Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[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.

 

[etudiant]

If the Japanese government statement that all three reactors have fuel 'melted through' the RPV is correct, does this not suggest the reactors are much more robust than expected?
Afaik, we have not had any bulk dispersal of core material through steam explosions here similar to what happened at Chernobyl. That has helped Japan avoid a true catastrophe.
The site would in fact appear pretty normal, even if it was awash in radioactivity, and the cleanup would be much less arduous, if the hydrogen explosions had been prevented. That is a separate problem from the reactor breakdown however.

 

[joewein]

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

Yes, there's a nearby dam. That's where they got their freshwater from.

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

Exactly. This water was pumped from locations with radiation levels of 1000 mSv/h, which are off-limits for workers.

The pipes to the central storage site where they've been pumping it are laid near one off the walls of the turbine building, so as to be as far away as possible from workers. The pipe areas are clearly demarcated with cones or bright tape.

In several spots where people have to cross the path of the pumping, the pipes have been been covered up with heavy lead wool to absorb the gamma radiation.

Now put yourself in the position of a fireman or other worker who has to replace a broken water injection pump. You'd have to walk up to a hose pipe filled with deadly water, disconnect it from the pump while trying not to spill any of it on yourself, swap the pump, hook up the pipe to the fresh pump and restart it all. Not many people would volunteer for that kind of job.

That's not really feasible until the radioactivity has been reduced by orders of magnitudes.

Which creates an interesting chicken and egg problem: How are they going to maintain AREVA's miracle water treatment system? Is that all radiation shielded? How will they replace chemicals, filters, etc.? This is not inside the La Hague reprocessing plant, there are no robot arms around in Fukushima 1.

 

[swl]

... 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.

I was wondering the same thing.
I fear that doing so would concentrate the contamination of the water, which then would release more contamination into the air as it boils off from the hot, melted, un-contained fuel.

 

[zapperzero]

How are they going to maintain AREVA's miracle water treatment system? Is that all radiation shielded? How will they replace chemicals, filters, etc.? This is not inside the La Hague reprocessing plant, there are no robot arms around in Fukushima 1.

They put the cesium absorption columns inside some kind of building on site. I think I remember reading that they are re-usable; you probably don't even have to move them to get the accumulated cesium out. So there's that.

 

[rowmag]

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.

I am going to disagree with the following bit of advice from that report:

Radiation risk during nuclear accidents should be communicated to the public using a
qualitative, intuitive scale vs. the traditional quantities of dose rate and activity. For
example, the units of ‘natural background dose equivalence rate’ could be adopted. To
avoid the necessity of adjusting for local background variations, the world average dose-rate
from natural sources should be used: 2.4 mSv/year or 0.27 μSv/hr. Thus the elevated levels
due to contamination would be presented in terms of the factor by which natural background
radiation is exceeded. This approach has several advantages. First, no effort is needed to understand the unit used. For instance, 10 times natural background is easier to grasp than
2.7 μSv/hr since no prior learning in a specialized field is required. Second, there is never a
need to convert between unit systems or to be mindful of numerical prefixes (milli-rem,
micro-Sv, etc.). Third, this method of conveying information about radiation levels reinforces
the concept that some level of radiation exposure is both natural and normal. Finally, use of
this unit implies no estimation of the magnitude of the health hazard from the radiation
levels. This is important since we do not know how hazardous chronic, elevated
background dose rates are, though it is noted that there are regions of the world with
background radiation dose rates one order of magnitude higher than the world-average and
yet with no measureable health consequences.

The most frustrating reports have been when instead of absolute numbers, we were told only so many times the legal limit, or so many times above background. Much more preferable to have actual absolute numbers to work with.

When the accident first happened, we were treated to endless variations on the exposure chart: how many Sieverts from one chest x-ray, from one trans-Pacific flight, etc. The public quickly learned the new unit, and later about units such as Bq/kg. This was a good thing, I think.

Also, background varies by location, so using "world average background" as the standard unit adds a layer of confusion. If I live in an area with a normal background rate of 0.1 uSv/h, and it goes up to 0.2 uSv/h, then my background has doubled, even if it is still below the world average of 0.27. How would one express this in a non-confusing way using the proposed units?

Give me numbers, and teach me parenthetically what the numbers mean, if necessary. But don't remove the absolute scale from reports, please.

(And yeah, I understand that the Sievert is a problematic unit, with all kinds of assumptions built in, but it is still better than "N times the legal limit," which tells me nothing. Was the legal limit conservative or aggressive? What was it in numerical terms?)

 

[elektrownik]

I was wondering the same thing.
I fear that doing so would concentrate the contamination of the water, which then would release more contamination into the air as it boils off from the hot, melted, un-contained fuel.

This is not problem of contamination, this is leak problem, they can't keep water in reactors and turbine buildings if they are not sealed and leaking radioactiva water to ground, sea, etc.

 

[Borek]

Give me numbers, and teach me parenthetically what the numbers mean, if necessary. But don't remove the absolute scale from reports, please.

This is off topic - and tricky. Most of PF users will be able to learn these numbers and to deal with them. Joe Public needs calculator to check how much change he will get from paying $3 for three $0.99 hamburgers. It won't work for him.

 

[zapperzero]

Give me numbers, and teach me parenthetically what the numbers mean, if necessary. But don't remove the absolute scale from reports, please.

Ah but you might get scared if you just know the numbers. Banana dose equivalents per football field provides some context, you know? Makes it all more... homely.

Just to think of that huge mountain of bananas you'd get from staying in Iitate village! Yummy!

 

[jim hardy]

i for one am increasingly frustrated by what looks like a psy-op. The release of information is gradually racheting up the severity. we are being spoon fed pablum.

now unit 2's containment cap is leaking? Duhhh,, what was the thud? Shouldn't the closure bolts be the ultimate relief valve?

anybody know of a decent photo of unit 3 roof?

I'm joining the conspiracy theorists.

noparse

 

[thehammer2]

I've been thinking about the water and I'm wondering if the contamination to the water is largely particulates or dissolved matter. If it's dissolved matter, would it be possible to saturate the water with non-radioactive isotopes before it's pumped in an effort to minimize the amount of radio-material it picks up on its pass through the reactor.

Two things I can think of right off the top of my head that might make this concept pretty much worthless are first that the main source of the contamination is very small particulates and not dissolved compounds and second, that when the water boils, it is distilled and drops its load of non-radiocompounds. Then, when it recondenses, it leaches whatever is available without selection, picking up some radioactivity from the core, making the preloading moot.

This is just something I'm wondering for my own curiosity.

 

[Bioengineer01]

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.

My guess is that if they do that without a proper heat exchanger you would soon have boiling water in all the basements...

 

[vanesch]

My guess is that if they do that without a proper heat exchanger you would soon have boiling water in all the basements...

I think the principal problem is that you don't want to mess around in trucks and pumps and everything with heavily contaminated water so that you can't easily work with those radiating and contaminated machines anymore.

 

[Jorge Stolfi]

Ah but you might get scared if you just know the numbers. Banana dose equivalents per football field provides some context, you know? Makes it all more... homely.

Just to think of that huge mountain of bananas you'd get from staying in Iitate village! Yummy!

[ Moved my post to the political thread https://www.physicsforums.com/showpost.php?p=3343723&postcount=199 ]

 

[rowmag]

This is off topic - and tricky. Most of PF users will be able to learn these numbers and to deal with them. Joe Public needs calculator to check how much change he will get from paying $3 for three $0.99 hamburgers. It won't work for him.

Good point, sorry. I will take it over here:
https://www.physicsforums.com/showpost.php?p=3343652&postcount=197

 

[Bioengineer01]

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.

In the video the ejecta phase happens a lot sooner than in the Unit 3 explosion, also the plume doesn't go as high by a large margin. Somebody with good video analysis equipment could quantify this differences, any takers?