in an LWR) is actually a neutron poison. When the tip (not an absorber) of the control rod was inserted, it displaced the water, which removed the -reactivity, or otherwise inserted more + reactivity - and boom - the neutron multiplication took off - very quickly.

Yes, that's right, especially because the tip of the bars were made of graphite, which is a better moderator than the water it displaced.

The other problem was that, due to an unforeseen power request, one had trottled up the reactor during the day before (which had been brought to low power for a day to do the experiment), and when the power request was over (I think around 11 PM), they *brutally* reduced the power of the reactor again to the "experimental level", creating a Xe-poisoning.

This Xe-poisoning tended to stop the reactor all together, and because the night crew wanted to do this experiment at all cost, they removed control rods much further away than normally allowed to keep it "live" and avoid stopping the chain reaction.

So essentially the control of the reactor was not with the rods anymore, but with the Xenon. Which is an extremely unstable situation.

 

[AntonL]

Referring to the latest http://www.jaif.or.jp/english/aij/110319FukushimaEventStatus-14e.pdf"

Holes have now been cut into the roofs of reactor building 5 and 6 so that hydrogen can vent and diminish possibility of an explosion.

That reactor 4 is still classed as a INES level 3 Serious Incident is a gross understatement.

Pressure readings are published for unit 1, 2 and 3
what do you make of them?

 

[M. Bachmeier]

You seem to have mixed up the measurements and your model's predictions in your last post...

With a model of I ~ I0 (x0/x)^2 exp(-mu*(x-x0)) and two points (100 meters, 4.13 mSv/hr, 300 meters, 87.7 mSv/hr) and one degree of freedom (mu), one can directly find the mu that fits the data (mu = ln(I1*x1*x1/I0*x0*x0)/(x1-x0) and you find mu = 0.0043 m^-1.

Going back and using this to find the value at 20 meters, we find on the order of 3 Sv/hr. Closer than that I wouldn't trust the model, since even at that distance we're already likely outside the region of validity of the model (which assumes the source is small compared to the distance we're measuring at, once we hit sizes of the same order of magnitude as the reactor buildings bets are off here). A safer prediction would be the value we find at 50m, which is like 430 mSv/hr



This is a very serious situation of course, but I find the idea of Michio Kaku accusing anyone else of being out of touch with reality hilarious

This is the second video... http://www.cnn.com/video/#/video/be....japan.nuclear.chernobyl.cnn?iref=videosearch

In his earlier video he was speaking hypothetically. Unless he is now in possession of information most everyone else doesn't have, he has made a very large jump into a conclusion.

 

[Andrew Mason]

A tip of the hat to the posters on this thread, particularly Astronuc. (Astronuc, are you getting any sleep?). The information is much appreciated. Have you seen the no. of views: over 58,000 so far in one week! That must be close to a record.

AM

 

[Reno Deano]

Prof. Kaku's argument is sound on the premise of preparing for a worst case situation. Since Chernobyl was a remote site, entombment was an easy option. I think Japan will wait to see if restored power will let them get a better hand on the situation. If the seawater injection has worked and re-flooding the spent fuel pools is carried out, then only a lengthy core stabilization, facility clean up and decommissioning is left. Oh, and the compilation of a lessons learned report that will fill a Harvard size library.

 

[AntonL]

Possible cause of hydrogen explosion of reactors 1 and 3 is published by http://allthingsnuclear.org/post/3940804083/possible-cause-of-reactor-building-explosions" - an excellent article

What bothers me is quote "A little-known test performed decades ago at the Brunswick nuclear plant in North Carolina may hold the key to answering that question." - why little-known - this is a design limitation/fault common to many nuclear power stations. If this had been common knowledge in the nuke industry safety manuals and emergency procedures may have been rewritten - I am sure they are now being re-drafted.

Now at Fukushima containment vessel pressure has been http://www.jaif.or.jp/english/aij/110319FukushimaEventStatus-14e.pdf" *1) to be steady at .140 to .150 MPa_abs [STRIKE]which is about the same as 70PSI Gauge[/STRIKE]. Now reactor vessels 2 and 3 are reported near 0 pressure Guage that is the pressure inside the the reactor vessel is the same as the pressure in the containment vessel leading to the conclusion that the reactor vessel is breached [STRIKE]and the containment vessel 'auto-vents' as described in the article[/STRIKE].

It is also reported that sea water flooding into the reactor cores is taking place continually one of two things can happen
1- worst case it boils of and steam is vented as above then slowly a massive NaCl crust must be developing
2- best case the reactors have cooled and the containment vessel slowly filling with water

*1) Reactor 3 CV pressure 0.045MPa_abs must be a typo as it is a vacuum and I think should read as 0.145MPa_abs as in previous reports

Edit: As pointed out later pressure conversion is wrong hence wrong part struck out

 

[AtomicWombat]

You seem to have mixed up the measurements and your model's predictions in your last post...

With a model of I ~ I0 (x0/x)^2 exp(-mu*(x-x0)) and two points (100 meters, 4.13 mSv/hr, 300 meters, 87.7 mSv/hr) and one degree of freedom (mu), one can directly find the mu that fits the data (mu = ln(I1*x1*x1/I0*x0*x0)/(x1-x0) and you find mu = 0.0043 m^-1.

Going back and using this to find the value at 20 meters, we find on the order of 3 Sv/hr. Closer than that I wouldn't trust the model, since even at that distance we're already likely outside the region of validity of the model (which assumes the source is small compared to the distance we're measuring at, once we hit sizes of the same order of magnitude as the reactor buildings bets are off here). A safer prediction would be the value we find at 50m, which is like 430 mSv/hr.

BHamilton, the point of my calculation was not to accurately model the radiation, but to show using two actual measurements at known heights that current radiation measurements do not rule out the possibility that the lava-like discharge from building 4 is coria.

The Chernobyl measurements were taken at a human scale, in the vicinity of the reactor core and close to fuel fragments.

Estimating the attenuation coefficient using these two measurements assumes gamma rays of only one energy are being measured as attenuation in air increases with gamma ray energy. (So no this is not a one parameter problem.) Furthermore we do not know where these measurements were made, only the height at which they were made, so the actual distance to the hypothetical source cannot be estimated.

I freely admit the model is flawed. It could hardly be otherwise. Almost certainly there are multiple sources of radiation on the site, including lofted radionucleotides. As I said my purpose was to determine if the radiation measurements made from the air rule out exposed coria. They do not.