Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[elektrownik]

Their smile looks really forced, doesn't it? And Edanos looks like he's thinking "Is he really going to swallow this tomatoe? I'm only going to eat my strawberry if he's eating his, too!" ;)

Taste like Chernobyl... ;)

 

[Giordano]

I'm trying to learn more about bioaccumulation, which is a new concept for me. Does anyone have some link to some credible material with concentration factors of for example Cs-137 in fish?

I have of course tried to search myself... with little success.

 

[bytepirate]

If the water is warm, then the cooling is not adequate.

If they took samples of the water, I wish they would also take video of the SFP, or at least the tops of the fuel assemblies. I would then be relatively easy to judge the condition of the fuel. The upper tie plates should be visible near the top of the racks. If not, then can assume the fuel rods are broken. Of course, the fuel rods could be breached. Then one would look for discolourations, or other abnormalities. They will need some special hooded/sipping fuel handling systems to hand the fuel.

is there any explanation for the explosion and the fires in #4, that works *without* massive fuel damage?
in this document: http://www.vgb.org/vgbmultimedia/News/Fukushimav15VGB.pdf the core damage of #1 is estimated to 60-80%, derived from the production of hydrogen necessary to blow away the top of the building.
#4 looks even worse...
in the same document, the time for dry-out of #4 SFP is estimated 10 days. the explosion was much earlier.
if that explosion was a hydrogen explosion (what else?), then it should be a save assumption, that the pool has a leak.
if the pool has a leak, then every new (even small) quake could make it larger.
if it is possible to get the fuel out there, i would put all my efforts in it, if i were tepco.

i would really appreciate a rebuttal of my 'analysis'.

 

[bytepirate]

I'm trying to learn more about bioaccumulation, which is a new concept for me. Does anyone have some link to some credible material with concentration factors of for example Cs-137 in fish?

I have of course tried to search myself... with little success.

http://www.dec.state.ak.us/air/am/rad/doc/RN4.pdf

 

[Jorge Stolfi]

Usually, if a system is critical, then the material is increased in volume, the critical system becomes subcritical, because the concentration decreases, particularly if the material mass is fixed, but the volume increase, and the surface area increases. Larger surface area means more leakage of neutrons from the system.

Yes, of course. Sorry. (That is what I always knew, but yesterday I wrongly concluded that density should not matter, only mass and shape. I had ignored the fact that the cross-section of nuclei remains constant as the volume is increased.)

 

[Giordano]

http://www.dec.state.ak.us/air/am/rad/doc/RN4.pdf

Thanks!

The concentration factor of Cs-137 in fish is stated as approx 100.

 

[ceebs]

Strawberries, tomatoes and vegetables from the Fukushima district are not only tasty and full of vitamins - by the process of irradiation they are preserved and last longer without refrigeration. Yokio Edano and comedian Yamazaki Shizuyo (Shizu-chan)

(apologies - could not help cynical humour)

I see that and can only be reminded of this

http://news.bbc.co.uk/1/hi/uk/369625.stm"

Probably the most derided politician to emerge out of the BSE scandal, John Gummer will always be remembered for making great public show of feeding his four-year-old daughter Cordelia a hamburger in the midst of the "mad cow" disease scare.

The press photographed Mr Gummer - then Agriculture Minister in the Conservative government - tucking into the burger with his little girl at a boat show in Suffolk on May 6 1990.

 

[Jorge Stolfi]

in the same document, the time for dry-out of #4 SFP is estimated 10 days. the explosion was much earlier.
if that explosion was a hydrogen explosion (what else?), then it should be a save assumption, that the pool has a leak.

The 3/11 earthquake included several minutes of large slow motion. Someone previously suggested that some of the water in the pool may have sloshed out (perhaps down the spent-fuel chute?)

The spent-fuel pools were "re-racked" recently to increase capacity. What does that mean? Perhaps stacking fuel in 2 layers (leaving only 5-6 meters of water above fuel instead of original 10 m?)

Hydrogen generation ins substantial quantities seem to require temperatures over 800C. At 660C or less, the neutron absorbing baffles in the pools melt or disintegrate.

 

[Cire]

I'm not going to dig up the maths again but under reasonable assumptions the explosion that destroyed building 3 had enough overpressure to exceed the RPV operating prerssure by 2-3 times.

Failure pressure and operating pressure are two completely different things. 10x operating pressure would not fail the RPV. It would fail the support plumbing and interconnects but not the pressure vessel.

For example, the Trieste, the deepest diving vessel ever made had a 5" thick steel pressure vessel. It was "rated" for 110MPA! That's ~16,000 PSI. That's the rated pressure, not the failure pressure. The RPV's in the plant are over an inch thicker then this example.

In no way did the hydrogen explosion overpressure the reactor vessel, or for that matter the steam pressure inside overpressure the vessel.

Corium melt dropping into the drywell is NOT the same failure mode as a water heater. The steam and Zr-H2o explosion would cause a pressure rise outside the RPV and the explosion could bypass the RPV, which does not fully occlude the primary containment.

If corium breached the bottom of a pressurized vessel the water vapor and gasses and whatever else wanted too would be ejected at near supersonic velocities producing a massive impulse on the RPV. If the RPV had no water or vapor and was depressurized when the melt occurred, then that would be a very different scenario. I haven't seen anyone argue the RPV was dry and unpressurized.

 

[sigyn]

Re: Comparison of Trieste and RPV, wall thickness: Does this not require the dimension of the vessel ? a 10 meter vessel will require thicker walls than a 1 meter vessel ?

 

[jmelson]

Can't agree more! Those drone videos are terrible. Like someone else said, US military totally wating money if that's the best they can do! A 300 dollar RC helicopter with a 200 dollar 12MP digital camera, (suspended on rubber bands for the vibration) and a 32GB sdcard would be far superior!

These images show definite artifacts from image conversion. I believe the live video was recorded on a mediocre (as opposed to broadcast-grade) video recorder, and then possibly converted from NTSC to PAL or something, before being converted to highly compressed JPG format. There is the typical faint blockiness of the JPG conversion as well as skewing that looks like time-base errors in a VCR.

If they did take this from a VCR recording, low-grade machines combine chroma and luminance, and once combined, a lot of information is lost.

Jon

 

[bytepirate]

The 3/11 earthquake included several minutes of large slow motion. Someone previously suggested that some of the water in the pool may have sloshed out (perhaps down the spent-fuel chute?)

The spent-fuel pools were "re-racked" recently to increase capacity. What does that mean? Perhaps stacking fuel in 2 layers (leaving only 5-6 meters of water above fuel instead of original 10 m?)

Hydrogen generation ins substantial quantities seem to require temperatures over 800C. At 660C or less, the neutron absorbing baffles in the pools melt or disintegrate.

re-racking:
http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/29/064/29064415.pdf
some more info:
http://www.irss-usa.org/pages/documents/11_1Alvarez.pdf

what i have learned from this is, that its not two layers, but a more dense packing of the elements.

this document:
http://www.energyjustice.net/files/nuclear/security/nasrptsfp5.pdf
gives an estimate from 'loss of cooling' to 'ignition' of 4 days.
so, may be they have just forgotten the SFP while dealing with three possible core melts...

btw: thanks for your graphs.

 

[Jorge Stolfi]

re-racking [...]
http://www.energyjustice.net/files/nuclear/security/nasrptsfp5.pdf
gives an estimate from 'loss of cooling' to 'ignition' of 4 days.
so, may be they have just forgotten the SFP while dealing with three possible core melts...

Curiously none of those documents seem to consider the fate of the neutron absorbers in a loss of coolant accident. According to a previous post, those are made of aluminum or silicone resin impregnated with boron carbide powder, and will melt or decompose well before the steel and zirconium elements are affected, even before there is significant H2 production. Even if there is no criticality, woudn't their failure increase the heat output of the spent fuel?

btw: thanks for your graphs.

You are welcome. BTW, I noticed that other people have started providing their own graphs, as well as the raw data in spreadsheet format.

 

[tsutsuji]

I wonder if we don't have translation issues here. The way I read that, it doesn't mean that cooling for the generators themselves was lost, but that the pumps that the diesels were to operate had nothing to pump. Perhaps the tsunami took out plumbing from the ocean or some heat exchange equipment. Diesels themselves require special coolant (SCA or OAT) to prevent internal damage (cavitation damage to cylinder sleeves, etc), sea water use would be extremely short term as a coolant in a diesel.

I agree that the previously quoted excerpt can also be read that way. But what about the following other excerpt from the same document :

3:42pm Emergency DG(diesel generator) stopped due to loss of equipment cooling water. (Tsunami was bigger than expected.) All AC power was lost for 1F1-4 and consequential isolation from UHS(ultimate heat sink), except for IC (isolation cooling system) in 1F1. RCIC(reactor core isolation cooling system) in 1F 2 Blackout + (mostly) loss of UHS
page 6/22 of http://www.f.waseda.jp/okay/news_en...ower_Plants_suffered_big_eart_quake110331.pdf

 

[Cire]

Re: Comparison of Trieste and RPV, wall thickness: Does this not require the dimension of the vessel ? a 10 meter vessel will require thicker walls than a 1 meter vessel ?

The force acting on the surface is always per unit area. The total area doesn't matter (being very generic here). The shape plays an important role. This is why pressure vessels are sphere's or tubes with spherical ends. If you take a cube and pressurize it it wants to become a sphere.

 

[bytepirate]

Curiously none of those documents seem to consider the fate of the neutron absorbers in a loss of coolant accident. … Even if there is no criticality, woudn't their failure increase the heat output of the spent fuel?
.

where should the additional heat come from?
if the absorbers melt, probably the heat distribution would be different, but not the total amount of heat.

however, i don't claim to be an expert, and i might be wrong here.

 

[MadderDoc]

I finally found ( I think) something identifiable from the fuel handling machine of unit 3, so now would like a second opinion.

The image of the object (which I think is the upper platform of the fhm) is a frame from the video at:
http://www.youtube.com/user/modchannel#p/a/u/2/gWzPU5fgThA

I have attached the captured frame in somewhat higher definition, as well as the Aug 2010 photo confirmed to be the FHM of unit 3.

 

[sigyn]

The force acting on the surface is always per unit area. The total area doesn't matter (being very generic here). The shape plays an important role. This is why pressure vessels are sphere's or tubes with spherical ends. If you take a cube and pressurize it it wants to become a sphere.

To simplify, consider a sphere. A 1 meter sphere will require thinner walls to hold a given pressure than a 10 meter sphere. Or is my understanding incorrect ?

 

[sigyn]

To simplify, consider a sphere. A 1 meter sphere will require thinner walls to hold a given pressure than a 10 meter sphere. Or is my understanding incorrect ?

O dear i found an instant counterexample.. a balloon. The skin gets thinner as I blow it up. But I suspect steel is not like rubber...

So: am i right in respect to steel ? a 10 meter spherical steel vessel requires a thicker wall than a 1 meter spherical steel vessel to hold a given pressure ?

I suspect it has to do with yield points and ductile flow and such

 

[Jorge Stolfi]

where should the additional heat come from?.

if the neutron absorbers fail, spontaneous neutrons would induce some fission in the remaining 235U and Pu, and possibly some chain reactions. That would increase the heat, both amount (energy) and rate (power). The absorbers are there precisely to prevent that from happening. (Criticality is a step further, when when the chain reaction grows exponentially.)

 

[tsutsuji]

Peter Thiemann, a former GE engineer who took part in the Fukushima plant design, provides a picture of the kind of diesel generator which, he says, is suitable to run the pumps : http://www.examiner.com/wilderness-photography-in-eugene/fukushima-the-path-not-taken-1

Large size picture available at http://www.flickr.com/photos/inmesol/5372515880/sizes/l/in/photostream/

 

[ceebs]

The force acting on the surface is always per unit area. The total area doesn't matter (being very generic here). The shape plays an important role. This is why pressure vessels are sphere's or tubes with spherical ends. If you take a cube and pressurize it it wants to become a sphere.

one major difference between the RPV and the Trieste is that the pressure is on the inside, so you're dealing with tensile stress rather than compressive stress that you were in the subs design

 

[Jorge Stolfi]

So: am i right in respect to steel ? a 10 meter spherical steel vessel requires a thicker wall than a 1 meter spherical steel vessel to hold a given pressure ?

Imagine cutting the sphere in half and then welding the two halves together. The force that tries to push the halves apart is the pressure P time the area of the cross-section, which is pi * R * R if the radius of the sphere is R. The area of the weld is the thickness of the shell T times the circumference 2 * pi * R. The tension on each square inch of the weld is the force divided by the weld's area, that is, (P * pi * R * R)/(T * 2 * pi * R) = 0.5 * P*R/T.

Therefore, to hold a given pressure, a shell 10x larger needs to be 10x thicker.

(By the way, a rubber balloon is more complicated because the wall gets thinner and the pressure changes as the radius increases.)

 

[sigyn]

"Therefore, to hold a given pressure, a shell 10x larger needs to be 10x thicker."

Thanks for the clear explanation. Reminds of the Magdeberg hemispheres.

 

[sp2]

Wow. Nice work.

Where did that video come from? I've looked at a lot of stuff in the last month, and I'm quite sure I haven't seen that.
(Even if I had, I doubt I would've caught that, without your pointing it out.)

So, that's superb confirmation of TCups' theory from a week or two back, right?
(At least, the part about the FHM 3 being blown sky-high, flipping over once or twice, and plummeting onto the North side of the wreckage of R3.)

Do I have that right?

Way to go.

I finally found ( I think) something identifiable from the fuel handling machine of unit 3, so now would like a second opinion.

The image of the object (which I think is the upper platform of the fhm) is a frame from the video at:
http://www.youtube.com/user/modchannel#p/a/u/2/gWzPU5fgThA

I have attached the captured frame in somewhat higher definition, as well as the Aug 2010 photo confirmed to be the FHM of unit 3.

 

[Astronuc]

Curiously none of those documents seem to consider the fate of the neutron absorbers in a loss of coolant accident. According to a previous post, those are made of aluminum or silicone resin impregnated with boron carbide powder, and will melt or decompose well before the steel and zirconium elements are affected, even before there is significant H2 production. Even if there is no criticality, woudn't their failure increase the heat output of the spent fuel?

The neutron aborber loss is strictly a concern about criticality or re-criticality, particularly where reinsert fuel is placed in the spent fuel pool. The loss of neutron absorber would not affect the decay heat in the spent fuel pool. The decay heat comes from alpha decay of transuranics (TU), and beta decay or positron emisson, and gamma emission, of many fission products, as well as some TU nuclides.

Of course there is some spontaneous emission of neutrons from some TU nuclides, e.g., Pu-240 and 242, but they are such low level that they would only contribute on the order of watts.

 

[biggerten]

I agree that the previously quoted excerpt can also be read that way. But what about the following other excerpt from the same document :

I still think it's the same thing, they don't say, for example, that the diesel lost coolant, but that the equipment lost coolant. But you may be right, I can't say for sure, I just notice that a lot of things come over in an odd kind of way.

 

[Cire]

one major difference between the RPV and the Trieste is that the pressure is on the inside, so you're dealing with tensile stress rather than compressive stress that you were in the subs design

This is true, however I believe the context of the initial question was the RPV being damaged by external overpressure from the H2 explosion. If I understood the question.

 

[shogun338]

The total amount of radiation released from the crisis at Tokyo Electric Power Co.’s Fukushima plant may eventually exceed that of the Chernobyl disaster, a Tepco official said yesterday.

Chernobyl Radiation

The 1986 disaster at the Chernobyl power plant in Ukraine spewed debris as high as 9 kilometers into the air and released radiation 200 times the volume of the combined bombings of Hiroshima and Nagasaki in 1945, according to a 2006 report commissioned by Europe’s Green Party. http://www.bloomberg.com/news/2011-04-12/taiwan-halts-plans-to-build-atomic-reactors-after-japan-crisis.html

 

[curie]

Criticality has to much to do with composition (fissile material, fuel matrix, moderator, burnable poisons (e.g., boron, gadolinia, . . .)), concentration (of each element species) and geometry (fuel lattice as well as size/array of fuel materials). Usually, if a system is critical, then the material is increased in volume, the critical system becomes subcritical, because the concentration decreases, particularly if the material mass is fixed, but the volume increase, and the surface area increases. Larger surface area means more leakage of neutrons from the system.

For completeness, add reflectors to the list of composition criteria. It could be possible for increased neutron leakage - due to increased surface area - to be compensated by (or over-compensated by) the presence of a reflector.