Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[rowmag]

there is a hudge disparity between the document found there
http://www.mext.go.jp/a_menu/saigaijohou/syousai/1305747.htm
and the one found there http://www.nsc.go.jp/mext_speedi/

Translation help is needed to know exactly what we are reading about

The first link only gives instantaneous simulations up to 3/16.
More recent updates are found here: http://www.nsc.go.jp/mext_speedi/past.html , which URL is found on the second link you gave above.

The second link you gave is the one I briefly explained in the post below:
https://www.physicsforums.com/showpost.php?p=3280525&postcount=5596

I'm not up for translating the whole thing, but if there are particular plots or other bits you are curious about, I can try to explain those (if someone else doesn't first).

 

[artax]

The attached capture shows smoke over unit 2, 3 and 4.

I would go for steam - all same color for all units.

Also I do not see the red arm of the concrete truck near unit 4, but maybe this is too small to be visible ?

Yes it is certainly steam as it soon disappears... however it is probably radioactive and the wind is now on shore so it will be falling inland and I expect TEPCO's radiation readings to rise considerably.

 

[ernal_student]

http://www.nsc.go.jp/mext_speedi/

On that site, you may be interested in this page with daily report collections:

http://www.nsc.go.jp/mext_speedi/past.html

Each collection has hourly reports, each showing a wind direction map and a plume flow map

 

[~kujala~]

71 tons is calculated from estimating heat generation from SFP4 to 1,600 kCal/hour / 2MW. Was estimated by Atomic Energy Society of Japan (AESJ), source if here (http://www.aesj.or.jp/en/release/chousacom_EN_01_110418.pdf).

Both are estimates ...

Thank you, now I have seen at least three different estimates, MIT estimate is conservative, AESJ seems to be quite optimistic, IRSN is somewhere between.

Is there any reasons to believe that some of these estimates could be questioned?

 

[Borek]

the wind is now on shore so it will be falling inland

Can be, but doesn't have to. Please remember there is an elevated terrain just behind the plant. It can be a horizontal whirl just on the shore, the air higher can be going in the direction of the sea, and sucking air from the sea over the buildings.

 

[jpquantin]

April 27th:
TEPCO: Water may be leaking from No. 4 reactor fuel pool
http://www3.nhk.or.jp/daily/english/27_09.html

April 28th
TEPCO: Water isn't leaking from No. 4 reactor pool
http://www3.nhk.or.jp/daily/english/28_05.html

Thanks !

From http://www3.nhk.or.jp/daily/english/27_09.html" :

TEPCO has poured in 140 to 210 tons of water over each of the last few days. The company found that water levels in the pool were 10 to 40 centimeters lower than expected despite the water injections.

Means they monitor water level at SFP4, but does not tell us when and how. Also 10 cm of water in SFP4 is 12 tons, 40 cm is 48 tons (if pool gate still there, more if not). Without knowing the time of measurement, no conclusion is possible. Would be soon after injection, I guess ...

From http://www3.nhk.or.jp/daily/english/28_05.html" :

But the company said on Wednesday that it now believes that the water has been evaporating at a rate in line with calculations by experts.

We come back to the boiling rate. I'd really love to have these experts calculations. Until now ...

If we take IRSN figure, we cannot tell for sure the SFP is leaking. The latest average loss is close to this figure (114 compared to my 124).

If we take AESJ figure, there MUST be leaks to explain the losses, because the boiling rate (70) is far below the average rate of loss (my 124).

Unless I'm incorrect, or data are corrupted, or calculation false, or FPC skimmer level not working correctly, or ... (etc).

Also what is surprising is that during video snapshot of Apr 28 I could not see evidence of a completely boiling pool. But this was just after the latest "full" signal, pool had just been refilled. And I must admit that I have not see many boiling SFP in my life ...

Any data on boiling rate estimates, based on number and "age" of rods in SFP4, would be appreciated ...

 

[jlduh]

Did somebody knew that tepco seem to have vented through the stack on this timelapse video at a moment indicated as the 13th of March at around 14h00 (see at t=around 0:30' on this video)



There may be (but I'm not sure) an other small venting at t=0:29' (13th of March at 10h00) and previously one at t=0:24' which is indicated as the 12th of March at 15h00.

I believed that there was no possibility to vent directly to the outside through the stack because this had to be actuated through a valved requiring electricity and there was total blackout at the plant at this date after the tsunami?

That's the reason that was presented by some on this forum to explain why they were venting manually inside the buildings, leading to the H2 explosions.

Any explanation?

I quote myself because i didn't get any comments on this right now and i find this confusing based on what was considered until now...

If venting through stack could be operated (i don't see very well on the frames which stacks are the plumes coming from: i think the N°3/N°4 stack for the plume the 13th March at 14h00, right?), why did they changed to Inside buildings venting with H2 risks of explosion if it was NOT because there was no other option because black out?

 

[zapperzero]

Why did they changed to Inside buildings venting with H2 risks of explosion if it was NOT because there was no other option because black out?

There is no way to intentionally vent inside. Hydrogen escaped into the building, then went boom.

 

[MadderDoc]

<..>
Has it been established that there is a direct vent path from the primary containment to the reactor building service floor?

Or is this yet more bad information we'll just have to live with until the experts sort it all out for us after having collected data for a few more years?

That would be over my cold crumbled curiosity.

From reading the document, link below, don't know it it has been previously posted, I get the impression that BWRs are by design meant to vent the primary containment through to the secondary then to filtering/scrubbing and final to exhaust.

http://www.sumofallfears.com/m/OCRDocuments:Role_of_BWR_Secondary_Containments_in_Severe_Accident_Mitigation

 

[Rive]

AFAIK it's the torus what's vented through some chimneys near the reactor (these are the high towers between U1&U2, U3&U4). The system is called 'Direct torus vent system', DTVS.

Of course I don't know if the vent path was 'official' or not - there was that blackout...

 

[|Fred]

I'm not up for translating the whole thing, but if there are particular plots or other bits you are curious about, I can try to explain those (if someone else doesn't first).

Let me rephrase , we have Two set of document exhibiting what seems to be contradictory data. My question aim to understand if those document are contradictory or if they do not exhibit the same kind of information


Data posted here: http://www.mext.go.jp/a_menu/saigaijohou/syousai/1305747.htm
For exemple http://www.mext.go.jp/component/a_menu/other/detail/__icsFiles/afieldfile/2011/05/03/1305746_0312_11.pdf

Are those simulation made at different date based on hypothetical scenario ? ? (they exhibit radiation level in populated area in the 0.1 Sv and more)





And data posted there's http://www.nsc.go.jp/mext_speedi/ and I'm reffering to http://www.nsc.go.jp/mext_speedi/past.html to be precise. ]
Are Those hourly projection based on actual condition ? or hypothetical scenario?
(they exhibit radiation level in amount of 0.0000000000000001 Sv)

"SPEEDIによる単位量放出を仮定した予測計算結果(これまでに行った1時間毎の予測)
○ 今回の事故においては、事故発生直後から、文部科学省の委託業務契約に基づいて財団法人原子力安全技術センターが予測計算を実施しています。 ただし、ここでは、上記のように放出源情報が得られていないことから、「単位量放出」を仮定した予測計算を行っています。 これは、原子炉施設から放射性の希ガス又はヨウ素が1時間あたり1ベクレル(Bq)放出(単位量放出)される状態が1時間続いたものと仮定して、放射性希ガスによる地上でのガンマ線量率(空気吸収線量率)の分布と、大気中の放射性ヨウ素の濃度分布の時間変化を予測するものです。 この予測は、これらの量の測定(緊急時モニタリング)の参考とするため、原子力防災関係者間で共有されてきました。 この予測結果は、現実の放出量の変化を反映したものではありませんし、気象予測の誤差の影響を含んでいます。
○ ここに示すこれまでの予測計算結果は、原子力安全委員会が文部科学省から提供を受けたものです。
⇒ これまでの予測計算結果はこちら"

 

[jlduh]

There is no way to intentionally vent inside. Hydrogen escaped into the building, then went boom.

Well, what i understood so far (correct me if I'm wrong!) is that in a sense they vented "intentionally", ie by manually operating one valve, but probably not in a path leading to the 120m (or so) high stack because H2 finished his way inside the buildings at N°1 and N°3 reactor.

But if I base my reflexion on what I see on the video I linked, then it appears that there was actually and obviously some venting done through the stack. So the other hypothesis (but it has to be assessed based on the actual layout of the pipes for venting, which we don't have of course...) would be there could have been a leak inside the building while venting this way through the stack? In this way the venting inside the building would have been really "unintentional". But nothing i think enables to confirm this, right?

Then of course, the other explanation for building explosions because of H2 would be H2 from SFP's in these buildings... For N°4 this is quite clear i think, for the others, I don't know... I'm talking about the root cause of the explosions at N°1 and N°3 (for N°2 with explosion apparently reported in the suppression chamber which is underground, i don't know...).

Not clear at all this stuff...

 

[AntonL]

Have you all seen the live cam?

http://www.youtube.com/watch?v=Ck_KEILBLlU&feature=player_embedded

Looks like fires breaking out in #3 and #4.

Nice night time shot showing steam of reactors 3 and 4 , reactor 2 is also steaming but not visibe on this screenshot from livecam

Source of reactor 4 steam is undoubtedly the SPF, but reactor 3 source seems to be very lower down the building and possibly from a breach in the PCV

[PLAIN]http://k.min.us/ikRwXa.JPG

 

[jlduh]

Concerning the possible "fires" at N°4 (i still cannot see the TBS video feed unfortunately), it's now night time at Daichi so any fire would be clearly seen and separated from "reflections hypothesis", no?

The Tepco still cam doesn't show anything... except night!

http://www.tepco.co.jp/nu/f1-np/camera/

EDIT; Thanks ANTON L for posting the captured frames of the TBS feed if something new happens, like the one just above, as I'm a little bit frustrated not to be able to get it live...

FRED, as you are probably also based in France, do you have access to the live feed? I wonder if it's access rights related.

 

[jpquantin]

About SFP4 boiling or not, I found this in http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1304482853P.pdf" :

SFP water temperature measured with a concrete
pump vehicle
Apr. 12 : about 90°C
22 before spray: about 91°C
23 before spray: about 83°C
23 after spray : about 66°C
24 before spray: about 86°C
24 after spray : about 81°C

SFP4 does not seem to have been in boiling mode continuously before Apr. 28.

Apr. 23 spray was 140 tons, Apr. 24 was 165. Weird that after Apr. 24 spray pool temperature was 81. Biggest leak, more volumes to cool down (further damage to gate) or alien heat generation? What else?

 

[AntonL]

Taro Okamoto' mural painting marred by graffiti "reactor image"
Shibuya station, Tokyo http://en.wikipedia.org/wiki/Tarō_Okamoto
[PLAIN]http://k.min.us/iniBHm.jpg

[PLAIN]http://k.min.us/inev1m.jpg
I must say this grafitti is in the style of the original, the images of the four destroyed reactors are iconic images that will stay with us forever.

Edit: It is not graffiti it is a panel added to the original
[PLAIN]http://k.min.us/ikNxOi.JPG
now we need to find out who the artist was

 

[jlduh]

About SFP4 boiling or not, I found this in http://www.jaif.or.jp/english/news_images/pdf/ENGNEWS01_1304482853P.pdf" :
SFP4 does not seem to have been in boiling mode continuously before Apr. 28.

Apr. 23 spray was 140 tons, Apr. 24 was 165. Weird that after Apr. 24 spray pool temperature was 81. Biggest leak, more volumes to cool down (further damage to gate) or alien heat generation? What else?

Well, the measured temp is probably in one local spot in the SFP, and nothing says that there could be a specific spot somewhere in the building (in the SFP, or outside of it, besides it, or below it, or...) where you could have a local temp high enough to boil and vaporize water if there is some there...

Like a local leak in contact with some exposed fuel debris sent outside of the pool by explosion for example? Just an example...

 

[AntonL]

SFP4 does not seem to have been in boiling mode continuously before Apr. 28.

Apr. 23 spray was 140 tons, Apr. 24 was 165. Weird that after Apr. 24 spray pool temperature was 81. Biggest leak, more volumes to cool down (further damage to gate) or alien heat generation? What else?

SPF4 has been boiling since March 13 or 14, the temperature measured in the furthest corner of the pool will be below boiling point. How else do you think 2.4MW of heat is being dissipated? show me one good way other than by boiling.
see https://www.physicsforums.com/showpost.php?p=3271575&postcount=5238"

 

[jpquantin]

SPF4 has been boiling since March 13 or 14, the temperature measured in the furthest corner of the pool will be below boiling point.

It is an explanation. My point is that if you have a 124 tons per day loss, this could be above boiling rate (your 80) and thus we could conclude there are (EDIT: other sources of losses, that could be) leaks. For sure.

How else do you think 2.4MW of heat is being dissipated?

"Cold" water sprayed => water is heated also removes heat from SFP. However assuming that you spray 210 tons of water at 20°C (biggest spray so far), time required to get it to 100°C under 2.4MW would be around 8 hours. Time between sprays are longer than that.

I think that SFP4 stops boiling with water sprays, and resume boiling a few hours after this.

About one of your previous post:

Decay Heat:
2000kW for spent fuel from unloaded reactor last operation 29 Nov 2010 (can be calculated)
+ 400kW long term stored spent fuel (estimated on the high side)
2400kW total

Can you explain how you get to 2000 kW + 400 kW?

 

[TCups]

SPF4 has been boiling since March 13 or 14, the temperature measured in the furthest corner of the pool will be below boiling point. How else do you think 2.4MW of heat is being dissipated? show me one good way other than by boiling.
see https://www.physicsforums.com/showpost.php?p=3271575&postcount=5238"

REGARDING TEMPERATURE MEASUREMENTS
Every temperature measurement of the SFP's I have seen are by IR images (maybe with laser interferometry?). Perhaps someone more knowledgeable than I can comment, but it would seem that IR images would read only the visible surface temperature, that the temperature would be somewhat averaged with the interposed air temperature, and that much of the surface of SFP remains obscured by the FHM, crane, and roof structures. If there has been insertion of any direct reading temperature probe(s) into the pools, I missed it (entirely possible).

REGARDING EXPLOSION AT 3
The initial fireball was not a fireball initially. The first visible event is ejection of a small white cloud of gas at the southeast corner of Bldg 3 which ignites into a glowing yellow-orange fireball a fraction of a second after it has left the confines of the building. I noted this early on. To my non-expert eye, this was a factor I weighted heavily in the hypothesis of a directed, forceful blast of superheated (if that is the correct term) steam resulting from an explosion within the primary containment, coming sidewise, from the transfer chute, and blowing out the side of the upper portion of the building, with hydrogen explosion within the building and vaporization of water from the SFP following.

As for implosion, I see only shadow effect, progressing from the upper to the lower portion of Bldg 3, not implosion. It also seems to me most unlikely that a massive exothermic reaction inside of a building would begin with significant, visible implosion of the building before it visibly explodes.

As for the bird song on the live video, this must be subject to closer scrutiny. The audio track may have been heavily edited with the bird song added just to increase the impact for a live video stream.

On the other hand, the presence of a live audio track accompanying the live video feed, which apparently matches the exact location of the existing videos of the explosion at Unit 3, might give credence to the theory that the only existing audio track of the explosion at Unit 3 (of which I know), was likewise recorded "live" by the same camera and microphone, even if the audio track were then edited at a later to visually synch it with the video for TV newscast.

REGARDING THE PRESENCE OF NEW FUEL RODS IN SFP3
@anton:

When data are given for the weight of new or spent fuel rods, is it correct to presume that the weights given are for the fuel rod assemblies and not strictly the weight of the enriched or spent fuel itself? Given the density of uranium, is the weight of the zirconium and remainder of the fuel rod assembly be insignificant with regard to the total weights given? Is it conceivable that new fuel rods or fuel rod assemblies might be transferred or stored in any configuration that might allow even the remote possibility of criticality outside of the core, even in the case of an explosion with mechanical damage or thermal damage or both?

 

[AntonL]

Can you explain how you get to 2000 kW + 400 kW?

see https://www.physicsforums.com/showpost.php?p=3242513&postcount=3526" there I plotted the decay heat for the first year.

400kW is estimated as heat load from old spent >> 1 year
2000kW was calculated for 4 month old spent fuel (today we can take 5 month and reduce to 1.6 to 1.8MW)

 

[rowmag]

Let me rephrase , we have Two set of document exhibiting what seems to be contradictory data. My question aim to understand if those document are contradictory or if they do not exhibit the same kind of informationData posted here: http://www.mext.go.jp/a_menu/saigaijohou/syousai/1305747.htm
For exemple http://www.mext.go.jp/component/a_menu/other/detail/__icsFiles/afieldfile/2011/05/03/1305746_0312_11.pdf

Are those simulation made at different date based on hypothetical scenario ? ? (they exhibit radiation level in populated area in the 0.1 Sv and more)And data posted there's http://www.nsc.go.jp/mext_speedi/ and I'm reffering to http://www.nsc.go.jp/mext_speedi/past.html to be precise. ]
Are Those hourly projection based on actual condition ? or hypothetical scenario?
(they exhibit radiation level in amount of 0.0000000000000001 Sv)

"SPEEDIによる単位量放出を仮定した予測計算結果(これまでに行った1時間毎の予測)
○ 今回の事故においては、事故発生直後から、文部科学省の委託業務契約に基づいて財団法人原子力安全技術セン ターが予測計算を実施しています。 ただし、ここでは、上記のように放出源情報が得られていないことから、「単位量放出」を仮定した予測計算を 行っています。 これは、原子炉施設から放射性の希ガス又はヨウ素が1時間あたり1ベクレル(Bq)放出(単位量放出)され る状態が1時間続いたものと仮定して、放射性希ガスによる地上でのガンマ線量率(空気吸収線量率)の分布と 、大気中の放射性ヨウ素の濃度分布の時間変化を予測するものです。 この予測は、これらの量の測定(緊急時モニタリング)の参考とするため、原子力防災関係者間で共有されてき ました。 この予測結果は、現実の放出量の変化を反映したものではありませんし、気象予測の誤差の影響を含んでいます 。
○ ここに示すこれまでの予測計算結果は、原子力安全委員会が文部科学省から提供を受けたものです 。
⇒ これまでの予測計算結果はこちら"

I wrote a long, detailed reply, which got lost because my login timed out while I was writing it, and I don't have the energy to redo it. But basically, the MEXT and NSC websites are plotting somewhat different quantities, using different source term assumptions. The MEXT plots are based on some assumptions about released iodine and rare gases for a reactor that shut down at 14:47 on 3/11 (they assume 1.9x10^19 Bq/h for noble gases, 1.7x10^18 Bq/h for iodine, at 17:00 on 3/12). The NSC calculations are for simple unit releases (1 Bq/h each of iodine and rare gases), because they didn't have any data on what got released when. So the NSC plots have to be scaled by some realistic estimate of source terms to get realistic integrated doses.

Also, the MEXT plots are for ground exposure (Bq/m^2), adult exposure (mSv) and infant thyroid exposure (mSv), while the NSC plots are for air concentrations of iodine (Bq/m^3) and air absorbed dose rates for gammas from rare gases (microGy/h). The MEXT source term is assumed to be at a height of 1 m, the NSC source term at 120 m (exhaust tower height?). The only thing the models seem to have in common is the wind pattern.

 

[jpquantin]

see https://www.physicsforums.com/showpost.php?p=3242513&postcount=3526" there I plotted the decay heat for the first year.

400kW is estimated as heat load from old spent >> 1 year
2000kW was calculated for 4 month old spent fuel (today we can take 5 month and reduce to 1.6 to 1.8MW)

Thank you for your explanation.

I also found that edgepflow used a different formula in https://www.physicsforums.com/showpost.php?p=3188377&postcount=113".

You can back-of-the-envelope estimate the decay heat power with infinite fuel exposure from (Ref. "Nuclear Heat Transport" El-Wakil):

P(t) = 0.095 Po ts ^ -0.26

Po = power before shutdown
ts = shutdown time is seconds

Applying it to SFP4 for 4 month old spent fuel would give 3.1~3.2 MW max. Can you explain the difference in your calculation please?

 

[AntonL]

Every temperature measurement of the SFP's I have seen are by IR images (maybe with laser interferometry?). Perhaps someone more knowledgeable than I can comment, but it would seem that IR images would read only the visible surface temperature, that the temperature would be somewhat averaged with the interposed air temperature, and that much of the surface of SFP remains obscured by the FHM, crane, and roof structures. If there has been insertion of any direct reading temperature probe(s) into the pools, I missed it (entirely possible).

The IR camera will measure the cooler temperature of the steam above a boiling surface.

As for the bird song on the live video, this must be subject to closer scrutiny. The audio track may have been heavily edited with the bird song added just to increase the impact for a live video stream.

On the other hand, the presence of a live audio track accompanying the live video feed, which apparently matches the exact location of the existing videos of the explosion at Unit 3, might give credence to the theory that the only existing audio track of the explosion at Unit 3 (of which I know), was likewise recorded "live" by the same camera and microphone, even if the audio track were then edited at a later to visually synch it with the video for TV newscast.

The bird song seems to be genuine it is very faint and random and wind noise can be heard too.

Back to the explosion of unit 3, if the three booms where recorded by the same microphone, and the camera being some 13 km distant (https://www.physicsforums.com/showpost.php?p=3282622&postcount=5737" ) the sound would have been some 39 seconds after the visual in still air. As the observation spot is on top of a mountain it is quite possible that echoes would be heard from nearby mountains. As the sound path for the echoes is different there would have been different Doppler shifts, signal compression and phase shifting of the sound wave by the different air velocities of the sound path so that the sound signatures of the echoes would not be the same.

 

[ernal_student]

And data posted there's http://www.nsc.go.jp/mext_speedi/ and I'm reffering to http://www.nsc.go.jp/mext_speedi/past.html to be precise. ]
Are Those hourly projection based on actual condition ? or hypothetical scenario?
(they exhibit radiation level in amount of 0.0000000000000001 Sv)

"SPEEDIによる単位量放出を仮定した予測計算結果"

"Results of SPEEDI's prediction/estimate calculations based on assumed emission quantities"

Translation key:
による due to / according to
単位 unit (of something measurable)
量 quantity / amount
放出 emission / release
を [direct object marker]
仮定 assumption / hypothesis
した "has done / was done"
予測 prediction / estimation
計算 calculation / forecast
結果 result / consequence

 

[AntonL]

Thank you for your explanation.

I also found that edgepflow used a different formula in https://www.physicsforums.com/showpost.php?p=3188377&postcount=113".

They have lost significant amounts of heat over 3 days, but the power output is still large. You can back-of-the-envelope estimate the decay heat power with infinite fuel exposure from (Ref. "Nuclear Heat Transport" El-Wakil):

P(t) = 0.095 Po ts ^ -0.26

Po = power before shutdown
ts = shutdown time is seconds

Applying it to SFP4 for 4 month old spent fuel would give 3.1~3.2 MW max. Can you explain the difference in your calculation please?

Maybe someone more knowledgeable should comment!

Above formula for decay heat is different to that shown in the Cambridge University slide that I used a basis for my caluclation, https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Decay%20Heat%20generation%20in%20Fission%20Reactors.pdf" also uses the same formula as the one in the Cambridge University slide except for the time unit is days in stead of seconds as below.
[PLAIN]http://k.min.us/ikop60.JPG

 

[Azby]

Let me rephrase , we have Two set of document exhibiting what seems to be contradictory data. My question aim to understand if those document are contradictory or if they do not exhibit the same kind of information


Data posted here: http://www.mext.go.jp/a_menu/saigaijohou/syousai/1305747.htm
For exemple http://www.mext.go.jp/component/a_menu/other/detail/__icsFiles/afieldfile/2011/05/03/1305746_0312_11.pdf

Are those simulation made at different date based on hypothetical scenario ? ? (they exhibit radiation level in populated area in the 0.1 Sv and more)





And data posted there's http://www.nsc.go.jp/mext_speedi/ and I'm reffering to http://www.nsc.go.jp/mext_speedi/past.html to be precise. ]
Are Those hourly projection based on actual condition ? or hypothetical scenario?
(they exhibit radiation level in amount of 0.0000000000000001 Sv)

I'm scratching my head at this as well. Some of the numbers seem off by several orders of magnitude. This English translation of data made available on 3/24 (sorry, can't find the original link at the moment) says specifically that these are estimates based on measuring dust (not specified if airborne or on the ground), and not reactor nuclide output. I'm trying to find the estimation procedure they used by which 1-5mSv external exposure correlates with 100mSv internal for infants' thyroids. Anybody?

 

[|Fred]

Rowmag sorry about that , and thank you once again for the invaluable help you provide us on the board.


What is a bit confusing is that "NSC" paper are also labeled from MEXT.
What you are saying troubles me as the Paper found on NSC seems to be really up to date (latest from yesterday) It seems weird to me that they keed doing analysis on wrong (assumed) data?

And the MEXT data are as well make on assumed data

So basically we have a software.. And instead of inputing the day by day measured data they inputed a couple of different data model ? Seems like non sens to me ?

 

[|Fred]

I'm trying to find the estimation procedure they used by which 1-5mSv external exposure correlates with 100mSv internal for infants' thyroids. Anybody?

Tcup might be able to explain that. There is a weight factor of (0.05) (might have change) for the Thyroids. but it still does not do the math

 

[rowmag]

Rowmag sorry about that , and thank you once again for the invaluable help you provide us on the board.What is a bit confusing is that "NSC" paper are also labeled from MEXT.
What you are saying troubles me as the Paper found on NSC seems to be really up to date (latest from yesterday) It seems weird to me that they keed doing analysis on wrong (assumed) data?

And the MEXT data are as well make on assumed data

So basically we have a software.. And instead of inputing the day by day measured data they inputed a couple of different data model ? Seems like non sens to me ?

The NSC web page mentions that they are running these models for MEXT. Not sure if MEXT also ran models themselves, but if so, it was clearly with the same software, if different input assumptions.

But anyway, these hourly plots are really only useful for seeing where stuff is heading, but not how much stuff is heading there. For the long-term integrations (such as http://www.nsc.go.jp/mext_speedi/0312-0424_in.pdf or http://www.nsc.go.jp/mext_speedi/0312-0424_ex.pdf ), there was apparently some attempt made at estimating realistic source terms, by using dust sampling measurements. (I.e., they use down-stream measurements and wind patterns to back-calculate the source terms.)

 

[jpquantin]

https://netfiles.uiuc.edu/mragheb/www/NPRE%20457%20CSE%20462%20Safety%20Analysis%20of%20Nuclear%20Reactor%20Systems/Decay%20Heat%20generation%20in%20Fission%20Reactors.pdf" also uses the same formula as the one in the Cambridge University slide except for the time unit is days in stead of seconds as below.

I've done a calculation with T0 = 365 days, assuming that no re-fuel had taken place at unit 4 since one year before its stop on Nov. 29th 2010, based on reports of 100% operation for one year http://www.jaif.or.jp/english/aij/index2.html" . I found 1.2 MW? Did you take T0 as 365?

 

[roliqq]

... (i still cannot see the TBS video feed unfortunately...

EDIT; Thanks ANTON L for posting the captured frames of the TBS feed if something new happens, like the one just above, as I'm a little bit frustrated not to be able to get it live...

FRED, as you are probably also based in France, do you have access to the live feed? I wonder if it's access rights related.

I am in Germany and was having the same problems. But for me it works connecting via proxy server

 

[rmattila]

I made some rough sketching of core burnup distributions assuming 12 month equilibrium cycles, 80 % availability, 6 irradiation cycles for each assembly prior to final discharge, and 170 kg uranium weight per assembly. For different batches I assumed the relative power fractions of 1.1, 1.2, 1.1, 1, 0.9 and 0.8. Roughly, for a 400-assembly unit with 1380 MWth around 140 EFPD I got the batch average burnups 3, 10, 17, 23, 28 and 33 and for a 548-assembly 2381 MWth unit about 4, 12, 21, 28, 35, and 42 MWd/kgU at the time of shutdown.

Then I took the decay heat data from burnup/shut down cooling calculations made (by someone else - credits due) for a "generic" BWR fuel assembly with different void histories, and calculated core-average power-weighted decay heats at different cooldown times. The results are in the attached file. This approach should give somewhat overestimated values, since it does not take into account the cooldown periods at refueling outages, but rather burns the fuel with constant power density starting from fresh fuel, and ending at 5, 10, 15 MWd/kgU etc., and then continuing with the cooldown calculation for 1800 days.

This is just an exercise I made in order to get some kind of an idea of the decay heats one could assume at this time. Therefore I have not had the time to do any double-checking of the results. Qualitatively, however, they seem to appear sensible. A decent decay heat calculation would follow the decay heat from each nuclide separately and take into accound the different saturation and cooldown periods during plant operation, but that's beyond my resources at the moment. It would, however, be nice to hear what kind of estimates others have for the decay heat of the earthquake-stricken reactors.

 

[SteveElbows]

REGARDING TEMPERATURE MEASUREMENTS
Every temperature measurement of the SFP's I have seen are by IR images (maybe with laser interferometry?). Perhaps someone more knowledgeable than I can comment, but it would seem that IR images would read only the visible surface temperature, that the temperature would be somewhat averaged with the interposed air temperature, and that much of the surface of SFP remains obscured by the FHM, crane, and roof structures. If there has been insertion of any direct reading temperature probe(s) into the pools, I missed it (entirely possible).

There are at least 3 different types of temperature measurements:

IR images that you mention.

Skimmer surge tank data that is published daily. Unit 4 temperature has been unavailable for ages (last available reading was 14th march) but this skimmer temp data is still available for unit 2.

More direct measurement. We don't know how often they do this, as data not published very often, but most of the headline news stories about boiling pools comes from this data. According to my notes, the following temperatures for pool 4 have been mentioned:

April 12th 90 deg C
April 22nd 91 deg C
April 23rd 83 deg C, then 66 deg C after spraying
April 24th 86 deg C, then 81 deg C after spraying

edited to add that I am not sure where I got the first couple of temperatures from, likely press or company reports, but it was an IAEA report from April 27th that gave me the more recent 'before and after spraying' data:

http://www.iaea.org/newscenter/news/2011/fukushima270411.html

In Unit 4 140 tonnes of fresh water was sprayed over the spent fuel pool on 23 April and 165 tonnes of fresh water was sprayed over the spent fuel pool on 24 April using a concrete pump truck. The nuclear emergency response headquarters reported that temperature measurements showed the spent fuel pool temperature to be 83 °C before spraying and 66 °C after spraying on 23 April, and the spent fuel pool temperature to be 86 °C before spraying and 81 °C after spraying on 24 April.

 

[SteveElbows]

A few pages back there has been some discussion about where the refueling crane (FHM = Fuel Handling Machine?) of unit 3 has gone, and if it could be below the big crane...

Looking at this image, I noticed that brownish-greenish structure with something that looks like a bent metal pole sticking out in the middle-left part of the image. There is some gray debris on its lower part, likely concrete pieces. Is it possible that this object is the unit 3 fuel crane that has maybe been ejected from the service floor in the unit 3 explosion? Would the size and its current position make any sense? The brownish color might be rust, and maybe we are seeing the bottom of the crane.

Its approximately the right size, and its in a place that would make sense.

However, looking at an image taken from a different angle clearly shows that its actually some sort of ground vehicle/crane that has an arm extending into the sky (the small one near bottom of this picture, not the larger more obvious crane):