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Fukushima No. 1 loss of coolant due to earthquakeHelpful Member!(7) 

trottiey (Nuclear) (OP)
11 Mar 11 12:19
I'm sure we're all anxiously waiting for some technically accurate news, so if you hear anything credible, please post it here.

Latest report that I have says that the reactor is shutdown, but coolant pumps are not running because of the power outage and failure of their auxillary generator. 2800 people evacuated - is that just the plant workers, or is that civillians? The government says there is no leak, but residents within 3 km of the reactor were told to stay inside.

The quake also caused a conventional fire and leak at the Onagawa plant. I bet you most of us on this list don't care so much about that, so please leave those reports off this thread.

Does anybody know how well these plants can thermosiphon?
Hotown (Mechanical)
11 Mar 11 12:29
Here's the best breakdown of events I've seen yet:

http://www.world-nuclear-news.org/RS_Massive_earthquake_hits_Japan_1103111.html?je

And here's my personal favorite...

http://www.reuters.com/article/2011/03/11/us-japan-quake-nuclear-clinton-idUSTRE72A4LR20110311

I bet they're running out of internet as well, we better ship some of that over too!
unclesyd (Materials)
11 Mar 11 17:34
Just crossing the news wire:
The pressure in the reactor is up 1.5 times the normal pressure.
The radiation is ?100? times the normal level.
The exclusion zone has bee increased from 6 to 10 kilometers.
None of the cooling towers are operating.

 
rmw (Mechanical)
11 Mar 11 18:45
I tend to believe nothing that I read about anything technical for about the first 24 hours.

The evening news journalists are now discussing it as if they knew something about it.  HA!

rmw
vanmorrison (Nuclear)
11 Mar 11 19:02
Helpful Member!(3)  trottiey (Nuclear) (OP)
12 Mar 11 0:46
Here's a summary of what I can figure out from sifting through conflicting news reports tonight:

The most affected unit is Fukushima Dai-ichi unit #1. It is a 460 MW BWR reactor built in the 1960's. Some news reports also refer to unit #2, but the reports are very conflicting about that.

There is lots of confusion among reporters between the containment structure and the pressure vessel. One of those is over twice its normal operating pressure and very hot. They are venting gas or steam, but it is unclear whether it is being vented from the coolant loop into the atmosphere, from containment into the atmosphere, or from the coolant loop into containment.

Radiation levels in the control room are 1000 times normal, but the reporters don't say if this is irradiation or airborne contamination, or what "normal" is. But the plant is now doing rapid shift changes, so that gives you some idea. One report said 250-500 mrem/hr.

The evacuation zone has grown to a 3km radius, and the stay-in zone has grown to a 10km radius. There are multiple reports talking about dozens of ships and hundreds of planes being sent to help the nuclear accident, but I'm guessing that's really just part of the general earthquake relief effort.

I've tried to trim out the speculative stuff, but it's still hard at this stage.
OperaHouse (Electrical)
12 Mar 11 4:59
I worked at one of those plants (Tokai 90 miles north of  Toyko) during startup. It is probably not damaged but still in shutdown. These plants had their own ocean dock facilities for unloading heavy equipment. Plant is right on the ocean. Think of that with a giant wave.  I remember a story that shipboard generators were used to start gas turbines during the big NYC blackout.  One or more ships could be used to provide additional power to the nuclear plant.

Have been looking at those areal views showing the off gas towers.  I climbed one to the top.  I remember it being a white knuckle experience.  Looks even taller now.  That kind of prank would get me kicked out of the country today.
unclesyd (Materials)
12 Mar 11 6:43
Here are bulletins from NISA that are updated ever few hours.
It gives status of each nuclear plant.

http://www.nisa.meti.go.jp/english/index.html
Helpful Member!  Power2go (Electrical)
12 Mar 11 6:52
There is much confusion in the press due to the information that "the plant is in battery controlled cooling mode" Running large cooling pumps on batteries is virtually impossible.

What really happens is that the emergency cooling system pumps are driven by the remaining steam from the plant. The motor operated valves in the system, and only those !, and the control systems are supplied from the batteries.(UPS systems)  

When steam power runs out you will be in big trouble. That is why the emergency diesel generator sets must be back on line as soon as possible and the engineers at the plant are working hard on this.   
trottiey (Nuclear) (OP)
12 Mar 11 8:07
Unit 1 exploded. It was captured on video from a few different angles. Aerial photography confirms that the containment building is destroyed. Evacuation radius is increasing, and officials staying behind are in yellow tyveks. One Japanese report says there is radioactive iodine and cesium in the atmosphere.

There is still a stream of "experts" telling the news cameras that an explosion is impossible, that even the melting of fuel is impossible, and the media dutifully reports on it since every story must have two sides. But it sounds to me like the worst has happened.
vanmorrison (Nuclear)
12 Mar 11 9:13
Does anyone know if it was the quake or the tsunami that took out the  diesel generators?

 
 
trottiey (Nuclear) (OP)
12 Mar 11 9:29
I think I can put some pieces together:
The earthquake hit at 14:46, local time.
World Nuclear News reports that the backup diesel generators started as planned, but failed an hour later.
A 10 m tall tsunami hit Sendai airport at 15:55 local time.
The Fukushami reactors are right on the coast according to Google maps, maybe 2-3 m above sea level.

So I would put money on the tsunami taking out the diesels.
Helpful Member!  Zogzog (Electrical)
12 Mar 11 10:31
Reports of the explosion is a H2 explosion, battery room I am guessing? Sort of fits in with the "cooling systems running on battery power" report.

USS Ronald Regan is headed over there and has the capability of providing power to on shore facilities. Wonder is that is the plan.  
trottiey (Nuclear) (OP)
12 Mar 11 10:51
The cooling pumps on a nuclear reactor typically take megawatts of power, well beyond the capacity of battery systems. I agree with Power2go's assessment above; they would have been running the valves on batteries, not the pumps.

Radiolysis in a nuclear reactor normally produces hydrogen and oxygen, which is continuously burned by electric recombiners. A number of possible failures could cause the recombiners to fail or be insufficient, resulting in accumulation of hydrogen. Hydrogen explosions are a common feature of nuclear meltdown scenarios.

They flew in more than enough generators a long time ago, but the problem is that you need a lot of copper and some fast electricians to run lines that can carry megawatts of power to the pumps. They did not succeed.

They say the reactor core vessel is intact, but it's a BWR, and I'm guessing some of the coolant piping is damaged. They say core pressure is decreasing, which would be consistent with a coolant pipe leak. The core vessel is in a containment well below ground level. A possible contingency in this scenario would be to flood the well with ocean water and boric acid. Some people speculate that the boric acid would be the "coolant" that Hillary Clinton mentioned.
owg (Chemical)
12 Mar 11 11:31
Thanks Trottiey for that helpful information. Does the hydrogen and oxygen produced contain any radioactive material? If so is it processed to clean it up before recombination? What normally happens to the water/steam that results from the recombination? Thanks.

HAZOP at www.curryhydrocarbons.ca

alehman (Electrical)
12 Mar 11 11:43
Last report is they are flooding it with seawater and boric acid,  as trottiey described.

Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.

trottiey (Nuclear) (OP)
12 Mar 11 12:00
Well, we're talking about coolant water here, water that flows over the fuel. So it will contain low concentrations of everything radioactive: particulates from the occasional broken fuel bundle, noble gases, activated corrosion products, activated anti-corrosion products, etc. It is typically poisonous for both biochemical and radiological reasons.

The hydrogen and oxygen itself gradually transmutes into radioactive isotopes by neutron capture while the reactor is running. The oxygen isotopes are all either stable or have very low half-life so they are not normally a health concern. The hydrogen isotope tritium has a half-life of 12 years, which is right in that sweet-spot that does the most damage if inhaled. But the tritium concentrations usually only reach hazardous levels in heavy water reactors, which the Fukushima reactor is not.

Tritium is lighter than air and floats away into space quickly, so fugitive emissions are normally not a concern. But if it recombines with oxygen or carbon, either through the explosion, fire, or just natural atmospheric recombination, the resulting water or hydrocarbon molecules are radioactive and easily absorbed into the body. There are regulations that limit how much that happens.
davefitz (Mechanical)
12 Mar 11 12:44
trottiey:

"there are regulations that limit how much that happens"- I think we may be  past the effect of regulations by now, at  this particular plant.

If the end result is a large plume of cesium contaminating downwind countries , or some other drastic result, it could have a huge impact on food supplies, cost of food, and reconsideration of continued operation of other similar reactors ( and that is a lot of installed capacity !).

If nothing else good comes out of this experience, other plants  will need to learn from this event, and be modified accordingly, if feasible.  
racookpe1978 (Nuclear)
12 Mar 11 12:55
I am speculating here: Understand I would be wrong to claim that I "know" what happened.   But I suspect that news reports that the containment building blew up are just plain dead wrong.  

Wrote this on a separate, more political website for those (non-engineers) to read.  Please extend your throughts.

Large amounts of Hydrogen - non-radioactive, regular but highly purified medium-pressure hydrogen gas at 35 to 50 psig - is used inside all of the medium to large generators worldwide to cool the inside of the generators from their electrical resistance to the 48,000 volt high-flow currents in the copper and iron. This hydrogen cooling system is supplied from large numbers of very high-pressure hydrogen bottle banks at 3000 - 3600 psig. (200+ bar, for you metric types.)

These hydrogen tanks are OUTSIDE the containment buildings - because they are non-radioactive and are a turbine building service system that does NOT connect to any reactor systems. The turbine, however, is lightly contaminated internally from residual particles deposited from the primary coolant because these power plants are boiling water reactors, and the turbines (not the primary coolant containment systems) ARE outside the containment concrete presssure-tight (blockhouse) domes.

If the high-pressure hydrogen tanks blew they would blow up like this (outside, with great dust blast and a sound wave) but the blast would NOT damage the reactor or the piping INSIDE the containment building.  However, radioactive contamination to nearby injured workers is very likely.    Any blast this size blows h*ll out of the turbine complex -> Ain't no power coming from this plant for a while.......

The small amount of hydrogen inside the containment dome that people were worried about at Three Mile Island WAS from decay and release of the melted fuel and decomposition of fuel element cladding. But the net pressure buildup from fission decay product gasses and this hydrogen inside the TMI dome was exaggerated at the time, and venting to relieve that pressure at TMI was the wrong decision by the government.  


 
electricpete (Electrical)
12 Mar 11 13:14
I agree we don't know the source of the explosion.
I haven't actually seen reports of hydrogen.

Regarding potential sources of hydrogen in the core, normal hydrolisis is not a big concern, but there is a zirconium-water reaction at high temperatures which can produce hydrogen.

See page 2 of 3 here
http://canteach.candu.org/library/20044507.pdf

=====================================
(2B)+(2B)'  ?

vanmorrison (Nuclear)
12 Mar 11 13:22
Yes there will be lessons learned, recommendations and plant modifications I am sure. However, nothing can be designed/engineered to withstand all Acts of God.  We may think we have control but it is an illusion.
trottiey (Nuclear) (OP)
12 Mar 11 13:40
racookpe1978's post is grossly misinformed. Hydrogen would never be used as an industrial coolant because of the explosive risk. Nuclear plants use lots of helium and some liquid nitrogen, but not hydrogen. That would just be stupid.

I've looked at a lot of pictures and videos of the accident, before, during and after, and I am quite convinced that it is the reactor building that blew up. There are reports that the containment structure is unharmed, but I'm think that's just a product of the language barrier and non-technical reporters. And political bloggers spouting nonsense.

Maybe they mean the pressure vessel is intact, or maybe they just mean the containment well still holds water, which allows it to be flooded with ocean water and boric acid. But the "containment structure," in the sense that english-speaking nuclear engineers use the term, appears to have failed.
Power2go (Electrical)
12 Mar 11 14:07
Now I get confused by trottiey's reply to the hydrogen cooling issue of generators. Doing some "googling" I have found numerous examples of large generators with hydrogen cooling.

ABB has a whole range of these with the appropriate Gas Analyzer Systems for Hydrogen-cooled Alternators. Go to their site to find examples of these generators.

When you follow this link (copy/paste)
 http://www.powergenworldwide.com/index/display/articledisplay/154893/articles/power-engineering/volume-106/issue-9/features/adequate-cooling-of-generators-is-essential.html

or search with "cooling large generators" in Google you will find enough info on this subject.



 
DrRTU (Mechanical)
12 Mar 11 14:14
My guess, D/Gs  were lost with tsunami . Small primary leak, H2 released as core goes past 2,200 F without cooling. Explosion results in containment building during venting.  
trottiey (Nuclear) (OP)
12 Mar 11 14:18
I apologize. Some google searching shows that I am plainly wrong about the use of hydrogen as coolant. I was not aware and am quite surprised by it.
jpankask (Mechanical)
12 Mar 11 14:19
Actually trottiey, you are incorrect.  Hydrogen is used inside the generator for cooling.  

When they say the containment structure is unharmed, they are referring to the inner steel containment shell.  Some reports I've read indicated the outer containment concrete was damaged, but the steel lining was still intact.  In other words, the containment structure is still providing it's function of containing the atmosphere and maintaining pressure boundary so that any releases to the environment are done on purpose, to control containment pressure.  The fact the containment pressure is higher than normal indicates the containment structure is working, though with less concrete reinforcement than designed.   
DrRTU (Mechanical)
12 Mar 11 14:26
Trottiey, rocookpe1978 is correct, most large generators are cooled with 100% H2. This is a very safe proven system of cooling. The H2 seal oil unit is very important system that keeps the H2 and oil  away from an explosive condition. This system are in fossil power plants. The generator & H2 systems are in the building that did not blow-up.
trottiey (Nuclear) (OP)
12 Mar 11 14:56
Yes, I've learned something today. Rocookpe1978's idea is plausible, and I apologize for dismissing it so harshly.

I still think it was the reactor building that blew up, not the turbine hall.
unclesyd (Materials)
12 Mar 11 14:58
Just watching the news when they showed a new clip on the power station station it appeared hat the dust cloud started forming almost instantly quite a blast wave emanating from the dust. It had some color to a height just a little over the height of the vent stacks.  Color indicates something is been burned along with the H2 which would have no color. There was no sound just images.
OperaHouse (Electrical)
12 Mar 11 15:28
I believe one news report said this was a BWR, Boiling Water Reactor.  Believe GE reactors were all BWR and Westinghouse were all PWR.  The BWR reactors were considered much safer.  These had two 10,000HP pumps to control the reaction. Thes were not cooling pumps but it gives you a flavor of how big the cooling pumps probably were. The faster you ran the pumps ther more power you got out.  This was to get rid of the bubbles in the reactor that slowed the reaction down. No pumps, the power is very low.  This is contrary to what you might think.  And certainly there is still a lot of heat generated if there is no place to dump it.  Further reduction of power is done by removing the rods.  I'm sure wiki has a better explanation and I havent been in a plant in 40 years.  Keep this in mind that these plants are probably that old.  Japan had a lot of protests about building new plants.  We had protests about every week when it waqs under construction.
zzzjim (Electrical)
12 Mar 11 16:03
Looking at Satellite news , a very clean  spherical shape rises quickly
above roof , any coloring could be a lense effect of hot gas ,
Hot Hydrogen will explode very suddenly mixed with Air .
   This appears before Dust  shoots out , from building collapse !
  
owg (Chemical)
12 Mar 11 16:14
Trottiey - Thanks for the response on the hydrogen and oxygen. However I am still not clear how the tritium would "float away" while leaving the hydrogen behind. Hydrogen has a mol wt of 2 and Tritium has a mol wt of 6. I would not expect much separation by gravity. What am I missing here?

HAZOP at www.curryhydrocarbons.ca

trottiey (Nuclear) (OP)
12 Mar 11 16:46
Nitrogen (air) has a molecular weight of 28, so both the hydrogen and tritium will float away quickly. Some of it (both hydrogen and tritium) will recombine with atmospheric oxygen and fall back to the ground as rain.
byrdj (Mechanical)
12 Mar 11 16:49
I found an informative posting by a Nuclear Engineer, of all places, the Talor Swift Fab club.  It is actually some one else quoting.  Sure wish I could find the originating forum.
well worth the read
http://connect.taylorswift.com/forum/thread/33330/Pray_for_Japan_Swifties/3
electricpete (Electrical)
12 Mar 11 19:36
Taylor Swift fan club... Lol.  

=====================================
(2B)+(2B)'  ?

rmw (Mechanical)
12 Mar 11 19:57
I would note that once all power had failed there was nothing to operate the pumps to maintain the hydrogen seals on the generator(s).

rmw
Zogzog (Electrical)
12 Mar 11 20:12
Swifties! LOL!
rmw (Mechanical)
12 Mar 11 20:22
I guess I need to get out more.....

rmw

PS: ByrdJ, you seem to get out too much :)
byrdj (Mechanical)
12 Mar 11 20:24
I found the original poster.  He is an SRO and post by the name Fermi2.
http://warships1discussionboards.yuku.com/topic/15893/8-9-Earthquake-Tsumani-in-Japan?page=3
 
byrdj (Mechanical)
12 Mar 11 20:31
rmw, I was just google for BRW and hydrogen venting and got a hit there.  :)

Being somewhat familar with a BWR plant, I find fermi's discriptions to be accurate
trottiey (Nuclear) (OP)
12 Mar 11 20:41
The most credible source of news continues to be World Nuclear News, although they have a new article for March 12th. I should have been checking there all along:
http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html

The nuclear accident has claimed its first fatality. A different worker has received a dose of 10.6 rem.

They're saying that the outer concrete building does not act as containment. There's another concrete containment structure nested inside it that is still standing. They have a couple of nice diagrams of it.
rmw (Mechanical)
12 Mar 11 21:25
I have been following that site since hotown posted it above second post of this thread.  It seems to have the most knowlegeable and objective news unlike the 24 hour channels that seem fixated on the words "explosion" and "meltdown".

byrdJ, Whew.....  I never knew who she was, but I was worried that you might be a fan..... :)  LOL

I am afraid that overall this is strike 3 for Nuclear power in the USA.  Maybe not elsewhere in the world, but here, sorry, but yes.  TMI was strike 1, Chernoyble strike 2, and this is probably the end of Nuclear power as a generally accepted form of power generation for as long as any of us will live to see it.  The sierra clubbies must be dancing in the street.

As an engineer, I hate it, but that is reality with our fickle public and their ability to be manipulated by the media.

rmw
electricpete (Electrical)
12 Mar 11 21:31
From your link:

Quote (world nuclear news):

Nevertheless the amount of radiation detected at the site boundary reached 500 microSieverts per hour - exceeding a regulatory limit and triggering another set of emergency precautions

http://en.wikipedia.org/wiki/Sievert

Quote (wikipedia):

1 Sv = 100 rem
If my math is right, the hourly dose at the site boundary would be
500 uS * 1E-6 S / (uS) * 100Rem/S = 0.05 Rem/hr = 50 mRem/hr

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
12 Mar 11 21:34
It sounds like the coolant system and containment are relatively intact, but relief valves being used to keep coolant pressure within limits and venting used to keep containment pressure within limits.

Quote (World nuclear news):

Tepco has said that the pressure within the containment of Fukushima Daiichi 1 reached levels of around 840 kPa, compared to reference levels of 400 kPa.
What is a reference level... similar to a design limit?

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
12 Mar 11 21:48
I am falling off my chair.  CNN has nuclear expert "Bill Nye the Science Guy" (yes you heard me right) interpretting events.  He explained the significance of Cesium.  Something along the lines of "It is an absorber of neutrons... it is used in the control rods to control the reaction" (paraphrased).

Guess he never heard of fission products.  Amazing.

=====================================
(2B)+(2B)'  ?

rmw (Mechanical)
12 Mar 11 22:00
ByrdJ,

Nice link.

I read a lot of Fermi's stuff, but most of it is based on normal procedures and that includes normal emergency procedures.

I tripped a power plant once and put a whole (islanded) city in the black and one take-away I will never forget is how helpless the plant was with no power.

Yes, the DC pumps protected the turbine as it coasted down, and yes, I had a boiler full of steam (every safety on the blasted thing was screaming), and yes, there was air (while it lasted), but there was no cooling water and with no heat sink, I couldn't use the steam to drive anything even if I could have manipulated the valves.  The air didn't last long enough for the operators to dash next door and get the stand-by combustion turbine (black start -  air) cranked.

The city didn't begin to recover until a portabale trailer mounted trailer mounted compressor owned by the sewer dep't was brought in to provide air to start the standby CT.  The situation in Japan is much more complicated than that.

I make the above point to say that once the auxiliary generators are defunct all bets are off and normal emergency procedures are out the door.

Who knows what is really going on in the hell that is their world right now?

rmw
electricpete (Electrical)
12 Mar 11 23:09
I'm still falling off my chair laughing. CNN went back to their heavyweight scientist Bill Nye again with the same question "What is the significance of the Cesium" and he repeated the same wackiness..

It is truly amazing they can't do better than that.

As a small proof of this circus, I took a picture of my TV (attached).  You can see one of the two banners at the bottom reads "Bill Nye: Cesium is used to slow and control nuclear reactions".

By the way it is true that Cesium does absorb some neutrons, but it's not like it's something that is built into the reactor ("used") and certainly not part of the control rods.  It is a fission product which appears as a result of nuclear fission.  There would be some trace amounts present in the coolant of even a healthy reactor, and if fuel cladding is breached, then much more.

I'd love to find a link to that interview on youtube.  It has not much information value but a whole lot of entertainment video.

=====================================
(2B)+(2B)'  ?

unclesyd (Materials)
12 Mar 11 23:32
There was just snippets from a news conference where the spokesman for Nuclear Agency stated that seawater was being used to cool reactor @3 as well as #1. All I caught about the presence of Cesium was it wasn't at dangerous level.

rmw,
I shutdown anywhere 1 to 5 power boilers several times, with radiation. My deeds were th prelude to Con Edison's loos Big Bertha.

 
trottiey (Nuclear) (OP)
12 Mar 11 23:34
The March 13th article from our favorite source is here:
http://www.world-nuclear-news.org/RS_Venting_at_Fukushima_Daiichi_3_1303111.html

If they follow the same pattern as the last two articles, they'll be updating this every couple of hours.
trottiey (Nuclear) (OP)
12 Mar 11 23:48
Best picture of the explosion damage so far:
http://resources1.news.com.au/images/2011/03/13/1226020/537109-fukushima-daiichi.jpg

If you compare to this diagram, it looks like the crane deck is gone, but the concrete is largely still standing:
http://www.world-nuclear-news.org/uploadedImages/wnn/Images/bwr%20cutaway.jpg
Power2go (Electrical)
13 Mar 11 4:42
For those interested there is a Wiki page on this plant which is updated with the latest news on the explosion. Follow this link:

http://en.wikipedia.org/wiki/Fukushima_I_Nuclear_Power_Plant

And further, could it be that the SoS Hillary Clinton referred to helping the Japanese out with Borid Acid when she referred some time ago that the US would sent "coolant" to Japan?
unclesyd (Materials)
13 Mar 11 7:02
It looks like they are getting ready to admit a partial meltdown in #1 Reactor, this is in the form of,"few few may have been compromised" "a few fuel rod casings may have been damaged" along with quite a bit of dancing around the questions.

#3 is going through the same cycle as #1 and they are mentioning possible H2 explosion as happened in #1.
Lets hope the #3 outer building is frangible like #1. I pickup that the the failure mode of the building was not d design, but a happening.

How effective is Boric Acid compared to Metallic Boron.  They used Boron Metal at Chernobyl as the melted core was exposed.  
owg (Chemical)
13 Mar 11 8:48
rmw has suggested that this may be strike 3 for nuclear power. That was my initial thought too, however on further consideration I wonder if this 40 year old design is finally shutdown safely, it might be a sign that safe design is possible even around the ring of fire. That should encourage those of us who live near the middle of the tectonic plates to continue with a nuclear power program.

HAZOP at www.curryhydrocarbons.ca

electricpete (Electrical)
13 Mar 11 11:50
I'm sure spin doctors on either side will claim a victory.
[*]Anti-nukes will say it proves nuclear power is dangerous.
[*]Pro-nukes will say look at how superbly the reactors did absorbing the most severe one-two punch imaginable, with only a very modest release of radioactivity... and that release was intentional to reduce pressure to preserve integrity of the containment pressure boundary.

Neither will mean much until the unit is stable and we understand the full extent of any release and we have a full understanding of what happened.

=====================================
(2B)+(2B)'  ?

alehman (Electrical)
13 Mar 11 12:08
Power2go (Electrical)
13 Mar 11 16:17
Thanks alehman for the interesting link. I have studied the image of the situation after the tsunami and came to some maybe interesting conclusions. I took a screen shot of the plants 1-4 buildings and compared this to the situation before the tsunami.
I have marked the "after" screen shot and added a picture of the plant in side view and have attached these to this message.

What you can see on the "after" picture is that the water did not go very far on land at the plant as there is a large raised area behind the plant which must be about 10m. I have marked the max waterlevel on the road. Most of the waves will have been disolved by the breakers in front of the plant and the structures in front which are badly damaged as you can see. Notice the parking lot on the top left of the picture which on the "after" is full of cars. I have also included a "before" and "after" screen shot of the village just north of the plant which is heart breaking to see when you think how many people must have died there.  

 
vanmorrison (Nuclear)
13 Mar 11 16:47
A star for Power2go. I apprecicate your before and after visuals and your compassion.

Regards,
Van  
electricpete (Electrical)
13 Mar 11 22:30
Previously there was an explosion at Fukushima Daiichi No. 1

CNN just reported an explosion at no 3.  I found a brief mention here:
http://twitter.com/REUTERSFLASH

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
13 Mar 11 22:32
http://af.reuters.com/article/energyOilNews/idAFTKB00732520110314

=====================================
(2B)+(2B)'  ?

Zogzog (Electrical)
13 Mar 11 23:19
They just had another quake and are about to get hit by another Tsunami in a couple minutes. Not good.  
alehman (Electrical)
14 Mar 11 0:17
Maybe not. The largest recent quake on the USGS web site is a 5.6, about an hour ago.

IAEA reports an explosion at unit 3.

Alan
"The engineer's first problem in any design situation is to discover what the problem really is." Unk.

rmw (Mechanical)
14 Mar 11 8:16
In another piece of brilliant journalistic excellence, Fox News this AM was announcing that the fuel rods in F-D #3 were "exposed" plus blah-blah-blah about nuclear radiation.

I am sure to the public that conjures up an image of the "explosion" having ripped the containment vessel assunder and there are the fuel rods exposed to the open air like a gutted deer carcass.

I don't think the public will be able to understand the sensationalism vs. what is actually going on.  Another nail in the coffin.

rmw
Helpful Member!  vpl (Nuclear)
14 Mar 11 9:55
Here's a link to the American Nuclear Society webpage following the Fukushima reactors: http://ansnuclearcafe.org/.  Another authoritative link is the Nuclear Energy Istitute: http://www.nei.org/newsandevents/information-on-the-japanese-earthquake-and-reactors-in-that-region/

The reactors are BWRs -- they have a steel containment building surrounded by a concrete/sheet metal reactor building.  From the TV pictures, it appears that the reactor buildings for Units 1 and 3 have been damaged.  However, from the various descriptions, it doesn't sound like the containment buildings are damaged.   

Patricia Lougheed

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blacksmith37 (Materials)
14 Mar 11 12:25
Wikipedia has a good (basic) description of a BWR.
Assuming the media got it partially correct : Where does the hydrogen that caused the explosions come from, a corrosion reaction ?
trottiey (Nuclear) (OP)
14 Mar 11 12:35
The hyrdrogen comes from radiolysis and from a zirconium oxidation reaction. The former dominates during normal operation, but the later dominates if the core overheats. You can find more information about this earlier in this thread.
electricpete (Electrical)
14 Mar 11 14:37
Fukushima Daiichi 2 has experienced loss of coolant for some period:
http://www.world-nuclear-news.org/RS_Loss_of_coolant_at_Fukushima_Daiichi_2_1403113.html


 

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(2B)+(2B)'  ?

blacksmith37 (Materials)
14 Mar 11 15:35
Thanks : Zr always struck me as a stupid choice, rather similar to Ti with its propensity to hydride, nitride, oxidize.
Rich2001 (Mechanical)
14 Mar 11 17:03
cloa (Petroleum)
14 Mar 11 20:02
Zirconium is good choice because of its low neutron cross section and general incredible corrosion resistance.

http://environmentalchemistry.com/yogi/periodic/crosssection.html
Blacksmith37- What do you prefer instead- Aluminium, Lead or Magnesium which are comparable or better metals for neutron cross section?
 
electricpete (Electrical)
14 Mar 11 20:17
A day ago, #2 was the only one of the 3 that we weren't worried about.  Then report of core uncovered in unit 2.  Now an explosion at a #2 in a different location than occurred in units 1 and 3....seems to be inside the containment:
http://news.ninemsn.com.au/world/japanquake/8224062/explosion-heard-at-japan-nuclear-reactor

Quote:

explosion occurred near the suppression pool in the reactor's containment vessel.

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unclesyd (Materials)
14 Mar 11 20:37
Aside from the above mentioned explosion in @2 there are several reports the they are evacuating personnel from the plant due to problems with @2's exposed fuel rods. There was also mention of the loss of the containment pool on @2.
NHK stated that this last explosion was the second one in @2 reactor.
 
unclesyd (Materials)
14 Mar 11 20:50
Just picked up on something I heard earlier. The fuel in @2 is a "duplex' fuel make from old nukes in Russia.  There were no
 percentages of each but the phrase a substantial amount of lutonium was present.  This fue lsi only ussed in @2 reactor.
vpl (Nuclear)
14 Mar 11 21:20
I realize that people read what they want into the various stories -- but I looked at the "evacuating personnel from the plant" as "things have stabilized enough that people can leave to tend to their families and homes."

There's a lot that is getting lost in translation.  These plants don't have suppression or containment pools (they have torii).   

Patricia Lougheed

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electricpete (Electrical)
14 Mar 11 21:31
The page that I linked above has been updated to delete the thing I quoted.... and updated with a more optimistic report:
http://news.ninemsn.com.au/world/japanquake/8224062/explosion-heard-at-japan-nuclear-reactor

Quote:

The seal around a reactor at a quake-damaged Japanese nuclear power plant does not appear to have been holed, the plant operator says, following an explosion at the plant.

Chief Cabinet Secretary Yukio Edano told reporters earlier on Tuesday that the suppression pool of the No.2 reactor at the Fukushima No.1 plant appeared to have been damaged.

The pool forms the base of the container vessel which seals the fuel rods.

Plant operator Tokyo Electric Power Co (TEPCO) "said it believes the container vessel has not sustained damage such as a hole, judging from the fact that the radiation level has not jumped," a spokesman for the country's nuclear safety said.

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vpl (Nuclear)
14 Mar 11 21:31
Here's a general diagram of the type of reactor at the Fukushima Daiishi site:

http://www.nrc.gov/reactors/generic-bwr.pdf

Here's the site for the Japan Nuclear and Industrial Safety Agency and their press releases.  They give a lot of technical information about radiation levels and plant parameters.

http://www.nisa.meti.go.jp/english/

Patricia Lougheed

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TERIO (Mechanical)
14 Mar 11 21:48
electricpete (Electrical)
14 Mar 11 22:24
I realize this is a very serious subject, much moreso for people in the middle of it.

I hope a less serious comment will not be frowned upon. It is after all pi day.

For anyone who wants a chuckle courtesy of Bill Nye (bless his heart) and CNN, see the video at  4:40 to 5:30 and at 9:45 here:
http://www.youtube.com/watch?v=af-41E5mndk
 

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electricpete (Electrical)
14 Mar 11 22:48
Take it with appropriate grains of salt, another report:
http://www.nydailynews.com/news/world/2011/03/14/2011-03-14_third_explosion_at_japanese_nuclear_plant_sparks_fear_of_more_radiation_release_.html

Quote:

A third reactor exploded late Monday at the Japanese nuclear plant crippled by Friday's earthquake, releasing a dangerous amount of radiation, officials said.

A fourth reactor was on fire and there were fears that the steel containment vessel protecting the plant's nuclear core had been breached - the worst-case scenario in such situations.

"There is a very high risk of further radioactive leaks," Prime Minster Naoto Kan said
in an address to the nation."I ask you to stay calm."

More than 180,000 people living in a 12-mile radius of the Fukushima Daiichi plant 150 miles north of Tokyo had already been evacuated over the weekend.

Kan asked that people living between a 12- and 18-mile radius hunker down inside.
"Remain indoors, at home or in your offices," he said. "Avoid going outside."

Officials evacuated staff plant after reactor No. 2 exploded - the third blast there since Saturday.

A heroic team of 50 workers stayed behind to continue trying to cool the reactors with seawater and avert large-scale meltdown.

"They are putting themselves in a very dangerous situation," Kan said.

Tokyo Electric said a reading of 8,217 microsieverts per hour of radiation was taken at the plant's gates after the explosion - a fourfold increase from 40 minutes earlier

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(2B)+(2B)'  ?

ScottI2R (Electrical)
14 Mar 11 23:28
Hello everyone,
At the risk of removing any doubt about my intelligence for any that were wondering, I am going to ask a couple of things about this whole mess. But first, EP, I really wish I could go to that you-tube video but that is blocked on our network here at work. I really could use a chuckle. This whole thing is making me sick.

Ok the questions: Assuming the reactor vessel is not breached and containing all the neutrons, is there a possibility in the event of a complete fuel meltdown into one big "puddle" creating a fission explosion? I guess is there sufficient quantity of fuel there to attain critical mass? Seems to me I read a long time ago that if you were to put 110 lbs of U235 in a lead box and put a lid on it, it would go critical almost instantly and boom....Please dont hold me to that amount and that element, just the concept. It was a very long time ago.
Also, does anybody know what created that fire in unit 4? All I get from the news sites is speculation.

Thanks in advance

Scott
 

I really am a good egg, I'm just a little scrambled!

cloa (Petroleum)
14 Mar 11 23:34
No risk of nuclear explosion as the carbon control rods are all inserted to mop up neutrons- any way its leaking some radiation to the containment area so the radiation is not concentrated in the reactor to increase the nuclear explosion risk.    
unclesyd (Materials)
14 Mar 11 23:58
Everyone is waiting for the official word but you may only get older waiting for the truth.
First part is what is know as the TEPCO scandals in Japan.

Time line on the Fukushima Nuclear Plant.

http://www.nirs.org/reactorwatch/accidents/nit92.pdf

http://www.nirs.org/reactorwatch/accidents/Fukushimafactsheet.pdf

I understand that these reactors are Light Water Reactors which are not the same as the BWR reactors in the US.

 
trottiey (Nuclear) (OP)
15 Mar 11 0:02
There is no risk of anything remotely resembling an atomic bomb. If the core does melt, it will spread out to a flat puddle over the "core catcher" in the primary containment. Geometry matters to criticality, and a "critical mass" is just the minimum amount of material you would need if it was shaped like a perfect sphere. Anything other than a sphere loses a greater percentage of neutrons before they have a chance to participate in a chain reaction.

I will not give you an outright "no" to a fission explosion because there is room to get tripped up in definitions. Spontaneous fission is still occurring, and that is what is producing all that heat and pressure and hydrogen. So fission is indirectly responsible for those hydrogen explosions, and might also cause a pressure explosion. But there is no risk of a meltdown causing criticality and restarting a chain reaction, which is what a true nuclear explosion would be.

As to Cloa's comment, the control rods at Fukushima Dai-ichi unit #1 are boron carbide and hafnium. I believe they would float on top of the uranium in the event of a meltdown, so they would not be effective. Past accidents, such as at Chernobyl, have taught us that pure carbon is an undesirable material in a reactor.
electricpete (Electrical)
15 Mar 11 0:04
Update from the good site
http://www.world-nuclear-news.org/RS_Possible_damage_at_Fukushima_Daiichi_2_1503111.html

The good news: It seems the fire was at unit 4, and is out, not a concern.

The bad news: There remains big concern for the failure of the unit 2 torus:

Quote:

The pressure in the pool was seen to decrease from three atmospheres to one atmosphere after the noise [unit 2], suggesting possible damage. Radiation levels on the edge of the plant compound briefly spiked at 8217 microsieverts per hour but later fell to about a third that.

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electricpete (Electrical)
15 Mar 11 0:08
By the way, that conversion again, 8217 microsieverts/hr is 822 millirem/hr

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(2B)+(2B)'  ?

guizmy (Mechanical)
15 Mar 11 1:58
Someone could tell us please the amount of radiations emissions to environment in Fukushima in comparison to Tchernobyl Reactor  with regard to the total quantity of Nuclear Fuel available in Fukushima's failing Reactors and their capacity versus Tchernobyl?

Would it be something like 3 times Tchernobyl in the case of the worst scenario possible?
 
cloa (Petroleum)
15 Mar 11 3:00
Radiation is not easy to compare nor is nuclear fuel- why do you need a comparision- its not the same. Tchernobyl or chernobyl was a nuclear chain reaction explosion.  
ScottI2R (Electrical)
15 Mar 11 3:20
Ok, further removal of doubt. First, Pete, I get 821.7 mRem. :) Trottiey, bar definitions, that was the explosion I was inquiring about. I realize they could still explode as a gigantic "dirty bomb" scenario, but like I said, I was referring to an actual A-bomb type detonation. I had no idea of how critical geometry was from a criticality standpoint. Let me say, I was aware of it, but I thought it was just for efficiency purposes, ie. the most bang for your buck. Thank you for edumacating me.

Now, my question is about the radiation levels at the plant. These 50 or so workers are being exposed to what I believe is a lethal dosage of radiation. Is the PPE they have sufficient to protect them from harm or are they already walking(working)dead? If so, what would be the maximum levels that they could safely work in with the proper PPE? A personal example is my arc flash protection I wear, it is rated for an 8 calorie blast, so I stay out of panels where there is potential for greater than that. Believe me, I have no desire to be in an 8 Cal blast either, but that is where my protection stops. We are not issued the 40 calorie "space suits" at my plant.
One more question if I may. What kind of radiation is this? Alpha, beta, gamma and how fast does it travel a given distance (when not propelled by an explosion)? I believe that if it were xray or gamma, it would travel at speed of light. Please correct me on all of this as you see fit.

Once again, thanks to all of you for your responses.

Scott

I really am a good egg, I'm just a little scrambled!

guizmy (Mechanical)
15 Mar 11 3:27
quoted wiki on Tchernobyl:

"Four hundred times more radioactive material was released than had been by the atomic bombing of Hiroshima. However, compared to the total amount released by nuclear weapons testing during the 1950s and 1960s, the Chernobyl disaster released 100 to 1000 times less radioactivity. The fallout was detected over all of Europe except for the Iberian Peninsula.

The initial evidence that a major release of radioactive material was affecting other countries came not from Soviet sources, but from Sweden, where on the morning of 28 April workers at the Forsmark Nuclear Power Plant (approximately 1,100 km (680 mi) from the Chernobyl site) were found to have radioactive particles on their clothes"
unquoted

So yes definitely I want to roughly compare to figure out the environmental and Health potential consequence of Fukushima.

By Nuclear Fuel I mean combustible or Nuclear Materials. Sorry for my english I am not native english speaker.



 
unclesyd (Materials)
15 Mar 11 4:39
The biggest problem with Chernobyl was it had an open core and bits of the core were all over the place.  The last word that i got is that all who initially worked on the roof and helicopter pilots are all dead.  The helicopter pilots were the first to go as they had to fly over the exposed core o drop Boron pellets. Hundreds of solders used to tunnel under the reactor suffered varying degrees of radiation poisoning.

As I understand, it is now possible to treat some exposures that were at one time considered lethal.
 
Power2go (Electrical)
15 Mar 11 4:54
First, thank you all for the information you have shared so far. It has helped in understanding what is going on at the Fukushima NPP.

Here are links to digital globe that has excellent images from after the latest explosion at reactor 3. The damage to this building seems more extensive then to the building of reactor 1 after the explosion there.

  http://www.digitalglobe.com/index.php/27/Sample+Imagery+Gallery

http://www.digitalglobe.com/downloads/featured_images/japan_earthquaketsu_fukushima_daiichi_march14_2011_dg.jpg

The 50 or so operators/engineers/staff (from the 800 normal) that remain in the plant have an impossible task. With the levels of radiation present they should be out of the place within 30min but 2 hours max. When they don't they will get radiation sickness and die. They can hardly cope with all the new incidents like the fire in the building of reactor 4. (which was already shut down over a longer period). When the operators are forced to leave the plant will be on its own and.......

Think of this: when you go for nuclear energy you should be able to maintain a high level of security, technical know how and safe storage of spent nuclear fuel for at least the next 10.000 year. Now take the 10.000 year and flip that back to the past and imagine where you are. (You will end up way before the Egyptian dynasties)        
 
unclesyd (Materials)
15 Mar 11 5:53
FYI:
These reactor are General Electric Mark I reactors.  There are 23 of these in the US.  
trottiey (Nuclear) (OP)
15 Mar 11 6:13
For ScottI2R regarding radiation protection:

Please don't be shy; it wasn't a stupid question. You can look further up through this thread to see a stupid answer on my part, and that's much worse.

Radiation is probably the most complex hazard that humans work with, so it's very hard to give simple answers. To start with, there are two broad types of radiation exposure: internal, for example breathing in radioactive dust, or external, like getting a sunburn from solar irradiation. The suits they wear provide protection against internal contamination but do little against external irradiation. The suits themselves are useful against almost any level of contamination, but their effectiveness depends primarily on the work practices of the user. For example, forgetting to shave can make your respirator ineffective. Carelessness while changing out of them can send surface contaminants airborne where you can breathe them. Your level of radiation protection training is the number one thing that determines what level of radiation you can work with safely, not the quality of the suit.

It's hard to tell how much dose the workers have received. There have been a variety of numbers and statements published by the press that are completely inconsistent and can only be explained as journalistic errors.  As best as I could gather as of March 14th, somewhere between zero and four workers may have received a lethal dose. One of those was physically trapped and may have died from conventional causes long before the radiation got him. The other three, if the reports are accurate, are being treated. I have not seen nearly enough information for further medical prognosis, either positive or negative.

I suspect that most of the workers on site are receiving doses well in excess of occupational limits but far below lethal levels. Any amount of radiation will increase your lifetime risk of cancer proportional to the does you take. The highest dose number I have seen so far was 106,000 microsieverts, which carries with it a 0.6% chance of cancer and other health effects. But there may be other numbers I haven't seen, and the situation is still deteriorating. Please check the FAQ section later, and I will try to address this.

Alpha, beta and gamma radiation are all present in this accident. All of them travel at the speed of light, but they get weaker with distance. (Alpha and beta are actually slightly slower, but not by much.) The particles, droplets and gases that emit this radiation travel at whatever speed the wind or water currents will take them. You can probably see that this is a really complicated problem.
trottiey (Nuclear) (OP)
15 Mar 11 6:37
Regarding the quantity of radioactive material that might be released:

With the recent escalation of events, do we need to consider the risk to the spent fuel bays? According to the diagram, spent fuel is stored within the reactor building secondary containment; is this correct? This is the part of the building that blew up on units 1 and 3, leaving those bays exposed to the atmosphere. Spent nuclear fuel needs to be kept underwater and cooled for a few years after removing from the reactor. If those pools drain or evaporate off their water, the zirconium cladding on the spent fuel can catch fire. Is this what happened in unit 4? How much fuel would be in those bays?
Power2go (Electrical)
15 Mar 11 7:06
As far as I understand from various news sources the spent fuel is kept in the secondary buildings, under water in large basins. At present there is a storage of 20 years (!) of spent fuel rods in the Fukushima NPP. The spent fuel basin in the number 4 building dried up and the fire started.

So much for safe storage of spent fuel rods.   
itsmoked (Electrical)
15 Mar 11 7:16
What is the torus for?  I can't puzzle that item out.

Keith Cress
kcress - http://www.flaminsystems.com

unclesyd (Materials)
15 Mar 11 8:00
Here is short description of the Torus.

http://www.nirs.org/factsheets/bwrfact.htm
jmw (Industrial)
15 Mar 11 8:20
I seem to be missing something here.
According to the media, the earthquake alarm tripped these reactors into shutdown mode, or some of them and one was down for maintenance.
The problem, we are told, is that the Tsunami damaged the diesel generators and the batteries were unable to cope.
Is there something more? It seems to me that even if the generators were wiped out, portable generators could be brought in within the time frame here and since this is a coastal station which receives much of its supplies and equipment by sea, the suggestion has been that ships docking there could provide power though it might take some doing to jury rig a connection.
So I have to think that the generator failure is not the primary problem.
So OK, the control rooms are damaged, but the first objective is tor restore water circulation... so it is a matter of powering some pumps and valves.
At the moment they are said to be flooding the reactors with sea water... they've power for that but are they flooding the reactors or simply pouring water over the containment? (which suggests the cooling water installation has suffered something else?)
Need to replace pumps? Airlift in.
So something in the media doesn't gell. It may well be my understanding.
So what am I missing?

JMW
www.ViscoAnalyser.com

 

davefitz (Mechanical)
15 Mar 11 8:30
jmw:

We will likely need to wait for the "root cause analysis report" that would be issued maybe a year from now to have something more reliable than guesses. And the publically available version will likely be edited  in some manner, but that is the price we pay everyday, for "consensus'.

Some reports claim the diesels were taken out by water contamination of the fuel- which would also likely damage the fuel injectors. Other possiblities include water entering the snorkel air intake.

The pumps and motors may use seal water, normally assumed to be filtered clean fresh water, and that assumption may have been violated and now whaterver the seal water or cooling water had contaced is likely fouled/ damaged by salt water / debris contamination.seized bearing etc follows quickly.

But one thing we can be certain- everyone involved is working at max dedication to solve this ASAP, and it is best to give them whatever support they need to succeed.
unclesyd (Materials)
15 Mar 11 9:01
Here is a synopsis of the Fukushima problems.   It has a lot of good links.

http://www.ieer.org/comments/Daiichi-Fukushima-reactors_IEERstatement.pdf









                                     

 








                                     

  
printing724 (Electrical)
15 Mar 11 9:11
Re exposure levels: electricpete's conversion is right on, 8217 microsievierts/hr is 822 mrem/hr.

(Disclaimer: what follows is from my Navy career which ended many years ago. I believe it to still be current)

To put that in perspective, the occupational limit in the US nuclear industry is 3,000 mrem (30,000 microsieverts) per quarter or 5,000 mrem (50,000 microsieverts) per year. This is based on a presumed "safe" level that does not add substantially to long-term cancer risks.

The Navy's limits when I was in were 300 mrem (3000 microsieverts) per quarter or 500 mrem (5000 microsieverts) per year.

Acute physical damage starts to occur at short-term exposure levels in the 50-100 rem (500,000-1,000,000 microsieverts) range. If the exposure level rises to 300-500 rem (3,000,000-5,000,000 microsieverts) the short-term survival odds drop to 50% or less..

At Fukushima, they reported a spike to 822 mrem (8217 microsieverts) at the perimeter, then decreasing to some level markedly lower. A worker would exceed his/her quarterly exposure limit in about four hours in that environment.

What we don't know is the source of the radiation. The significant decline indicates (to me) that it originated from a point source rather than area contamination. If it was from a point source, the exposure levels closer to the source go up as the square of the distance. If that is the case, workers nearer to the source will exceed their limit that much quicker.

It is possible that reducing the number of workers on site is a measure intended to miinimize exposure.

In any case, our hearts must go out to the workers at that site. They have suffered personal losses like everyone else who lives in the surrounding area, yet they are at work trying to keep a bad situation from becoming much worse.

Kevin Snyder
SW2010 x64 SP3
Win 7 Pro
Core2 Quad Q6600 2.4Ghz 8Gb
NVIDIA Quadro FX570
3D Connexion SpacePilot Pro

rasevskii (Electrical)
15 Mar 11 10:03
for davefitz and jmw:

Yes you are missing something here: As I posted in the OilDrum thread, is that the  auxiliary station service electrical supply was wiped out by the Tsunami, that is all the electrical equipment at a an elevation of few meters above Sea Level was flooded out by corrosive salt water, and was therefore rendered inoperable, and could not be re-energized from whatever source.

We are talking of 4.16 KV systems (possibly 6KV), 480V, and lower voltage systems. The outdoor sea water pumps. plainly visible in the aerial views. on all 4 units were flooded out, as well as the Diesels (several MW) and even the two fuel tanks for the Diesel station were carried away.

Al electrical equipment was rendered useless, instantaneously, that was flooded out by salt water. Unrepairable. Only replaceable.

Even the reportably "brought in gensets" could not be connected to the existing (ruined) switchgear.

Evidently some other MV large motors (feed pumps?) were also flooded out and were therefore made uselass, rendering the reactors without any cooling supply. This is conjecture on my part, not having seen any any elevation drawings or one-line electrical diagrams of the station. Such information would be useful in further analysis of the situation.

rasevskii
unclesyd (Materials)
15 Mar 11 10:51
rasevskii

In this rather lengthy paper there drawing of the different Pressure Suppression water system on the reactor..

The case is thus or somewhat similar:
POGO

http://www.oecd-nea.org/nsd/docs/1986/csni86-126.pdf
electricpete (Electrical)
15 Mar 11 19:33

Quote (electricpete):

The good news: It seems the fire was at unit 4, and is out, not a concern.
Perhaps that was premature.

Would anyone venture a guess what's going on with this fire in unit 4?

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
15 Mar 11 19:35
Apparently the fire broke out again, and there were reports of consideration for bringing in helicopters to dump water on it.

I can take a guess, but I'd rather hear someone else guess what this represents.

=====================================
(2B)+(2B)'  ?

unclesyd (Materials)
15 Mar 11 20:32
It just came across on the news that they are has the same problem with #5 and #6 as they are having on #4.

There was some Congressman on TV calling for all the US nuclear plants to be shutdown.   

If I could only harvest all the hot going out today I could run a very big turbine.  I've come to the conclusion that a bow tie makes one an expert.

Also today an expert said shutdown the nukes and use a renewable energy source, natural gas and others. He wouldn't name the others.

A person stated that all we needed was a smart electrical grid which would replace the Nukes. I've seen some numbers on a smart grid but nothing like the 20% from nukes.   
electricpete (Electrical)
15 Mar 11 22:50
http://www.nzherald.co.nz/natural-disasters/news/article.cfm?c_id=68&objectid=10712720

Quote:

3.41pm: Japan's top government spokesman says that a surge in radiation means workers are unable to continue even minimal efforts at Fukushima Daiichi. Chief Cabinet Secretary Yukio Edano said work on dousing reactors with water was disrupted when workers were forced to withdraw after radiation levels surged early in the day.

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unclesyd (Materials)
15 Mar 11 23:09
One way to resolve the worker's radiation exposure.  one question is this an increase in the radiation field or total radiation to the body.

"On Wednesday morning, the Japanese government raised the permitted radiation exposure for plant workers by 2.5 times to allow them to work longer, according to NHK TV".
 
electricpete (Electrical)
15 Mar 11 23:17
It sounds a little bit like giving up. One would think there would be some reinforcements available, with radiation suits ....

=====================================
(2B)+(2B)'  ?

cloa (Petroleum)
16 Mar 11 1:30
This thread really should have been called Fukushima Daiichi as the plant at Fukushima Daini is well under control (cold shutdowns)  and wasn't that bad to start with. Any thoughts about when they'll restart Daini as we really need the power?   
electricpete (Electrical)
16 Mar 11 7:47

Quote:

One would think there would be some reinforcements available, with radiation suits ....  
I guess that technology is not here yet:
http://www.radshield.com/product_page_detail.asp?ProductID=985&ProductCatID=27&Search=

Quote:

Tailored for evacuation in a dispersed low energy environment. The Demron™ Radiation Protection Suit is a full body suit complete with an integrated hood, heat-sealed seams, and seam seal tape for added protection. The suit was engineered to provide protection during the evacuation of a dirty bomb. Due to advanced molecular design, the Demron™ coverall allows for better heat dissipation than other impermeable protective fabrics, providing the user with a cooler core environment. The suit is an excellent shield of high-energy beta particles, such as those emitted from Strontium-90, and provides at least 50% shielding of gamma rays up to 130 Kev
I know 130kev = 0.13MeV is a fairly low energy gamma compared to certain like the N-16 6 MeV gamma.  Are most fission product gammas also above 0.13 mev (?)

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(2B)+(2B)'  ?

unclesyd (Materials)
16 Mar 11 8:13
trottiey (Nuclear) (OP)
16 Mar 11 10:33
The increase in permitted dose sounds like a planned emergency measure. Please see my explanation about this in thread466-294445: Radiation protection 101 for Fukushima.

Radiation suits protect primarily against internal radiation exposures, although it does also block external alpha and beta. Personal protection against external gamma is generally not worth the weight. See my radiation protection thread for an explanation of the difference between internal and external exposure.
Zogzog (Electrical)
16 Mar 11 12:38
Anyone know the status of power? I heard they had some diesels on site but could not restore power because the switchgear had salt water contamination. I have a 1,000,000 sq-ft warehouse full of switchgear and am wondering if and how I can assist.  
MintJulep (Mechanical)
16 Mar 11 12:46
Where is all the sea water going?

Reports continue to say "injecting sea water".

The pressure vessel was full of water to start with.  So where is all this water going?

There was some venting of steam, but how much water could that account for?   
Zogzog (Electrical)
16 Mar 11 13:26
Recently my company refurbished approximately 75 portable 5kV generator sets that are used for general emergency and conflict situations and deployed and maintained by the Army's 249 Engineering Battalion. Other users include FEMA and state governments.

Each unit is specially designed to be easily transported by C-17 military aircraft and all members of the 249th are fully trained on their operation and service.

Wonder why these units are not deployed there?
guizmy (Mechanical)
16 Mar 11 14:54
Guys, pardon me to brainstrom on some of the worst scenario one can imagine.

Suppose the control of the situation is lost, and all reactors are lost with all nuclear material releasing radiations to atmosphere making a whole area of 500 km diameter having no more acceptable levels of radiation for any human being.

Question is : who will keep operating the remaning nuclear facilities in the affected critical 500 km area? are theses facilities equipped to withstand fulong shutdown period full autonomous mode?
trottiey (Nuclear) (OP)
16 Mar 11 15:10
Zogzog, I suggest you contact the IAEA with your offer of assistance.

guizmy, I am not aware of any plausible scenario where a 500 km evacuation zone would be warranted for civillians, and a similar sized evacuation zone for nuclear workers is ludicrous. The appearance of Godzilla would seem more likely to me.

guizmy's second question is interesting, but I do not know the answer.
 
rasevskii (Electrical)
16 Mar 11 15:11
for Zogzog:

There appears to be a complete news blackout on the detailed status of anything at Fukushima. Some reports say that the workers are operating in complete station blackout conditions. It may be too late in any case for more generators to be sent in. I think that we have been talking about a complete loss of all station service due salt water intrusion into all equipment at near seawater level.

That would have been 4.16 KV (or 6Kv) and all lower voltage level equipment that was lost.

It is obvious that the outdoor seawater pump motors were all flooded out, and the Diesels in a building near the lower right had the same fate. Imagine the damage as the salt water flooded into the energized and operating plant...

In any case two fuel tanks seen in the Before views were not there in the After views.

Latest reports talk of reduced staff due high radiation levels.

BTW what KW are these Diesels that you refurbished? Are they 4160 60HZ or reconnectable for 50Hz and other voltage...(unless that is secret of course.) You said 5KV, was that a typo?

Obviously detailed incident info belongs to the plant owner, as would be in any organization. We can only conjecture based on our field experience in similar installations.

rasevskii
trottiey (Nuclear) (OP)
16 Mar 11 15:22
You call this a "complete news blackout"? Really?

You can access all the press releases at this website:
http://www.nisa.meti.go.jp/english/

There have obviously been communication failures, but I'm guessing that the workers on site are a little to busy to do interviews right now.
Zogzog (Electrical)
16 Mar 11 15:34
Yes, 5kV. They were 750kW each, trailer mounted, 64,000 lbs for whole package. They are called "Field mobility packages" and are in use in Iraq and Afganastan. I think there was some flexibility on voltage and frequency output, but I do not know that for sure.

I get the feeling that the reason there is not any emergency power hooked up by now is Japan has not accepted the help? Matter of national pride maybe? I can't be the only guy with the means to do this sort of thing. The Ronald Regan is steaming off the coast and I would think they have the capabilities to do this sort of thing. Haliburton? FEMA? Someone?  
rasevskii (Electrical)
16 Mar 11 15:44
for trottiey:

Sorry, I should not have said that. I was thinking only of the electrical side. Thanks for the link. I had not seen that before.

rasevskii
 
trottiey (Nuclear) (OP)
16 Mar 11 17:06
It is difficult for me to imagine an evacuation zone of more than a few hundred metres for nuclear workers, and even then that could only be temporary while we draw up better plans and gather (or build) better equipment. We have the training and equipment to work safely with extraordinary radiation levels, and we have never encountered a hazard so great that we could not devise some way to work with it safely. Fukushima appears to be testing the limits, but your 250 km speculation is inconceivable to me.

And yes, bringing in helicopters to fight a fire was certainly envisioned long ago. They are frequently used in conventional fires, they were used in Chernobyl, and I myself had speculative conversations about them with some of my peers on the very day of the earthquake. I'm sure I wasn't alone, and the mission plans would have been drawn up long ago, just in case.

Communication needs to be better than this, it's true! I think most nuclear professionals understand the need for accuracy and completeness of information. That's why I'm here on this forum trying to help in my own way. But I also think some of the difficulties can be attributed to language barriers, journalistic errors, and outside factors related to the earthquake and tsunami.
VE1BLL (Military)
16 Mar 11 17:28
CBC News - "A new power line could soon restore electricity to cooling systems at Japan's tsunami-damaged nuclear plant, its operator said early Thursday..."
ScottI2R (Electrical)
16 Mar 11 17:51
CNN--(Contradictory News Network)

Am I reading this wrong, or is this yoyo saying that cesium and iodine do NOT harm the body?

Quote:

[6:48 a.m. ET Wednesday, 7:48 p.m.  in Tokyo] Tests revealed traces of radiation in tap water in Fukushima city, 80 kilometers (50 miles) from the Daiichi nuclear plant, the local government said Wednesday. The Fukushima prefecture's nuclear department said amounts of radioactive cesium and iodine that are not harmful to the human body were found in water samples taken at 8 a.m. Wednesday (7 p.m. ET Tuesday). Government officials said the traces found are connected with the nuclear plant. A measurement of the tap water supply taken later in the day found no traces of iodine or cesium.

Scott

 

I really am a good egg, I'm just a little scrambled!

electricpete (Electrical)
16 Mar 11 17:54
One way to parse the sentence would be that the phrase "that are not harmful" applies to "amounts", rather than "cesium and iodine"

=====================================
(2B)+(2B)'  ?

trottiey (Nuclear) (OP)
16 Mar 11 18:32
Either way, the Fukushima prefecture's statement about cesium and iodine, as reported above, is technically incorrect. No safe threshold has been scientifically established for the stochastic health effects of radiation. See thread466-294523: Putting Radiation Dose in Perspective for a discussion of this.
itsmoked (Electrical)
17 Mar 11 2:56
trottiey:
Thanks for this link:
http://www.nisa.meti.go.jp/english/

Very informative.

Keith Cress
kcress - http://www.flaminsystems.com

ScottI2R (Electrical)
17 Mar 11 4:30
Very informative I agree. However, data for f-daiichi is inconclusive / insufficient. I speculate that no suppression pool temps are available is because they are dry? And by the way, are these pools pressurized as one would believe by the parameters listed on the NISA site? I realize instrumentation can fail during an "event", however, the other plant experienced the same event (minus the reactor troubles) and all the data is present and available on it's chart. Sorry to start sounding a little cynical here, but I don't think the people that NEED to know (IE. Bill Nye the Science Guy) are being kept in the loop. (That was sarcasm). It really doesn't matter what I am told, although I would appreciate as I am sure we all would, a better, more technically accurate report of what the devil is going on over there. If the media cannot supply a knowledgeable person to report the situation in proper wording so those with no scientific background can understand, then they should shut their babbling pie holes. All they do is add hype and sensationalize a serious disaster / tragedy. Accountability for this can go all the way to the back burner for now. Solving and stopping the problem should be at the top of everyone's list. To do this, every relevant bit of data should be known.  And I do understand about "panic". However, it is my opinion is that the Japanese government is downplaying this to a degree that will endanger the public more than help them.
I apologize if this post seems harsh, but I am just a little tired of vague details, speculation, and conjecture that I am getting from public sources, not including this forum of course. The links here are the best  yet.  And, I guess I am tired as well....these 7-12's are wearing on me. Once again, SORRY.

Good night for now,
Scott
 

I really am a good egg, I'm just a little scrambled!

unclesyd (Materials)
17 Mar 11 6:36
Sott12R,

You are not the only one that poses the same questions about how much CMA, large scale, is going on.  I was listening to a Professor from MIT discuss the same problem about the available information and who is privy to it.  He hit the IAEA very hard because as of yesterday they were not involved in any form and had no people in the loop.  He also didn't like the position of the NRC for their comments, like we have it under review and so on. Whether this was by design or circumstance, that is the question.  This type behaviour reminds me of the many times while working on problem or project when things start to go wrong in any sense there is nobody to be found. Let things turn around and get on track you have a hell of a time getting a seat on the front row.
As you state I too personally think that the information has not been updated and transparent as it needs to be.  Whether or not a person can participate in the resolution of the problem materially is not the issue, but for people in the Nuclear Industry first hand information could be very valuable in any event going forward.  If a person is skilled and dedicated in their job they act like a tickler file going forward. I can't count the times a short remark about a previous event turns on the light.  The problem now is no one outside the circle will get the actual scenario of the event, only the opinions by one given in very sanitized version.

My favorite example of a dedicated employee was a Continuous Polymerization process operator who was cognizant of everything that went on around her while on the job. Though not officially in the loop her comments about a series of events prior to a particular failure were about 90% of resolving the problem.  How she worked was shown one day when she ask me what was the purpose of that metal tag sticking through the insulation on pressure vessels the only person who ask me that question in 40 yeas working around them.    
trottiey (Nuclear) (OP)
17 Mar 11 6:46
Journalists need to be able to cover any possible story, and they can't be experts on everything. Even their science correspondents can't possibly be an expert in every science and engineering field. I think it would help if they recognized that engineering is quite separate from science and kept an engineering correspondent around. (And in some cases, they need to realize that engineering includes a lot more than just software and electronics.) It's the lack of media knowledge about engineering, much more so than about science, that seems to cause most of the errors.

It would also help if the electric utility had been able to provide someone who could translate the technical stuff for the journalists and politicians. When you get to the point where the prime minister exclaims "What the hell is going on?" on national TV, I think it's clear that TEPCO bears some responsibility for inadequate communications.
Spartan5 (Civil/Environmental)
17 Mar 11 8:49
This strikes me as an extremely serious issue:
http://www.nytimes.com/2011/03/18/world/asia/18nuclear.html?_r=1&hp=&pagewanted=print

Quote:

The military also announced that it had postponed plans to drop water on Reactor No. 4, which Gregory Jaczko, the chairman of the United States Nuclear Regulatory Commission, on Wednesday pinpointed as a cause for serious alarm.

On Thursday afternoon, the Self-Defense Forces and the Tokyo Metropolitan Police had begun deploying eight water cannon trucks to Reactor No. 3. Before the radiation level drove them back, the Tokyo Metropolitan Police had planned to use the trucks, which are usually used in riot control, to spray at least 12 tons of seawater into the reactor.

The Self-Defense Forces planned to send five fire trucks, carrying a total of 30 tons of seawater. The Japanese government said that the reactor typically needs 50 tons of water a day to keep from overheating.

Tokyo Electric Power Company, which operates the reactors, was also working to complete a high-power line to the plant to restore the electricity needed to run the cooling systems, according to a senior Japanese nuclear industry executive.

The maneuvers seemed at odds with the most startling assertion by Mr. Jaczko that there was now little or no water in the pool storing spent nuclear fuel at the No. 4 reactor, leaving fuel rods stored there exposed and bleeding radiation into the atmosphere. His testimony before Congress was the first time the Obama administration had given its own assessment of the condition of the plant, apparently mixing information it had received from Japan with data it had collected independently. "We believe that radiation levels are extremely high, which could possibly impact the ability to take corrective measures," Mr. Jaczko said.

His statement was quickly but not definitively rebutted by officials of Tokyo Electric, the plant's operator.

"We can't get inside to check, but we've been carefully watching the building's environs, and there has not been any particular problem," Hajime Motojuku, a spokesman for Tokyo Electric, said Thursday morning in Japan.

Later, a spokesman for Japan's Nuclear and Industrial Safety Agency, Yoshitaka Nagayama, was more equivocal, saying, "Because we have been unable to go to the scene, we cannot confirm whether there is water left or not in the spent fuel pool at Reactor No. 4."

At the same time, officials raised concerns about two other reactors where spent fuel rods were stored, Nos. 5 and 6, saying they had experienced a slight rise in temperature.

On Wednesday night, Mr. Jaczko reiterated his earlier statement and added that commission representatives in Tokyo had confirmed that the pool at No. 4 was empty. He said Tokyo Electric and other officials in Japan had confirmed that, and also stressed that high radiation fields were going to make it very difficult to continue having people work at the plant.

There is zero containment around this fuel which was removed from the reactor #4 in December and stored in a giant open air swimming pool in the building that has been destroyed by a hydrogen explosion.
MagicSmoker (Electrical)
17 Mar 11 9:00
Here's an exceptionally well done comparison of before/after pictures of various sites in the area of the tsunami, including the F-Dai-ichi complex:

http://www.abc.net.au/news/events/japan-quake-2011/beforeafter.htm

 
Power2go (Electrical)
17 Mar 11 10:47
Thanks MagicSmoker but I have noticed that the before and after pics concentrate on the impact of the tsunami on various locations. For the Fukushima plant we are of course now further with the before and after situation. On 13 March 16:17 I have posted my own before and after pictures on this forum which you can find when you scroll back.

The situation at Fukushima is now going completely out of hand with high levels of radiation which even prevent high flying choppers to release their loads of water.

The US is now sending an unmanned robot plane that can hover above the plant to get a good look inside to see the condition. Hope the electronics of that plane can handle the radiation levels.

In the meantime Japan is loosing so much electrical power due to the damages and shutdowns of various other plants that a total black-out of large cities like Tokyo gets closer and closer. The Japanese Governement has urged citizens to cut down on electricity.

In the north, like from Sendai, people are massively escaping the threat of a nuclear dissaster. At the moment the wind is more or less from the west (off land) but when that turns to north-east people living in the larger Tokyo area will be in big trouble.     
http://www.jma.go.jp/en/amedas/205.html?elementCode=1     
jimbofitz (Electrical)
17 Mar 11 12:57
Does the nuclear industry (especially in Japan) use robots for inspections in high radiation areas or to move radioactive material around?  I, for some reason assumed that robotics could be involved to limit human interaction with radioactive material.  Could they send something in to get a ground level look at the pools and reactors?  Or to aim the hoses?

Just a thought...
 
trottiey (Nuclear) (OP)
17 Mar 11 13:01
Settle down. Stress may be good when fighting off an animal, but technological problems require clear level-headed thinking. Stress from this event may have more potential to damage public health than the radiation does. An internet forum can't do much to help Fukushima directly, but through education we can alleviate some of the stress.

The choppers would have to fly really low in order to dump their water (or other substance) accurately. And it seems plausible that the radiation beams and plumes of smoke would be much stronger in the vertical direction, through a missing roof, than horizontally through thick concrete walls. It means that an important contingency is unavailable, but there are others.

If the wind shifts, that may increase internal exposure hazards. In the worst-case scenarios, that may contribute to a statistical rise in the incidence of cancers and other health effects in the coming years. This rise would likely only be detectable through epidemiological studies. It is too early to quantify the harm, but it is conceivable that the power shortages might wind up having more significant public health effects than the radiation.  
Zogzog (Electrical)
17 Mar 11 14:10
Some good news, finally. (From WNN)

There are now 130 new personel at the plant, nuclear experts, engineers, rescue, military.

Several fire trucks are pumping water into the spent fuel pool and the best news, they have restored one of the emergency diesels so they now have power to the pumps to cool the cores. Unless something unexpected happens, it looks like the worst is behind us.

 
electricpete (Electrical)
17 Mar 11 16:01

Quote:

it looks like the worst is behind us.
I hope you're right, but I'm not so optimic.

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
17 Mar 11 16:02
optimic should've been optimistic

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(2B)+(2B)'  ?

printing724 (Electrical)
17 Mar 11 16:58
Has anyone seen or know anything regarding the effects of the drastically altered primary plant chemistry? From what I can tell, they are pumping in seawater, it is turning to steam, and the steam is being vented into the wetwell. If so, this leads to a massive buildup of chloride and sodium ions in the primary plant fluid. Not to mention the effects on pH control.

I would guess that the zirconium oxide coating (where intact) would be resistant, not sure about bare zirconium or other metals exposed to this brine solution. No one is worried about a crud burst here, or long term effects. But are there short term aggressive corrosion vectors that could come into play? (I hope not, and hope this is a rhetorical question)

I don't remember much of my reactor plant chemistry from when I was in the Navy, but chloride concentrations in the ppm range made us go ballistic as far as the secondary side of the steam generators were concerned (because of chloride pitting of the stainless steel tubes). The appropriate measurement unit for chlorides in the Fukushima plants is probably close to pounds per gallon...

Kevin Snyder
SW2010 x64 SP3
Win 7 Pro
Core2 Quad Q6600 2.4Ghz 8Gb
NVIDIA Quadro FX570
3D Connexion SpacePilot Pro

racookpe1978 (Nuclear)
17 Mar 11 18:05
Robotic access for photography or temperature/radiation measurement is doable, but depending on how much internal damage is to the twisting access "maze" inside the containment building, and the amount of other flooding, debris, fallen doors or administrative burden (tables, chair, bookcases falling over, filing cabients, etc) you will likely not be able to simple "drive" a robot to anywhere useful.  

What's needed is access, assessment, disassembly, repair, re-assembly, and testing of connections, doors, debris field, piping and tubing.   

Can't do that robotically.   Pulling even an empty 2-inch 50 mm) hose through a debris-filled corridor with even only one or two twists or bends will require several hundreds pounds of force - no small robot can do that.    
cloa (Petroleum)
17 Mar 11 18:24
Zirconium is passive to chloride corrosion at every concentration. Its only second to tantulum in passivity. The real question is after suffer radiological damage is it still passive.  
rmw (Mechanical)
17 Mar 11 19:22
Does anyone know if the aux diesel generators in this plant are recips or combustion turbines.  I don't NEED to know this, just curious.

rmw
unclesyd (Materials)
17 Mar 11 19:58
I haven't heard of anything but there are only straight unadorned Diesels generators.  According to latest news they have a new power line hooked up and are waiting on someone to push the button on the pumps.  The big question is whether the pumps damaged.  At the same time the US is sending so very large high pressure pumps for a backup.  
The US has officially told the Japanese that we are not receiving enough information.  This report also stated part of the problem was Japanese trying DIY on the event and failed miserably.  Supposedly the reason that the pumps were not brought in earlier is part of the DIY syndrome.
The sowed some closeup pictures of the reactors and the damage is more than just a little or only this or that was damaged.  

  
rmw (Mechanical)
17 Mar 11 20:18
I've seen both recip and CT driven aux generators in Nuke plants.  It would seem to me that on the engine side, a recip would be easier to recover from a flooded situation than a CT, but the generator now, well that is problematic no matter what the driver.

I was just curious.

I'll bet aux turbines are built on the turbine deck in future seaside Nuke plants, especially in earthquake prone zones.

rmw
MintJulep (Mechanical)
17 Mar 11 20:49
In the plant I worked at - same BWR design and similar vintage to Fukoshima - the back-up generators were turned by reciprocating diesels.

Great big things.  Size of a house.  I don't remember the manufacturer anymore.

You might put a turbine genset on the main turbine deck, but you'd have to be crazy to put one of these up there.  You'd shake things to pieces.
rmw (Mechanical)
17 Mar 11 21:37
Oh, I think turbine deck foundations are capable of withstanding some wicked vibrations - e.g. a main turbine shucks a blade or two...

And, foundations can be designed to isolate vibrations.  I just spent a week on a cruse ship and if I hadn't other wise known that there were some massive recip diesels driving the gen sets, I never would have known by feeling vibrations transmitted through the hull.

They certainly have some pretty massive other pieces of equipment on the turbine deck - again thinking of main turbine-generators and at times the turbine driven BFP's.

I think it can be done.

rmw
Zogzog (Electrical)
18 Mar 11 14:02
BJC (Electrical)
19 Mar 11 0:28
"Does anyone know if the aux diesel generators in this plant are recips or combustion turbines.  I don't NEED to know this, just curious."
The load pickup schedule is very fast. If I remember correctly first load was picked up in lless than 9 seconds. The cooling system is continually heated and lube oil is circulating all the time.
There would be dual seperate compressed air starters with air injected into the cylinders. Combustion turbines can't start that fast.

 
rmw (Mechanical)
19 Mar 11 10:05
So.... for those Nuke plants were the aux genertors are in fact CT's, are they just screwed?

How do they get around that fast start requirement?

rmw
electricpete (Electrical)
19 Mar 11 18:16
There may be a CT at a nuke plant, but I'm pretty sure there will also be one or more DG's.

=====================================
(2B)+(2B)'  ?

rmw (Mechanical)
19 Mar 11 18:34
The plants I am referring to are in Ontario and had multiple CT's but I didn't pay any attention to whether or not they had any DG's.  Logic would say that they must have.

rmw
cloa (Petroleum)
20 Mar 11 7:40
http://online.itp.ucsb.edu/online/plecture/bmonreal11/rm/flashtv.html


I don't think anyone has linked this before- as well as nuclear risks there is a bit of presentation on Fukushima's present state and while fission due to plutonium pooling was stated as a possibility, that possibility is now discounted as the dangerous fuel rods seem to have collapsed (with no nuclear explosion) so a fission reaction is unlikely. The expert says that a final solution for Fukushima is going to be difficult, a salt pile is growing in the reactors, there is a lot of debris and top access is difficult with the heavy radiation so covering the top is difficult. It might need explosives to allow the rods to fall lower. Fortunately military helicopters are getting close now to water bomb, Japanese are accepting international assistance. Maybe a few more helicopter could clean it up a bit and cover the top.       
electricpete (Electrical)
27 Mar 11 2:05
http://www.bloomberg.com/news/2011-03-27/status-reports-on-the-reactors-at-japan-s-fukushima-nuclear-plant-table.html

Quote:

No. 1: Contaminated water in the turbine structure contains 10,000 times the radiation of regular cooling water, NHK said. The company has started removing contaminated water from the basement of the turbine building and will prepare more pumps to drain the water, the agency said. The unit has been damaged since a March 12 hydrogen explosion destroyed the building's walls. The seriousness of the reactor's threat to safety is rated level five on an international scale of 1-7.

No. 2: Contaminated water in the turbine structure contains 10 million times more radiation than normal cooling water, NHK said. The company plans to remove contaminated water as early as today, the agency said. The company plans to start using freshwater on fuel pool from March 28, the agency said. The containment chamber may have been damaged in a March 15 explosion, and a power cable was reconnected to the unit on March 19. The reactor is rated a level-five threat.

No. 3: Contaminated water in the turbine structure contains 10,000 times the normal radiation, NHK said. The company is considering ways to remove the contaminated water, the agency said. A March 14 explosion damaged the unit's fuel cover. The reactor is rated a level-five threat

=====================================
(2B)+(2B)'  ?

owg (Chemical)
27 Mar 11 6:27
Zogzog - thanks for the "decent technical information". Even that says "After the total failure of plant cooling systems, seawater is being pumped into the reactor cores of units 1, 2 and 3 to prevent overheating and further core damage." but does not say where the seawater goes after the reactor cores, perhaps to the sea.

HAZOP at www.curryhydrocarbons.ca

frankiee (Marine/Ocean)
27 Mar 11 12:40
rmw.
My plant here in Ontario has 4, 15,000 KW non seismic all with separate fuel source and 2 CTs for emergency that are seismic and 5MW each
electricpete (Electrical)
27 Mar 11 13:03
Regarding my post 27 Mar 11 2:05 - it seemed alarming that they were reporting water activity of 10 million times normal coolant activity, which previously they were concerned about 10 thousand. This morning I hear there was probably a mistake in the reading... more info to come.

frankiee - CT's but no DG's?   How fast do the CT's start up?

=====================================
(2B)+(2B)'  ?

trottiey (Nuclear) (OP)
27 Mar 11 14:04
The analysis results from the turbine building basement, in becquerels per cubic centimeter, are here:
http://www.nisa.meti.go.jp/english/files/en20110327-1-5.pdf

Some rough calculations suggest the numbers are big enough to kill you by acute radiation poisoning within days if you drink an undiluted sip.
electricpete (Electrical)
27 Mar 11 15:49
Very interesting chart.

It seems like we should be able to draw some conclusions from examining the isotopes. For example if one plant has higher long-lived isotopes, that favors spent fuel pool as a source while if one has higher short-lived isotopes, that favors reactor as a source.  But at first glance, I didn't see any simple pattern like that.

I looked for the highest concentration of anything on the chart. Looks like Unit 2 I134 at 2.9E9y Bq/cm3 and a half-life of only 53 minutes.  With such a short half-life, that can't be left over from power operation... must be a decay daughter. What decay chain gives us I134?

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
27 Mar 11 15:57
It is kind of odd that I134 is more than 100x higher than anything else on the chart. Yet since it has a short half-life, it must have been created by decay recently.  You'd think the activity of the parent isotope of I134 (whatever it is) would show up in comparable concentration but there is nothing comparable to I134 in concentration.

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
27 Mar 11 17:01
I guess the I134 is probably a bogus number (awaiting more info).

Quote:

Officials at Japan's stricken Fukushima Daiichi nuclear plant late Sunday retracted their announcement that they had found puddles at the facility's No. 2 reactor containing 10 million times more radioactivity than would be found in water in a normally functioning nuclear reactor.

"The number is not credible," Tokyo Electric Power Co. spokesman Takashi Kurita, said, according to the Associated Press. "We are very sorry."

It was not immediately clear what led to the inaccurate reading of the water, or what the real level was. The company said on its website that there was a "mistake in the assessment of the measurement of iodine-134."

=====================================
(2B)+(2B)'  ?

trottiey (Nuclear) (OP)
27 Mar 11 19:15
The revised results are out:
http://www.tepco.co.jp/en/press/corp-com/release/betu11_e/images/110327e15.pdf

So you would actually have to drink a tumbler or so of the stuff to guarantee death. Or go wading through it for a few hours.

I've got to say I'm relieved. Not because of the toxicity level, but because the presence of any significant amount of I-134 would have indicated very bad stuff about the internal state of that reactor.
unclesyd (Materials)
28 Mar 11 12:05
The news is reporting all manner of difficulties at the site along with another earthquake (6.5). The can't pump the highly radioactive water from the turbine building as there is no place to put it.  The sea level radioactivity around the plant is rising.  To top this off there are reports of radioactive rain on the US East Cost, no mention of levels other than it's safe.

The reports of rain showing radioactivity got me to thinking about what levels of radioactivity were seen in rainwater during the  atmospheric testing era.   In reality it may not have been measured design as the instrument's of the day with any accuracy were lab instruments and quite bulky.   For measuring low levels of radioactivity  the "Cutie Pie"" was about the only thing outside the labs.  I remember going to class on the operation of the meter we were told to always keep the polyethylene cap on the meter due to high levels of Beta Radiation occasionally seen.
 
MintJulep (Mechanical)
28 Mar 11 12:49
"under the limit"

What limit?
unclesyd (Materials)
28 Mar 11 14:15
Isn't the Iodine Isotope I -131 instead of I -134
electricpete (Electrical)
28 Mar 11 15:05
The link 27 Mar 11 19:15 lists 3 isotopes of Iodine.  I assume they are all fission products or decay daughters of fission products. For example certain isiotopes Tellurium (52 protons) can beta decay to Iodine (53 protons)
 

=====================================
(2B)+(2B)'  ?

trottiey (Nuclear) (OP)
28 Mar 11 19:06
There are at least 5 isotopes of iodine with any semblance of stability. Iodine-131 is generally the isotope of most concern to health because its half life is 8 days - short enough to be highly radioactive, but long enough to find a human being and infiltrate it.

Iodine-134 only has a half-life of 53 minutes, and it is not a decay daughter of any long-life fission product. Therefore the presence of iodine-134, if it had been real, would have indicated that the reactor resumed criticality in the last few days, and/or that some new physics was taking place. Very unexpected and very bad. But it was just a lab error.
electricpete (Electrical)
29 Mar 11 13:18
A gloomy interpretation of events is that Unit 2 fuel has melted through the reactor vessel, and unit 2 containment is also breached from the hydrogen explosion:

http://www.guardian.co.uk/world/2011/mar/29/japan-lost-race-save-nuclear-reactor

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(2B)+(2B)'  ?

MintJulep (Mechanical)
29 Mar 11 13:27
I also noted that article states that the drywell has been flooded.

Earlier I saw some news agency's cartoon animation showing that the drywell had been flooded, but discounted it in light of a preponderance of reports suggesting that seawater was being introduced to the reactor vessel only.

 
cloa (Petroleum)
1 Apr 11 1:21
Given the desperation of the water flooding and difficulties in access, a lot of water probably missed its desired targets so where would spilled water have gone?   
mauner (Mechanical)
1 Apr 11 12:47

How can you determine that fuel has melted through the reactor vessel based on radiation levels?

What does the RPV provide 4" steel = 1/10 thickness?

Does anyone know the contact raditation reading for a spent fuel bundel out of water?

Could abnormal radiation levels occur due to a shift in the fuel when it melted to the bottom of the vessel?

What about the CRDM's and the undervessel support structure?
electricpete (Electrical)
1 Apr 11 13:28

Quote:

What does the RPV provide 4" steel = 1/10 thickness?
If you're talking about shielding for gamma's, the rule I remember is 1" steel reduced to 1/10. So 4" would reduce gamma radiation to 0.0001.  I'm sure it depends on gamma energy  

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
1 Apr 11 13:37

Quote:

How can you determine that fuel has melted through the reactor vessel based on radiation levels?
I assume the conclusions came from not only review of radiation levels but review of isotope levels present in the water of turbine building and in the ditch.  I guess maybe (?) they suggest a direct path from melted fuel to the outside.

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(2B)+(2B)'  ?

electricpete (Electrical)
1 Apr 11 13:41
[quote electricpete]If you're talking about shielding for gamma's, the rule I remember is 1" steel reduced to 1/10. So 4" would reduce gamma radiation to 0.0001.  I'm sure it depends on gamma energy   [quote]
Whoops, I was wrong ....you were right.  2" of lead of 4" of steel or 24" of water is about a tenth thickness.
 

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(2B)+(2B)'  ?

electricpete (Electrical)
1 Apr 11 13:47
I would also mention that if you google Richard Lahey cited in the link above, you'll see he is no slouch.  He was very involved in BWR development at GE and remains very involved in advanced nuclear technology development today.  One caveat I would mention is that his words are paraphrased in tha that link by a journalist, I would like to see what he wrote directly.

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
1 Apr 11 13:59

Quote:

I guess maybe (?) they suggest a direct path from melted fuel to the outside.
Well, I guess it is obvious there must be some path when fission products show up outside. But perhaps the ratio of the isotopes gives some idea about the path. For example, certain isotopes travel as gas, certain are water soluble, certain travel only as particles etc.

=====================================
(2B)+(2B)'  ?

electricpete (Electrical)
1 Apr 11 14:01
Correction: "certain isotopes" should've been "certain elements".  (it is generally not the specific isotope, but the specific element that is relevant for transfer mechanisms).

=====================================
(2B)+(2B)'  ?

cloa (Petroleum)
1 Apr 11 18:54
Naturally- if its Radon assuming its one of isotopes that has a half life long enough for the small quantities to get out then it escape as a gas.  
cloa (Petroleum)
1 Apr 11 19:00
Does anyone know what radiation protection clothing that Fukushima workers are using- since I heard of a company that produces clothing that is an effective as lead plates but actually wearable?
electricpete (Electrical)
1 Apr 11 19:54
I don't know what they're using, but there was a related link in my post dated 16 Mar 11 7:47

=====================================
(2B)+(2B)'  ?

trottiey (Nuclear) (OP)
1 Apr 11 19:58
The workers at Fukushima are just wearing plastic suits and respirators to block intake of radioactive contaminants. They're probably also wearing safety glasses if not using a full-face respirator. Plastic sheet provides some protection from external beta, but negligible protection from external gamma.

External gamma shielding basically comes down to mass - a pound of tungsten provides no more protection than a pound of lead. Some applications use tungsten because it's denser, non-toxic and can somehow be mixed more easily with flexible plastics. No doubt there exists some tungsten aprons out there, but that weight would still slow you down too much to be useful. Better to get your job done quickly and get out of the radiation field. Also, lead aprons can become contaminated and carry the contamination around with you.
vpl (Nuclear)
19 Apr 11 9:38
For anyone still interested, here's a link to the Tokyo Electric Power Company's website providing information about Fukushima Dai-ishi.

http://www.tepco.co.jp/en/nu/fukushima-np/index-e.html
http://www.tepco.co.jp/en/news/110311/index-e.html

Lots of pictures at the second URL (which can be reached from the first one; look under "Press Release")

Under the first URL, you can find the location of the monitoring points and the associated radiation levels at those points.

Patricia Lougheed

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electricpete (Electrical)
19 Apr 11 13:06
That is informative stuff.  Can someone explain the pressure and temeprature readings for Units 2 and 3 on slide 10/28:
http://www.tepco.co.jp/en/nu/fukushima-np/f1/images/f12np-gaiyou_e.pdf

Temperature > 100C, should have positive pressure at saturation.
Some kind of instrument error?

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(2B)+(2B)'  ?

vpl (Nuclear)
19 Apr 11 13:54
Pete

I have no more information than what was provided here on a publicly available website, so your guess is as good as mine.  Might it be due to the different locations where the readings are being taken?   

Patricia Lougheed

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trottiey (Nuclear) (OP)
19 Apr 11 15:44
The latest plant parameters still list the reactor water temperature as "Impossible collection due to low system flow rate," and most of the RPV temperatures and pressure are still "under investigation."
www.nisa.meti.go.jp/english/files/en20110418-1-3.pdf

The highest RPV temperatures reported in all documents are from the main feedwater nozzle. This nozzle is relatively high on the RPV and is probably dry. I'm guessing that cooling water is only being injected through the Low Pressure Coolant Injection (LPCI) system, which feeds the recirculation loops below the main feedwater nozzle.

There's another set of published temperatures for the bottom head of the RPV, and these are around 110-120 C. We can expect the boiling point to be elevated by a couple metres of head and a lot of salt left behind from the seawater cooling. On top of that there could be some metastable superheating happening, or heat conduction could be keeping the metal temperature higher than the water temperature. And then there's always the possibility of sensor failure(s) as well.
itsmoked (Electrical)
19 Apr 11 16:07
They've been negative since day one of the disaster.  I'd guess they're bad sensors or sensor circuitry.   

Keith Cress
kcress - http://www.flaminsystems.com

trottiey (Nuclear) (OP)
19 Apr 11 16:26
I'm guessing that Keith is referring to the RPV gauge pressures? They're slightly negative, but only by 1% or so of the full operating pressure. That's probably within the normal instrument error band. I'm guessing that the RPV's in units 2 and 3 are fully vented to the atmosphere, and the true gauge pressure is zero.
vpl (Nuclear)
19 Apr 11 17:30
I agree with trottiey -- the #2 and #3 reactor vessels are probably at atmospheric pressure.

Patricia Lougheed

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Zogzog (Electrical)
23 May 11 9:19
vpl (Nuclear)
23 May 11 9:37
Zogzog (and others):  Tokyo Electric has a website devoted to the Fukushima Daiishi reactor recovery (http://www.tepco.co.jp/en/nu/fukushima-np/index-e.html).  If you scroll down, about 3/4 of the way down, there is a clickable link "Photos for Press."

A bunch of amazing pictures, including the ones shown above.
 

Patricia Lougheed

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itsmoked (Electrical)
23 May 11 15:26
Nice Patricia!

Now I just need something to download them all so it doesn't take me a week of watching them all crawl down the screen..

Keith Cress
kcress - http://www.flaminsystems.com

cloa (Petroleum)
23 May 11 19:30
International Business Times makes the typical mistake of confusing epicentre with landfall. On land it was only a maximum magnitude  of 7 was recorded.   
dicer (Automotive)
6 Jun 11 19:24
It's pretty common knowldedge that 3 have melted down. And is orders of magnitude worse than chernoble.
cloa (Petroleum)
6 Jun 11 19:55
There are meltdowns and fuel rod melting. Chernobyl was the former total containment loss. Fukushima is the latter.  
Helpful Member!  Duwe6 (Industrial)
10 Jun 11 17:31
Concur.  Due to its design, the fuel assemblies (rods?) at Chernobyl actually smelted themselves and released evaporated radioactive elements, including metals, directly into the air.  This was due to it using graphite for a moderator.  It burned, the steam piping ran in vertical openings in the graphite pile, and the burning graphite got a pretty effective chimney effect going.

3-Mile Island melted at least the upper half of the fuel rods, due to lack of cooling water.  Moron operator keept turning off pumps when they automatically came on.  He was trained in-house by the utility.  First-rate Navy-trained operators cost too much for them, so they got a $6-billion cleanup bill.

At Fukushima, they lost offsite power due to the eatrhquake, and internal power due to automatic shutdown because of the earthquake.  Then the 6-15 foot tall wave drown out their diesel generators.  Pathetic engineering, as this was a readily forseeable scenario.  Japan holds tsunami drills all the time.

Without power, the decay heat of the used fuel boils off the water.  If you don't replace the water, the fuel melts.  One small firetruck could have delivered enough make-up water by suctioning from the seawater intake canal, and pumping into the the steam system.  It all would have run back into the reactor.  The firetruck method has actually been tried at a BWR before:  look up "Brown's Ferry fire".

My guess is that the main problem in Japan was an inability to make a decision in a timely manner.  The Japanese culture is to mull problems over for days, hold several meetings, discuss it over drinks, and finally achieve some sort of consensus -- in a week or three.  

"Reactor desparately needs water NOW -- pump water into reactor.  Only have seawater, and it will ruin the entire system -- system will be ruined tomorrow by the impending meltdown -- start pumping seawater."  

It just took them too long to acknowledege the inevitable.  And we in the USA may have that same lack of alacrity in a big emergency, if the utilities persist in training for Normal Ops, and leaving out ugly emergencies.  The Navy trains for the hard stuff first, thus they develop superb operators.

"It ain't Rocket Science, it's just a big teakettle with some pecularities"
owg (Chemical)
12 Jun 11 8:33
Thanks Duewe6, for a lucid explanation.

HAZOP at www.curryhydrocarbons.ca

Duwe6 (Industrial)
26 Jun 11 15:08
Anything with an integrated circuit chip gets 'fried' due to the gamma-ray and neutron flux.  They ran into this at 3-Mile Island.  You have to operate robots on an umbilical, with only macro-sized components on the robot.  Microelectronics cannot take the radiation.
itsmoked (Electrical)
26 Jun 11 15:39
While that's true I don't think either of those problems had anything to do with radiation.

Keith Cress
kcress - http://www.flaminsystems.com

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