Japan Earthquake: Nuclear Plants at Fukushima Daiichi

[Jorge Stolfi]

I didn't even know steam could be produced by water at a temperature of 50 degrees Celsius. I also thought steam was invisible.

My guess: what is leaking through the gap around the pipe is air (or some other gas) at minimum 50 degrees, saturated with water vapor. As it meets the cooler air and pipe in the ground storey, some of the steam condenses into fog, some into the pool of liquid water around the pipe. The bubbles are not boiling but the warm gas bubbling through this puddle.

Er, could they put a gas chromatograph on those robots, please? Us gawkers want to know what that gas is...

 

[Jorge Stolfi]

To complement my guess: if the basement is half-flooded with water at 50 C, but at near atmospheric pressure, then the space above the water should be filled with saturated air-steam mixture at 50 C.

One puzzling detail is what is pushing that wet air through the crevice and through the water, since the pressures on both sides should equalize through the stairwell. It would require a closed door somewhere between that part of the ground floor and that part of the basement. I suppose that is not entirely unlikely?

EDIT: Instead of a door, the air pressure difference could be explained also by a low passageway in the basement that is open but entirely submerged.

 

[jim hardy]

are you guys able to make out the numbers on those new gages?
http://www.tepco.co.jp/en/news/11031.../110604_10.jpg

also the youtube linked three pages ago is now "removed by user

Originally Posted by Lambert View Post

this may be off topic but I found it as interesting nontheless :

Fascinating.

musta been good?

also - water vapor is just another gas and when above its boiling point is not too un-ideal.
What we call steam is the white stuff that's actually tiny liquid droplets that've condensed into water.
you see them on wingtips of fighter planes doing high-g maneuvers in summer airshows - air above wing cools below dewpoint and the water vapor becomes visible.
http://gwatt.smugmug.com/Airplanes/MacDill-AFB-Open-House-2008/F-18-Making-VaporDSC3336/468150589_8K57R-X2.jpg


so the steam we see in that video is real humid air entering a cooler room. Must be awfully muggy below decks.

 

[Bandit127]

http://www3.nhk.or.jp/daily/english/03_31.html

1 Ci = 37,000,000,000 Bq

Fukushima (in the water there)

720,000,000,000,000,000 Bq

Unless I made a math error, that's
19,459,459 Curies currently in just the waste water there. That doesn't include the material spread out over the land, around the world, or into the ocean from leaking water.

What was the figure for Chernobyl again?

(edit)

Ah, found it.

Chernybyl released about 1,300,000 Ci of Ce-137 and 2,400,000 Ci of Ce-137

I think a crucial difference here is that those large amounts of Curies are still contained (for the moment at least). Not as contained as we would like - but not spread out over the land either.

I don't know what the experts think, but I see the large amounts of water being used has got a benefit - and that is to reduce the amount of radiation that is being released to the environment in the way that it was in Chernobyl.

 

[MadderDoc]

are you guys able to make out the numbers on those new gages?
http://www.tepco.co.jp/en/news/110311/images/110604_10.jpg<..>

I think so;
Left instrument scale 0 - 0.5 (current reading 0.1)
Right Instrument scale 0 - 0.4 (current reading 0.2)
Center instrument scale 0 - 0.1 (current reading 0.1)
All scales in MPa

 

[robinson]

I think a crucial difference here is that those large amounts of Curies are still contained (for the moment at least).

So you checked my math? Wow, that is a lot of radioactivity. And that is just in the basements and such. Makes one wonder what the real amounts are spread all over the island and in the ocean.

It would nice to know the elements causing it as well. I don't doubt somebody already knows, but isn't going to say.

 

[Lambert]

are you guys able to make out the numbers on those new gages?
http://www.tepco.co.jp/en/news/11031.../110604_10.jpg

also the youtube linked three pages ago is now "removed by user


musta been good?

Yeah it was a interview of Kei Sugaoka, here is the info from the youtube video before it was nuked:

"Uploaded by laborvideo on Jun 3, 2011

GE Nuclear Inspector And Whistleblower Kei Sugaoka Speaks Out About Fukushima , GE & Obama
General Electric nuclear plant inspector Kei Sugaoka was one of the inspectors at the Fukushima Daiichi plant in 2000. He noticed a crack in the steam dryer which he videotaped. He was later ordered by TEPCO to edit this part of the tape which is illegal in the United States. He went public and some TEPCO managers were fired. He thought that things would change but they have not. Additionally as a result of being a whistleblower he was also fired by General Electric and has been struggling to get the truth out about these dangerous plants. This interview was done on May 5, 2011.
http://www.youtube.com/watch?v=fBjiLaVOsI4&feature=
http://criticality.org/2011/05/whistleblower-shutdown-17-nuclear-reactors/
http://www.nytimes.com/2011/04/27/world/asia/27collusion.html?hpw
http://www.baycitizen.org/disasters/story/inside-japans-failing-nuclear-react ...
http://search.japantimes.co.jp/cgi-bin/fl20040523x2.html
Production of Labor Video Project www.laborvideo.org laborvideo.blip.tv
(c)2011"


most of the links are dead now, kind of crazy... here is another link i found which is also interesting:

http://www.youtube.com/view_play_list?p=0AA0A2E17C94FC6C

 

[elektrownik]

I done this a long time ago

I think so;
Left instrument scale 0 - 0.5 (current reading 0.1)
Right Instrument scale 0 - 0.4 (current reading 0.2)
Center instrument scale 0 - 0.1 (current reading 0.1)
All scales in MPa

http://www.tepco.co.jp/en/news/110311/images/110604_10.jpg

I see now, Hight side pressure - 0,1 MPa, low side pressure 0,2 MPa, and differential pressure - 0,1 MPa
So reactor presure is 0,2 MPa - 0,18 MPA = 0,02 MPa
equation from here: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110602_02-e.pdf
So we should now add 0,1013 to result
so 0,1013 + 0,02 = 0,1213 so it is litle bigger than atmospheric pressure ?

weee my computations were correct, look on tepco data summary 6/4 at 12:00
http://www.tepco.co.jp/nu/fukushima-np/f1/images/11060412_table_summary-j.pdf
0,025MPa + 0,1013=0,1263
So where all nitrogen go ?



Ps. also water level in unit 1 sfp hit low record - only 1m, if they will not inject water fuel will be exposed in less than 24 h

REACTOR 1 RPV IS AT ATMOSPHERIC PRESSURE !

 

[Bioengineer01]

To complement my guess: if the basement is half-flooded with water at 50 C, but at near atmospheric pressure, then the space above the water should be filled with saturated air-steam mixture at 50 C.

One puzzling detail is what is pushing that wet air through the crevice and through the water, since the pressures on both sides should equalize through the stairwell. It would require a closed door somewhere between that part of the ground floor and that part of the basement. I suppose that is not entirely unlikely?

EDIT: Instead of a door, the air pressure difference could be explained also by a low passageway in the basement that is open but entirely submerged.

What do you mean by basement when you refer to Unit 1? There is no basement below the PCV, just a concrete basemat? correct?
https://www.physicsforums.com/attachment.php?attachmentid=36166&stc=1&d=1307221110

 

[elektrownik]

What do you mean by basement when you refer to Unit 1? There is no basement below the PCV, just a concrete basemat? correct?
https://www.physicsforums.com/attachment.php?attachmentid=36166&stc=1&d=1307221110

No, not correct, floor -2 (torus) and -1, look on the tepco flood drawings, they show clear those floors

 

[LabratSR]

Could Hydrazine have anything to do the steam/water vapor/smoke/whatever seen in the video? Like lowering the boiling point or some other chemical witchcraft?

 

[Bioengineer01]

No, not correct, floor -2 (torus) and -1, look on the tepco flood drawings, they show clear those floors

Do you have a link to the tepco flood drawings?

 

[Borek]

Could Hydrazine have anything to do the steam/water vapor/smoke/whatever seen in the video? Like lowering the boiling point or some other chemical witchcraft?

If memory serves me well it is added in concentrations so low its presence shouldn't have any visible effect.

 

[shadowncs]

OT
just watched the http://www.tepco.co.jp/en/nu/f1-np/camera/index-e.html" wondering if it's not playing in a loop, things were so quiet. And there comes this badger-like animal going right on the roof to the right of the pipes & then jumps down and goes out of frame. Amazing. I'm convinced now the camera is for real :)

 

[jim hardy]

Thanks Elekrownik

the numbers on the photo are so blurry i can't make them out. i was seeing like 13 on right gage, didnt make sense. i hope they put up a clearer photo.

referring to their diagram and thinking real simple , as i have to ---

there's 0.18 mpa of water above right gage in addition to any pressure in reactor
so if it reads 0.18 mpa reactor is atmospheric alright ,,

and 0.1 mpa of water above left gage including what's in vessel
so the water level in vessel is at least 0.08 mpa lower than upper tap. Were it at upper tap the gages would read same.

mpa to feet of water?
for in my head calcs i use an atmosphere is close to 0.1 mpa and is 32 feet of water..
so 0.8 mpa is 0.08 X 32 = 25.6 feet?

i don't remember where the taps are relative to core. Will look for it. What's 25.6 feet below upper tap? Hopefully not the lower tap...

 

[elektrownik]

Do you have a link to the tepco flood drawings?

Yes, here: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110530_04-e.pdf
There is drawing of - 2 and -1 of unit 6 which is abwr, but it is like unit 1 in case of underground floors, there was also separated drawing for unit 1 but I can't find it now...

 

[jim hardy]

If memory serves me well it is added in concentrations so low its presence shouldn't have any visible effect.

to my recollection its purpose is to scavenge oxygen. It's N2H4. it gives up hydrogen to combine with free oxygen or OH to make water molecules. It turns itself into ammonia(NH3) which you smell as you go by condenser air ejectors, and N2 and maybe H2 which you don't smell. it's a common boiler water additive for corrosion control, used because it's good for the boiler though pretty toxic to people in high concentration.
Since it turns itself into water and volatile gasses it doesn't measurably affect the usual properties of water.

old jim

 

[jlduh]

OT
just watched the http://www.tepco.co.jp/en/nu/f1-np/camera/index-e.html" wondering if it's not playing in a loop, things were so quiet. And there comes this badger-like animal going right on the roof to the right of the pipes & then jumps down and goes out of frame. Amazing. I'm convinced now the camera is for real :)
View attachment 36167

I've seen this animal several times on the webcam, the first time i was quite surprised!

Well this means that the area is not dangerous, right? A real nature park

 

[joewein]

What do you mean by basement when you refer to Unit 1? There is no basement below the PCV, just a concrete basemat? correct?
https://www.physicsforums.com/attachment.php?attachmentid=36166&stc=1&d=1307221110

See this Italian article that Jorge Stolfi posted a link to a while ago:
http://giappopazzie.blogspot.com/2011/05/post-tecnico-4-approfondimento-sulla.html

Here is the radiation map showing the 3-4 Sv/h hot spot where the video was taken in the bottom right corner.
http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110604_01-e.pdf

Notice the tunnel / truck entrance at the left. That puts it at ground floor level (1F in Japanese terminology). Below that is the first basement (B1F in Japanese terminology). That is the space that holds the suppression chamber (torus). All of that space is flooded.

The bubbling could be from rising water levels that displace air / nitrogen down there, like the bubbling from a sinking ship gradually filling with water.

Alternatively it could be from nitrogen still being injected that somehow makes its way there.

The third possibility would be that the temperature down there is way higher than 50C. Maybe the thermocouples no longer show correct data if they're immersed in hot water all around? If there are 720,000 TBq in the basement water, what's the heat output from that?

 

[joewein]

I forgot a fourth possibility: The bubbling could be from a hydrogen/oxygen mix produce by radiolysis of water from that 720,000 TBq, but I have no idea what the expected volume per minute would be.

In any case, one would hope that if this was the case, there would be plenty of injected nitrogen at the same time to keep the hydrogen diluted below 4% or things could get ugly. The problem I see is that if N2 is injected into the RPV and from there flows into the dry well, it's not going to do much for hydrogen produced in the basement...

 

[Bioengineer01]

yes, here: http://www.tepco.co.jp/en/nu/fukushima-np/images/handouts_110530_04-e.pdf
there is drawing of - 2 and -1 of unit 6 which is abwr, but it is like unit 1 in case of underground floors, there was also separated drawing for unit 1 but i can't find it now...

thanks!

 

[SteveElbows]

I've seen this animal several times on the webcam, the first time i was quite surprised!

Well this means that the area is not dangerous, right? A real nature park

Im glad others have seen an animal on the camera, because I thought I saw one the other day but I wasnt sure if Id gone mad by staring at wobbly compression artefacts for too long.

By the way someone seems to be putting up timelapse footage from the camera to youtube, which is handy for watching what happens without wasting too much time as a whole hour goes by in just 3 minutes.

http://www.youtube.com/user/fuku1live#p/u/3/-ljGxLDpHlc

 

[robinson]

Interesting.

http://www.youtube.com/user/fuku1live#p/u/0/yB3IKblc-b0

Is that the latest explosion in building 4 we see on the video?

 

[Bioengineer01]

See this Italian article that Jorge Stolfi posted a link to a while ago:
http://giappopazzie.blogspot.com/2011/05/post-tecnico-4-approfondimento-sulla.html
...

Thanks! Your link is great, now I understand, there is no basement from my perspective, but they call the thorus level basement, as I suspected.

One question, why nobody considers that possibility that the water in the flooded basement has come in contact with the Corium?

 

[AntonL]

Some food for thought: If the basements that contain the torus is being flooded and the torus is not filled 100% with water, I could imagine the torus will want to rise, resulting in stresses on the torus-RPV connections that have nor been considered, which in turn could result in further RPV containment failure.

 

[AntonL]

are there any better links to the new video NHK obtained?

http://www3.nhk.or.jp/daily/english/05_06.html

 

[AntonL]

Don't know exactly where this video has been taken by packbot (N°1 Unit, but where precisely is not clear), but it's a new one (June 3) and this is showing some boiling water inside the building...

http://ex-skf.blogspot.com/2011/06/fukushima-i-nuke-plant-reactor-1.html
(Steam coming from water 50°C? Doesn't make sense to me...)Direct link to Tepco site to download video, the title is just this:
"Confirmation of steam situation at a reactor building of Fukushima Daiichi Nuclear Power Plant Unit 1 (ZIP 5.55MB)"
http://www.tepco.co.jp/en/news/110311/images/110604_09.zip

For the first time, we see for real a Boiling Water Reactor...
...]

quoting http://search.japantimes.co.jp/cgi-bin/nn20110605a3.html

The utility said it took the reading near the floor at the southeast corner of the building. The steam appears to be entering from a leaking rubber gasket that is supposed to seal the area where the pipe comes up through the first floor. No damage to the pipe was found, Tepco said.

So if the area is sealed with a gasket, then it is safe to say that some steam has condensed to water on top of the gasket and the escaping steam is now blowing bubbles through this puddle of condensed water giving the impression of boiling water.

Furthermore, the assumption can be made that the basement is slightly pressurised forcing the steamy atmosphere of the basement through this point.

 

[Jorge Stolfi]

What do you mean by basement when you refer to Unit 1? There is no basement below the PCV, just a concrete basemat? correct?
https://www.physicsforums.com/attachment.php?attachmentid=36166&stc=1&d=1307221110

The basement is the free space below ground level. Most of it is occupied by the cylindrical concrete block that supports the primary containment vessel, and by the surge suppression torus. According to some floorplans I have seen, the whole basement has a square outline; it is divided by thick internal walls into an octagonal room that spans the four outer walls and houses the torus, plus four small triangular rooms at the corners. Presumably those five spaces are connected by doors, stairs, pipe passages, etc..

The leak of radioactive steam just found on the ground floor seems to be located over or near the southeast wall of the octagonal room in the basement.

 

[Jorge Stolfi]

http://www.youtube.com/user/fuku1live#p/u/0/yB3IKblc-b0
Is that the latest explosion in building 4 we see on the video?

Those light flashes just after the 2 minute mark are being reflecetd only by objects that are very close to the camera. So I suppose that someone offcamera just happened to sweep the beam of a flashlight over the structure that housing the camera.

(Perhaps someday some computer genius will have the idea of adding a *single-frame* forward/back button to a video streaming widget. Until then we will have to live in a world of fleeting impressions...)

 

[radio_guy]

I've seen this animal several times on the webcam, the first time i was quite surprised!

Well this means that the area is not dangerous, right? A real nature park

I have seen it a few times.kinda neat

looks like a red panda?

 

[joewein]

One question, why nobody considers that possibility that the water in the flooded basement has come in contact with the Corium?

With the levels of radioactivity of the water in the basement it is quite obvious that the water must have been in contact with melted fuel rods. What makes you say that nobody is considering this?

 

[Cire]

Here is a different thought on dealing with the problem of scattered fuel in the RPV's. (Big assumption coming). (Firstly, I don't believe there is any corium in the RPV's.) I do believe there probably are piles of fuel pellets on the bottom.

First they have to get the cooling loop closed. Water in and water out need to be the same. Once a true cold shutdown is met you can do something fairly radical.

You dissolve out the UO2 from the RPV's using nitric acid. You then precipitate out the uranium. Apparently cerium nitrate + nitric acid with a little ozone dissolves fuel pellets at fairly low concentrations of nitric acid.

In this way you slowly transport out the fuel from the reactors.

Of course this isn't very useful is your cooling loop starts in the RPV and ends in the basement.

 

[Quim]

the assumption can be made that the basement is slightly pressurised forcing the steamy atmosphere of the basement through this point.

It seems to me that the strategy should be to begin a civil engineering project which will deny the area of the reactors any source of water. Let the blobs of corum reside where they wilt (probably laying atop some very hot concrete sub flooring and at the center of a large and expanding area of very hot material.

Would someone more adept than I find time to do the math and guesstimate how far from the centers of the corium puddles will the temperature of the surrounding rock and dirt be likely to achieve and remain at at least 100c?

If that distance were ten meters or more, wouldn't the natural dried out environment of the pile provide all the buffering with the outside world needed?

Remove or divert any landside drainage or stream flows (below or above ground) and provide good runoff paths for storm water. We're only talking about ten acres or so of land. That doesn't seem like any major civil engineering project.

It would create it's own buffer on the sea side.

The Japanese don't have any history of desert horticulture - this could be their big chance.

Once this very manageably sized piece of land reaches equilibration temperature it will be self regulating and self drying and I can't see why it would ever have any threat of significent emissions.

Stop feeding it water.

Build access tunnels and bury it.
Break out the putzmeisters.

Think of it as an opportunity!
When all you got is lemons, you make lemonade.
New thread?

 

[andybwell]

You guys and gals, of course, knew this all along. Right?

"The dangers of fukushima are greater than we think."

http://us1.campaign-archive1.com/?u=...&id=68c85cc08a

Edit by Borek: large quote possibly violating owner copyright deleted.

 

[swl]

It seems to me that the strategy should be to... deny the area of the reactors any source of water. Let the blobs of corum reside... atop some very hot concrete sub flooring and at the center of a large and expanding area of very hot material...

Once this very manageably sized piece of land reaches equilibration temperature it will be self regulating and self drying and I can't see why it would ever have any threat of significent emissions...

If there were dangerous materials released from the boiling and burning fuel and concrete, including explosive Hydrogen, said materials could be problematic.

 

[Quim]

If there were dangerous materials released from the boiling and burning fuel and concrete, including explosive Hydrogen, said materials could be problematic.

In what manner would a tad of hydrogen gas seeping out of a warm pile of sand be dangerous?

 

[swl]

In what manner would a tad of hydrogen gas seeping out of a warm pile of sand be dangerous?

Another explosion would be bad.

Just a video of the unit one explosion, if you've seen it, no need to click.

But we should be equally concerned about the release of radioactive material from the burning and boiling corium.

 

[Quim]

we should be equally concerned about the release of radioactive material from the burning and boiling corium.

Now that's exactly the point.

I propose encasing it (them) in a ten meter thick* cocoon of dry sand.
You propose pouring water on it .
Right?

Shall we continue from there?


*(ten meter radius around each corium at minimum)

 

[Quim]

Gundersen:

A bit too much hyperbole for me.

He has discredited himself so that I don't listen to him.

But the other side is just as bad.

 

[Quim]

nuclear pool #4

SFP4?

That is not releasing any radiation into the environment .

It is not a current problem and there is nothing preventing the safe unloading of it's contents.

What are your concerns?

 

[elektrownik]

unit 1 SPF 650mm but at 6/5 05:00am, fuel should be exposed now or not long from now

 

[MiceAndMen]

Thanks! Your link is great, now I understand, there is no basement from my perspective, but they call the thorus level basement, as I suspected.

One question, why nobody considers that possibility that the water in the flooded basement has come in contact with the Corium?

That's a distinct possibility. I don't think anyone has ruled it out. It's not much of a stretch to think that the cooling water flowed into the RPV, some of it circulated in contact with the corium at the bottom, and then ended up in the drywell. When the level of water in the drywell rose to the height of the connecting pipes that lead to the wetwell, it flowed into the torus. That path is normally used to convey steam, but those ducts could just as easily pass water once everything at the bottom became flooded.

AntonL mentioned how the torus might want to float if its surrounding trench/basement became flooded. That could be true also, but it's possible the gaseous vent system - electrically operated - failed or shorted out once submerged, and eventually structural failure ensued thus releasing any trapped air/nitrogen/hydrogen/etc.. There was a reported sound of an explosion at Unit 2 early on that TEPCO attributed to structural failure of the torus. Would anyone be surprised if the toruses (tori?) in units 1 and 3 also failed and people just weren't around at the time to hear the noise?

 

[Quim]

unit 1 SPF 650mm but at 6/5 05:00am, fuel should be exposed now or not long from now

Mar22-11, 09:57 AM #833
AntonL

Below SFP data FU = fuel units followed by pool volume and heat load of the FU
Unit 1 - 292 FU 1200m3 60kW
Unit 2 - 587 FU 1425m3 400kW
Unit 3 - 514 FU 1425m3 200kW
Unit 4 - 1331 FU 1425m3 2000kW + 200 brand new FU


Is 60kw a danger?
It doesn't sound like it to me.

 

[MiceAndMen]

You guys and gals, of course, knew this all along. Right?

"The dangers of fukushima are greater than we think."

http://us1.campaign-archive1.com/?u=...&id=68c85cc08a

Part 2

...

That link is dead, andy, and I respectfully suggest that what you posted may violate the copyright of whatever source you got it from. That is way more than a 'fair use' amount of quoting there. Maybe you could find a better link and trim the quoted part?

Edit: It looks like you got if from chrismartenson.com and you basically quoted the entire "Part 2 of Arnie Gundersen Interview: Protecting Yourself If The Situation Worsens". I'm not going to hit the 'report' button on you, but you should really consider editing that post. We can all click on a link to what Gundersen has to say if we choose.

 

[MiceAndMen]

SFP4?

That is not releasing any radiation into the environment .

It is not a current problem and there is nothing preventing the safe unloading of it's contents.

What are your concerns?

I can't answer for him, but I think Gundersen buys into the whole "building 4 is leaning and about to fall over" nonsense. One may draw one's own conclusions there.

 

[MiceAndMen]

unit 1 SPF 650mm but at 6/5 05:00am, fuel should be exposed now or not long from now

Those numbers should be of concern to even casual observers, but all we hear from TEPCO is silence. If it's an instrumentation problem then they should come out and say so. Immediately if not sooner. And if it's not an instrumentation problem then they should have given some sort of public information about it hours ago.

And some people wonder what TEPCO should be doing differently. Pshaw!

@Quim ... Those fuel rods should not be allowed to become uncovered regardless of the current heat load.

 

[elektrownik]

Mar22-11, 09:57 AM #833
AntonL

Is 60kw a danger?
It doesn't sound like it to me.

Yes but they are still hight radioactive, you don't want radioactive fuel rods to be exposed to air... water is not only coolant but also radiation shield

 

[Borek]

I forgot a fourth possibility: The bubbling could be from a hydrogen/oxygen mix produce by radiolysis of water from that 720,000 TBq, but I have no idea what the expected volume per minute would be.

Unlikely - as it was discussed earlier, for the radiolysis to be effective it has to occur in vigorously boiling water, otherwise hydrogen and oxygen have way too much time to combine back.

 

[jlduh]

Mar22-11, 09:57 AM #833
AntonL

Below SFP data FU = fuel units followed by pool volume and heat load of the FU
Unit 1 - 292 FU 1200m3 60kW
Unit 2 - 587 FU 1425m3 400kW
Unit 3 - 514 FU 1425m3 200kW
Unit 4 - 1331 FU 1425m3 2000kW + 200 brand new FU Is 60kw a danger?
It doesn't sound like it to me.

Well, sorry to say this but your conclusions seem odd to me...

If exposing burnt fuel rods was no danger, then it would be very easy to handle the nuclear waste after several months of decay. Obviously we all know (or should know) it is not! You can compare the numbers of decay heat and say that the one in N°1 SFP is lower than the others, especially N°4 which is really more dangerous due to the high number of spent rods, but you just cannot say seriously "hummm 60 KW, that's no danger if exposed"...

As already said, water is a coolant AND a shield. Also even 60KW of heat concentrated for a long time in localized areas if no more water to dissipate it and your temps are going to increase, little by little but as surely as an apple is falling from Newton tree. Could the real specialists calculate the temps at the surface of the rods if totally exposed to air in current radiological conditions of decay? Could they also estimate the radiation we could get let's say at 1m, 10m and 100m, assuming absolutely no shielding?

If Gunderson was discredited for you, then make sure you are not going to discredit yourself ALSO... I think this guy has much more experience in this field than most of us and has proved to be true in most of it's statements (I said most, not all, as I'm also kind of suspect of this N°4 building leaning theory).

 

[Luca Bevil]

Hi to all.
I run a rapid back of the envelope calculation on the CS137 quantity TEPCO estimated.

If I got it right from Wolfram Alpha the activity of CS137 is 3.214 TeraBq/gram.

Having TEPCO estimated overall CS137 at 720,000 TeraBq, that would lead to 720,000/3.214=224,020 grams of CS137.

I then tried to understand in what relation that value is in respect to the total CS137 inventory that can be expeced from 1,2,3 cores.

I know this has been much more accurately estimated somewhere before in this 3d but I unfortunately do not have the possibility of searching the whole discussion right now.

However from wiki I got a fission yield of 6.0899% for CS137. That yield together with the mass ratio of U235 vs CS137 leads me to estimate in about 6.26 tonns the amount of U235 that has to undergo fission to pruduce this amount of CS137 (224,020/0.060899*235/137 grams).

Now if I remeber correctly at 32% of thermal efficiency 1 tonn of U235 has to undergo fission to produce 1 Gigawatt for one year.

Being almost exactly 2 gigawatts the overall power output of the concerned units, it would seem that the estimated CS137 already in the water is in the order of magnitude of 3 yrs worth of fission process.

In other words that would lead me to think that this estimates means that much of the molten fuel is already soluted in water.
On the other hand this conclusion, in a way reassuring, seems unreaalistic to me.

what I am I doing wrong ?
what do you think ?
thanks in advance