Japan Earthquake: nuclear plants


by gmax137
Tags: earthquake, japan, nuclear
M. Bachmeier
M. Bachmeier is offline
#829
Mar22-11, 09:15 AM
P: 184
Quote Quote by AntonL View Post
BLAST MECHANISM AT FUKUSHIMA
Why the SPF water level went low, certainly wave action initiated by the earthquake are a cause, the earth shook for minutes instead of seconds, I believe 5 minutes, Kobe earthquake was 15 seconds. Other reasons like leakage or borrowing water for cooling reactor to avoid
meltdown, we can speculate.
Consider again the effects of the initial earthquake:

(1) Report from worker inside #4 at the time of the earthquake describing equipment (likely heavy) brought in for inspection toppling over (large potential for damage to key systems).

(2) The tectonic plate under the area dropped, now leaving several coastal areas subject to flooding due to high tide. Take a rectangular container of water (full near to the top) and drop it 5 cm to a hard flat surface and see how much water is lost. Now grab hold of that same container and shove it 5cm to the side and measure how much additional water is lost.

(3) What was the height (above sea level) of the plant before and after the earthquake?

(4) How far to the east did the entire land mass shift?

Obviously (4) is an oversimplification, but one could get an idea of how much energy was transferred into wave motion in the SFP. The energy was transferred over approx. 5 min. so there's no way to be sure if the wave amplitude of successive motions were more additive or had the effect of canceling out, but since the local effect was to drop down and move toward the east it would not be unreasonable to expect significant water loss (in all SFP's) and that kind of wave motion could damage the transfer gates regardless of power loss and seal failure. Add to that a loss of circulation (cooling system) and the rate of evaporation increasing with temperature rise and you don't need any other explanation for reactor #4's SFP.
Reno Deano
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#830
Mar22-11, 09:21 AM
P: 128
Busy minds and good speculation. Would like to know just what vent path was used by the operators to vent the reactor and primary containment (PC)? The space between the shield plugs anbd the PC Dome Cap (Steel) probably would not contain enough hydrogen to blow the shield plugs off, but just displace them and open another vent path.

Just some idle thoughts.
TCups
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#831
Mar22-11, 09:43 AM
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P: 494
Not a nuclear engineer here, and maybe I have some fundamental misunderstanding that needs to be corrected, but . . .

What the heck is the whole "torus" design and function about if not for containment of pressure vented from the reactor vessel???

If there is a pressure containment function implied by the torus design, under normal circumstances, why wouldn't the RV be vented into the primary containment and torus?

If there were some unusual or emergent circumstance, why might the RV be vented elsewhere (ie to the outside of the primary containment?)

If hot hydrogen gas, under pressure, were accumulating in the torus and drywall containment, wouldn't it tend to rise, accumulate under the drywell cap, potentially leak from under the drywell cap and then spontaneously vent externally?

If the accumulated hydrogen within the drywell and torus containment were to ignite and explode, wouldn't the exit path of the explosion "vent" through this same pathway?

I am obviously somewhat confused here.

artax
artax is offline
#832
Mar22-11, 09:56 AM
P: 159
someone's removed the shake from some of the vids but the bit I'm interested in isn't there!
http://www.youtube.com/user/KurtsFilmeVideo#p/u
AntonL
AntonL is offline
#833
Mar22-11, 09:57 AM
P: 521
Here is a time line of the explosions and reported CV venting
Unit 1 - 12.03.2011 at 15:36 : CVv 15:00 on 12.03.11
Unit 3 - 14.03.2011 at 11:01 : CVv 09:20 on 13.03.11
Unit 4 - 15.03.2011 at 06:14
Unit 2 - 15.03.2011 at 06:20 : CVv 11:55 on 13.03.11

There is a correlation between Unit 1 CV venting and Hydrogen blast.

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 (yes 2MW not a typo)

This sets a new light on my earlier proposal
Unit 1 exploded due to H2 leak of venting system - possibly earth quake damage
Unit 2 to 4 exploded due to hydrogen generation from equipment pools.
Reno Deano
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#834
Mar22-11, 09:58 AM
P: 128
The Torus is design for steam water suppression during a LOCA. Venting of gas from the Dry Well and RPV is via other systems.

See: http://www.nrc.gov/reading-rm/basic-ref/teachers/03.pdf
romillyh
romillyh is offline
#835
Mar22-11, 09:59 AM
P: 5
Re M Bachmeier comments in Post 830:

For anyone who's in any doubt about what a strong ground wave looks like, how fast it travels, and what it can do to objects of any weight, it's worth looking at a rather grisly video of an underground H-bomb test for Project Cannikin in Amchitka, Alaska. Blast was magnitude 7.0 on Richter scale. Detonation was 2 km below surface. Video is just 0:47 long.

http://www.youtube.com/watch?v=qp6aZIhHiRE

Imagine this going on for 5 mins! Are the Fukushima plants "anchored" directly to the ground/rock (i.e. they take the full force of the bucking), or do they have some kind of disconnect to absorb strong ground movements, as one understands quake-"proofed" buildings in Japan do?

Re 5 mins: From memory, seismic trace of the main M9 quake as recorded by the British Geol Survey in Edinburgh can actually be seen continuing for around 50 minutes, though this was recorded the other side of the planet (echoes, reverbs?) and the after-events obviously tail off in magnitude after the main shock.
romillyh
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#836
Mar22-11, 10:02 AM
P: 5
And sorry, I should add to that last message (836) that I saw somewhere that the force of the quake at Fukushima -- what actually hit it, as opposed to the magnitude 9 over the epicenter -- was around M7.
donvance
donvance is offline
#837
Mar22-11, 10:06 AM
P: 1
I bought my Iodide tablets for me and my family! Being prepared is important! Do not be fooled by the Iodate tablets, Iodide is the way to go! They are good for a 14 day protection!
Get some everyone and be prepared, or just spend 1000's and build yourself a fallout shelter???
AntonL
AntonL is offline
#838
Mar22-11, 10:08 AM
P: 521
Quote Quote by TCups View Post
Not a nuclear engineer here, and maybe I have some fundamental misunderstanding that needs to be corrected, but . . .

What the heck is the whole "torus" design and function about if not for containment of pressure vented from the reactor vessel???

If there is a pressure containment function implied by the torus design, under normal circumstances, why wouldn't the RV be vented into the primary containment and torus?
[/IMG]
Under 'normal' circumstance steam is vented from RV into the torus and bubbled through the hopefully cool water so condensation can take place and CV pressure should not rise only the torus water level would rise.

Under 'meltdown' condition steam and H2 is vented from RV into the torus. If CV pressure rises CV contains steam and compressed H2 and N2 - no O2.

Torus is part of the primary containment and in later models no longer used as in the Mark 3 reactor
Fukushima Daiichi Units 1 to 5 are Mark 1 and Unit 6 is a Mark 3


When a melt-down takes place you want no water near it otherwise you will have a steam explosion.
The torus, in mark 1, and meltdown containment in mark 3 keep the water well away from the hot meltdown
Borek
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#839
Mar22-11, 10:32 AM
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Quote Quote by donvance View Post
I bought my Iodide tablets for me and my family! Being prepared is important! Do not be fooled by the Iodate tablets, Iodide is the way to go! They are good for a 14 day protection!
Get some everyone and be prepared, or just spend 1000's and build yourself a fallout shelter???
Taking them without a reason is dangerous for your health. I guess someone made a perfect deal selling you something you don't need.
Reno Deano
Reno Deano is offline
#840
Mar22-11, 10:45 AM
P: 128
Quote Quote by donvance View Post
I bought my Iodide tablets for me and my family! Being prepared is important! Do not be fooled by the Iodate tablets, Iodide is the way to go! They are good for a 14 day protection!
Get some everyone and be prepared, or just spend 1000's and build yourself a fallout shelter???
Iodine levels at 100 times background is not dangerous at all. BTW, I assume your doctor told you about the possible serious side affects of taking KI? Can you imagine being in a underground shelter during a 9 magnitude earthqake?

The off site contamination is being blown way out of proportion. They should be discussing the actual relative low risks of eating foods with only slightly higher than background radionuclide contamination. Tens of thousand of nuclear works and bomb testing fallout survivors that received thousands of times hight doses, did not suffer any serious consequence over their exposures. Very low concentrations of long live primordial Uranium is present in most of our water and food stuffs anyway.
TCups
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#841
Mar22-11, 10:49 AM
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P: 494
Quote Quote by AntonL View Post
Under 'normal' circumstance steam is vented from RV into the torus and bubbled through the hopefully cool water so condensation can take place and CV pressure should not rise.

Under 'meltdown' condition steam and H2 is vented from RV into the torus. If CV pressure rises CV contains steam and compressed H2 and N2 - no O2.

Torus is part of the primary containment
OK, so . . .

1) In unit 4, it is beyond dispute -- if the explosion was a hydrogen explosion, then the hydrogen came from spent (and possibly un-spent) fuel rods in the SFP, not in the empty RV.

2) In units 1, 2, 3, if hydrogen exploded, it would need oxygen and therefor, the source of the explosion was not within the RV

3) In units 1, 2, 3, hydrogen could have been and was likely to have been produced by both an overheating reactor core in the RV and by overheated fuel rods in the SFP.

4) With loss of cooling, the hot cores in the reactor were, IMO, the more likely first source of trouble and first source of hydrogen production (correct?)

5) If a RV's steam and hydrogen were vented into the drywell torus, bubbling through the suppression pool of cool water, would the hydrogen then be in an atmosphere of air or of nitrogen, flooding the torus?

6) Is it possible for hydrogen (or hydrogen and oxygen) to have accumulated in the upper portion of the drywell containment, near the drywell cap, under pressure (for example if the normal venting system -- ducts, pipes -- had been damaged?

7) Except for Unit 4, why IYO, is the source of exploding hydrogen more likely from the SFP than, somehow, from the RV via leakage into the primary containment?

8) Is it not possible or even likely, that whichever came first, if an explosion occurred in Unit three, then both accumulated hydrogen in the upper building, external to the primary containment, and hydrogen leaking from under the drywell cap, would have ignited and led to explosions both inside the drywell containment and inside the upper building structure?

9) Why do you think the SFPs were the primary source of all explosions?
M. Bachmeier
M. Bachmeier is offline
#842
Mar22-11, 10:49 AM
P: 184
Quote Quote by donvance View Post
I bought my Iodide tablets for me and my family! Being prepared is important! Do not be fooled by the Iodate tablets, Iodide is the way to go! They are good for a 14 day protection!
Get some everyone and be prepared, or just spend 1000's and build yourself a fallout shelter???
Yes, I think it's a 'miracle' that there haven't been more attempts to advance questionable remedies, concoctions, 'medicines' and alike associated with fears of radiation. What do you think????????????

Sorry for being off topic... I just couldn't help myself.
AntonL
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#843
Mar22-11, 10:52 AM
P: 521
Quote Quote by TCups View Post
9) Why do you think the SFPs were the primary source of all explosions?
By demonstration of Unit 4
AntonL
AntonL is offline
#844
Mar22-11, 10:58 AM
P: 521
Now German tabloid Bild reports that unit 1 reactor temperature has risen to 380 to 390 degrees C, normal operating temperature is 300 degrees C, for days we had no temperature indications. I conclude that batteries must be recharging so control room function is coming online.
TCups
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#845
Mar22-11, 11:02 AM
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P: 494
Quote Quote by AntonL View Post
By demonstration of Unit 4
But Unit 4 was unique in that the unspent fuel from the core was removed from the core and put in either the SFP (most likely) or as some suggested, in the equipment pool. Either way, the rods in Unit 4 wold have been "hotter", and yet, the explosion in unit 4 came last. That could have been a difference precipitated by earlier or greater loss of coolant in Units 1, 2, and 3. Possible, but not entirely likely, IMO -- unless coolant "borrowing" was somehow in play.
Arcer
Arcer is offline
#846
Mar22-11, 11:26 AM
P: 14
Quote Quote by artax View Post
BUMP!!

Not a very good image I know, but the vid has been pulled from you tube japan, and these fuel rods are s'posed to be a few cm thick and four metres long, and I assume very stiff as they're ceramic (?) or is that just the pills inside?
Anyway, would anyone else like to suggest what these are falling out the back (seaward or eastern side of unit 3
At a rough count there seems to be about 30 to 40 of those rods scattered about which is about a full fuel rod assembly. Most of them seem to have fallen and come to rest as a loose bundle with the rods almost in parallel.

That's as if they'd slid out together through a hole in the building wall. With the cask lorries parked outside it's possible they're new fuel rods decanted out of an open transport cask during inspection after delivery. Maybe a transport cask overturned? Or a new fuel rod storage canister might have overurned and spilt part of its fuel rod contents. It doesn't explain how the wrapping bands around the assemblies might have broken but maybe they're not as tightly bound together as they appear in photographs.

It's speculation of course.


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