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Japan Earthquake: nuclear plants

by gmax137
Tags: earthquake, japan, nuclear
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NUCENG
#7759
May18-11, 01:22 PM
Sci Advisor
P: 916
Quote Quote by Jorge Stolfi View Post
AFAIK, the space just below the reactor pressure vessel is densely packed with pipes, cables, and the hydraulic actuators of the conctrol rods. So any corium that breaches the RPV will have to melt through or flow around that mess before it reaches the concrete cap at the bottom of the drywell.

Could it be that the black smoke of #3 was caused by corium coming in contact with the hydraulic fluid of the actuators? The oil could have either burned inside the drywell, with whatever oxygen remained there, or it may have been vaporized and burned after escaping the drywell.

It seems that the steam emitted by #3 is leaking from the primary containment (into the refueling opening, and escaping from there through gaps around the service pool gates). The black smoke apparently came from the same area -- i.e. the service floor, as opposed from the lower levels. There seems to be little on the service floor that could burn.
The hydraulic fluid is water.
SteveElbows
#7760
May18-11, 01:28 PM
P: 630
Quote Quote by radio_guy View Post
honestly, I am surprised we have not seen any thermal images Aerial or otherwise from any sources, i'm sure the drones we flew over the plants some time back have this capability.
There were aerial thermal images released fairly early on, back when they lacked other means to try to establish a rough idea of temperature of pools & reactors.
SteveElbows
#7761
May18-11, 01:34 PM
P: 630
Quote Quote by SteveElbows View Post
There were aerial thermal images released fairly early on, back when they lacked other means to try to establish a rough idea of temperature of pools & reactors.
Or were they IR images and these are different to thermal imaging? Showing my ignorance here!
zapperzero
#7762
May18-11, 01:39 PM
P: 1,042
Quote Quote by radio_guy View Post
They might not have access due to radiation?
Well, there's a pipe. When they put water into it, the water ends up in the RPV. There's your access.
radio_guy
#7763
May18-11, 01:39 PM
P: 24
Quote Quote by SteveElbows View Post
There were aerial thermal images released fairly early on, back when they lacked other means to try to establish a rough idea of temperature of pools & reactors.

I did see those from back in march, I believe from satellite and I should have clarified a bit.

The line of thinking when cameras were mentioned was inspecting what was going on with the core, and I think closer than satellite level thermal imaging would be a great way to figure it out, and give some ideas where and what shape the core or whats left of it would be in.

on adding the camera through the water inlet:I suspect that's possible and I was just not thinking in terms of large scale length of controls. I think bore scope and 100'-200' comes to mind.
seeyouaunty
#7764
May18-11, 01:46 PM
P: 13
Quote Quote by SteveElbows View Post
There were aerial thermal images released fairly early on, back when they lacked other means to try to establish a rough idea of temperature of pools & reactors.
The attached jpg shows the thermal images you mention. I can't remember where i got the picture from, its been sitting on my desktop for a while.
Attached Thumbnails
fukushima thermal1.jpg  
SteveElbows
#7765
May18-11, 01:52 PM
P: 630
Quote Quote by zapperzero View Post
Well, there's a pipe. When they put water into it, the water ends up in the RPV. There's your access.
Is it fair to think of it as a simple pipe though? I tend to imagine it as them pumping water into existing systems, and such systems may involve far more than piping. There may be multiple points where any probe would meet something other than easy to navigate pipe, barriers to entry that it wont get round but water will.
zapperzero
#7766
May18-11, 02:15 PM
P: 1,042
Quote Quote by SteveElbows View Post
Is it fair to think of it as a simple pipe though? I tend to imagine it as them pumping water into existing systems, and such systems may involve far more than piping. There may be multiple points where any probe would meet something other than easy to navigate pipe, barriers to entry that it wont get round but water will.
There are, for sure. Kinks and bends and valves and all that. Some borescopes are steerable just for this reason.

http://www.youtube.com/watch?v=UgRRuo_yKRk
razzz
#7767
May18-11, 02:15 PM
P: 205
Quote Quote by clancy688 View Post
Here's an interesting hypothesis regarding the spent fuel pools and explosions:

http://tec-sim.de/images/stories/fusfpfail.pdf
Well that was interesting. It was all the fuel pools fault because unknown check-valves failed after a loss of power turning the feed lines into siphoning lines lowering the water levels until air reaction with fuel rod created hydrogen that eventually exploded disrupting the remaining water in the pools to create an airlock (air bubble) in the plumbing thus halting the siphoning action. This hypothetical scenario happens 4 times (4 SFP).

They completely ignored loss of coolant in the RPV probably glowing white hot cracking itself or connections and blowing seals. Note their 8-1 drawing shows vents above the drywell concrete sectional cap near floor level.

Also never discussed why SFP 4 fuel assemblies appear undamaged while they describe uncovered fuel assemblies burning like torches.
v13
#7768
May18-11, 02:16 PM
P: 6
Not being an expert, I want to try to add something to the conversation:

It seems to me (based on what I read here) that all reactors suffered somehow the same or similar problem, but one of them did not explode. So the key to understanding what happened should be reactor #2. It should be much easier for tepco to study #2 since it hasn't exploded.

Also, using that thought, the thermal images show that the smaller building at the top of reactor #2 (behind the "NHK WORLD" logo) is also warm (just like the sea). Don't know if this helps.
StrangeBeauty
#7769
May18-11, 02:23 PM
P: 61
Quote Quote by v13 View Post
...study #2 since it hasn't exploded.
Yes, it did explode.

I suggest going (way) back in the thread and reading, or at least going here to get a synopsis:
http://en.wikipedia.org/wiki/Fukushi...lear_accidents
NUCENG
#7770
May18-11, 02:51 PM
Sci Advisor
P: 916
Quote Quote by SteveElbows View Post
OK here is the most interesting data on this subject. Im choosing reactor 2 because reactor 3 has a very annoying gap of data from around 3pm-3.30pm.

Pages 10 and 28 of the following document show what the RCIC was doing at reactor 2 between 14:41 and 15:47:

http://www.tepco.co.jp/nu/fukushima-...atogensho2.pdf

I have attached just a couple of the charts to this post to give you a taste of what Im looking at without having to look at the whole pdf if you dont want to. Anybody prepared to have a stab at describing what this shows?
pp1,2.APRM Average Power Range Monitors 6 channels show scram at around 1446 hr
p3. Narrow Range and Wide Range Reactor water level shows shrink due to void collapse at scram followed by level recovery due to feedwater control system opening wide to recover level. Main Steam Isolation valve closure then bottled up the reactor and SRV cycling to maintain pressure within ipen and closed setpoints.
pp 4,5 Core Spray - electrical noise on p4. this system should not have any flow at high pressure. p5 is as expected.
pp 6, 7. High Pressure Coolant Injection not used.
p 8. residual heat removal RHR pumps A and C started at 1508 hr probably in containment cooling mode with suction on torus. Would need valve operation information to be certain.
p 9. RHR service water pumps A and C start to support containment cooling mode. (cooling water to heat exchanger)
p10 Reactor Core Isolation Cooling RCIC started automatically on low reactor water level at 1450 but was turned off manually to prevent overfilling RPV (RWL does not appear to have reached high level trip on pp 3,4. Normal operating practice. RCIC restarted at 1502 at approx 27 l/s injection to vessel from condensate storage tank.
p 11. not sure but top graph may be low level enable signal for RCIC.
p 12,13. EDG 2A and 2B started on LOPA Loss of Offsite Power. EDG 2A was loaded about 1506 hr.
p 14 LOPA at 1447, No loss of coolant accident LOCA signal
p 15. Narrow range and wide range reactor pressure. After scram and void collapse pressure dropped, After Main steam isolation valve closure pressure rose to SRV cycling setpoint.
p 16 SRV F was cycling. gradual change in cycling rate shows decay heat decreasing.
p 17 Main steam isolation valve closure at 1448
p 18. Probably main steam flow rate t/hr showing MSIV closure.
pp 19-20 nothing to note
p 21. RWL slow change up to 1800 mm and dow to 300 mm uder operation of RCIC and SRVs
pp 22-25.nothing significant to note
pp 26, 27. Loss of AC trips RHR and RHRSW pumps at 1537.
p 28. RCIC flow dialed back due to increasing RPV level and RCIC secured at 1528. Restarted at 1540 at 31 l/s.
p 29. EDG 2A tripped at 1537. EDG 2B tripped at 1542 due to tsunami, flooding.
pp 30-32. nothing to note
p 33. RPV pressure continues to cycle on ERV setpoint
p 34. SRV F continues to cycle.
p. 35. Nothing significant.
NUCENG
#7771
May18-11, 03:26 PM
Sci Advisor
P: 916
Quote Quote by ihatelies View Post
They were not reported missing before the explosion. They were reported missing on March 16, the day after the explosion, and clearly the press release said they were missing due to the explosion.

http://www.theaustralian.com.au/news...-1226022252864

They were found about two weeks later, dead because the lost blood and went into shock.

http://www.businessinsider.com/fukus...nd-dead-2011-4

There does seem to be an effort after the fact to say they were a victim of the Tsunami, not the explosion - wonder why?
The following Press release was before the first explosion:
Press Release (Mar 12,2011)
Plant Status of Fukushima Daiichi Nuclear Power Station (as of 0AM March 12th )


All 6 units of Fukushima Daiichi Nuclear Power Station have been shut down.

Unit 1 (shut down due to earthquake)
- Reactor was shut down and nuclear steam is cooled by the isolation condenser.
- Currently, there is a possibility of a release of radioactive materials
due to decrease in reactor water level. Therefore, the national government
has instructed evacuation for those local residents within 3km radius of
the periphery and indoor standby for those local residents between 3km and
10km radius of the periphery.

Unit 2 (shut down due to earthquake)
- Reactor was shut down and although nuclear steam had been cooled by the
Reactor Core Isolation Cooling system, the current operating status is
unclear. However, reactor coolant level can be monitored by a temporary
power supply and the level is stable.
- Currently, there is a possibility of a release of radioactive materials
due to decrease in reactor water level. Therefore, the national government
has instructed evacuation for those local residents within 3km radius of
the periphery and indoor standby for those local residents between 3km and
10km radius of the periphery.

Unit 3 (shut down due to earthquake)
- Reactor was shut down and is cooled by the Reactor Core Isolation Cooling
system.
- Currently, we do not believe there is any reactor coolant leakage inside
the reactor containment vessel.

Unit 4 (shut down due to earthquake)
- Reactor has been shut down and sufficient level of reactor coolant to
ensure safety is maintained.
- Currently, we do not believe there is any reactor coolant leakage inside
the reactor containment vessel.

Unit 5 (outage due to regular inspection)
- Reactor has been shut down and sufficient level of reactor coolant to
ensure safety is maintained.
- Currently, we do not believe there is any reactor coolant leakage inside
the reactor containment vessel.

Unit 6 (outage due to regular inspection)
- Reactor has been shut down and sufficient level of reactor coolant to
ensure safety is maintained.
- Currently, we do not believe there is any reactor coolant leakage inside
the reactor containment vessel.

We measured radioactive materials inside and outside of the periphery of
the nuclear power station (outdoor area) by monitoring car and confirmed
that there was no difference from ordinary level.

No radiation impact to the external environment has been confirmed.
We will continue to monitor in detail the possibility of radioactive material
being discharged from exhaust stack or discharge canal.

Two subcontract workers were injured in the nuclear power station premise.
One with a broken bone was transported to the hospital by an ambulance and
the other by a company car.
Further, there are 2 TEPCO employees whose presence has not been confirmed.

We are presently checking on the site situation of each plant while keeping
the situation of aftershock and Tsunami in mind.
SteveElbows
#7772
May18-11, 03:44 PM
P: 630
Quote Quote by NUCENG View Post
pp1,2.APRM Average Power Range Monitors 6 channels show scram at around 1446 hr.....
Excellent, thanks for the detail, much appreciated. Im not going to pretend to understand every aspect of that but its great to see it explained and at least a proportion of it sinks in to my mind.

So would I be right to think that, just looking at that data, things went ok in the time period covered? My presumption is that most of the data for 2 & 3 at this early period does not tell a tale of woe or of bad failures, but I wanted to learn more about what a 'normal' post-SCRAM & grid power loss event would look like, and I wanted to rule out any of the more interesting patterns on the graphs being tales of problems.

So thanks to you and the others who gave early feedback about this stuff, I will try to build upon this and get a proper understanding of these systems.

Can I ask whether you have looked at the control rod data that was released as part of this same 'data from the time of the earthquake & tsunami' bundle the other day? I could understand some of it, and again there were a couple of instances where it was showing the number -99 or the word BAD, and I wasnt sure whether this was a sign that there were problems at some stage with control rods, or whether this kind of data blip is to be expected under the circumstances, or whether I was reading it wrong. Let me find the document that I am talking about and I will post again on this subject.
NUCENG
#7773
May18-11, 03:53 PM
Sci Advisor
P: 916
Quote Quote by jlduh View Post
I think that it's oversimplified to say the roofs would still have been there, many other things would have been there i think... (of course I'm talking about the other reactors than just N1).

Heavy damages to the structures and all the equipements around have considerably increased the difficulties for workers around to restore or contain the situation...

This venting mess (with all the problems that occurred on the vent system) is a good part of the current situation IMO. Not the initial cause of course.
Yes it would be oversimplified to say the roofs would still be there. That's why I did NOT say they would still be there. I said I didn't know but MAYBE they would still be there. MAYBE not, but delayed venting surely didn't make the explosions less likely. Fair enough?
PietKuip
#7774
May18-11, 04:04 PM
P: 184
Quote Quote by radio_guy View Post
I did see those from back in march, I believe from satellite and I should have clarified a bit.

The line of thinking when cameras were mentioned was inspecting what was going on with the core, and I think closer than satellite level thermal imaging would be a great way to figure it out, and give some ideas where and what shape the core or whats left of it would be in.

on adding the camera through the water inlet:I suspect that's possible and I was just not thinking in terms of large scale length of controls. I think bore scope and 100'-200' comes to mind.
I collected some thermal images here:
http://www.flickr.com/photos/2625591...577079/detail/

The were taken from high up, but not a satellite. It was a Japanese army helicopter. They stopped at the end of April.

Yes, these things are not too big to drive around on a small robot: http://commons.wikimedia.org/wiki/Ca...EC_Thermo_Shot
NUCENG
#7775
May18-11, 04:06 PM
Sci Advisor
P: 916
Quote Quote by SteveElbows View Post
Excellent, thanks for the detail, much appreciated. Im not going to pretend to understand every aspect of that but its great to see it explained and at least a proportion of it sinks in to my mind.

So would I be right to think that, just looking at that data, things went ok in the time period covered? My presumption is that most of the data for 2 & 3 at this early period does not tell a tale of woe or of bad failures, but I wanted to learn more about what a 'normal' post-SCRAM & grid power loss event would look like, and I wanted to rule out any of the more interesting patterns on the graphs being tales of problems.

So thanks to you and the others who gave early feedback about this stuff, I will try to build upon this and get a proper understanding of these systems.

Can I ask whether you have looked at the control rod data that was released as part of this same 'data from the time of the earthquake & tsunami' bundle the other day? I could understand some of it, and again there were a couple of instances where it was showing the number -99 or the word BAD, and I wasnt sure whether this was a sign that there were problems at some stage with control rods, or whether this kind of data blip is to be expected under the circumstances, or whether I was reading it wrong. Let me find the document that I am talking about and I will post again on this subject.
I am trying to catch up. What is the link? All I looked at so far was the unit 2 data you posted a link for.
ihatelies
#7776
May18-11, 04:18 PM
P: 45
Quote Quote by NUCENG View Post

Two subcontract workers were injured in the nuclear power station premise.
One with a broken bone was transported to the hospital by an ambulance and
the other by a company car.
Further, there are 2 TEPCO employees whose presence has not been confirmed.

We are presently checking on the site situation of each plant while keeping
the situation of aftershock and Tsunami in mind.
So did they find them, then lose them again? Because 4 days later they said this:

During a news conference, the agency said the workers, whose names were not released, were in the turbine area of the No.4 reactor when the blast occurred. The Fukushima plant had been damaged after Friday's earthquake and tsunami.
http://www.theaustralian.com.au/news...-1226022252864

And two weeks later they found them dead of internal bleeding in the turbine basement. I thought this an interesting cause of death, because they could have said they died of blast damage from the explosion, and no one would have given it a second thought, however internal bleeding likely came from some other cause.


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