Japan Earthquake: nuclear plants

elektrownik

A lot of steam/smoke on tepco web cam, I didnt saw so much sience many days...

clancy688

We had that discussion about core damage maybe a week or so before.

Core damage is estimated by drywell and wetwell radiation, they're recalculating how much of the core's inventory is outside the zircalloy shielding based on these numbers.

See here: http://physicsforums.com/showpost.ph...postcount=5187

The only information these estimates provides us is "there's x% of the core inventories inside the RPV". It doesn't say anything about meltdowns.
It's also possibly that nothing has molten, but the zircalloy ruptured and great parts of the fuel rod's fission products were simply washed out.

GJBRKS

Oke , perhaps not molten , maybe broken

But it 100% cannot be above the waterline , so all former fuel % above the current waterline is damage %

default.user

We had the development of hydrogen gas. This is only possible if zirconium is delivered at a temperature of at least 800 degrees Celsius.

It is fair to speak of a molten core.

Let us not always start from point zero. the facts are proved scientifically.

Uranium pellets have a higher melting point. That's right. It says nothing about a possible criticality of the corium.

We have, therefore possibly increasing or constant temperatures in the reactor cores.

We have corium, whose whereabouts is not clear.

We have no values ​​of deuterium, americium or cobalt. All these data would be needed for a reliable analysis of the situation on the ground.

wrote with google-translator

Kind regards from germany

jpquantin

Yes skimmer surge tank and SFP communicate through their upper part, and FPC skimmer level does not give SFP level. However, it gives an indication on the moments the SFP is full, and whether a water injection or spray fills in the pool or not.

If FPC skimmer level increases, it means water has overflowed from the SFP, and thus that the SFP was full during the previous water injection / spray.

Amount of water added between two "SFP full" signals gives an estimate of the amount of its losses between those two signals.

Second indication is given when dealing with temperature. The only reported SFP temperature is that of SFP2. Temperature increases with skimmer level. Temperature of the SFP seems to be measured in the FPC skimmer. When SFP overflows, water coming from it flows in FPC skimmer, mixing with water already there. One could deduce temperature in SFP, when we have temperature and level before and after overflow.

Now what does it tell us for the various SFP ?

SFP1: skimmer level has never raised, even when Tepco performed the (only reported) refill on Mar 31st (90 tons). We have no proof by this measurement that SFP1 has enough water. We can wonder how Tepco follows SFP1 (absence of steam above SFP1 ?).

SFP2: we have 9 signals showing that SFP was full (between brackets the tons of water required to get "full" signal again, followed by the caculated loss rate [tons per day])
- 01/04/2011 17:05
- 04/04/2011 13:37 (70 => 24.5)
- 10/04/2011 12:38 (96 => 16.1)
- 13/04/2011 14:55 (60 => 19.3)
- 16/04/2011 11:54 (45 => 15.6)
- 19/04/2011 17:28 (47 => 14.5)
- 22/04/2011 17:40 (50 => 16.6)
- 25/04/2011 11:18 (38 => 13.9)
- 28/04/2011 11:28 (43 => 14.3)

SFP2 seems basically quite full all the time. Its max loss in this period is 96 tons, which is roughly only 6% of it. SFP2 level seems under control. What about temperature ? For example, for the last "full" event (28/04/2011 11:28), level before overflow was 5400 (millimiters in skimmer) and temp was 50°C. After it, was 6000 and 71. What was the temperature of the added Water, assuming FPC skimmer is of cylinder form ? Well FPC skimmer 2 has leaks, which are about 400 millimeters per day.

So at the exact end of injection, level could have been 6400. Well my own calculation shows water temperature above boiling point ... Any clue to calculate this ? Any info on FPC skimmer form and dimensions ?

SFP3: we have no report of FPC skimmer level. The only information is that they have added at least 1000 tons of water to it since beg. of earthquake. For SFP3 also we can wonder how they monitor the level of it (and temperature).

SFP4: we have only 4 signals (same reporting than SFP2):
- 13/04/2011 06:57 (prior to this: about 1550 tons injected / sprayed)
- 15/04/2011 18:29 (140 => 56.4)
- 17/04/2011 21:22 (140 => 66)
- 27/04/2011 14:44 (1210 => 124)

SFP4 has important losses. Simply by boiling, SFP4 would lose max 71 tons per day. The last figure tells us that SFP4 leaks, and is capable to leak importantly (53 tons per day in some circonstances). One important fact is that losses became accelerating since Apr. 17th. The most problematic is that I do not see any refill since the 27/04/2011 14:44; extrapolating this could mean SFP4 has left about 570 tons since then, roughly 1/3 of its height (assuming gate is still there ...). When was the video showing SPF4 underwater was taken ?

hbjon

The reason gold can be panned is because it is heavier than water and all the other material that is is suspended in. I can't see U235 or U238 washing too far away. And why is it some users can get away with putting up nonsense and I get threatened within an inch of my life? Kind regards from Minnesota.

elektrownik

There is something wrong, I never saw so much steam/smoke on tepco web cam sience tsunami, It looks very bad...
http://www.tepco.co.jp/nu/f1-np/camera/index-j.html

SteveElbows

April 28th according to TEPCO.

Thanks very much for the quality thoughts on the fuel pools. Earlier on I had been taking the published readings as direct indications of pool height, and it was only when I looked at the trends over time that the real story of the skimmer surge tanks & their relationship to the pool started to dawn on me. So your post was very helpful and saved me lots of work.

I will probably still try to keep somewhat of an open mind about this data and what it means, just in case there is some factor we are missing, or for example if they have already tried to convert the raw skimmer water temperature into a pool temperature before publishing the data. I doubt this but its just one example of things I cannot be sure about.

Certainly I believe they have some other data available to them that does not get published very often, but I've no way to know how often they get this data themselves and choose not to publish. For example I believe they have mentioned the unit 4 pool temperature being at 91 degrees C at some point, perhaps just before they went on the massive spraying binge that finally ended on the 27th. I assume they used a sensor hanging from the pumping crane, but detail or regular updates on these temperatures are not often to be found. Perhaps they really arent measuring it more often than we get to hear about, but if I were them I would want as much data as possible.

Borek

Have you checked temperature at the place?

bytepirate

i happen to live near a 'cloud factory' (that's how my children call it, we would say cooling tower ;-))
the amount of steam seen varies a lot with weather conditions (btw even the colour does, sometimes it looks like smoke from some angles, when it's certainly only steam).

i would not worry to much.

EDIT:
almost the same as here, i am tempted to take a walk to compare with my cloud factory ;-)

http://www.weather.com/weather/today...Japan+JAXX0010 (i know, fukushima city is way from the plant. should not make a big difference though)

triumph61

There are Water Level Data.
The Level rises at27. (last time spraying)4250mm suddely to 28. 6550mm. Today the Level is 5550mm.
At 27. Tepco said the Pool is leaking. At 28. Tepco said the Pool is NOT leaking. Whats happend? Did they find the leaked? Perhaps they also restore the cooling?

MadderDoc

I am sure you have noticed that a part of the metal roof structure is missing on the roof in the south end. That's because in the course of the blast it ended up in the yard between units 3 and 4. Fortunately its attachment to the south edge of the roof has been that much retained that one can see that one end has been torn apart, while the other end appears to have been affected by a similar heat-damage what we are talking about effect. Are we to assume three separate fire/blast events, two on the roof and one in the yard?

Detail from one end of the roof structure landed in the 3/4 yard:

MiceAndMen

That was my reaction as well. houseoffoust has managed to collect a few items of interest but the presentation and analysis is frequently amateurish.

~kujala~

Sorry if this has been discussed earlier.

France's IRSN has calculated that SFP 4 would lose max 115 tons per day.

http://www.world-nuclear.org/info/fu...nt_inf129.html

MIT has calculated that even after 1 year the decay heat for units 2 & 3 after scram would be 5 MW per unit. Units 2 & 3 contain the same amount of reactor fuel assemblies that SFP 4 has spent/partially fuel assemblies (4 months old).
http://mitnse.com/2011/03/16/what-is-decay-heat/

(MIT is stating that their calculation is conservative, though.)

How was this 71 tons calculated? And can we be absolutely sure about it?

jlduh

To Steveelbows: thanks for the quite exhaustive summary of the evacuation decision versus released contamination data sequences, most of the articles you list have been posted or discussed here in early pages of this thread (i remember reading most of them...), but this is important at some point to assemble individual images to build the "film" of the events. I remember very well the fact that in many statements, there was this dichotomy: alarming results in some areas (North west mainly) BUT no worry, no immediate health risk and so on (i wrote one post on this special dialectic). Your demonstration is pretty self explanatory of what some other members were trying to enlighthen...

To Fluuketies: very interesting photos, very very interesting really. They must have been posted by a Tepco employee, don't you think? Surprised to see so many pictures of cracks in the shroud core and lost objects in places where they shouldn't be (SFP, torus, well, etc.)

To GJBRKS; the document you posted from Lochenbaum

http://www.ucsusa.org/assets/documen...s-excerpts.pdf

is also VERY INFORMATIVE on SFP's failure modes from safety stand point! I'm currently reading it and you can learn a lot about these SFP's and their extended number of spent fuel rods -up to sometimes 7 cores (cited in this document)- whereas the initial design (and safety considerations) was only for 1/3 of a core...

This doc (published in 1996!) clearly illustrates the increases of risks due to the lack of spent fuel treatment options; so they accumulate in greater numbers over longer time in SFP, which is, based on this document, a much higher risk in terms of radioactive consequences than the ones associated with core damage (no containment, bigger amount of fuel, etc.).

Concerning the "bellows seal" whose temperature is rising at N°3 reactor (205°C currently), so this seal in fact is situated (if i understand properly) at the top end of the reactor: it seals the reactor vessel with the drywell, which is necessary during refuelling operations. During refuelling, the containment cap and the reactor cap are removed and water is poured in the well above the opened reactor. This seal is used to create the waterproof volume filled with water (the well). If this seal is leaking, then water during refuelling would leak directly into the containment vessel.

jim hardy

i too wonder about those explosions, especially unit 3, and await the condition of the reactor vessel & containment.

I doubt the fuel pool had anything beyond a zirc-water fire.
That is exothermic as you all well know, in fact reacting a pound of zirconium with water releases about 1/4 as many BTU's as burning a pound of coal with air. And of course a fair bit of hydrogen.
So a fast zirc-water fire would be a vigorous event that'd exhale a cloud of H2 ready to burn as soon as it got mixed with enough air.. that's sure plausible.

i am curious about the orange flash at beginning of #3 video, and if you find the right youtube there was one in first fraction of a second of unit 1 as well. Both orange flashes went horizontal.

As pointed out in someone's earlier post , i too thought hydrogen burned invisible and in unit 1 video you can sorta see a distortion in the air moving out and up in first few instants of blast.

<Speculation alert> might that be the hydrogen cloud igniting?

I'd post a link to a good video image , but last time i did that it disappeared from Youtube a few hours later.

Does anybody know of a frame by frame?

And is there anything to be gleaned from the burst of orange flame?
Orange is the color of burning salt but they weren't spraying seawater into the pools yet, as best i could find.

if this is just board clutter - advise and i'll desist. i troll for fish not attention.

old jim

jim hardy

[q]This doc (published in 1996!) clearly illustrates the increases of risks due to the lack of spent fuel treatment options; ...[/q]

now you're on the same soapbox i preach from.

We as a nation are not doing right by spent fuel. The promise was for a robust reprocessing industry to deal with it and that didn't happen.
John McPhee's book "The Curve of Binding Energy" is a fascinating glimpse into the whys.

if we aren't willing to do something well we shouldn't do it at all.

old jim