2011 Japanese Earthquake and Tsunami - News and Analysis

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vina
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by vina »

ramana wrote:CANDU uses heavy water and natural uranium as fuel. The rods have to be continousoly moved. The rods get converted to PU!.

US reactors are light water reactors and use enriched uranium ~2-3 %. And they don't produce maal. So essentially anti-proliferation measure.
Oh they do. The remaining 97% to 98% U-238 will capture neutrons and become Poo , just like it happens in CANDU. The only difference is in CANDU, you dont need to enrich the fuel because you use heavy water and the ordinary natural uranium which does contain some U-235 is sufficient to sustain a chain reaction. Ordinary water absorbs a certain percentage or neutrons and you cant have a chain reaction in a LWR/PWR without enrichment.

However , in CANDU, you need to get heavy water. So in both cases there is a trade off. But sure, CANDU makes "more Poo" than a LWR probably would I guess.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by vera_k »

vina wrote:
vera_k wrote:My reading suggests the CANDU/PHWR design would have been safer here, since it can be passively cooled (i.e. without power).
Who told you that ? They CANDU /PHWR as they are in India , Canada, S.Korea need the pumps to be working. The diff is per my reading and the pics I have seen in Al-Hundi and Com(ed)y Central (aka Frontline) is that it is a pressure tube system with end shields (calandria) as the reactor pressure vessel unlike a giant one piece pressure vessel like in Pressurized Light Water Reactors.

Performance of nuclear power in India
A passive decay heat removal system (PDHRS) has been introduced for preservation of inventory and enhancement of heat sink for station blackout/loss of power supply events.
Advanced Nuclear Plant Design Options to Cope with External Events
Emergency condition core (ECC) heat removal - PHWR 540
If the IAEA engineer is correct, the AHWR design is the most evolved in that it doesn't use pumps even for cooling the reactor at full power.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Sanku »

negi wrote:
Sanku wrote: There are reports which blame the earthquakes too, for cracking/breaking the chambers
Where ? At the Fukushima power plant ?
Yes, apparently the water loss in used fuel storage came from cracks due to earthquake damage, as well as damage to various plumbing to reactors which make it difficult to keep pumping water in.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Sanku »

vina wrote:
Sanku wrote:No you cant, especially dangerous, questionable LWR, BWR types.
Yawn.. Talk about so See Near (aka Short Sighted) that you cant see beyond your nose!
Well facts are facts, and such hyperbole works well, till it does not.

Good to see near only and make decisions based on what you can see, we are getting a taste of this variety of far-sightedness.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by vina »

vera_k wrote: If the IAEA engineer is correct, the AHWR design is the most evolved in that it doesn't use pumps even for cooling the reactor at full power.
The AHWR is not built yet. The PHWR 540MWe tweaked to 700MWe (both are essentially same, but with some boiling allowed per what I read in the 700MWe version to extract more energy) have these passive heat removal sytems. The bulk of the installed 220MWe systems don't (including the MAPS ones that were hit by the Tsunami). They need to have the pumps operating. The Injuns installed the emergency generators ABOVE the flood line while the Japanese were unlucky there that the Tsunami washed above their designed flood line or they installed it at whatever level and trusted their Tsunami barrier.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by vina »

Sanku wrote:Well facts are facts, and such hyperbole works well, till it does not.
Well, I did point out hundreds of BWR/PWR/LWR/MetalCooled ones operating in conditions greater than richter scale 10! Facts are facts!
Good to see near only and make decisions based on what you can see, we are getting a taste of this variety of far-sightedness.
:rotfl: :rotfl: . That takes the cake. So see-near is nearly blind! A blind man taking decisions is surely ridiculous!
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Sanku »

vina wrote:
Good to see near only and make decisions based on what you can see, we are getting a taste of this variety of far-sightedness.
:rotfl: :rotfl: . That takes the cake. So see-near is nearly blind! A blind man taking decisions is surely ridiculous!
Dearest Vina; actually you didnt realize, I was paraphrasing what you said a little while ago, its just that you dont understand the same point when it comes from some one else in a different way.

:mrgreen:
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by abhishek_sharma »

Will Japan's nuclear crisis end in catastrophe?

http://www.slate.com/id/2288391/
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by shiv »

vina wrote:
Can you really design any nuclear plant to withstand a 9 scale earthquake? Is any part of Japan safe for reactors?
Actually, that is a massive yes. Don't believe me, ask your Unkal Googal yourself. There are hundreds of such reactors in operation even today and they are designed for far more violent motions than what you get to see in a Richter scale 9 or even 9.5 or even 10 kind of earthquakes.

Hint.. They are ship based reactors and ships experience far more violent g forces and motions than any earthquake can throw up. Ask any sailor about roaring forties and a plimsoll line for WNA (winter north atlantic) and the 20 to even 35 meter waves that are common
That is an interesting point. I did not know there were hundreds.

I have been trying to do some reading about nuclear explosions in relation to fortified underground bunkers and one point that came out was that shear forces when waves travel from one type of medium to another causes breaks - for example underground water and sewage pipes.

I wonder if, in ships, the entire ship moves with the wave and shear forces acting on individual reactor components are minimized. Would that be an additional reason for earth based reactors to be more vulnerable?

In fact the idea sounds good. Why not place all nuclear reactors on ships and float them in an artificial lake inland?
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Sanku »

shiv wrote: In fact the idea sounds good. Why not place all nuclear reactors on ships and float them in an artificial lake inland?
I am sure you know the answer already and are playing with rest of us :( -- but anyway here goes -- Size and scale.

The ones on ships can nowhere produce as much electricity as is needed to compare them to land based ones.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Lalmohan »

well reactors i presume are mounted on shock absorbers and flexible foundations like other large structures in earthquake areas. therefore the same degree of shaking should be tolerable. the key in all cases seems not to be shock, but the ability to sustain cooling. passive designs (which i don't understand as yet) seem to be the way to do it
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by krishnan »

Well even if you do end up puting all that in a ship and let it float, what will happen when tsunami hits , or even a big wave hits it. What if the ship topples up
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by shiv »

krishnan wrote:Well even if you do end up puting all that in a ship and let it float, what will happen when tsunami hits , or even a big wave hits it. What if the ship topples up
The walls of the artificial lake will crack, the water will drain out and the ship will hit the bottom of the artificial lake. Provided that bottom is shallow and your prayers effective, the reactor will l remain intact. :oops: Sorry OT
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by negi »

Google chacha says shear forces do not propagate across a fluid medium.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by wig »

Japan's nuclear crisis appeared to be spinning out of control on Wednesday after workers withdrew briefly from a stricken power plant because of surging radiation levels, but desperate efforts to avert a catastrophic meltdown quickly resumed.

Early in the day another fire broke out at the earthquake-crippled facility, which has sent low levels of radiation wafting into Tokyo in the past 24 hours, triggering fear in the capital and international alarm.

Workers were trying to clear debris to build a road so that fire trucks could reach reactor No. 4 at the Daiichi complex in Fukushima, 240 km (150 miles) north of Tokyo. Flames were no longer visible at the building housing the reactor, but TV pictures showed rising smoke or steam.

A helicopter flew to the site to drop water into the No. 3 reactor -- whose roof was damaged by an earlier explosion and where steam was seen rising earlier in the day -- to try to cool its fuel rods
.

http://www.reuters.com/article/2011/03/ ... SS20110316
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Lalmohan »

workers were withdrawn for 1 hr...
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by SwamyG »

Sorry if these were posted in one of these threads:
What is decay heat?
A primer on spent fuel pools
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by A_Gupta »

http://bravenewclimate.com/2011/03/16/f ... h-summary/
Far less alarmist than the general press.
Is it more accurate?
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by ramana »

In the US there is a standard ref eqk for which the full seismic spectrum data is there called El Centro Eqk. The containment bldg with the reactor pressure vessel (RPV) is modelled and subjected to the El Centro eqk adjusted for local/site specific siesmic loads correction factors. The resultant seismic spectrum is used as the forcing function for the design of the plant for normal eqk. loads. For SSE (max eqk) the spectrum is scaled up to account for 1:500 loads.

Usually modern bldgs have 2-3Hz natural frequency and resonate in the low frequencies of the eqk spectrum. (This is why higher floors bldgs feel the response unless they are on isolators when they sway.)

Most eqpmt has 12-20 hz natural frequency and thus sees the rigid body motion only. Where things get dicy is a pipe break which causes whipping motion and local high frequency excitation. (Pipes behave like snake with head cut-off and whip around damaging anything nearby.)

The other issue is when the system dumps the steam during sudden shutdown into the torus or the cooling pool. It is a mixture of steam and water (flashes due to atmospheric pressure) and that causes high frequency loads (~200 HZ for torus designs).

In Fukushima case it was only the Eqk loads that matter and that wasn't the problem. Again loss of on site power to cool the reactor core after shutdown is the issue. And this is mulitple back up systems failure HPCI, LPCI, D-G sets in operable, battery power ran out.

Truly black swan in engineering design of nuclear power plants. Hazards analysis was not comprehensive to envisage such a failure.

In hind sight folks can claim they located D-G sets above water/flood line but that is by site geography or topography and not by design to minimize hazards. Any one claiming that now is a intellectual charlatan.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by vina »

shiv wrote:I wonder if, in ships, the entire ship moves with the wave and shear forces acting on individual reactor components are minimized. Would that be an additional reason for earth based reactors to be more vulnerable?
Yes, the ship behaves as one structure and hence individual components are not vibrating out of sync. The analogy is like this. Assuming that you put scatter different stuff on a bed sheet and stick it to the sheet (some papers, rocks, a stone ) and two people hold each end and give it a flutter, each piece will do a crazy jig by itself and do funny things. That is the ground based reactor in an earth quake.

Now put that in a stiff steel sheet and pitch it up and down and roll it sideways, yaw it and do all sorts of stuff, the individual pieces are largely in sync with each other and dont do random things relative to each other. That is the stuff on a ship.

Notice however, that no structure is infinitely stiff and a ship too bends and flexes under it's own weight and the action of the waves, but the stuff like piping electrical connections etc are designed for that kind of motion, which anyways are rather small.

Even planes. For eg, the Concorde underwent so much aero thermic heating that it expanded by nearly a couple of dozen inches in flight and the first set of carpets on the floor were ripped apart because it was one single piece thing!
In fact the idea sounds good. Why not place all nuclear reactors on ships and float them in an artificial lake inland?
The key single point of failure is the active cooling systems and the need for a large heat sink. The way I think is to have a fully hermetically sealed reactor of the ruggedized navy type that is installed a bit off the coast in underwater some 20 to 30 meter deep water in a floating/semi submersible offshore platform or better still tethered to the bottom. Those kind of things can take any kind of pounding under any weather, esp the fully underwater ones will be totally unaffected. Now you are in direct contact with the ultimate heat sink, the ocean, no need for any Paki like pumps for cooling , you can do cooling of the core convection of primary coolant , which in turn can transfer heat to the sea water directly . You eliminate mutiple points of failure that way in a fail safe mode and in the unlikely event of something going really wrong, your Musharraf is well covered because the infinite cooling available will prevent any meltdown. Not sure if such a thing is workable on land.. Maybe in the Great Lakes in Unkil land, but definitely wouldn't pull that stunt in Ulsoor lake in Bangalore Kerala.

So even in a worst case scenario, the thing sinks to the ocean bottom, it will be perfectly fine and stable until kingdom come.No chance of any explosion due to meltdown or anything.

Atleast land acquisition wont be a problem. Out of sight, out of mind. Somehow I dont see the Mr & Mrs Karat and Mr Yechury getting on to a catamaran and picketing something some 1km out into the sea. It will draw a huge collective yawn.

I do think engineering wise, the Nuke establishment need to rethink their strategies on the entire thing. Too much dependence on all the ducks lining up all the time has been the problem. And if one duck doesn't line up and acts Paki, there is serious trouble. They need to miniaturize (easily doable as the ship board plants show), increase ruggedness, have fail safe methods in engineering based on passive designs with no or very few points of failure which are very well addressed in the design.

Sure, you could ask, but then you cant have a nuke plant away from the coast! Maybe you shouldn't! In fact, think of it. The Russian method of disposing off their Naval Nuke reactors is to encase it in lead and concrete and dunk it into the deepest ocean close by! There you are ,it gets cooled perpetually, no need for any more Pakiness, concrete hardens with cooling as time goes by, everything safely, nothing corrodes over time , no radioactivity escapes, all Piss and Plogress onree.

Think of this. If this Fukushima plant had been a barge mounted one, anchored some 500m off the shore, there would have been absolutely NO effect of either the earthquake or the Tsunami!The long wavelengh Tsunami waves rise and crest only when they encounter a shoreline. In open water, you will simply not even notice it! As for earthquakes, you have an earthquake only every 5 mins in Japan. In sea, you have an "earthquake" by wave motion every second!
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by vera_k »

vina wrote:The AHWR is not built yet. The PHWR 540MWe tweaked to 700MWe (both are essentially same, but with some boiling allowed per what I read in the 700MWe version to extract more energy) have these passive heat removal sytems. The bulk of the installed 220MWe systems don't (including the MAPS ones that were hit by the Tsunami). They need to have the pumps operating.
Kaiga plant located at perfect spot
Jha says in Fukushima type of an incident when the back up diesel generators fail, in PHWR type reactors the water in the steam generator can be made to fall on the reactor core to cool it. "Suppose there is a loss of coolant and you cannot pump water into the core because of generator failure, this passive cooling system can be used to cool the reactor," observes the author of "The Upside Down Book of Nuclear Power."
The IAEA document lists several reactor types that employ passive cooling for decay heat removal. Dare say new constructions should be biased towards those types.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by ramana »

A request please dont get into polemics in this thread. Thanks, ramana
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

SwamyG wrote:Sorry if these were posted in one of these threads:
What is decay heat?
A primer on spent fuel pools
Thanks. Mitnse site is a nice resource (posted before by Mort W, me etc). My post a few days ago essentially had the same content about decay heat, and looks like my calculation around that time is consistent with the figures and graphs given in above blog :) (we used the same formula - but obviously a little different estimation about the amount etc.. )
Meanwhile looks like there is about 3000 tons of spent fuel stored.. (I was thinking - and posted in previous post.. 'hundreds - if not more' in my rough estimation ..)
http://www.nirs.org/reactorwatch/accide ... rpoint.pdf
Above is a nice power-point presentation (around Nov 2010) about the spent fuel at the plant's last inspection... pretty handy if one wants to do some calculations.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

shiv wrote:
ramana wrote: I don't think multiple incidents are mostly postulated with single event probability. I mean prob of a 9.0 eqk is very low. Probability of a major tsunami from that is even lower. And the probability of both occurring simultaneously is extremely low. Yet it happened.
Ramana I am sure that this was the logic used to declare that those reactors were safe, but 8.0 plus earthquakes and Tsunamis are not that uncommon and seem to occur as frequently as one in 10-15 years. So a reactor in a coastal seismic zone would have a 100% probability of facing at least one major earthquake and/or Tsunami in a 40 year lifespan.

List of major Tsunamis: 100 years
http://www.livescience.com/3731-tsunamis-history.html
April 1, 1946: The April Fools tsunami, triggered by an earthquake in Alaska, killed 159 people, mostly in Hawaii.

July 9, 1958: Regarded as the largest recorded in modern times, the tsunami in Lituya Bay, Alaska was caused by a landslide triggered by an 8.3 magnitude earthquake. Waves reached a height of 1,720 feet (576 meters) in the bay, but because the area is relatively isolated and in a unique geologic setting the tsunami did not cause much damage elsewhere. It sank a single boat, killing two fishermen.

May 22, 1960: The largest recorded earthquake, magnitude 8.6 in Chile, created a tsunami that hit the Chilean coast within 15 minutes. The surge, up to 75 feet (25 meters) high, killed an estimated 1,500 people in Chile and Hawaii.

March 27, 1964: The Alaskan Good Friday earthquake, magnitude between 8.4, spawned a 201-foot (67-meter) tsunami in the Valdez Inlet. It traveled at over 400 mph, killing more than 120 people. Ten of the deaths occurred in Crescent City, in northern California, which saw waves as high as 20 feet (6.3 meters).

Aug. 23, 1976: A tsunami in the southwest Philippines killed 8,000 on the heels of an earthquake.

July 17, 1998: A magnitude 7.1 earthquake generated a tsunami in Papua New Guinea that quickly killed 2,200.

Dec. 26, 2004: A colossal earthquake with a magnitude between 9.1 and 9.3 shook Indonesia and killed an estimated 230,000 people, most due to the tsunami and the lack of aid afterward, coupled with deviating and unsanitary conditions. The quake was named the Sumatra-Andaman earthquake, and the tsunami has become known as the 2004 Indian Ocean tsunami. Those waves traveled the globe – as far as Nova Scotia and Peru.

List of major Earthquakes (8.0 plus)
http://www.good.is/post/the-10-largest- ... t-century/
  • 1. Valdivia, Chile, May 22, 1960: 9.5
  • 2. Prince William Sound, Alaska. March 28, 1964: 9.2
  • 3. The west coast of Northern Sumatra, Indonesia, December 26, 2004: 9.1
  • 4. Kamchatka, Russia, November 5, 1952: 9.0
  • 5. Off the coast of Ecuador, January 31, 1906: 8.8
  • 6. Rat Islands, Alaska, February 4, 1965: 8.7
  • 7. Northern Sumatra, Indonesia, March 28, 2005: 8.7
  • 8. Assam, Tibet, August 15, 1950: 8.6
  • 9. Andreanof Islands Alaska, March 9, 1957: 8.6
  • 10. Southern Sumatra, Indonesia, September 12, 2007: 8.5
Japan should not have nuclear reactors?
Shivji - Nice. Can you add another column about the damage (for simplicity let us just consider number of deaths for each event) and study the effect of nuclear component (number of added deaths due to nuclear reactor component) here to be really objective and answer the question about "Japan should (or not) have nuclear reactors?"

If one also study this kind of statistics (between x type of power plant vs y) and then publish the data, it would have more meaning.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Theo_Fidel »

Ship based nuclear reactors have caused some horrible nuclear situations. And yes a few such reactors have gone down, mostly submarines. Most recently the Kursk. A major reason for retrieving the back end of the Kursk was to prevent nuclear fouling of the waters. Marine reactors also have long tradition of accidentally venting radiation into the ocean. Another major complication is the need for highly enriched fuel. This is very expensive. Also marine reactors are not as efficient as land based ones in converting heat to electricity. The high motion puts limits on turbine efficiency.

There is another key point the media are missing. While the radiation is being blown to sea it will then enter the fish food chain. Esp. stuff like radioactive Caesium and Strontium. There it will get concentrated up the food chain and return to shore in the form of fish catches and Salmon runs up the rivers. We have not heard the last on this radiation.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by astal »

Some simplistic physics : Rate of flow of water required per second to cool a reactor that is producing 10 MW and 20 MW of residual heat. (water at inlet is at 20 deg C and assume that the heat capacity of water is constant over the range of 20 to 90 deg C.)

Heat Produced at 10 MW : 10^7 Joules s
Heat capacity of water : 4185 joules per Kg or liter per Deg C
Max temp of water : 90 Deg C
Inlet water temp : 20 Deg C
Delta Temp : 70 Dec C

at 10 MW, Rate of flow required = 10^7/4185*70 = 34 liters per second for 10 MW
at 20 MW Rate of flow required = 2*10^7/4185*70 = 68 liters per second for 20 MW

Are these very approximate figures in the ball park or an I making too many simplifying assumptions?
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

...Are these very approximate figures in the ball park or an I making too many simplifying assumptions?...
Very good! (This is why physics is practical to get answers - at least to know the range)
One critical thing is (and it is good news), cooling depends on "boiling the water" which requires much more energy (5 times more than heating it from 20 to 90 degrees)
IOW 4185 joules (per Kg) to raise 1 Deg C)
but 2,240,000 joules (per Kg) to boil 1 Kg (from 100 degree water to 100 degree steam)
(They push the (sea) water, then let it boil and went) ( so you need less water but some how push the water in (inside with steam pressure))
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by ramana »

AmberG, They dont want to let the sea water coolant boil. It only to cool. Some of it might get converted to steam initially.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by abhishek_sharma »

U.S. Calls Radiation ‘Extremely High’ and Urges Deeper Caution in Japan

http://www.nytimes.com/2011/03/17/world ... clear.html

Fearing worst, countries & cos begin evacuation from Japan

http://timesofindia.indiatimes.com/worl ... 723654.cms
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

Theo_Fidel wrote:Ship based nuclear reactors have caused some horrible nuclear situations. ....

There is another key point the media are missing. While the radiation is being blown to sea it will then enter the fish food chain. Esp. stuff like radioactive Caesium and Strontium. There it will get concentrated up the food chain and return to shore in the form of fish catches and Salmon runs up the rivers. We have not heard the last on this radiation.
Quite true about ship based nuclear plants (the design doesn't have to be efficient and safety consideration has different calculus there...)

About fish in the sea is much less of a concern (the effects are fairly well studied).. amount of Cs and Sr quite small etc.. (lake/pond fish are bigger concern)

Things which they will pay attention is local milk (Iodine absorbs when animal eat grass etc..) (fortunately half life is very small - 2 month or so it will be gone for all practical purpose).. and food like mushroom, potatoes etc which will carry Cs for decades (or more).

Fortunately it is easy to test the food. And we have learnt a lot after Chernobyl. What happened in Chernobyl was criminal, they did not evacuate (or even informed the public) for days/weeks.. and hundreds (or thousands) cancers would have been avoided if they just informed the public and not let the kids drink local (Iodine tainted) milk for 2 months or so... .. :(
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by ramana »

AmberG, I want your opinion as physicst of the news reports from US about radiation in Japan. I get the feeling that US experts and media are overstating the case to induce panic which is not to be seen in Japan.

---Cherhnobyl did not have concrete containment dome.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

ramana wrote:AmberG, They dont want to let the sea water coolant boil. It only to cool. Some of it might get converted to steam initially.
Ramana - From what I know (and am told) it is indeed 'boiling' (and conversion to steam) which absorb the lion's share of energy. Of course they have to cover all the rods with water but now the water is not being "circulated" but rather "feed and bleed" (force sea water.. let it boil and let the steam escape..)

Could be wrong in all the details, and obviously I don't know exactly what is happening there ... but that will be my guess. ..

(Above, of course, is for reactor itself, not for spent fuel in the pool)
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

ramana wrote:AmberG, I want your opinion as physicst of the news reports from US about radiation in Japan. I get the feeling that US experts and media are overstating the case to induce panic which is not to be seen in Japan.

---Cherhnobyl did not have concrete containment dome.
FWIW: US Media (eg CNN) is definitely overstating (or at least making many wrong/ plain provable false statements).. but reputable US (and Japanese experts (recent statement by Chu - confirms partial melt down) are telling that things have gone worse..

Fire in spent fuel is, very large concern (understandable that in all that chaos people did not pay attention to unit 4 etc).. the amount of spent fuel (about 3000 tons!) if burns through will be serious.. (rough estimation still gives 10-20 MW heat energy being generated there)

In all (from what I know), I think that the effect would be local ( zero or near zero death(s) - years of cleanup etc..)...( was really hoping that no melt down before cooling process is fixed).... all we can do is to wait ...

Meanwhile close to 50 US experts are in Japan right now
ramana
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by ramana »

Spent fuel has residual decay heat and is not same order of magnitude as reactor core. Besides the fires in spent fuel area are oil fires and not hydrogen fires. So there is lots of ill informed fear and confusion.

I don't know what agenda CNN has with it 24 hr coverage of doom and gloom with anxious looking reporters who have no dog in the issue. CNN calling a British peacenik was a move to sow more confusion. The guy had no clue of what type of reactor was the plant based on. Another time they had a motor mouth expert sitting in US while the anchor is in Japan with a dosimeter round his neck despite being in Tokyo!
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Theo_Fidel »

In the US an area with 10 times above normal radiation due to human causes would be uninhabitable. No way anyone would move there. This accident will be killing Japanese for the next thousand years and beyond.

There is a terror of the word 'nuclear' here that does not exist elsewhere to the same degree. Part of it is knowledge. The rest of the world is too blase about the impact of long term radioactive contamination. Even in India people die all the time in Singhbum and Kerala due to radiation cancers. We are a bit callous about it.

As far as the spent fuel, what ignited the oil? Anyone considered that. I suspect it is an underplay of the seriousness of the situation. All the pictures show a cloud of smoke that is radioactive. Aerosolized radiation is the worst form. No way to control it. The spent fuel rods are even worse by all estimates as they are essentially open to sky now. A scientific blogger estimated that if the top of the spent fuel was uncovered by 1 inch the radiation dose at the railing is fatal in 16 Seconds! :eek: :( It is the spent fuel that is causing the huge spikes in radiation.

The thing that really scares me is the plutonium in the Reactor 3 spent fuel that is now exposed. No roof.
Last edited by Theo_Fidel on 17 Mar 2011 03:44, edited 1 time in total.
saket
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by saket »

ramana wrote:Spent fuel has residual decay heat and is not same order of magnitude as reactor core. Besides the fires in spent fuel area are oil fires and not hydrogen fires. So there is lots of ill informed fear and confusion.
As far as I can understand, the no. 4 reactor was shut down for maintenance and the fuel from the reactor core was transferred to the spent fuel pool, but the fuel moved from the core may not have been "completely spent". Is it possible that they had temporarily transferred "not completely spent" fuel to the spent fuel pool, which might have required more cooling?
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by VikramS »

saket:
The fuel in pool in reactor #4 is not spent fuel but active fuel, just there for storage, while the reactor was down for maintenance. So while everyone was looking at the reactor cores, we now have exposed active fuel.
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

Spent fuel has residual decay heat and is not same order of magnitude as reactor core. Besides the fires in spent fuel area are oil fires and not hydrogen fires. So there is lots of ill informed fear and confusion.
Ture it is not the same order of magnitude but still of the order of 10KW/ton (even after an year) ( see for example:
http://www.world-nuclear.org/education/phys.htm
So for 3000 tons it is still of the order of 30 MW!
I don't know what agenda CNN has with it 24 hr coverage of doom and gloom with anxious looking reporters who have no dog in the issue. CNN calling a British peacenik was a move to sow more confusion. The guy had no clue of what type of reactor was the plant based on. Another time they had a motor mouth expert sitting in US while the anchor is in Japan with a dosimeter round his neck despite being in Tokyo!
That is true. (Like the MIT blog said, in one report of CNN they found a serious error in every paragraph) .. and speaking of that dosimeters.. I even saw Sanjay Gupta misquoting rem as Sv (I am sure it was just spoken in error, as I am sure as a Dr. he would certainly know about safe and unsafe dose - but AC or no one else correct him).. and one 'PhD' nuclear expert, when checked (I could not believe the plain ignorance in some of his statements, so I googled him), came out to have 'PhD' in political science.. and NO training in any kind of physics...:)

Steven Chu and other experts OTOH are very trustworthy...
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

Ramana et al -
Adding to above - Check out the details I gave about the spent fuel storage inspection report about the plant
(Here is the link agian:
http://www.nirs.org/reactorwatch/accide ... rpoint.pdf

It has quite a bit of details - about 700 Fuel assemblies are generated per year- pools are 12m*29m*11m - 19 months of cooling - storage period of 50 years ...
The pools have monitors for temp, level, radiation and radiation in air etc..
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Re: 2011 Japanese Earthquake and Tsunami - News and Analysis

Post by Amber G. »

From mitnse.com.. (Sorry if already posted)
Units 1 and 2: TEPCO has released estimates of the levels of core damage at these two reactors: 70% damage at Unit 1 and 33% at Unit 2. They have also stated that Unit 1 is being adequately cooled.

Outlook: It is difficult to make conjectures at this point about the final disposition of the damaged fuel without further information. However, during our only operating experience with a partially melted and subsequently cooled core, Three Mile Island, the fuel mass was fully contained by the reactor vessel, resulting in minimal radiation release to the public. A decision is currently being made on how to best supply cooling water to Unit 2.

Unit 3: At 8:34 AM JST, white smoke was seen billowing from the roof of Unit 3. The source of this smoke was not investigated because workers were evacuated due to radiation levels. These levels had been fluctuating during the early morning hours before rising to 300-400 millisievert/hr around the time that the smoke appeared. It was unclear at the time whether these rising levels were a result of some new event at Unit 3, or were lingering as a result of Unit 2’s recent troubles.

Outlook: In order to provide some perspective on worker doses to this point, radiation sickness sets in at roughly 1000 millisieverts. A future post will deal further with the health effects of various amounts of radiation. Response to the smoke seen at Unit 3 appears to be in an information gathering phase at this point. Chief Cabinet Secretary Yukio Edano speculated that the smoke from Unit 3 might be the result of a similar wetwell explosion to that at Unit 2, but there is not enough information currently available to support or refute that statement.

Units 4-6: Flames at Unit 4 were reported to be the result of a pump fire, which caused a small explosion that damaged the roof of Unit 4 .... Efforts at Units 4-6 are focused on supplying cooling water to the spent fuel storage pools. Temperatures in these pools began to rise in the days after the quake. At the time of the quake, only Unit 4’s core had been fully offloaded to the spent fuel pool for maintenance; roughly 1/3 of the cores of Units 5 and 6 had been offloaded. This explains in part why the temperature in Unit 4’s pool has risen faster than at the other reactors: it has a higher inventory, both in fuel volume and in heat load.

Outlook: The fuel within these pools needs to remain covered with cooling water in order to prevent the low levels of decay heat present from causing it to melt, and also in order to provide shielding. Boiling of the water results in reduction of the water level in the pools, so if/when the pools get hot enough for boiling to begin, water needs to be added to replace what boils off. The staff of Unit 4 plan to begin pumping water to the spent fuel pool from ground level as soon as radiation levels from Unit 3 are low enough for them to return. This pumping operation should be relatively easier than injection of cooling water into the reactor vessels at Units 1-3 because the pools are at atmospheric pressure.

...Japan indicates that radiation levels as a result of the Unit 4 fire were higher than those reported previously. Radiation levels early this morning at the outside of Unit 3 measured at 400 millisieverts/hr. At the present time however, radiation levels at the boundary of the facility are 1530 microsieverts/hour. We will continue to update as further reliable information is available.
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