Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[pdObq]

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/drone/hcrop/reactor2-W-1.png
http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/drone/hcrop/reactor4-W-2.png

Those are from the great Air Photo Service set. Bot are views from East looking West. The East blow-out panel in #4 is the fourth from left, second from top. Note the clean edges.

Thanks for the pictures. Ok, so the upper building structure of unit2 is the same as 3&4, but different from unit1. Is there basically one slow popout panel (different name to distinguish these panels from the fast blowout panels used for unit1) on the E side and one on the W side? From the fact that the unit2 popout panel just fell down vertically, it seems it really just popped out due to a slow pressure increase. Seems like there was some change in philosophy between unit1 and units234 roof structures.

This is what I understood from what you mentioned a few weeks back. But, (and this is pdObq question) to your knowledge
Was the design of the UNIT 1 meant to be weak permissive for explosion on this floor to be less damaging to the containment bellow ?

Yes, that's exactly my question. Thanks.

yes unit 1 is different, 2,3,4 have one blow panel on the turbine building side, you can see it for unit 2, also there was some ir image posted here where those blow panels were visible. Unit 1 reactor hall wall and roof is the same like 2,3,4 roof, steel construction with concrede without steel in concrede, 2,3,4 construction is concrede with steel rods inside (http://en.wikipedia.org/wiki/Reinforced_concrete)

I don't think unit1 upper wall panels are from concrete, but rather are some sort of steel panels just as on the roofs, see the quote from an earlier post of rive below. Otherwise, I agree.

U1 had no concrete over the service floor: the wall panels were steel, screwed (?) to the steel pillars. U2 - U4 has concrete pillars and concrete panels. My bet is that the destruction could be less severe without concrete, even with the more powerful reactors inside. But I don't know.

By the available pictures some reactors in the US (with MK1 containment - I've looked only for those) has pure metal upper parts. I'll check tomorrow.

Thanks, I am looking forward to your findings.

 

[unlurk]

unable to find anything above 4.0.

Do you have a link to the Japanese language site?

The hydrogen blasts are probably going to show up below 2 on the Richter scale.

 

[MadderDoc]

In reply to myself and clarification regarding the translation, this sentence implies that the radiation will be released intentionally and not unintentionally (due to a consequence of some event that might happen) on the 8th May.

I wonder if this might have anything to do then, with the planned flooding of the containment of unit 1? Tepco is having a hot potato in unit 1, has done all the forework, and quote Tepco, 'the plan could bring the unit to cold shutdown within days.'.

I don't know what is to be expected during such a fast transition of the conditions inside the containment and the rpv, but I imagine it might involve the need to do some venting.

Any current airmass that is inside the containment now would be to some degree steam. With a fast cooling, this steam would condense out, leaving behind other gaseous species in up-concentrated form within containment and pressure vessel. I'd expect those gaseous species to include nitrogen, hydrogen, isotopes of noble gases (some of those radioactive), but hopefully not oxygen.

 

[Bandit127]

I wonder if this might have anything to do then, with the planned flooding of the containment of unit 1? Tepco is having a hot potato in unit 1, has done all the forework, and quote Tepco, 'the plan could bring the unit to cold shutdown within days.'.

I don't know what is to be expected during such a fast transition of the conditions inside the containment and the rpv, but I imagine it might involve the need to do some venting.

Any current airmass that is inside the containment now would be to some degree steam. With a fast cooling, this steam would condense out, leaving behind other gaseous species in up-concentrated form within containment and pressure vessel. I'd expect those gaseous species to include nitrogen, hydrogen, isotopes of noble gases (some of those radioactive), but hopefully not oxygen.

Do we know if the bottom of the RPV is still dry on the containment side? If so, we might expect it to be very hot.

Different people have different views on the current extent of fuel rods melting.I suspect that, if the reactor cores are still contained in the pressure vessels, melted fuel rods are now boiling at over 2,000 degrees Celsius inside an egg-shape crust measuring 4 meters in diameter and 2 meters in height.The crust should be around 20 – 30 centimeters now.

Dr. Michio Ishikawa, Chief Adviser(Former President & CEO)
Japan Nuclear Technology Institute(JANTI)
http://www.gengikyo.jp/english/shokai/Tohoku_Jishin/article_20110413.htm"

I suggest that cooling the hot RPV is going to create a lot of steam, and that could be what they are expecting.

I may be way off here and stand to be corrected.

EDIT - clarified the question about the RPV being dry on containment side

 

[Jorge Stolfi]

I took another frame of the TBS/JNN feed and drew some [black] lines
looks OK to me

What we see here are the West and South faces of building #4. Check the close-up pictures:

http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/drone/hcrop/reactor4-E-3.png

The North face was quite deformed by the explosion, the Northwest corner is quite deformed and from a distance it will seem to be tilted.

Moreover the camera does seem to be slightly tilted. Here in green are my guesses as to the true vertical and horizontal lines (below left). Also note that the camera sems to be quite a bit higher then the buildings, so the top part of unit 4's outline is the top of the West wall on the left, and of the East (not South) wall on the right. Both slant down to the right in the image, due to the camera's tilt added to the prespective effect.

Note that the top edge of the North wall and the top of the East wall near Northeast corner are not visible because they are hidden by a large piece of dark gray debris, that sticks out of the roof and blends with the sky in the grabbed frame. I have drawn in pink (below right) what would have been the outline of the building before the explosion.

[PLAIN]http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/misc/inqMBW-e.jpg[PLAIN]http://www.ic.unicamp.br/~stolfi/EXPORT/projects/fukushima/povray/blueprint/foto/misc/inqMBW-f.jpg

 

[Jorge Stolfi]

@Jorge Stolfi

somehow we missed the following correction by tepco of 24 April, this explains the 10 fold fall of the radiation in torus of unit 3. Maybe you can correct your graphs accordingly when time is on hand

Yes, thanks; I just saw TEPCO's errata sheet that someone recently posted on this thread. It was a 100 fold fall btw. I plan to fix the plots later today.

(Several days ago I tweeted @tep_co about the CAMS drop and got back a reply that they would look into it "later". It seems that they had someone check all their past faxes for transcription errors...)

 

[dh87]

Could that much steam be generated from H2 + O2 ? The interior space of floors 3-4-5 is somewhat less than 30,000 m^3. Wikipedia says that explosion can happen with H2 concentration from 4% to 74%. If we take 40% (max that will burn anyway), that would be at most 12,000 m^3 of H2, which after the explosion would would become 12,000 m^3 of hot steam, which at atmospheric pressure would expand adiabatically to ... huh ... (end of my physics).

Anyway, 12,000 m^3 of H2 at 1 bar ~ 1000 kg of H2 <--> 9000 kg of H2O So the maximum H2 explosion assumed above would generate a mushroom comparable to that of the explosion of a boiler with 9 m^3 of liquid water, overheated to some temperature TBD. Is that compatible with your experience?

However for this maximum scenario we need 9 tons of water combining with zirconium (in the core, in the SFP, or both) to produce that 1 ton of H2. Is this reasonable?

If we take the lower figures, we get perhaps 20,000 m^3 of space filled with 4% H2. That means less than 70 kg of H2 <--> 630 liters of liquid water. That seems more reasonable as far as H2 generation goes; but would it yield enough steam for the mushroom we saw?

If we cannot match the amount of H2 likely to have been produced with the size of the mushroom cloud, two other possibilities are an explosive rupture of the RPV (several tons of superheated water there), or a criticality in the SFP (vaporizing some of the water).

The reaction is 2 H₂O + Zr --> ZrO₂ + 4 H₂. For your high end estimate, making 1e+06g of H₂ requires (1e+06g/2g/mole)/4*91g/mole = 11e+06g Zr. This seems like a lot of Zr available for oxidation since only the surface Zr is immediately available, if I understand the chemistry correctly. The low end is probably too low because the escaping hydrogen will fall below 4% and won't explode, whereas there were explosions in the escaping material.

 

[razzz]

http://atomicpowerreview.blogspot.com/"

 

[zapperzero]

Malfunctioning RHR valve in Kashiwazaki-Kariwa NPP

http://www.monstersandcritics.com/news/asiapacific/news/article_1637433.php/Tokyo-Electric-says-valve-at-nuclear-plant-not-working-properly

EDIT: I thought this interesting because some RHR systems at Fukushima Dai-ni were broken also post 3-11.

 

[elektrownik]

http://www.tepco.co.jp/nu/fukushima-np/f1/images/00_05061300.pdf
#3 243C water level decreasing
#2 torus 130Sv/h
#1 Water injection now 8m^3/h

What else can it be with #3 ? I see 2 options: recriticality or bigger crack/leak in RPV...

 

[MadderDoc]

Do we know if the bottom of the RPV is still dry on the containment side? If so, we might expect it to be very hot.

Dr. Michio Ishikawa, Chief Adviser(Former President & CEO)
Japan Nuclear Technology Institute(JANTI)
http://www.gengikyo.jp/english/shokai/Tohoku_Jishin/article_20110413.htm"

I suggest that cooling the hot RPV is going to create a lot of steam, and that could be what they are expecting.

I may be way off here and stand to be corrected.

EDIT - clarified the question about the RPV being dry on containment side

The experiment that was conducted with increased injection rates April 27th-29th indicates to me that Tepco quickly achieved temperature below boiling and atmospheric pressure in the containment, while the readings from the RPV reacted promptly displaying a decrease in pressure and temperature. So perhaps a steam surge from a quick submersal of the PV is not that much of a worry, such a surge would seem liable to condense and dissipate into the water present in the containment. Certainly inside the RPV must be very hot, but if the pressure and temperature readings from the drywell can be trusted, I can't see the outside of the vessel as glowing hot.

 

[Rive]

http://atomicpowerreview.blogspot.com/"

There is that schedule:

What's the 'big equipment hatch' they want to open? All I could find is the big containment plug which cannot be relevant.

 

[GJBRKS]

http://www.tepco.co.jp/nu/fukushima-np/f1/images/00_05061300.pdf
#3 243C water level decreasing
#2 torus 130Sv/h
#1 Water injection now 8m^3/h

What else can it be with #3 ? I see 2 options: recriticality or bigger crack/leak in RPV...

3rd option : reduced flow and pathways because of salt accretion

Also , when watching the lhttp://www.youtube.com/watch?v=Ck_KEILBLlU&feature=player_embedded" , I don't see as much steam rising from #3 as from #2 and #4.

Less steam might imply less cooling

 

[jensjakob]

130 Sv/h in no 2 torus - that is quite a lot?

How can that be?

 

[elektrownik]

130 Sv/h in no 2 torus - that is quite a lot?

How can that be?

If the core or part of core melt from RPV and drywell to torus, but sensor can be damaged also

 

[elektrownik]

3rd option : reduced flow and pathways because of salt accretion

but they don't use salt water science many days...

 

[AntonL]

http://www.tepco.co.jp/nu/fukushima-np/f1/images/00_05061300.pdf
#3 243C water level decreasing
#2 torus 130Sv/h
#1 Water injection now 8m^3/h

What else can it be with #3 ? I see 2 options: recriticality or bigger crack/leak in RPV...

4th Option - 9m³/h water not reaching the reactor, a leak could have sprung somewhere or the flow meter is faulty.

130 Sv/h in no 2 torus - that is quite a lot?

How can that be?

electrowink has been looking at his computer screen too much and needs new glasses :)
it is 12.4 Sv/h and water injection rate is 9m³/h

 

[Rive]

I don't think unit1 upper wall panels are from concrete, but rather are some sort of steel panels just as on the roofs, see the quote from an earlier post of rive below.
...
Thanks, I am looking forward to your findings.

Actually, I made a mistake: the roof had some concrete-like upper cover over the steel. But the walls are steel.

Judging by the pictures:
Browns Ferry: steel.
Brunswick: steel.
Cooper: steel.
Duane: steel.
Monticello: steel.
Santa Maria de Garoña (not in the US): possibly concrete.
Vermont Yankee: steel.

Those are which I have pictures about - there are many other such NPP. Maybe Google Earth can provide some pictures (at least, uploaded by users?), I don't know. Ps.: I could find a picture of the 'Fuel prep machine' in use. Maybe it would be interesting to compare it with the south edge of U4 where Nancy of Houseoffoust suspects that shattered fuel assembly.

3rd option : reduced flow and pathways because of salt accretion

We can turn this upside down: as the freshwater solves the accreted salt maybe the core 'restructures' itself?

 

[GJBRKS]

electrowink has been looking at his computer screen too much and needs new glasses :)
it is 12.4 Sv/h and water injection rate is 9m³/h

hmmm... using his glasses ? ( he refers to #2 S/C (B) CAMS data , it's indeed 1.3E2 there )

 

[GJBRKS]

but they don't use salt water science many days...

true , not since 25th of March , so that seems unlikely unless some salt has reshifted

 

[artax]

anyone know why that live webcam is down, can anyone get anything?

http://lucaswhitefieldhixson.com/fukushima-i-nuke-plant-live-video-feed-tbs

 

[AntonL]

hmmm... using his glasses ? ( he refers to #2 S/C (B) CAMS data , it's indeed 1.3E2 there )

OK time that I visit the optician

 

[PietKuip]

I agree with you guys, something was different about unit 3. Way more energetic.

I too have looked for a mechanism to cause criticality in the pool but can't find one. It'd take something to remove the poison to let it go critical. and they weren't spraying the pools yet i believe.

There was also fresh fuel in the same pool.

So a possible scenario might be the spent fuel boiling away the water, zirconium oxidation making the water alkaline, hot alkaline water eating away the aluminum of the Boral absorbers between the fresh fuel rods -> criticality.

A chemical explosion could have triggered prompt criticality.

A Tepco worker has said that radiation readings in the emergency control room bunker went up by a factor of 12 at the time of the #3 explosion.

 

[AntonL]

anyone know why that live webcam is down, can anyone get anything?

http://lucaswhitefieldhixson.com/fukushima-i-nuke-plant-live-video-feed-tbs

I hear the birds and see lots of fog just a grey screen

 

[artax]

That was live the other day... and it's night-time now,...but even at night you could see the buildings/ tree line against the sky, I think it's down.
I know it's serious but this made me laugh!

 

[PietKuip]

As the experts have pointed out, it is a complicated situation with water from different sources being mixed and added to and drained from at various rates, and with various transport and filtering mechanisms in play, in some configuration that is not well understood because it is all happening underground and out of sight... BUT, what I am naively hoping to see is that the long-term trend of the I-131/Cs-137 ratio is going down.

The measurements in air are showing a downward trend consistent with the 8-day halflife of I-131:
https://spreadsheets.google.com/spr...tEdE5IbzlocmczREZ2Z3Y0TEk2WVdwUVE&hl=en&gid=1

 

[jlduh]

http://www.tepco.co.jp/nu/fukushima-np/f1/images/00_05061300.pdf
#3 243C water level decreasing
#2 torus 130Sv/h
#1 Water injection now 8m^3/h

What else can it be with #3 ? I see 2 options: recriticality or bigger crack/leak in RPV...

The RPV D/W bellows seal temp is now close to its highest since recorded. But it was still a bit higher in mid April (253°C). What has to be watched is the rate of increase of this TEMP (around 1°C per hour) and especially if the the rate continues to be like that in the next days.

https://spreadsheets0.google.com/sp...ZDbX39YK-iFb0Iw&hl=ja&authkey=CP6ewJkO#gid=40

Concerning the water level decrease, it's not so obvious i think for the moment, because when you look at time series you see that it's fluctuating (depending on which reading you take), but lf you take reading A it has long been at around -1800/-1850mm and this changed the 5th of May (yesterday) when it dropped to -2000/2050mm. So there has been a sudden drop of 20cms of the water level in the RPV (if the readings are accurate and reliable, which is unsure) but the trend is not so clear than the temps, which started to rise about one week ago before the change in water level.

As a reminder here are the datas:
https://spreadsheets0.google.com/sp...DZDbX39YK-iFb0Iw&hl=ja&authkey=CP6ewJkO#gid=2

So it's difficult to draw based on these data a correlation between the two, and to find out what is causing what...espacially with the poor infos we get from Tepco on what they are actually doing!

Maybe i missed some infos from tepco (plus i was out of internet connection for 2 weeks beginning of April) but do we know for sure how and precisely where tepco is injecting the water into the reactor pressure vessel in N°3? Are they using the nozzles at the top? Didn't see any sketch on this.

The leaks in the RPV can be at various places, and they can be numerous. It's a high possibility that there are leaks at the bottom where there are a lot of insertions (around 250 insertions holes if I'm not wrong) from control rods and various measuring equipements coming out of the core. We heard about i think a long crack in the side wall of the vessel, but no confirmation. What is sure is that water will take, under gravity, the easiest path to go out, from top to bottom.

If my understanding is correct, if i consider the way the reactor is now "cooled", there couldn't be no flow (and so no cooling) inside the core if there was no leakage from the RPV, right?

If it is so, we can be very happy that these babies are heavily leaking otherwise we would have had very quickly some BIG BOOOOMs if this cooling of last resort couldn't be established through the leakages? After the story of SFP N°4 being saved by the miraculous explosion which opened not the Red Sea but the gate in between the SFP and the well (still to be confirmed i think), we are very lucky again with these reactors in some kind of "stable mode" for weeks now only beacuse there are leaks everywhere! Again this should be integrated in the design parameters when they start to "think the unthinkable" (sarcasm inside! but this is related to my yesterday post on the future new guidelines in France for safety in case of severe accident ).

Considering this very empirical way of cooling the stuff, there can be various reasons explaining why temperatures are changing, independently from the flow injected. The core is damaged and the geometry is lost, you have probably debris, crust or melted stuff inside, and this is evoluating. Some debris can obstruct some canals inside the core fuel rods, which will reduce locally the flow, or stop it, and then local temp will rise, and so one. So this is very difficult to know what is going on inside. But one thing is sure: this thing is very alive and its "stable mode" is an appearance from the outside.

And chance doesn't last for always...

 

[rowmag]

As the experts have pointed out, it is a complicated situation with water from different sources being mixed and added to and drained from at various rates, and with various transport and filtering mechanisms in play, in some configuration that is not well understood because it is all happening underground and out of sight... BUT, what I am naively hoping to see is that the long-term trend of the I-131/Cs-137 ratio is going down. There seem to be hints that Unit 2 and/or Unit 3 is making at least sporadic efforts to be difficult (from a simple-minded reading of these plots, and with no knowledge of typical measurement errors).

And here's the sub-drain isotope update through 5/5:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110505e13.pdf

The measurements in air are showing a downward trend consistent with the 8-day halflife of I-131:
https://spreadsheets.google.com/spr...tEdE5IbzlocmczREZ2Z3Y0TEk2WVdwUVE&hl=en&gid=1

That's true. And the internal reactor parameters don't all seem to point the same direction, either. (#3 temperature goes up, but drywell radiation readings continue down. #2 radiation reading goes up in one monitor, but not in the others nor in temperatures...)

Maybe it's all just garbage readings.

 

[yakiniku]

That's a good point, of course. I'm just looking at the other slides like "Monitoring of Radiation Dose when opening the airlock to implement the work" and "Environmental Impact Assessment caused by opening the airlock to implement the work," and sensing that the officials are covering their hindquarters with the anouncement. Plus the "opening of airlock" is the only thing marked in red on the schedule!

Thanks for the attachment. I had not seen it. I agree it corroborates with the information in the blog post. It is interesting to see the estimate of opening the airlock is an airflow of 22,000m3/h. That's based on an assumption of no wind on the outside of the building.

 

[MadderDoc]

There is that schedule:

What's the 'big equipment hatch' they want to open? All I could find is the big containment plug which cannot be relevant.

And there would be need for clearing 'debris under the big equipment hatch'. This would seem to indicate opening a hatch somewhere below the level of the service floor in one of the walls. The north and the west wall seem the likely candidates since the east and the south walls have attached buildings.

In the west wall there is a clear signature of a small hatch above service floor level and a faint signature of a larger rectangular shape below it, with two pipes? sticking out from the wall above it. Otoh, below there is rather more equipment and small buildings than debris.

The north wall is hard to come by good photos of, from what I have seen no signature of any openings in the wall can be discerned. Otoh at the foot of this wall there is not much but debris, and probably relatively high activity debris to boot.

See attachments