Nuclear disaster in Japan and wider Nuclear discussion

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Nov 10, 2009
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Excerpt from the scientific american 2007

Not an answer to any post in particular, just general info COAL vs NUCLEAR

..........the waste produced by coal plants is actually more radioactive than that generated by their nuclear counterparts. In fact, the fly ash emitted by a power plant—a by-product from burning coal for electricity—carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy. * [See Editor's Note at end of page 2]

At issue is coal's content of uranium and thorium, both radioactive elements. They occur in such trace amounts in natural, or "whole," coal that they aren't a problem. But when coal is burned into fly ash, uranium and thorium are concentrated at up to 10 times their original levels.

Fly ash uranium sometimes leaches into the soil and water surrounding a coal plant, affecting cropland and, in turn, food. People living within a "stack shadow"—the area within a half- to one-mile (0.8- to 1.6-kilometer) radius of a coal plant's smokestacks—might then ingest small amounts of radiation. Fly ash is also disposed of in landfills and abandoned mines and quarries, posing a potential risk to people living around those areas.

In a 1978 paper for Science, J. P. McBride at Oak Ridge National Laboratory (ORNL) and his colleagues looked at the uranium and thorium content of fly ash from coal-fired power plants in Tennessee and Alabama. To answer the question of just how harmful leaching could be, the scientists estimated radiation exposure around the coal plants and compared it with exposure levels around boiling-water reactor and pressurized-water nuclear power plants.

The result: estimated radiation doses ingested by people living near the coal plants were equal to or higher than doses for people living around the nuclear facilities. At one extreme, the scientists estimated fly ash radiation in individuals' bones at around 18 millirems (thousandths of a rem, a unit for measuring doses of ionizing radiation) a year. Doses for the two nuclear plants, by contrast, ranged from between three and six millirems for the same period. And when all food was grown in the area, radiation doses were 50 to 200 percent higher around the coal plants.

McBride and his co-authors estimated that individuals living near coal-fired installations are exposed to a maximum of 1.9 millirems of fly ash radiation yearly. To put these numbers in perspective, the average person encounters 360 millirems of annual "background radiation" from natural and man-made sources, including substances in Earth's crust, cosmic rays, residue from nuclear tests and smoke detectors.
 
From today's la Repubblica.

How safe are the nuclear power plants? There are currently 400 in the world and they have demonstrated a rather low incident record. However, as improbable as an incident may be, the Japan scenario allows us to appreciate that risks do exist.

While even as improbable as it is for an incident to occur, the potential consequences of one actually taking place (like Chernobyl) are both enormous and disastrous. Each nuclear incident has a global potential, which lasts decades if not longer.

The technicians assure us that with the new technologies the probability of an incident is considerably reduced, however, the recently under construction facilities at Olkiluoto (Finland) and Flamanville (France) have been halted by the authorities precisely because the computer software that is supposed to automatically shut the reactor down in case of an emergency is not considered completely reliable.

In the Fukushima case there has been an unnerving chain of banal causalities, for nothing remote, given the potentialities having to do with the seismic zone in which it was built. The quake interrupted the electrical supply, so you had to pump water in to cool the bars. Yet the diesel motor responsible for this broke. In the meantime, the uranium bars continued to become hotter arriving near the 500 degrees centigrade, at which point a melt-down begins. While the high temperature caused (probably) one of the tubes that brings water to the reactor (this is the leading hypothesis) making the roof of the structure collapse.

But what exactly exploded? "If it had been the reactor's chamber -explains Paddy Regan, a British nuclear physicist- this is essentially what took place at Chernobyl and the escape of radiation would be enormous". If rather the damage has been limited to the external structure and "so long as the internal steel chamber has remained in tact -explains Robin Grimes, prof. at Imperial College, London- the large part of the radiation would be contained".

Yet there's third, terrifying, possibility, which till now has never taken place: that either the quake or the explosion has damaged the floor of the reactor chamber and that the radioactive combustible fuel has seeped into the ground, were it would be impossible to contain or recover.

More than a Chernobyl, therefore, Fukushima potentially recalls Three Mile Island (1979), for which a catastrophe was fortunately evaded and so the "incident" was without victims. Yet the Japanese crisis brings to light how many uncontrollable external events can be determining.

If everything goes well, catastrophe will once again be avoided, however, there's always the chance, as in the case of the Fukushimi inhabitants, that we can resign ourselves to an iodine diet.
 
Nov 10, 2009
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daiichi No3

From wikipedia

Unit 3 :Unlike the other five reactor units, reactor 3 runs on mixed uranium and plutonium oxide, or MOX fuel, making it potentially more dangerous in an incident due to the neutronic effects of plutonium on the reactor and the carcinogenic effects in the event of release to the environment.[52][53][54]
 
Nov 10, 2009
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Le breton said:
From wikipedia

Unit 3 :Unlike the other five reactor units, reactor 3 runs on mixed uranium and plutonium oxide, or MOX fuel, making it potentially more dangerous in an incident due to the neutronic effects of plutonium on the reactor and the carcinogenic effects in the event of release to the environment.[52][53][54]

A french source, relaying a japanese source, indicates that preparations are being made to inject sea-water in Daïchi No 2 as well.
But may be this is a confusion in the numbering system of the 2 Fukushima nuclear sites (Daiichi and Daiini)
 
Aug 9, 2010
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You've got to keep in mind that there is a chain of 'procedures' and protocol that are to be followed. A 'state of emergency' at the lowest level means that whatever is adversely happening needs to be announced as part of these incident reports. It does not necessarily mean that the whole plant is ready to blow or an impending out of control downward spiral is looming.

Conditions are being handled as they occur, and even though the worst earthquake has happened, there is no indication that a massive 'meltdown' and total uncontrolled chaos is happening while authorities are standing around helplessly watching.
 
mewmewmew13 said:
...Again, Ferminal had posted some excellent resource links, in particular the world nuclear news....good update

http://www.world-nuclear-news.org/RS_Battle_to_stabilise_earthquake_reactors_1203111.html

To quote part of the news article:
"Monitoring of Fukushima Daiichi 1 had previously shown an increase in radiation levels detected near to the unit emerging via routes such as the exhaust stack and the discharge canal. These included caesium-137 and iodine-131, Nisa said, noting that levels began to decrease after some time."

Cesium-137 is a byproduct created when uranium fuel is irradiated to create the heat necessary to generate power. It is an element present in the uranium fuel, which is contained by the fuel's metal cladding. The presence of this element outside the plant is not good news, and indicates the possible breach or partial meltdown of the reactor core. This is one thing that has authorities concerned, and if conditions change (e.g. levels of radiation or Cs-137 increases) the evacuation zone around the plants may need to be expanded. I hope people in those areas are aware of this and are prepared to get out if necessary.
 
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on3m@n@rmy said:
To quote part of the news article:


Cesium-137 is a byproduct created when uranium fuel is irradiated to create the heat necessary to generate power. It is an element present in the uranium fuel, which is contained by the fuel's metal cladding. The presence of this element outside the plant is not good news, and indicates the possible breach or partial meltdown of the reactor core. This is one thing that has authorities concerned, and if conditions change (e.g. levels of radiation or Cs-137 increases) the evacuation zone around the plants may need to be expanded. I hope people in those areas are aware of this and are prepared to get out if necessary.

The Cs 137 in the environment is certainly why that French expert Imentionned yesterday (post No120) assumed there was a partial meltdown then denied by the Japanese authorities.

Cs137 has a very long half-life, about a century or so I believe, didn't check.
 

flicker

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I am curious to know if radiation releases from striken Japanese A-plants are accuratley protrayed. Obviously the governments of countries would not want to invoke political incidents nor panic. People downwind really have no area to evacuate too.
 
Le breton said:
The Cs 137 in the environment is certainly why that French expert Imentionned yesterday (post No120) assumed there was a partial meltdown then denied by the Japanese authorities.

Cs137 has a very long half-life, about a century or so I believe, didn't check.

1/2 life of CS-137 is about 30 years, which is still a very long time for something that emits gamma radiation to be around. Gamma penetrates most substances very easily with a high energy that is damaging to the thing we are concerned about... human tissue.
 

flicker

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on3m@n@rmy said:
1/2 life of CS-137 is about 30 years, which is still a very long time for something that emits gamma radiation to be around. Gamma penetrates most substances very easily with a high energy that is damaging to the thing we are concerned about... human tissue.

So in other words any environment contaminated by CS-137 can pass into the food chain for 30+ years?
 
Mar 16, 2009
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The news doesn't seem tb be getting any better
Another tsunami alert in Japan, 3m-high waves expected
Hydrogen explosion at damaged Fukushima Dai-ichi nuclear plant

SOMA, Japan: Soldiers and officials in northeastern Japan are warning residents that the area will be hit by another tsunami and are ordering residents to higher ground.

Sirens around the town of Soma went off late Monday morning and public address systems ordered residents to higher ground.

10-foot tsunami seen off Japan as blast hits nuclear power plant
An estimated 10-foot (three-meter) tsunami was seen off Japan by helicopter Monday, according to Japanese broadcaster NHK.

Defense officials said water levels off the northeastern coast have dropped five meters and the tsunami is expected to hit around 11:30am local time, officials said.

Local residents in coastal areas of Fukushima prefecture have been warned to head for higher ground.

The news comes as smoke could be seen billowing from the Fukushima nuclear plant, after an explosion in reactor Unit 3. NHK said it was a hydrogen explosion.

Kyodo News Agency said the tsunami could be three meters high, citing Fukushima prefectural officials.

Meanwhile, in Tokyo, Japanese officials say they believe a hydrogen explosion has occurred at the stricken Fukushima Dai-ichi nuclear plant, similar to an earlier one at a different unit in the facility.

An official said the inner reactor container survived the explosion.
 
flicker said:
I am curious to know if radiation releases from striken Japanese A-plants are accuratley protrayed. Obviously the governments of countries would not want to invoke political incidents nor panic. People downwind really have no area to evacuate too.

I don't know but my guess is the Japaneese government (or the responsible organization in Japan) is providing radioactive release information as accurately as they can. If they did not and people in surrounding areas suffered adverse health affects as a result, the company that operates the nuclear power plants as a minimum could have their operating licenses revoked, possibly permanently. The Japaneese Atomic Energy Commission would probably have something to say about that.
 
Apr 21, 2009
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flicker said:
Why oh why are nuclear powerplants built in earthquake danger zones.
We have one in California at Diablo Canyon. Near San Luis Obisbo.

and San Onofre near Carlsbad, CA.
 
Jun 15, 2009
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flicker said:
So in other words any environment contaminated by CS-137 can pass into the food chain for 30+ years?

Better talk about 300 years. After 30 years HALF is gone, after another 30 years another 1/2 of the half left is gone etc. etc.

Good night, and good luck all Pro-Nuclear-Pipo. And i havn´t even start talking of the dangerous danger and long long longevity of Plutonium.
 
flicker said:
So in other words any environment contaminated by CS-137 can pass into the food chain for 30+ years?

That's the right idea, but longer than 30 years. Half life works like this. Let's say we start with a lump of 100% Cs-137. The percent of the Cesium-137 that remains after X years of decay is:

Decay.... Percent
Years..... Remaining
30.......... 100
60.......... 50
90.......... 25
120........ 12.5
150........ 6.25
180........ 3.13
210........ 1.56
240........ 0.78
270........ 0.39

That's one of the things that makes it so important to control/contain. That other important things being its high penetration factor and high energy make it a very damaging.
 
Nov 10, 2009
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python said:
an explosion at unit #3 confirmed.

Video
http://www.youtube.com/watch?v=T_N-wNFSGyQ&feature=player_embedded

‘just hours after Monday's explosion, Tokyo Electric Power Co. said a third reactor — this one at Fukushima Unit 2 — had lost its cooling capacity, which could lead to overheating and an explosion similar to the previous two blasts’

http://www.npr.org/2011/03/14/134501905/crisis-at-nuclear-plant-adds-to-japans-woes

However Unit 2 has been cooling for 2 days, so should be in better shape.
Also, only unit 3 uses MOX (was reloaded in MOX just a few months ago!)
 
Sep 25, 2009
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Le breton said:
However Unit 2 has been cooling for 2 days, so should be in better shape.
true, but...
despite some common sense considerations something is going on. either we an't let know everything or the authorities themselves are struggling to understand.

here's the tepco press release about the unit 2 (your specific concern). this was issued just several minutes ago (date references emphasis by me):

At 2:46PM on March 11th 2011, the turbines and reactors of Fukushima
Daiichi Nuclear Power Station Unit 1 (Boiling Water Reactor, rated output
460 Megawatts) and Units 2 and 3 (Boiling Water Reactor, Rated Output 784
Megawatts) that had been operating at rated power automatically shutdown
due to the Tohoku-Chihou-Taiheiyou-Oki Earthquake.
(previously announced)

In response, water injection into Unit 2's reactor were being carried out
by the Reactor Core Isolation Cooling System. However, as the Reactor Core
Isolation Cooling System failed today, it was determined that a specific
incident (failure of reactor cooling function) stipulated in article 15,
clause 1 has occurred at 1:25 pm today.



as usually i monitor primary sources and there is something ominous i feel we are not being told.
Also, only unit 3 uses MOX (was reloaded in MOX just a few months ago!)
by itself it should not have affected the cooling down process though the new fuel core density might be slightly different. it looks like the operators, like with the unit 1 explosion, were blind somewhat when they took a decision to release primary containment pressure into the reactor building...
 
Jul 3, 2009
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Radiation levels taken after Unit 3 explosion:

Radiation readings on site remained low after the blast, albeit elevated from normal operation. In the service hall the reading was 50 microSieverts per hour. At the entrance to the plant the figure was 20 microSieverts per hour.



At 12:30pm, the radiation dose measured at a monitoring point on the Fukushima Daiichi site indicated a level of 4 microSieverts per hour. However, a subsequent reading at 1:55pm showed a reading of 15 microSieverts per hour but an increase of radioactive material was not confirmed. A monitoring post at the Fukushima Daini plant – some 10 kilometres south of the Fukushima Daiichi plant – indicated no change in the radiation dose there.

http://www.world-nuclear-news.org/RS_Explosion_rocks_third_Fukushima_reactor_1402111.html

The times are local, so the info is a bit old.
 
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Water levels have now dropped again, critically low in reactor 2, which poses a serious threat of a meltdown at this point.
 

flicker

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mewmewmew13 said:
For those who are uneasy about the nuclear problems in Japan, please read this well-written article:

http://online.wsj.com/article/SB10001424052748704893604576198421680697248.html

Also, a good opinion on nature's destruction vs man-made ...

http://online.wsj.com/article/SB10001424052748704893604576198723013907008.html[/QUOTe

A people are being evacuated for a reason.
B the safe guards built into the plant failed
C Tokyo power Co. are destroying their own reactors to prevent a disaster.

Wall Street Journal has a feel good story. It is not like they are reporting the situation.