Japan Earthquake: nuclear plants

MadderDoc

It is not a continuous rail, it is in 6 sections corresponding to the wall structure. The sections appear to have been laid out on slip pads on top of the pillar supports. This would seem to be in order to guard against heat expansion's cracking up the building over time, so the rail sections are unlikely to be firmly attached to the pillars. The rails sections from the west wall seem to have just slid off the wall pillars once they landed top down.

zapperzero

I am not saying there was no heat involved. I am saying that the blast bent and scoured those beams. IOW, some of the superficial damage that you see (rusty bits where paint used to be) is caused by heat. The sagging and twisting, it's because of the blast and (afterwards) gravity.

Please, don't tell me you believe those beams were melted into that position.

I mean, sure, there is enough energy in a ton (or even half-ton) of hydrogen to do that. But how was it done? Those beams were not melted one by one with a H-O torch. They were blasted. You can see the blast yourself. Why do you find it hard to believe that it could have bent and twisted steel? Do you not think a pressure spike of 1.5-2 MPa (at least, much higher if reflected) could have done what we are seeing?

Take a look at this, please.
http://www.hysafe.org/download/1009/...on%201_0_1.pdf

LabratSR

Scheduled Access Route for the Robot (Quince 2) of the
Investigation in the TIP Room on the First Floor at Unit 3
Reactor Building, Fukushima Daiichi Nuclear Power Station

http://www.tepco.co.jp/en/nu/fukushi...20522_02-e.pdf

MadderDoc

Perhaps. You are not being very specific, I much prefer to be working from evidence.

I think it is fair to say that the roof construction of Unit 3, or what remains of it is _not_ uniformly damaged, and in that context the SE corner of the construction stands out as being in particularly worse shape. Also it appears to be damaged in ways or degrees we do not see elsewhere. While most parts of the roof construction could well with some mechanic work be reconstructed reusing most pieces, the SE quadrant looks like a scrap the lot job (or whatever of it you can identify) and do a total rebuild.

Likewise, looking at the east wall, or what remains of it, it is not uniformly damaged. The south half of it is the more damaged part. Within the north and the south sections otoh, the damages share a common pattern, as regards e.g. discoloring and concrete matrix degradation. In the north section the roof construction has neatly come unplugged from its sockets on the pillars. In the south section the complete top layer of the pillars with the sockets come off in pieces, and it is not at all clear that anything there became neatly unplugged.

Then of course there is the video evidence, which again indicates a peculiarity, a prominent fire phenomenon, linked to the SE corner of the building.

To be sure 'hydrogen explosion' can go a long way to explain the damages to Unit 3, in general terms. And there are some knobs one can screw on. More hydrogen, more flame front speed, its all on the shelves for the picking. But, what does it do to explain the peculiarities? High on my wishing list would be the explanation of the peculiar damages to the SE corner of the building and its curious coincidence with the peculiar fire phenomenon above that corner, one of the hall marks of the Unit 3 event. While of course the peculiar mushroom cloud and its curious coincidence with a pressure drop in the reactor tops the list..

zapperzero

Frames 1-15 in the glydensgaard thing. That's a fireball.

Oh, yes.

The explosion originated in the S-E corner, so I'd expect the peak overpressure to be higher there. The thing you insist on calling a "fire phenomenon" looks to me like your regular run-of-the-mill fireball. Would you say it's something else?

Peculiar how? Blasts make mushroom clouds. Bigger the blast, bigger the cloud. 1 ton of hydrogen is nothing to sneeze at.

Ah. The pressure drop. There was a nice theory, back there in the killed explosion thread, as to how the hydrogen explosion may have made a lot of water in the SFP flash-boil, to produce the steam. But maybe it didn't, or not so much. Maybe some pipe broke somewhere, or the reactor cap was jarred, and it burped.

I am in a peculiar situation. I know how to explain, but I don't know that there is a way to make you, or anyone else who has never seen a big (or even moderate) explosion and its immediate effects understand just how destructive they can be.

I am very okay with the hydrogen explosion theory, because of Occam's razor. I'd even be happy with a "mere steam explosion" theory, were it not for the fireball we can so clearly see.

I found this thing, maybe interesting:
http://www.japantimes.co.jp/text/nn20110607a5.html

The chief of the JSDF firefighter crew whose men were injured on the day says they saw 20 mSv/h in the immediate aftermath of the explosion.

MadderDoc

By 'fireball' I would understand a detached roundish area of space with ongoing combustion, drifting by its own inertia and buoyancy. The fire phenomenon over unit 3 otoh appears to be stationary, to have an origin, to shoot out of the building as a jet, and to wax and eventually wane into the smoke, as if its source of fuel was being cut off. Since the phenomenon is not unambiguously a fireball, I prefer not to call it that, until the nature of it has been resolved.

I wouldn't _dream_ of sneezing in the presence of 1 ton of hydrogen confined in the upper floors of unit 3. Assuming it is mixed with air, that would be close to stoichiometric, I could get myself killed :-). But seriously, 'Blasts make mushroom clouds. Bigger the blast, bigger the cloud.' doesn't cut it. You've got 1 ton of hydrogen: so how big a mushroom cloud, of which composition, would that be able to produce? Cf. "He who refuses to do arithmetic is doomed to talk nonsense."

Yes, that was an interesting aspect to the story. Funny how in retrospect that JSDF mission has become fuzzily one of "to spray water onto the crippled reactor". In fact the problem was that Tepco was running out of seawater in the backwash pit to inject into the reactor vessel of Unit 3. They had moved the hose to the deepest spot of that pit to be able to get the last drops out of it, while they were desperately trying to secure water, any kind of water to refill the pit. Then in the morning of March 14th, those SDF water supply vehicles arrived, each with 5 cubic meter of fresh water, which it was decided to dump into the backwash pit. The first of these vehicles were about unloading its cargo, when the building exploded.

MadderDoc

Occam's razor does not say that either mere this, or mere that, is to be chosen as the better explanation, simply because it is simpler. What it does, that razor, is to prod kindly not to add to an explanation any complexity which does not add explanatory power. Thus, if you was happy with 'mere steam' then it would be because you already felt it explained things. And if you then saw a fireball, it would be perfectly alright with Occam to make further assumptions to your 'mere steam' theory, modify it, such as to make it explain that fireball too. Unless of course you've found evidence to contradict you present theory, that is another cup of tea.

However, in the present context there seems to be nothing contradictory in having steam as well as hydrogen involved in an explanation of the events in Unit 3. In fact these events played out in the presence of a high grade potential source of both, and with limited opportunity for release of one without the other.

zapperzero

The shock front pushes the hydrogenated air in front of it away, until there is no more hydrogen (cut off). This is a hydrogen blast, not a puff from your local RenFaire fire-eater.



Well if I could do it, I would. I can tell you how many tons of water vapor you get from burning a ton of hydrogen and how much volume it would occupy at normal temp and pressure. Would that help?

I cannot tell you what else was in the air inside that building or what else is in the cloud (although I strongly suspect there was a lot of steam from the SFP), I cannot tell you if there was an inversion layer that day or how high it was, I can't tell you the outside temp. I cannot say exactly what the nature of the black smoke is, although I strongly suspect it is powdered ceiling. So... sorry, approximations and guesswork it is.

Funny coincidence, that. I wonder if water injection had already stopped.

SteveElbows

I know its been pretty quiet in terms of news this month, but I am under the impression this will change by the end of the month. I think someone already mentioned the reactor 3 TIP room survey, but there are a few other things happening as well:

There will be a new press tour on Friday which I suppose should give us a few new images. Its likely to focus on reactor 4 again due to ongoing noise about the danger of pool collapse, which continues to cause them PR headaches.

According to a press report that I cannot lay my hands on right now, they have been doing robot gamma camera surveys inside the reactor building to identify containment leak points that will need to be fixed. Data from this survey is supposed to be compiled by the end of May. I believe its for reactor 3 but I need to double-check this detail.

Also I note this report in the business press, but I haven't tried looking for the original source document yet:

http://www.businessweek.com/news/201...sus-government

zapperzero

We are in violent agreement on this one.

MadderDoc

Does your observations of this shock front allow you to estimate its speed?

It seems OK, for a starter.

Well, perhaps you can think of something. The options for what gases could have been around apart from hydrogen are limited.

Funny thing is that any source (that I've been able to find) leaves uncertainty as to whether injection to the reactor pressure vessel was ongoing at the time of the explosion. Only thing that is clear is that water transfer to replenish water to the drained backwash pit had been started.

MadderDoc

Let's just hasten on then, there's nothing to be learnt from violent agreement.

zapperzero

Yes. You can estimate it yourself, even, from the video you posted. I'd say it's supersonic, but only just.
14400 cubic meters of saturated steam, or a sphere roughly 15 meters in radius, if I have not misplaced my brains again.

I think it was jim hardy who suggested that because of the decrease in pressure, the SFP may have flash-boiled, releasing huge amounts of steam and nearly emptying itself in the process.

zapperzero

You'd think by now we'd be able to invent a robot that can twist and pull door handles. Disgusting.

radio_guy

both quince and the packbot can open doors.

there must be some situation that makes it not ideal for them to do this to have a human go in, open the door then send the robot in?

MadderDoc

Perhaps somebody can figure out the function of the human from the video of the similar expedition to the TIP room of unit 2:
http://photo.tepco.co.jp/en/date/201...20322-02e.html

jim hardy

no, i remember that suggestion being made though.
i dont see a mechanism for that much heat transport into pool.
so i didnt comment on it.

my observation was this
if you could get 10^18 neutrons into the fuel that's in the pool
and fuel there had Keff of 0.95 (not unreasonable)
it should make enough heat to boil about a thousand pounds of water into steam, which is a good cloud.
But i couldnt come up with a source of that many neutrons arrviing in pool without an unfortunate and exotic series of events. Even if the core were up in the steam separator region of RPV it's still a couple tenth value thicknesses of concrete from there to pool, and substantial water. At home i have a cross section drawing of the building showing the path.. Looks might unlikely.

So i have settled in with mdoc's 'other source' for steam.
unless you guys find some other evidence like the wall between RPV and SFP to be blown away, which i doubt.

old jim