Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[SteveElbows]

resulted in a low blast that everybody has interpreted as a replica of 5.6 on Richter scale ?

When do you think this may have happened?

 

[SteveElbows]

What's all this >200Sv/hr in the #1 dry-well about?

http://atmc.jp/plant/rad/?n=1

This subject seems to keep coming up every day for several days in a row now. Is someone posting scare stories about this data elsewhere on the internet, or is it just that lots of people have been using that atmc website graphs all along and are now wondering why its showing scary stuff?

In any case, this subject has been addressed here multiple times in recent days. Main summary of points:

The atmc website makes some bad errors with what data it uses sometimes, so it is not a good idea to use it as main source. Use TEPCO data instead, which shows 2 x drywell CAMS and 2 x suppression chamber CAMS readings for all reactors.

Main data site index page: http://www.tepco.co.jp/en/nu/fukushima-np/index-e.html

The CAMS readings are part of the pressure & temperature data sheet, so for reactor 1 it is:

http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/11052606_level_pr_data_1u-e.pdf

So yes, one of the sensors is sometimes showing values of 200 or higher. But the other sensor shows much lower values, and TEPCO think the sensor(s) may be damaged because they don't agree with each other, and one of them fluctuates a lot.

Other thing to note is that this is not a new thing, only reason its suddenly being noticed is because TEPCO only started publishing the data for this sensor again recently (around may 17th), after not bothering for many weeks, probably because the readings seemed unreliable.

In conclusion, there are too many unknowns about this data to make any conclusions, and if there is a problem its not a new event, it happened quite a long time ago. I do not think the CAMS data is good enough to be able to use it to reach interesting and firm conclusions about how much of the core fell into the drywell, so there is no point getting excited about the big numbers. All it really tells us is that fuel got damaged, and we know that already.

 

[havemercy]

On April 22 :

According to RBC, the epicenter of the earthquake was located at a depth of 35.8 km at a distance of 74 km from the city of Fukushima, and only 22 km from the nuclear power plant "Fukushima-1. According to the US Geological Survey, tremors were recorded at 19:25 MSK.

http://mysouth.su/2011/04/in-fukushima-prefecture-earthquake-of-magnitude-5-6/

 

[elektrownik]

The problem is that second sensor which show low value can't be correct if any amount of corium is in drywell, this hight value can be corect if corium hit drywell cams sensor... Chernobyl was >300Sv around core, at this time we know on 99% that unit 1 core melted from rpv and damaged drywell

 

[mscharisma]

The Incinerator building basement, where the contaminated water from unit 3 had been moved, was suspected of leaking :

The missing water has finally been found in a tunnel joining two buildings. There has been no leak into the ground water, according to http://mainichi.jp/select/science/news/20110527k0000m040110000c.html

Does this fall into the good or the bad news category? No leak into groundwater is surely good, but there wasn't supposed to be any kind of leak, I assume? What, if anything, does it tell that also the wastewater facility leaks somehow?

 

[Borek]

blast that everybody has interpreted as a replica of 5.6 on Richter scale ?

On April 22 : According to RBC, the epicenter of the earthquake was located at a depth of 35.8 km at a distance of 74 km from the city of Fukushima, and only 22 km from the nuclear power plant "Fukushima-1. According to the US Geological Survey, tremors were recorded at 19:25 MSK.

No idea why you think these things are in any way related. Epicenter was 22 km from the plant, not under reactor building. Besides, there were many quakes in the area since the big one, why this particular one caught your attention?

 

[havemercy]

Because it is the nearest of the plant.

 

[elektrownik]

Because it is the nearest of the plant.

If there would be explosion which would generate 5.6 quake then you wouldn't see reactor buikdings anymore...

 

[clancy688]

In my opinion, ANY steam explosion that triggered a 5.6 magnitude quake would've been a boom that would give the Hiroshima bomb a run for its money...

 

[SteveElbows]

be patient guys my first try at photo well maybe second

Has this been posted?

found it at Cryptome..was taken March 16, and the deck looks a lot worse in later photos.
it's in the zipped file of full size photos and has this name: aerial-2011-3-18-14-50-0.jpg
(editing mine, with MS-Paint, which clobbers the resolution)

you can see the concrete cap not there but i can't tell for sure about the yellow thing on right. In the hi-res it's a maybe.

Would one who knew how to lighten be able to see down into that black hole and tell if yellow containment cap is there?

In my opinion this is one of the classic illusions from the early Fukushima pictures. I remember when I first saw it, it was briefly quite compelling because the apparent chasm was in roughly the right place. But subsequent photos and video destroy the illusion pretty well. See the problem is that with other footage we can get a glimpse of how much the crane & associated debris occupy this area, and we can see how the smoke/steam and lack of light in that part of the building create a range of shadowy unrealities in this part of the building. What looks like a nice well rounded hole appears to me to mostly be darkness and smoke, with perhaps a bit of crane and roof adding to the effect when seen from the angle that footage was taken at.

No footage has emerged that gives us a really clear idea of the exact state of things there, and no really compelling evidence has emerged from that zone, despite many people likely studying such footage a lot due to the frequent debates about whether any part of reactor 3 launched into the air. When combined with what other data tends indicate, lots of people are going to assume that nothing major launched from reactor 3, and it will now take some compelling evidence to convince a lot of people to reconsider this issue. I am not really expecting it to happen, but I'll be ready to eat my words if it does.

I remain very interested in the exact nature of containment damage at reactor 3, so I hope that one day we get a better look at the damaged areas. The closest I have got towards identifying any potential trouble, and getting a look at things I can actually identify at reactor 3 that arent badly obscured, was a picture I posted a while back. Taken from a helicopter video, it shows area where dryer storage pit/pool is joined to area above reactor, where removable concrete wall is in place. Image quality not clear enough to say with any certainty, but it is possible that we can just glimpse the very edge of one set of the semi-circular plugs that sit above the reactor. The only evidence for this in attached photo is thin black line, that may be slightly curved, in area to left of the emerging smoke. This is where top of the dryer pool concrete wall becomes part of the service level floor, and traveling further in that direction we would expect to find reactor plugs making up the next part of the floor. So perhaps this thin line is where the wall ends and the plugs begin. But because of where the crane & its supporting structure has fallen, we can only see a small portion of this service floor area, so I can't be sure of anything.

 

[Borek]

Because it is the nearest of the plant.

At 22 kilometers? Seismographic data are much better than that. If memory serves me well, places where underground nuclear tests were done were located with few hundred meters accuracy.

Edit: according to wikipedia, 5.6 is about 4 kT TNT, about one fourth of Hiroshima bomb, that would be hard to miss.

 

[Bandit127]

If there would be explosion which would generate 5.6 quake then you wouldn't see reactor buikdings anymore...

According to Wikipedia (sorry..) a 5.6 quake is equivalent to 3.8 kilotons of TNT.
http://en.wikipedia.org/wiki/Richter_magnitude_scale"

For a sense of scale - if I recall correctly from previous posts, the explosion of the Unit 3 building was expected to register about 2.2. (Working backwards from the table, I would estimate the equivalent would be about 30 kilogrammes of TNT).

Edit - Oops! Thanks Borek - I must type faster.

 

[havemercy]

Ok, then it is not possible. Thanks.

 

[jim hardy]

Jorge :
""I suppose that neutron absorption is the main factor preventing re-criticality. TEPCO has been using boron in the emergency cooling water; the effect should be like that of soot particles making smoke clouds black instead of white. Also the corium itself may (or may not) include neutron-absorbing material from the control rods.

Is this correct? ""

i'd say so. Without moderator or reflector the neutrons simply keep on going and leave the neighborhood. They can eventually emit an electron and so become a hydrogen nucleus(proton).

"To have fission one needs to have a significant fraction of the emitted neutrons slowed down and scattered back to the fissile material. If the fuel is immersed in a large amount of moderator, and there is no absorption, every neutron that leaves it will eventually be scattered back to it, by "drunkard's walk" statistics. (This is the same effect that makes sunlit clouds look white.) "
well as you said, not every neutron will make it back, some of the 'staggering drunks' fall by the wayside. It takes maybe a dozen collisions with a light nucleus like hydrogen to slow a neutron to the energy favorable for fission, maybe forty with something heavier like sodium. Remember energy in elastic collisions divides in some proportion to masses involved. Each collision stands a chance of inelastic absorbtion without fission so there's some loss by absorbtion.
You need to have about half the neutrons survive moderation to get critical.

Here's a link to a short course - you'll have no trouble with the slides. i may have posted it before, sorry, the senior moments sort of run together anymore.

http://www.if.uidaho.edu/~gunner/ME443-543/LectureNotes/ReactorPhysics.pdf

If the corium contains melted control rods it's probably safe. The addition of melted steel reactor parts could make it safe. The seawater salt is mildly absorbtive.
But its Russian Roulette.

btw i really liked your charts and bragged on them in another forum. Thanks!

old jim

 

[jim hardy]

Thank you Steve Elbows for posting this comment:
""No footage has emerged that gives us a really clear idea of the exact state of things there, and no really compelling evidence has emerged from that zone, despite many people likely studying such footage a lot due to the frequent debates about whether any part of reactor 3 launched into the air. When combined with what other data tends indicate, lots of people are going to assume that nothing major launched from reactor 3, and it will now take some compelling evidence to convince a lot of people to reconsider this issue. I am not really expecting it to happen, but I'll be ready to eat my words if it does...""

That is where I am too. It's an open but doubtful question and the absence of good photos does lend to conspiracy theory. I don't like conspiracy theory and have been looking to dispel it.

To that end i put a couple early photos over on scribd, not wanting to clutter this board with a long essay.
If you have fifteen minutes to kill, and promise to not accuse me here of fearmongering , i welcome your comment at this link, or about it here:
http://www.scribd.com/jim_hardy_9

It's an honest question. I want to rule some things out but the "optical illusions" keep on cropping up.
The link at scribd tells how to get the three high resolution photos you need to see what i see. It just won't show in the low res ones. I would post them if knew how to preserve the hi-res. One of them is from first ten seconds of that helicopter video and requires training your eye to look for it. I want to know if i am seeing what is not there.

i am working on a photobucket album but even photobucket destroys the resolution, you just got to go back to the source. and that's too much to ask of folks in a general audience.



So, happy surfing. Keep up the good work here fellows.

 

[SteveElbows]

That is where I am too. It's an open but doubtful question and the absence of good photos does lend to conspiracy theory. I don't like conspiracy theory and have been looking to dispel it.

To that end i put a couple early photos over on scribd, not wanting to clutter this board with a long essay.
If you have fifteen minutes to kill, and promise to not accuse me here of fearmongering , i welcome your comment at this link, or about it here:
http://www.scribd.com/jim_hardy_9

It's an honest question. I want to rule some things out but the "optical illusions" keep on cropping up.

Yikes! Trying to read your instructions for locating things of interest on the photos caused my brain to meltdown! And then I realized that the other 'feature of interest' you were pointing to is one I already gave my thoughts on for you here a while back.

Bottom line for me is that even the original resolution versions of these images are no way good enough to use to prove very much one way or another. People can stare at the images we've had for ages now as much as they want, I don't expect anything new and compelling to leap out (although its always possible I suppose). Dont get me wrong, I am interested in some of the things you have pointed out, but I've given up expecting to learn anything about them unless I get more footage, but we don't get much from these areas since march. I am not afraid to point out stuff in new images, such as the pile of 1000mSv rubble the other day, even when I am not at all sure what they are, nothing wrong with a bit of speculation, but I feel that most existing images have been done to death and little has been learnt.

 

[jim hardy]

Thanks Steve

i appreciate your honest assessment.

it is speculative.

jim

 

[jim hardy]

here's a generic refueling photo, shows top of vessel open with head bolts installed. Note circled walkway - vessel protrudes above refueling cavity floor and walkway presumably crosses vessel to containment flange. I think the outer green ring is the bolt circle for containment cap, perhaps NucEng or somebody with BWR experience can correct me.

never mind deck loop it's just a hose..
four white spots must be reflections of ceiling lights.

pls excuse if a repeat.

 

[GJBRKS]

here's a generic refueling photo, shows top of vessel open with head bolts installed. Note circled walkway - vessel protrudes above refueling cavity floor and walkway presumably crosses vessel to containment flange. I think the outer green ring is the bolt circle for containment cap, perhaps NucEng or somebody with BWR experience can correct me.

never mind deck loop it's just a hose..
four white spots must be reflections of ceiling lights.

pls excuse if a repeat.

Here is a close up from a T-Hawk video of the reactor 4 cap ,

[PLAIN]http://www.inkers.nl/uploads/reactor_cap.JPG

http://www.youtube.com/watch?v=AUx7lIUsogA"

 

[SteveElbows]

Note circled walkway - vessel protrudes above refueling cavity floor and walkway presumably crosses vessel to containment flange.

Fuel is moved along that channel, to and from the fuel pool, its not for humans to walk along. At least that's my understanding of it, I am no expert.

 

[Most Curious]

The "cattle chute" is to move fuel. Those are not bolts sticking up but studs. After reactor lid is installed they thread nuts on them, etc.

I presume a few studs are removed to facilitate fuel transfer and, of course, some for replacement if damaged or suspected of being defective. Big suckers - wonder how many foot-pounds??

 

[MadderDoc]

<..>It's an open but doubtful question and the absence of good photos does lend to conspiracy theory. I don't like conspiracy theory and have been looking to dispel it.

I think it is fair to say that the access to photos and videos have left some of us with unanswered questions now for months about the happenings at unit 3 during the last half of March 2011, questions which Tepco reasonably should be well-positioned to answer. Conspiracy may not be the right word, but it is an awkward situation indeed.

 

[MiceAndMen]

I think it is fair to say that the access to photos and videos have left some of us with unanswered questions now for months about the happenings at unit 3 during the last half of March 2011, questions which Tepco reasonably should be well-positioned to answer. Conspiracy may not be the right word, but it is an awkward situation indeed.

We should take up a collection to pay for another round of hires photos from the Air Photo Service guys. Their photo survey on March 24 was over two months ago and we haven't seen a whole lot of new pictures from the air since then.

 

[jim hardy]

""Big suckers - wonder how many foot-pounds?? ""

looks like the reactor head is pretty thick, too...
as a non - MechE i confuse the terms bolt and stud. I guess a stud is just a bolt without a head, may be other differences.

Mechanical engineers (i'm not one but used to drink beer with some) want a certain amount of tension in a bolt. Tension tells them how tightly the bolt is pulling the pieces together .


We non-mechanical folks think of a bolt as solid, but actually it's a real stout spring that you stretch ever so slightly by torquing the nut.
For big ones they measure the stretch instead of torque because it's a more precise indicator of tension.
Torque can fool you, for if there's a lot of friction in the threads from rust or dirt then the torque is being wasted in twisting the bolt instead of stretching it.

Those big fellas probably have a small hole down the center for a measuring rod to measure how much they're stretched.

Here's a table of strengths of various steels for various grades of bolts
http://www.americanfastener.com/technical/grade_markings_steel.asp
There's about a 3 fold range of strength.
i'd bet these are an exotic alloy like ASTM A490, about halfway down.

PS thanks guys for your comments on the dearth of good unit 3 photos that appeared while i was typing.
I will fix my explanation of the "optical illusion" so it's readable. Sure would like your critique , but i respect the high level of discourse here and won't put up gibberish.

old jim

 

[Bodge]

How come Greenpeace are detecting upto 120,000 bq of I-131 in 1kg of seaweed found 52km south of Fukushima Daiichi? [collected 5th May]

Even if gigantic releases of I-131 were made during the 1st week after the quake, would large amounts still be detectable 60 days after fission supposedly ceased?

Is this certain proof that fission is ongoing at Daiichi?

Does anyone know how many terabecquerels of I-131 could have been released if all fission stopped 11th March, but 90% of all 3 cores melted?

If the release was as high as 1 petabecquerel then that would still leave close to 4 terabecquerels after 8 half lives. That's then got to be distributed over 100km of coastline and make its way into seaweed...

I am still confused!

http://www.greenpeace.org/internati...ublications/nuclear/2011/RAP110522-GPJ-01.pdf

http://www.greenpeace.org/internati.../publications/nuclear/2011/Report SCK CEN.pdf

 

[clancy688]

Does anyone know how many terabecquerels of I-131 could have been released if all fission stopped 11th March, but 90% of all 3 cores melted?

In https://www.physicsforums.com/showthread.php?t=493058" thread I calculated with NUCENGs help the I131 and C137 core inventories of Fukushima Daiichi 1-3 at March 11th. Allover, it's ~6000 PBq I131. But TEPCO claimed that there were 81000 PBq I131 available for release.

http://www.nisa.meti.go.jp/english/files/en20110412-4.pdf"

http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110421e2.pdf" But there are probably more leaks.

 

[jim hardy]

That'd be the place to look for iodine. Seaweed concentrates it.

""Seaweed is particularly rich in iodine: that is, concentrations are 100-1000 times higher than in fish. For example, kombu, a typical and commonly consumed seaweed, contains approximately 130 000 µg of iodine/100 g, while values in sardine and horse mackerel, taken as examples of the highest iodine concentrations in fish, are approximately 250 µg of iodine/100 g (Science and Technology Agency, Japan, 2001).""

http://www.nature.com/ejcn/journal/v56/n5/full/1601380a.html

 

[Bodge]

wow

Between 6 and 81 exa-becquerels of I-131 released.

After 10 half lives there could be upto 80 peta-becquerels of I-131 remaining in the environment (including on site).

 

[clancy688]

wow

Between 6 and 81 exa-becquerels of I-131 released.

Er, no... that's what was initially in the cores. Just that there were three meltdowns doesn't indicate how much got released.
Most of the stuff is probably still inside the leaking containments.

 

[Most Curious]

""Big suckers - wonder how many foot-pounds?? ""

looks like the reactor head is pretty thick, too...
as a non - MechE i confuse the terms bolt and stud. I guess a stud is just a bolt without a head, may be other differences.

Yea, there are a gazillion varieties of bolts and studs! Sizes, materials, thread types, qualities and on and on.

Mechanical engineers (i'm not one but used to drink beer with some) want a certain amount of tension in a bolt. Tension tells them how tightly the bolt is pulling the pieces together .


We non-mechanical folks think of a bolt as solid, but actually it's a real stout spring that you stretch ever so slightly by torquing the nut.
For big ones they measure the stretch instead of torque because it's a more precise indicator of tension.
Torque can fool you, for if there's a lot of friction in the threads from rust or dirt then the torque is being wasted in twisting the bolt instead of stretching it.

Those big fellas probably have a small hole down the center for a measuring rod to measure how much they're stretched.

Here's a table of strengths of various steels for various grades of bolts
http://www.americanfastener.com/technical/grade_markings_steel.asp
There's about a 3 fold range of strength.
i'd bet these are an exotic alloy like ASTM A490, about halfway down.


old jim

I am an aircraft mechanic - A&P - and old racecar mechanic. We use stretch to tension small bolts too! A "range" of torque is specified and a range of "stretch". Threads are to be clean and either dry or lubed depending on the manufacturer's instructions. Ya better not get too much stretch before you reach specified torque or the bolt is likely entering into the plastic range rather than the elastic where you want it! Those get removed, threads mashed and put in the round file.

Sorry about the off topic post - just fascinating how LARGE those studs are and the incredible loads on them with 1000 PSI ++ against that reactor head!

The containment head picture seems to show it uses bolts. I have heard two theories - one that it bolts into the concrete surrounding the steel of the DW (which I doubt) and the other that the bolts go into the steel flange on the DW.

Either way, it looks like #3 leaked!

 

[clancy688]

I hope that's not counting as "offtopic":

There's a lot of talk about recriticality at Unit 3. By chance, I just discovered that there was indeed a criticality. But not during the course of this accident. 23 years ago:

http://search.japantimes.co.jp/cgi-bin/nn20070323a3.html

http://www.thefreelibrary.com/2ND+L...e+happened+at+TEPCO+reactor+in...-a0161020955

Apparently, japanese reactors have a habit of "losing" their control rods. Is that of any concern for the current accident? Just wondering...

 

[Astronuc]

Apparently, japanese reactors have a habit of "losing" their control rods. Is that of any concern for the current accident? Just wondering...

Having inadvertent withdraw of a control rod, or rod drop accident, is a design basis accident, and it is a concern. Having a lot of control rods dropping out at the same time would be a really big deal.

Rod drop accidents are a concern because they insert positive reactivity into the core which if uncontrolled can result in a burst of power to the point were the fuel and core are damaged, which is both a safety and economic concern.

Rod drop scenarios typically involve a stuck rod in the core which is critical, such that when the rod drops, the core goes supercritical and power surges.

When all control rods are in the core, the drop of one or a few would not cause a criticality.

If they all fell out, then the reactor would spike in power and one could have a severely damaged core.

In the Fukushima event, if the core melted, then the stainless steel control rods melted with the fuel. I'm not yet convinced that any of the cores 'melted'. I do expect that there is a significant amount of cladding breached and probably broken, and perhaps pellets have disintegrated.

I would like to see the analyses (which predict melting) that have been performed to understand what assumption were made with respect to heat transfer in the core.

 

[westfield]

snip >
you can see the concrete cap not there but i can't tell for sure about the yellow thing on right. In the hi-res it's a maybe.

< snip

Is this the yellow curved looking debris in the smashed NW corner of RB #3 you are looking at? It may be the large yellow tank as seen in the not so smashed RB #4

http://i1185.photobucket.com/albums/z360/fukuwest/misc/Unit3nwcornerdisplacedlargeyellowtankatlowerfloorcopy.jpg"

 

[jim hardy]

""I would like to see the analyses (which predict melting) that have been performed to understand what assumption were made with respect to heat transfer in the core. ""

here's a hypothetical analysis done some years back of a Brown's Ferry (TVA) BWR , section nine is the analysis of severe core damage they thought would happen if one of these things ever got a long term loss of all AC power. section 8 is the lead-in, around page seventy.

http://www.ornl.gov/info/reports/1981/3445600211884.pdf
i think it's been linked here before. surely there's newer ones.

the others i know of, SARA, GENFLO, and ORNL's Severe Accident Mitigation have been already linked here by other folks.

Here's an interesting one on bottom head failure , it sort of meshes with reports from Japan...
http://www.osti.gov/bridge/servlets/purl/6124656-R8y05j/6124656.pdf

and this one is too math intense for me but you'll do fine with it
http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/25/044/25044840.pdf
it's by swinkendorf, and it's referenced by some ANS guys in their correspondence.
i have his doctors thesis also on similar subject and am looking for the link i downloaded it from because it's 220 pages.. will put link up when find it.

hope this helps. jim

 

[Godzilla1985]

Y'all should take ten minutes of your time and have a good look at Jim's photo analysis of the "Snaggleteeth", found here: http://www.scribd.com/doc/55934120/A-couple-of-Fukushima-Photos

Don't recall seeing any attention brought to that particular spot before in this thread.