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Japan Earthquake: nuclear plants

by gmax137
Tags: earthquake, japan, nuclear
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bytepirate
#3637
Apr13-11, 02:49 PM
P: 61
what i don't understand (one thing out of many, i admit) is:
- explosion and fire in #4 at 15th and 16th
- *nothing* for 4 days
- start of spraying on 20th

is it possible, that the explosion was *not* a hydrogen explosion?
is it possible, that enough hydrogen for an explosion has been generated *under water* (maybe due to the re-racking?)
what has burned? if the zircaloy burned, would it stop burning before its all used up? *if* all zircaloy burned away, wouldn't the release be much larger?

#4 is very strange (#1 as well ... and i am far from grasping, what exactly happened to #2. and #3...)
shogun338
#3638
Apr13-11, 02:50 PM
P: 133
Cask for 38 fuel assembly BWR Type
Provide by Tokyo Electric Power Compay ---I don't know why there showing a pic of the cask . There talking about trying to remove the spent fuel with a crane or another large machine into a new cooling pool now so maybe this has something to do with it . They could put some of the older cooler fuel into these . --- Tepco said it is planning to move the spent fuel rods out of the storage pools at reactors 1 through 4 so they can be moved to a safer location, although details on when and how haven't been decided yet.

Some of the options Tepco is considering include pulling the rods out with a crane or building a special structure nearby to pull them out.
http://search.japantimes.co.jp/cgi-b...0110413x1.html
Attached Thumbnails
cask_38 1.jpg  
AntonL
#3639
Apr13-11, 02:53 PM
P: 521
Quote Quote by sp2 View Post
Umm, forgive me, but how do you possibly know any of this without knowing rates of leakage, or amounts sloshed out in the quake (not to mention more water sloshed out in later quakes, and likely changes in leakage rates over time, etc.)?
Also not to mention that we have no idea if there was water in the pool when TEPCO said there was, and, if so, how much.
Forgive me, but it seems to me you're building your whole analysis there on a mind-boggling set of unsupported assumptions.

Please correct me if I'm missing some things.

Also, is vertical stacking of spent-fuel rods something that's actually done? (Or even can be done?) I thought re-racking referred to cramming in the extra assemblies on the bottom of the pool with the rest?
Is that wrong?

Thanks.
I am presenting the best case neglecting possible leakage and spillage. If the pool was ever completely dry unit 4 would be in a greater mess than it is now,

OK vertical stacking may be a figment of my imagination, but if hydrogen developed that all racks were exposed, that is the pool would be empty, and water was only added 5days later that does not make sense, my explanation seems a bit more realistic.
bytepirate
#3640
Apr13-11, 03:00 PM
P: 61
Quote Quote by shogun338 View Post
Cask for 38 fuel assembly BWR Type
Provide by Tokyo Electric Power Compay ---I don't know why there showing a pic of the cask . There talking about trying to remove the spent fuel with a crane or another large machine into a new cooling pool now so maybe this has something to do with it . They could put some of the older cooler fuel into these . --- Tepco said it is planning to move the spent fuel rods out of the storage pools at reactors 1 through 4 so they can be moved to a safer location, although details on when and how haven't been decided yet.

Some of the options Tepco is considering include pulling the rods out with a crane or building a special structure nearby to pull them out.
http://search.japantimes.co.jp/cgi-b...0110413x1.html
from http://search.japantimes.co.jp/cgi-b...0110413x1.html:
"The temperature was rising and we don't know the water level of the pool, so we thought it would be safer to pour water," said NISA's Nishiyama said.

what is the 'FPC skimmer level', that they publish? i assumed, that this is the waterlevel in the SFP...
TCups
#3641
Apr13-11, 03:01 PM
TCups's Avatar
P: 494
Quote Quote by shogun338 View Post
Cask for 38 fuel assembly BWR Type
Provide by Tokyo Electric Power Compay ---I don't know why there showing a pic of the cask . There talking about trying to remove the spent fuel with a crane or another large machine into a new cooling pool now so maybe this has something to do with it . They could put some of the older cooler fuel into these . --- Tepco said it is planning to move the spent fuel rods out of the storage pools at reactors 1 through 4 so they can be moved to a safer location, although details on when and how haven't been decided yet.

Some of the options Tepco is considering include pulling the rods out with a crane or building a special structure nearby to pull them out.
http://search.japantimes.co.jp/cgi-b...0110413x1.html
The "picture" I attached was my PhotoShop alteration of where it appeared the overhead crane would leave a cask for loading/unloading in the accessory pool. Please excuse me for not being more specific that the illustration was part of my hypothesis, not a known fact.

http://i306.photobucket.com/albums/n...icture30-4.png

As for "conspiracy land for blast damage" -- well, maybe I am a conspirator, but I am starting from pictures of what I believe to be accurate. These include the location of what appears to be the accessory "cask" pool on the working diagram I have, the location shown for the FHM when the overhead crane is in use, the pattern of external damage to the building including the access tunnel and lower floors below the service access floor for the SFP and reactor containment, etc.
PietKuip
#3642
Apr13-11, 03:06 PM
P: 184
Quote Quote by AntonL View Post
If you read my earlier thread this pool must have been boiling since March 14 latest, It has a 2 to 2.4 MeggaWatt heater in it and that boils 67 to 81 Tons of water a day, Tepco are adding 120 Tonnes a day.

Tepco/NISA/NSC are not forthright with the data they provide, it is being squeezed out of Tepco little by little and released to the public even at a reduced rate. After releasing this data today, they will release some more related bad news soon.
They prepared for telling the worst news as early as several weeks ago: Surprise 'critical' warning raises nuclear fears
Jorge Stolfi
#3643
Apr13-11, 03:16 PM
P: 279
Quote Quote by Dmytry View Post
The real question is: How the hell would it reach detonation limit, 18%, without getting ignited first?
Perhaps the rising steam and/or initial hydrogen combustion removed most of the oxygen from the atmosphere inside pool and just above it?

And what about criticality or near-criticality in the #4 SFP, after loss of the neutron-absorbing baffles? Can we rule that out?
gmax137
#3644
Apr13-11, 03:24 PM
P: 854
Quote Quote by sp2 View Post

Also, is vertical stacking of spent-fuel rods something that's actually done? (Or even can be done?) I thought re-racking referred to cramming in the extra assemblies on the bottom of the pool with the rest?
Is that wrong?

Thanks.
I have never heard of vertical stacking - that 23 feet of water above the assemblies is there for shielding when they move the fuel into the rack. If you had a rack on top of a rack, then the top of the fuel assembly being moved into the top rack would be nearly out of the water. No way they would do that, I just can't believe it.

All of the re-racking I've seen is to fill what was open space with more racks or to squeeze the assemblies closer together in a 'tighter' rack.
Jorge Stolfi
#3645
Apr13-11, 03:33 PM
P: 279
Quote Quote by sp2 View Post
Also, is vertical stacking of spent-fuel rods something that's actually done? (Or even can be done?) I thought re-racking referred to cramming in the extra assemblies on the bottom of the pool with the rest?
These docs were posted by user bythepirate :
http://www.iaea.org/inis/collection/...4/29064415.pdf
http://www.irss-usa.org/pages/documents/11_1Alvarez.pdf

These docs (Czech and US) indeed talk only about using a more compact arrangement of fuel assemblies within each rack, packed solid against each other instead of the original very open arrangement.

However "re-racking" is a general term and may include other bright ideas. And even if re-racking at Fukushima was single-layer, they may have used two layers too. Is the estimate above correct (capacity 1444 after re-racking, actual contents 1535)?
cphoenix
#3646
Apr13-11, 03:39 PM
P: 20
Another thing that makes a hydrogen detonation less plausible: There are still panels attached in the top row at building 4. Even at building 1, all panels were blown clean off the top two rows. It's hard to see how hydrogen could have exploded with enough force to damage concrete but left panels intact near the roof.

Meanwhile, something stripped concrete away from rebar in the below-decks row (third from top). That didn't happen even in building 3. And I haven't seen anything that looks like soot. I'd speculated that it was oil vapor that exploded, not hydrogen; that could have been heavier than air, and created a below-decks explosion. But I'd think that would leave soot.

I haven't seen any video of building 4 exploding. Someone else posted that they hadn't either. So, thinking outside the box...

What if building 4 did not actually explode? Is it plausible that most or all of the damage was mechanical, from aftershocks?

In the third-from-top row (the upper below-decks row) there are panels that appear to be made of rebar-reinforced concrete. Some of those panels have rebar exposed around the edges, and flat concrete left in the middle. It's hard to imagine that an explosion would do that. But twisting the beams that the panels were mounted between might crumble the panels from the edges in.

Are there any observations that would contradict the quake-damage theory for building 4?
Dmytry
#3647
Apr13-11, 03:40 PM
P: 505
Quote Quote by Jorge Stolfi View Post
These docs were posted by user bythepirate :
http://www.iaea.org/inis/collection/...4/29064415.pdf
http://www.irss-usa.org/pages/documents/11_1Alvarez.pdf

These docs (Czech and US) indeed talk only about using a more compact arrangement of fuel assemblies within each rack, packed solid against each other instead of the original very open arrangement.

However "re-racking" is a general term and may include other bright ideas. And even if re-racking at Fukushima was single-layer, they may have used two layers too. Is the estimate above correct (capacity 1444 after re-racking, actual contents 1535)?
can they lay extra fuel horizontally?
Dmytry
#3648
Apr13-11, 03:41 PM
P: 505
Quote Quote by cphoenix View Post
Another thing that makes a hydrogen detonation less plausible: There are still panels attached in the top row at building 4. Even at building 1, all panels were blown clean off the top two rows. It's hard to see how hydrogen could have exploded with enough force to damage concrete but left panels intact near the roof.

Meanwhile, something stripped concrete away from rebar in the below-decks row (third from top). That didn't happen even in building 3. And I haven't seen anything that looks like soot. I'd speculated that it was oil vapor that exploded, not hydrogen; that could have been heavier than air, and created a below-decks explosion. But I'd think that would leave soot.

I haven't seen any video of building 4 exploding. Someone else posted that they hadn't either. So, thinking outside the box...

What if building 4 did not actually explode? Is it plausible that most or all of the damage was mechanical, from aftershocks?

In the third-from-top row (the upper below-decks row) there are panels that appear to be made of rebar-reinforced concrete. Some of those panels have rebar exposed around the edges, and flat concrete left in the middle. It's hard to imagine that an explosion would do that. But twisting the beams that the panels were mounted between might crumble the panels from the edges in.

Are there any observations that would contradict the quake-damage theory for building 4?
that none of the aftershocks was even remotely strong enough to so effectively destroy something that withstood original quake?
clancy688
#3649
Apr13-11, 03:55 PM
P: 546
A little bit offtopic:

I heard, that La Hague in france emits several hundred PBq Krypton-85 every year. In my opinion, Krypton-85 is not dangerous to human health, because it's a noble gas and as such very volatile (= doesn't contaminate areas / humans). Furthermore, it has a very short half time in the human body. Is that correct? Or are there errors?

Because 300 PBq Krypton-85 every year sounds a bit much - if it would pose a hazard to human health.
bytepirate
#3650
Apr13-11, 03:57 PM
P: 61
Quote Quote by Jorge Stolfi View Post
These docs were posted by user bythepirate :
http://www.iaea.org/inis/collection/...4/29064415.pdf
http://www.irss-usa.org/pages/documents/11_1Alvarez.pdf

These docs (Czech and US) indeed talk only about using a more compact arrangement of fuel assemblies within each rack, packed solid against each other instead of the original very open arrangement.

However "re-racking" is a general term and may include other bright ideas. And even if re-racking at Fukushima was single-layer, they may have used two layers too. Is the estimate above correct (capacity 1444 after re-racking, actual contents 1535)?
the common spent fuel pool has an area of 12m*29m and can take 76 racks (90 assemblies each). makes a rough estimate of a size of 2m*2m for each rack (based on the picture on page 11 of http://www.nirs.org/reactorwatch/acc...powerpoint.pdf)
the SFP in #4 has 11m depth and contains 1425m, thus the area is roughly 129m -> 32 racks -> 2880 assemblies (?). maybe the racking is more dense in the common SFP?

a *very* speculative thesis:
+ after the quake they tried to re-insert the core to the RPV
- why should they do this?
- two workers were found dead in #4
+ the crane stuck, when the core was directly above the RPV
- covered by water, but not very much
+ water boiled away
+ the core produced hydrogen and an explosion
+ the core fell into the RPV
+ the fire after the explosion has been caused by something else


this would explain the thermal images, that show heat in the place of the RPV.
and this would explain the 4 day 'silence' between explosion and spraying.

but i have to admit, that i am not convinced ;-)
razzz
#3651
Apr13-11, 04:29 PM
P: 205
Quote Quote by cphoenix View Post
Another thing that makes a hydrogen detonation less plausible: There are still panels attached in the top row at building 4. Even at building 1, all panels were blown clean off the top two rows. It's hard to see how hydrogen could have exploded with enough force to damage concrete but left panels intact near the roof.

Meanwhile, something stripped concrete away from rebar in the below-decks row (third from top). That didn't happen even in building 3. And I haven't seen anything that looks like soot. I'd speculated that it was oil vapor that exploded, not hydrogen; that could have been heavier than air, and created a below-decks explosion. But I'd think that would leave soot.

I haven't seen any video of building 4 exploding. Someone else posted that they hadn't either. So, thinking outside the box...

What if building 4 did not actually explode? Is it plausible that most or all of the damage was mechanical, from aftershocks?

In the third-from-top row (the upper below-decks row) there are panels that appear to be made of rebar-reinforced concrete. Some of those panels have rebar exposed around the edges, and flat concrete left in the middle. It's hard to imagine that an explosion would do that. But twisting the beams that the panels were mounted between might crumble the panels from the edges in.

Are there any observations that would contradict the quake-damage theory for building 4?
cphoenix brings up a good point about how concrete appears fractured by impact and not by explosion. Impact from pieces of a motor or tank or some other hard materials in flight hitting a concrete panel would not pulverized standard mix concrete. Lightweight concrete maybe would pulverize, like used for floors since rebar is not normally placed in lightweight concrete flooring applications. Flexing motions usually don't disturb reinforce concrete (bridges: flex, expand and contract like crazy).

Back many posts, read that summary of worst case scenarios where seawater interactions were not discussed and another conclusion (in this day in age) that the properties of hydrogen in particular conditions was not fully understood (yet). Steam or super-heated steam mixing with hydrogen along with some other gases or fuels makes for many variables.

Even one damaged rod in a pool via debris impacting let alone low water level(s) leading to exposed fuel would ruin your whole day.

Overhead cabling tram system is the only way to work and avoid the radiation and preform the heavy lifting required.

I believe the air blast nukes were less contaminating, only because the plume or mushroom cloud ejected higher into the atmosphere since in a controlled burst you could wait for optimum weather conditions.
elektrownik
#3652
Apr13-11, 04:44 PM
P: 296
[QUOTE=bytepirate;3245053]
a *very* speculative thesis:
+ after the quake they tried to re-insert the core to the RPV
- why should they do this?
- two workers were found dead in #4
+ the crane stuck, when the core was directly above the RPV
- covered by water, but not very much
+ water boiled away
+ the core produced hydrogen and an explosion
+ the core fell into the RPV
+ the fire after the explosion has been caused by something else
QUOTE]

Why ? To slow down vaporization of water from sfp ? Fresh fuel which was removed from core has bigger temperature than old fuel, so if they believe that they can restore cooling systems they want to slow down vaporization by removing some fuel from overpacked sfp...
bytepirate
#3653
Apr13-11, 05:00 PM
P: 61
Quote Quote by elektrownik View Post

Why ? To slow down vaporization of water from sfp ? Fresh fuel which was removed from core has bigger temperature than old fuel, so if they believe that they can restore cooling systems they want to slow down vaporization by removing some fuel from overpacked sfp...
but wouldn't that be putting out a fire with gasoline? they have to cool it anyway...

maybe they were just about to reinsert the core (scheduled). quite unlikely, but the whole disaster is quite unlikely too (one in a million years for a core melt with containment failure, i have been told). add (or rather multiplicate) this new unlikeliness and the heart of gold can travel quite a bit...
Jorge Stolfi
#3654
Apr13-11, 05:03 PM
P: 279
Does anyone know what is the topscale reading of the Fukushima Daiichi CAMS meters (100 Sv/h?) (I cannot find that info with Google.) Thanks...


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