Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[westfield]

In the photo at the southwest corner of Unit 3 RB it looks like the SBGT pipe might be severed or at least has some debris laying on it. There is no damage to Unit 4 RB yet. If any of you graphics experts can look at this it may be evidence to rule out Hydrogen from Unit 3 causing the explosion or damage in unit 4 through the common stack.

The main duct leading from Unit #3 to the main stack was severed during the Unit #3 explosion. Additionally some days later it appears a concrete wall slab then fell or was deliberately made to fall from the SW upper level of RB#3 and this possibly bent the "elbow" at the severed end when it fell to the shape it is now. The slab is now lying on the ground at the SW corner of RB#3. The main point being that particular pathway was eliminated as soon as RB#3 blew up.

Thats all quite clear however that doesn't eliminate some possible alternate path through other ducting that did remain intact, for instance the ducting running along between the RB's and their respective turbine buildings south down to the central waste treatment facility.

It guess it also doesn't eliminate the possibility that plenty of hydrogen had already made its way to RB#4 prior to RB #3, and that main duct, blowing up.

Edit : Of course the SFP in RB #4 is also a candidate for the hydrogen but NUCENG was only asking about the ducting so that is all I referred to.

 

[Quim]

It guess it also doesn't eliminate the possibility that plenty of hydrogen had already made its way to RB#4 prior to RB #3, and that main duct, blowing up.

The hydrogen for the #4 explosion came from the #4 spent fuel pond as a result of radiolysis.


NUCENG finally came around on that one in post #8496.

The fairy tale about hydrogen from unit 3 weaving its way to #4 is just a Tepco smoke screen.

 

[westfield]

I'm responding to westfield #94104

snip >

I don't know about a "tool pool" do you mean the equipment pool?
That would also be on the east side of the bldg, north of the containment structure.

Yes I do mean the equipment pool where the steam separator and so on are stored during refuelling\maintenance. I'm not saying something in the equipment pool is the source of the steam just that a large consistent amount of steam has been seem appearing to be coming from containment but emanating via the removable concrete modules that separate equipment pool from reactor void. I will try and find the image that shows this reasonably well. What I'm saying is that those removable concrete modules that form the wall appear to be largely undamaged and I'm also suggesting that the steam is coming out from around the containment void and not so much directly from above the void.

But the main point is it's still a stretch to presume that steam escaping from containment is indicative of the source for the explosion.

 

[westfield]

The hydrogen for the #4 explosion came from the #4 spent fuel pond as a result of radiolysis.


NUCENG finally came around on that one in post #8496.

The fairy tale about hydrogen from unit 3 weaving its way to #4 is just a Tepco smoke screen.

NUCENG may well have come to that conclusion in post #8496 but NUCENG also just asked that question about the main duct.

That the SFP in RB #4 is a prime candidate for the hydrogen is obvious however I reasoned that NUCENG was looking for alternatives to SFP scenario because there has been no evidence reported of fuel assembly degradation in SFP of #4.

 

[Jorge Stolfi]

Mueller divides the fission products into high, medium, and low volatility. At Fukushima, a lot of iodine and some cesium probably were boiled off (together with all the noble gases). However, there's been considerable extraction of the spent fuel by boiling water. Most of Muller's medium volatility fission products (Ba, Sr, Rb, but I'm not sure about La) are going to be readily soluble in water in most chemical forms, and these can be washed out of the spent fuel.

However, once the fuel is melted the water cannot penetrate it (perhaps not even make contact with it) and therefore cannot leach out anything directly. Only the volatile elements escape from the molten fuel as vapor and then condense in the surrounding water.

Moreover many compounds of Ba and Sr are insoluble, it is not clear they would be carried out by the water even if it could somehow penetrate the fuel.

Mueller wrote, "Only medium and low volatility FPsare relocated to the lower head. These FPs generate about 30% of the total decay heat." I am not clear on whether he's saying that only 30% of the heat generation is left or that the fraction of total decay heat that these generate is only 30%, and hence that there's still a lot of heat generation even if these are removed.

Not sure what is your question, but my understanding of his scenario is that the radioactive elements that remain in the molten fuel at the bottom of the RPV are such that the decay heat generated inside that mass (in watts) is 30% of the decay heat generated by the full inventory of radioactive elements; i.e. 30% of the decay heat that would be generated by the core at that same moment, if proper cooling had been maintained since shutdown.

 

[Jorge Stolfi]

But the steam is coming from the SFP and the "tool pool".

My undertanding, from all the picures that I have seen, is that the steam from #3 is leaking from the primary containment into the refueling pool. The latter is (probably) still closed by the shield plugs (three concrete discs, each divided into two halves).

Since the #3 explosion, the massive crane (and perhaps other debris) is pressing down on top of those plugs. Thus the steam that is leaking into the refueling pool is now forced to escape sideways, through gaps or cracks around the shield plugs and the gates that separate the refueling pool from the dryer storage pool (aka equipment pool) and from the spent-fuel pool. The two thick white setam plumes seen in the satellite photo seem to match this scenario quite well:

http://www.satimagingcorp.com/galleryimages/worldview-2-fukushima-daiichi.jpg

Note that the south plume is too narrow to come from the SFP itself; the latter is wider than the refueling pool and extends almost all the way to the south face of the building.

I would guess that the thinner white haze seawards (east) of building #3 is partly steam produced or released by the explosion, partly fine concrete dust that was thrown high up by the explosion, has not yet settled down, and is being carried eastwards by the wind. The whitish "haze" on the opposite (west) side of #3 may be actually a light blanket of concrete dust covering the ground, roofs, and everything else in that area. (Note that the east haze casts a shadow on the ground, while the west "haze" apparently doesn't.)

 

[dh87]

However, once the fuel is melted the water cannot penetrate it (perhaps not even make contact with it) and therefore cannot leach out anything directly. Only the volatile elements escape from the molten fuel as vapor and then condense in the surrounding water.

Moreover many compounds of Ba and Sr are insoluble, it is not clear they would be carried out by the water even if it could somehow penetrate the fuel.

I don't know exactly how to think about the melted fuel, and Mueller points out that the lack of experimental evidence makes a lot of this into conjecture. Inside molten corium, elements and salts can migrate, but I don't know who will go where. The crust could be a nearly homogeneous and impermeable layer, or it could have thinner and thicker places, cracks, nooks and crannies and be sufficiently permeable to allow boiling water to extract things over time. For even money, I'd bet on the latter, but I wouldn't risk much.

BaO and SrO are certainly soluble. There are clearly other possibilities. I'm not sure what the distribution of compounds is. The distribution won't necessarily be the same as in normal spent fuel, because the high temperatures and mixing may give products near thermal equilibrium, a state that might not be reached in solid fuel.

 

[NUCENG]

NUCENG may well have come to that conclusion in post #8496 but NUCENG also just asked that question about the main duct.

That the SFP in RB #4 is a prime candidate for the hydrogen is obvious however I reasoned that NUCENG was looking for alternatives to SFP scenario because there has been no evidence reported of fuel assembly degradation in SFP of #4.

Actually, I was looking for evidence for or against TEPCOs theory of hydrogen going through SBGT ducts and piping from unit 3 to unit 4. If you look back this isn't the first time I asked whether the SBGT piping at the SW corner of RB #3 failed before or after unit 4 was damaged. If we can disprove that theory, by showing that the alleged pathway was already broken, and eliminate zirc water reaction in SFP4 because the fuel remained covered, it only leaves radiolysis in SFP #4 or external damage from a second explosion in Unit 3. It is like my questions about recriticality. Each new piece of evidence needs to be considered honestly even if it may mean a previous theory is weakened or disproved by that evidence. Being wrong is not a bad thing. Being wrong and refusing to accept that possibility is very wrong.

 

[Jorge Stolfi]

Seen on twitter:

MIT Faculty Report on Fukushima: Fukushima Lessons Learned (MIT-NSP-025)
http://mitnse.com/2011/06/03/mit-faculty-report-on-fukushima

Seems a bit dated already, right? AFAIK release estimates are now 20% of Chernobyl not 10%, and the containment of #1 and #3 seem to be leaking too.

 

[cphoenix]

Actually, I was looking for evidence for or against TEPCOs theory of hydrogen going through SBGT ducts and piping from unit 3 to unit 4. If you look back this isn't the first time I asked whether the SBGT piping at the SW corner of RB #3 failed before or after unit 4 was damaged. If we can disprove that theory, by showing that the alleged pathway was already broken, and eliminate zirc water reaction in SFP4 because the fuel remained covered, it only leaves radiolysis in SFP #4 or external damage from a second explosion in Unit 3. It is like my questions about recriticality. Each new piece of evidence needs to be considered honestly even if it may mean a previous theory is weakened or disproved by that evidence. Being wrong is not a bad thing. Being wrong and refusing to accept that possibility is very wrong.

Did someone disprove the steam-explosion hypothesis while I wasn't looking?

 

[sp2]

I was referring only to the current state of the damaged cores and SFPs at Fukushima units 1-4. I do not include the contamination due to the release of fission products so far; this is an entirely different problem, although one rooted in the same precursor.

I appreciate the mistrust/distrust of the nuclear industry. The event at Fukushima has betrayed whatever trust had been established.

My immediate concern is the situation at hand, and the minimization of further contamination - aside from the technical considerations.

The imperative is to cool the cores in order to reduce/mitigate further release of fission products. Then, to the extent possible, a closed system for cooling and prodessing of the radwaste must be established. To the extent possible, a containment system must be established to prevent further releases into to the atmosphere. These are the technical considerations.

Thanks, Astro. I do appreciate the distinction, and I'm sorry to blow my top in your general direction, but I think (hope) you can understand why someone might get a little exercised about the talk of a 'solution.'
(And yes, the language used *does* matter.)

Have a good night.

 

[jim hardy]

It is like my questions about recriticality.

i'm in information overload. would you put up a pointer to them, or a search term to look for?

g'nite all, over & out till morning

 

[Quim]

In the photo at the southwest corner of Unit 3 RB it looks like the SBGT pipe might be severed or at least has some debris laying on it. There is no damage to Unit 4 RB yet. If any of you graphics experts can look at this it may be evidence to rule out Hydrogen from Unit 3 causing the explosion or damage in unit 4 through the common stack.

I'm no graphics expert but when I zoom in on the SBGT pipe in this picture, it is as clear as a bell that the pipe was broken while #4 was still intact. When I compare it to other pictures I have of that pipe break (after #4 blew but before the pipe was bent downward) the pipe is in an identical condition as this satellite picture.

I will add that the helicopter crew which went up to dump water in the SFPs reported that the SFP at #4 still had water in it - so they tried to dump their load on #3 (I'll find that for you if you are missing that information.)

The radiolysis theory would seem to be proven by this satellite picture showing the broken pipe before #4 blew.

What do you think?

 

[Quim]

Yes I do mean the equipment pool where the steam separator and so on are stored during refuelling\maintenance. I'm not saying something in the equipment pool is the source of the steam just that a large consistent amount of steam has been seem appearing to be coming from containment but emanating via the removable concrete modules that separate equipment pool from reactor void. I will try and find the image that shows this reasonably well. What I'm saying is that those removable concrete modules that form the wall appear to be largely undamaged and I'm also suggesting that the steam is coming out from around the containment void and not so much directly from above the void.

I'd like to see that picture when you find it. I don't see steam rising from where the equipment pool would be.

But the main point is it's still a stretch to presume that steam escaping from containment is indicative of the source for the explosion.

I'm not saying for the explosion. I'm saying for the beginning of the explosion which I see as a two part explosion.

IMO the event began with a belch of flaming hydrogen laden steam from under the containment lid(s) then there was a second source of energy for the vertical blast.

 

[razzz]

From http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-accident-tellurium-132.html"

...The data was revealed on June 3 evening by the Nuclear and Industrial Safety Agency. The monitoring survey of the air was done from March 12 morning till March 13 night, and the most of the data had been withheld until June 3. Tellurium-132 was detected from the morning till the early afternoon on March 12 at 2 locations in Namie-machi, and Okuma-machi and Minami-Soma City. The concentration was between 23 to 119 becquerels per cubic meter, exceeding the safety limit of 20 becquerels per cubic meter.

　当時の原子炉建屋は換気装置が止まり外に空気が出ない状態。蒸気を放出するベント作業は十二日午後に行われ、その直後に水素爆発が起きた。

At that time, there was no air escaping the reactor building as the air exchange system had stopped. The venting to release the steam was done in the afternoon of March 12, and a hydrogen explosion [in the Reactor 1] happened after the venting.

　東京電力は、核燃料の損傷が最も進んでいたとされる１号機が漏出元とみており、「格納容器内の圧力が高まり、接ぎ目から水素とともにテルルが漏れ出したのでは。建屋内の圧力も高まって外に漏れ、風に乗って広がったことが考えられる」と説明している。

TEPCO thinks that tellurium came from the Reactor 1 whose fuel core was most damaged, and explains, "As the pressure inside the Containment Vessel rose, tellurium, along with hydrogen, may have escaped from the joints [on the Containment Vessel]. The pressure inside the reactor building also rose, and then tellurium leaked outside the building and was carried by the wind and spread wide."

　ただ、拡散しやすい揮発性のヨウ素１３１の検出量はテルルの半分程度。テルルと同じ金属性のセシウム１３７は浪江町の一カ所でテルルを上回った以外、微量しか検出されなかった。

However, volatile and therefore more easily dispersed iodine-131 was detected at half the amount of tellurium. Cesium-137 was detected in one location in Namie-machi in the amount exceeding that of tellurium; however, at other locations, it was detected in only minute amount.

　京都大原子炉実験所の山本俊弘准教授（原子炉物理）は「現在分かっている状況では、テルルが遠方に飛散することは考えにくい」と述べた。

Associate Professor Toshihiro Yamamoto of Kyoto University Research Reactor Institute (reactor physics) says "Under the circumstance that we have understood so far, it is hard to believe that tellurium would spread far."...

 

[razzz]

http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-accident-japanese.html"

 

[tsutsuji]

http://www.fnn-news.com/news/headlines/articles/CONN00200956.html :

Today (June 7th) pumps will be tested and water will be poured for the first time in the caesium removal unit and in the desalinating unit of the water purification facility.

The installation of the steel pillar below unit 4 SFP is starting.

http://mainichi.jp/select/jiken/news/20110607ddm003040107000c.html :

It was discovered that the 13 km long Yunotake fault which runs in Iwaki city 40 km south of Fukushima Daini was activated by aftershocks of the 11 March earthquake. The problem is that this fault had been overlooked in past earthquake safety designs. NISA instructs all NPP operators to review their earthquake safety assessments to ensure similar faults elsewhere are not being overlooked.

 

[westfield]

I'd like to see that picture when you find it. I don't see steam rising from where the equipment pool would be.




I'm not saying for the explosion. I'm saying for the beginning of the explosion which I see as a two part explosion.

IMO the event began with a belch of flaming hydrogen laden steam from under the containment lid(s) then there was a second source of energy for the vertical blast.

pls don't get me wrong, I'm not discounting anything, just pointing out things I have seen around the site which may be of use.

Here is a short clip of the steam emanating from the north side of the containment "void".

At other times it's been more active like in this poor quality image

http://i1185.photobucket.com/albums/z360/fukuwest/misc/sfpinRB302.jpg

 

[elektrownik]

http://enenews.com/5-77-microsieverts-per-hour-of-radiation-measured-near-tokyo-at-ground-level-govt-is-desperately-trying-to-keep-it-quiet-video"
Is this measure correct ? Or this is mistake ?

 

[westfield]

Actually, I was looking for evidence for or against TEPCOs theory of hydrogen going through SBGT ducts and piping from unit 3 to unit 4. If you look back this isn't the first time I asked whether the SBGT piping at the SW corner of RB #3 failed before or after unit 4 was damaged. If we can disprove that theory, by showing that the alleged pathway was already broken, and eliminate zirc water reaction in SFP4 because the fuel remained covered, it only leaves radiolysis in SFP #4 or external damage from a second explosion in Unit 3. It is like my questions about recriticality. Each new piece of evidence needs to be considered honestly even if it may mean a previous theory is weakened or disproved by that evidence. Being wrong is not a bad thing. Being wrong and refusing to accept that possibility is very wrong.

Indeed. How do we rule out that the hydrogen wasn't already in RB #4 via common ducting before RB #3 exploded?
Can we rule out other alternate ducting routes between the buildings?
I was hoping someone would know what other potential SGTS pathways there are between the buildings, if any.

Fwiw, I also find the SGTS theory a bit implausible and SFP #4 fuel more obvious but I have no real background or proof to back my feelings, just seems unlikely (and unsafe) that not one of the many valves in the SGTS would be closed on LOP, unlikely there would be no "backflow" prevention devices given the sort of gases they are moving around and unlikely that the gas made its way via their shared lines PAST the stack instead of up and out of the stack.

However it seems difficult to definitely rule out the possible SGTS communication between buildings unless we have intimate knowledge of all the potential ducting pathways between the buildings.

I am anxiously awaiting more information like everyone I guess.

 

[elektrownik]

Unit 2 plot and data shows something bad - temperature of control rods connection to RPV increasing:
http://www.tepco.co.jp/nu/fukushima-np/f1/images/11060712_temp_data_2u-j.pdf
Also the same for unit 3: http://www.tepco.co.jp/nu/fukushima-np/f1/images/11060712_temp_data_3u-j.pdf

 

[zapperzero]

Wow, I missed this picture up until now.

At 3 minutes after explosion there were two distinct and separate sources of steam release: the containment structure and the SFP.

This all but confirms T-Cups theory about the source of the blast coming from under the containment lid.

Hm. It could be anything, really. However, one spot is approximately where the reactor would be. It makes sense to think of steam pouring out from an unseated RPV cap or some broken pipe or something... Just no way to tell without putting a robot with a camera in there. Which no-one seems to be in a rush to do.

 

[biffvernon]

http://enenews.com/5-77-microsieverts-per-hour-of-radiation-measured-near-tokyo-at-ground-level-govt-is-desperately-trying-to-keep-it-quiet-video"
Is this measure correct ? Or this is mistake ?

The reading is on the ground in a road gutter near a drain. Probably cesium 137 gets washed down from a large area and concentrates by a few orders of magnitude. It illustrates that relying on average measurements over an area are not appropriate when assessing the risks to small children with a propensity for playing in the street. And this is a suburb of one of the the world's biggest cities. How do we solve a problem like this?

 

[zapperzero]

The reading is on the ground in a road gutter near a drain. Probably cesium 137 gets washed down from a large area and concentrates by a few orders of magnitude. It illustrates that relying on average measurements over an area are not appropriate when assessing the risks to small children with a propensity for playing in the street. And this is a suburb of one of the the world's biggest cities. How do we solve a problem like this?

With counters. And paint. And polymer glue. And roaming cleanup crews. And a lot of time.
The Japanese civil defense organization is supposed to be the best in the world. They just need some tools and some training.

 

[Calvadosser]

I have been reading everything I could find since the situation began unfolding. In recent weeks, as talk of these water containers has increased, I've yet to find a single report that talks about any significant number of storage units showing up prior to August. It's June now.

My suspicion is that, for at least some period, the sea will be the only possible place to put the excess water. With rain still coming and, I believe, buildings still uncovered, I just don't see how this will work...

I am assuming the water they are pumping in comes from the tap/faucet. The water then emerges, contaminated with radioactive material, and hangs around in ever-increasing volumes.

My question probably has a very obvious answer. Why don't they use the contaminated water they have hanging around and pump that back into the (used-to-be) reactors?

The water would become more heavily contaminated each time it passed through but they would no longer have an ever-increasing volume of water to store and dispose of.

 

[Bodge]

Japanese Government Admits "Melt-Through" in Reactors 1, 2 and 3

"Yomiuri Shinbun (original in Japanese; 6/7/2011) reports that the Japanese government will now admit in the report to IAEA that the "melt-through" may have taken place in the Reactors 1, 2 and 3 at Fukushima I Nuke Plant."

Thanks again to http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-accident-japanese.html" for the story

So, are the reactor cores in the Drywell, the Torus or the Basement for all 3 reactors?

 

[zapperzero]

I am assuming the water they are pumping in comes from the tap/faucet. The water then emerges, contaminated with radioactive material, and hangs around in ever-increasing volumes.

My question probably has a very obvious answer. Why don't they use the contaminated water they have hanging around and pump that back into the (used-to-be) reactors?

The water would become more heavily contaminated each time it passed through but they would no longer have an ever-increasing volume of water to store and dispose of.

Some of it is taken from a nearby lake I think...

To your question: the radioactivity of that water is non-trivial. Re-circulating the water would bring that up to deadly pretty quickly.

 

[Bioengineer01]

I'd like to see that picture when you find it. I don't see steam rising from where the equipment pool would be.




I'm not saying for the explosion. I'm saying for the beginning of the explosion which I see as a two part explosion.

IMO the event began with a belch of flaming hydrogen laden steam from under the containment lid(s) then there was a second source of energy for the vertical blast.

Hey, I whole agree with this, the two stages are pristine clear, and most likely whatever the phenomena that created the event, one explosion triggered the other one... and acted as a detonator

 

[zapperzero]

Hey, I whole agree with this, the two stages are pristine clear, and most likely whatever the phenomena that created the event, one explosion triggered the other one... and acted as a detonator

Those are indeed two stages, but of the same event, i.e. a fuel-air explosion. The fuel in this case is hydrogen. Slightly unusual, because detonating mix can have a wide range of concentrations. Stage one is the flame front. Stage two is ejecta.

Here's a video of the largest fuel air bomb ever built, for reference. The black cloud you see at the beginning is the fuel that's been spread by a small charge. Ignore it. Look what happens when the light turns on. Blast. Ejecta.

 

[joewein]

http://enenews.com/5-77-microsieverts-per-hour-of-radiation-measured-near-tokyo-at-ground-level-govt-is-desperately-trying-to-keep-it-quiet-video"
Is this measure correct ? Or this is mistake ?

Oh, it makes perfect sense. Look what spot he picks: he sets the dosimeter down next to a roadside drain, where in case of rain all the water from the road surface would have run off, carrying with it the surface contamination accumulated from a large surface area.

Roads are relatively clean radiation-wise compared to grass and dirt because of this easy runoff, but the flip side is that the sewers collect more fallout from dust washed off the hard road surface. That's why there have been alerts about sewage sludge already.

I imagine that when the rain stops, a hot spot would remain where the last of the water gradually dried up around the concrete slab of the drain, similar to how you can see lime stone build up around the drain of a sink from hard water.