phonedawgz remember when you said this?
"
Graphite burns. Burning graphite mixed with a melted radioactive core launches radioactive particles into the atmosphere. Last I checked water doesn't burn.

This reactors core is located inside a containment vessel. The core could melt and there still could not be the release of radioactive particles."
https://www.fiero.nl/forum/F...6/HTML/083486-2.html

Seems to be you were inferring that without the graphite core radioactive particles would not make it to the atmosphere, that happened though. Fukushima fallout made it across the world, not high level, but still detectable.
Hence you were trying to deceive and deception is lying.

I loved this...
"Like making some dumb ass statement like the Japanese government was going to begin to cap the reactor in the next three hours? Clearly there has been one side of this discussion that has been continuously way off the mark."
https://www.fiero.nl/forum/F...6/HTML/083486-4.html

Now lets go see who actually posted that thread...
https://www.fiero.nl/forum/Forum6/HTML/083486.html

Nice

[This message has been edited by dennis_6 (edited 10-30-2011).]

Radiation Cleanup Confounds Japan
BY YUMIKO ONO

KORIYAMA, Japan—Nearly eight months after the Fukushima Daiichi nuclear accident scattered radioactive material over surrounding communities, Japan still is struggling to figure out how to clean up the mess, exacerbating fears about health risks and fanning mistrust of the government.
http://online.wsj.com/artic...008192502423920.html

Hey phonedawgz its from a source you use. Is it wacko?

News
Unknowns about radioactive materials warrant vigilance amid delayed gov't action
Municipal government staff measure radiation levels in Tokyo's Adachi Ward on Oct. 18. (Mainichi)
Municipal government staff measure radiation levels in Tokyo's Adachi Ward on Oct. 18. (Mainichi)

What does it mean that, in addition to the radioactive iodine and cesium that the government has heretofore focused on, extremely dangerous plutonium has been found in soil over 40 kilometers away from the stricken Fukushima No. 1 nuclear plant, and the likewise toxic strontium has been found in Yokohama, some 250 kilometers from the power station?

Radiochemical expert Michiaki Furukawa, who is a professor emeritus at Nagoya University and serves on the board of the non-profit organization Citizens' Nuclear Information Center (CNIC), says that some reports about plutonium have been misleading.

"When the disaster first happened, there were media reports saying 'plutonium won't make it far because it's a large and heavy element,' but no one who's done serious research in environmental radioactivity would say such a thing," he said.

According to soil surveys conducted in June and July by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) in 100 locations within 80 kilometers of the power plant, plutonium-238 believed to originate in the stricken plant was found at a total of six sites in the village of Iitate and the towns of Futaba and Namie, all in Fukushima Prefecture. In Iitate, 45 kilometers from the plant, 0.82 becquerels of the radioactive element were found per square meter, while the figures in Namie and Futaba were 4 becquerels and 0.57 becquerels, respectively. In the Fukushima prefectural city of Minamisoma, 15 becquerels of plutonium-239 and plutonium-240 combined were detected.

"At the very least, plutonium-238 had to have come from the explosions (at the plant). The plutonium that had heated up inside the reactors turned into fine particles when it came in contact with water, and was dispersed with the water vapor released in the explosions. Since the plutonium takes the form of particles -- unlike the gaseous radioactive iodine -- it probably didn't fly 100 kilometers," Furukawa says. "As for health risks, we probably don't have to worry much about them at those levels."

According to Jinzaburo Takagi's acclaimed book, "Purutoniumu no kyofu" (The Horrors of Plutonium), plutonium is a man-made element created by a U.S. researcher in 1940, and named after the planet Pluto. Any nuclear fission fueled by uranium will create plutonium as a by-product.

Many plutonium isotopes emit alpha rays, which cause massive genetic damage. Plutonium has little effect when it is outside the body, the element's radiation stopping 0.04 millimeters into the skin and exerting no internal effects. Once it is inside the body, however, it wreaks havoc on cells and the genes within far worse than that from radioactive cesium. Yet, it is unlikely to be absorbed when traversing the digestive system, which expels the element. It will stay inside the body for a long time if it enters through the lungs, however, damaging genes and eventually causing cancer.

The various plutonium isotopes are categorized by their life span, according to which plutonium-238 through plutonium-244 are considered the most problematic. The half-life -- or the time it takes for their radioactivity to decrease by half -- is long: 87.7 years for plutonium-238, 24,100 years for plutonium-239, and 6,570 years for plutonium-240.

According to guidelines for acceptable radiation levels in food products that the Ministry of Health, Labor and Welfare (MHLW) issued to municipal governments on March 17, the maximum permissible amount of plutonium in food was 1 becquerel per kilogram of water, milk and other dairy products, and 10 becquerels per kilogram of vegetables, grains, meats, eggs, fish and other foods. The maximum permissible amount of radioactive cesium was 200 becquerels and 500 becquerels respectively, which attests to the high toxicity of plutonium. As for inhaled plutonium, the government has not set any standards.
A government map displaying radiation levels in 10 prefectures relatively close to the Fukushima No. 1 Nuclear Power Plant. Areas in red show over 3 million becquerels of cesium per square meter, whereas those in light brown show less than 10,000. (Data as of Sept. 18. Image courtesy of the Ministry of Education, Culture, Sports, Science and Technology)
A government map displaying radiation levels in 10 prefectures relatively close to the Fukushima No. 1 Nuclear Power Plant. Areas in red show over 3 million becquerels of cesium per square meter, whereas those in light brown show less than 10,000. (Data as of Sept. 18. Image courtesy of the Ministry of Education, Culture, Sports, Science and Technology)

Are plutonium levels that have been detected since the nuclear crisis began really not a major cause for concern? Hiroshi Ishihara, who heads the Medical Treatment for the High Dose Exposure Research Group at the National Institute of Radiological Sciences (NIRS) in Chiba, puts it succinctly: "The plutonium levels we're seeing are several orders of magnitude lower than levels that would constitute a health hazard."

Ishihara explains that the total of 15 becquerels of plutonium-239 and plutonium-240 that were found in Minamisoma, is around the same levels that have been released in past nuclear experiments, and cannot necessarily be attributed to the Fukushima disaster. Meanwhile, Ishihara says the 4 becquerels of plutonium-238 that were found in Namie come from the ongoing crisis, but as Furukawa also says, it's unlikely to have any health impact.

Ishihara also agrees with Furukawa on the point that inhaling plutonium is dangerous, as once it's inside the lungs it finds its way into the liver, and is eventually deposited in the bones. The metabolic half-life -- the time it takes for an organ to eliminate half of a substance introduced into it -- of plutonium in the lungs is unknown, and for the liver and bones is 20 and 50 years, respectively. Mice and dogs that are given massive amounts of plutonium to inhale develop lung and bone cancer.

So at what levels does plutonium begin to affect human health? Ishihara says that "inhaling 910 becquerels or more of plutonium-238 is believed to slightly raise the possibility of cancer." He adds that cumulative radiation exposure in such a case comes out to 100 millisieverts in 50 years.

"The plutonium that was released in the latest incident has already been absorbed into the ground, making it difficult for humans to absorb," Ishihara says. "Even if one were to have inhaled plutonium soon after the explosions took place, it's hard to think that the amount was enough to have any effects health-wise."

What can be said, then, of the strontium that was also detected in the MEXT soil survey that detected plutonium? Strontium-89 was found in almost half of the survey sites, including the Fukushima Prefecture city of Shirakawa 79 kilometers from the power plant. In Namie, 22,000 becquerels of strontium-89 was found per square meter, while 5,700 becquerels of strontium-90 was found in Futaba. The Yokohama Municipal Government announced that 195 becquerels of strontium-90 had been detected in its Kohoku Ward.

Strontium, like calcium, is highly water-soluble and is easily absorbed by plants. Once inside the human body, it accumulates in the bones and can cause leukemia. Strontium-89 has a half-life of 50.5 days while strontium-90 has a half-life of 29.1 years, and according to some reports, both isotopes have a metabolic half-life of 16 to 26 years.

Says Tetsunari Iida, director of the Institute for Sustainable Energy Policies (ISEP), a non-profit organization advocating the abandonment of nuclear power: "Strontium is representative of the so-called 'ashes of death,' and emits beta radiation. Strontium hadn't been detected until now because the government had been taking measurements only of gamma radiation, emitted by cesium. The levels of strontium that have been found are not surprising in and of themselves, but the fact that the element was found in Yokohama tells us that it has probably made its way to other places including Tokyo, Gunma Prefecture and Nagano Prefecture."

Asked about the recently released MEXT aerial survey results on the spread of radioactive cesium, Iida criticizes the government for having taken too long.

"It was the local residents who first found strontium in Yokohama, right? We still don't have a clear idea of the scope of radioactive contamination and exposure that we face. The central and municipal governments must conduct meticulous, comprehensive surveys to obtain measurement of various types of radioactive materials," Iida says. "The government must not limit surveys to select locations or conduct rough sample surveys using the time it takes to take measurements of alpha and beta rays as an excuse."
This satellite file image taken on March 14, 2011, and provided by DigitalGlobe shows the damaged Fukushima Dai-ichi nuclear facility in Okuma, Fukushima Prefecture, northeastern Japan. (AP Photo/DigitalGlobe)
This satellite file image taken on March 14, 2011, and provided by DigitalGlobe shows the damaged Fukushima Dai-ichi nuclear facility in Okuma, Fukushima Prefecture, northeastern Japan. (AP Photo/DigitalGlobe)

Iida adds that radiation experts who claim that annual exposure up to 100 millisieverts of plutonium and other radioactive elements is safe cannot be trusted. "It is the policy of the International Commission on Radiological Protection (ICRP) -- which provides the basis for radiation-related legislation around the world, among others -- to refrain from setting any safety standards for things whose safety have not yet been confirmed."

The Nuclear Safety Commission of Japan says that it takes a similar stance. "(The effects of small amounts of radioactive materials on health) have not been confirmed epidemiologically, and we do not take the position that plutonium is safe in amounts up to 910 becquerels."

"With any substance, there are those who are sensitive to it and those who are not," says Furukawa. "We could conduct as many animal tests as we want, but we cannot run human experiments, which means that we can't devise an accurate model showing the incidence of cancer caused by radioactive materials."
http://mdn.mainichi.jp/mdnn...2a00m0na003000c.html

http://fukushima-diary.com/.../10/deformed-kitten/
Kitten with deformity like that of chernobyl child.

8 years old girl has 2915 Bq of Cesium
Posted by Mochizuki on October 31st, 2011 · 3 Comments

Fukushima local government made an innocent girl a radioactive material.

Minamisoma local government has finally published the result of WBC for 2884 elementary and junior high school students.

They announce ONLY 274 of them had cesium 137 ,but the result about cesium 134 is concealed.

According to their trustworthy report,only 9 students had more than 20 Bq/ kg,but data about cesium 134 is concealed.

The worst case was the 8 years old girl. She had

Cesium 134 1192Bq
Cesium 137 1723Bq
Total 2915Bq

No wonder they did not check other radioactive material ,such as strontium or plutonium.
http://fukushima-diary.com/...28Fukushima+Diary%29

Monday, October 31, 2011
Ministry of Education Map on Tellurium-129m, Silver-110m in Soil in Fukushima

The Ministry of Education and Science announced on October 31 the "result" of the survey they did in June. Much like announcing the result in July (2PM on July 29, to be exact) of the survey they did in March about radioactive fallout in Tohoku and Kanto, where radioactive iodine, cesium tellurium and silver were found in abundance in Tokyo (see my post on August 1).

So, if tellurium and silver fell in Tokyo, it is very small wonder that they were in Fukushima soil within the 100-kilometer radius of Fukushima I Nuclear Power Plant.

Maps from the Ministry's announcement on October 31 are as follows. The amounts of tellurium and silver have been adjusted to the amounts as of June 14. I re-oriented and enlarged the maps for easier viewing but the resolution is not that great.

Tellurium-129m, half life about 34 days (the unit is becquerels/square meter):


Silver-110m, half life about 250 days (becquerels/square meter):

Silver-110m probably came from melted control rods, and went all the way to Tokyo.

The announcement is NOT accompanied by the table that has actual measurements at these locations. But Mainichi Shinbun (10/31/2011) reports that the highest amount of tellurium-129m was found in Okuma-machi at 2.66 million becquerels/square meter.

The Ministry's fallback position of course is "they won't affect the health very much because the radiation from these nuclides is "small" compared to those from radioactive cesium.

Sure. They are shorter-life nuclides, which means radioactivity is stronger. Even if they simply pass through the body without accumulation, I would think they zap the body with radiation as they pass through. External exposure is another matter. I fearfully recall that many kindergarteners and elementary school pupils all over Tohoku and Kanto were made to plant rice with bare feet and hands back in April and May. (And they are made to dig up the sweet potatoes with bare hands now.)

What's interesting is the third map which plots the ratio of tellurium-129m to cesium-137. The tellurium-129m ratio is very pronounced south of Fuku-I nuke plant, toward Iwaki City and southern Ibaraki Prefecture:

http://ex-skf.blogspot.com/...ap-on-tellurium.html

Absolute proof you are wrong, I love how you compare elements that are not comparable now lets see some reality.
Remember I said 296 kg/Bq was not dangerous but certainly not a trace, you called me a idiot and wacko and then went on posting elements that have different safe levels, so now lets see what the safe levels of Cesium are...
From a article that is talking about Tokyo Tap water
The Nuclear Safety Commission of Japan sets a safety limit of [/u]200 becquerel per kilogram for cesium-134 and cesium-137[/u]. The limit for iodine-131 consumption is 300 becquerel per kilogram.

For vegetables, Japan has a limit at 2,000 becquerel of iodine per kilogram and 500 becquerel of cesium a kilogram.

http://www.bloomberg.com/ne...-in-tokyo-water.html

So if the soil had been water, it would be well over the limit, hardly a trace. Now are you gonna admit you were wrong like a man or just attack me some more. It must be a terrible feeling to call someone a idiot and a wacko and then be wrong.

[This message has been edited by dennis_6 (edited 11-01-2011).]

Top 25 NRC internal documents about Fukushima released under freedom of information act.
http://enenews.com/top-25-n...-from-enformable-com

Listed in no particular order

1. March 14th, 2011 – NRC ONLY Update – All 3 Reactor cores likely damaged
2. March 15th, 2011 UPDATE: 2000 EDT Telecon on Fukushima Daiichi – Unit 4 New Fire Broken Out – Doses in Area around 30R/hr
3. March 15th 2011 – Unit 2 Containment Probably Breached – Loud Explosion – Containment Pressure Drop – Radiation Spike – Spent Fuel Fire
4. March 15th, 2011 – All 3 Reactors have known fuel damage – 50 Staff on site – 5 may have received fatal radiation doses
5. March 15th, 2011 – Fukushima Daiichi Units Degrading – Zirconium Fire at Reactor 4 SFP – Reactor 2 Possible Reactor Vessel Breach & Ex-Vessel Core Reaction
6. March 12th 2011 12:52 PM FOAI Communication – Reactor 1 Water level was known to be below top of active fuel
7. March 11th, 2011 – BBC is reporting radiation levels at reactor are 1000x normal. I feel like crying.
8. March 15th, 2011 – Core Exposed at #2 Fukushima Daiichi
9. March 15th, 2011 – Responding to inaccurate information in the news media – HELP CORRECT INACCURATE AND/OR MISLEADING NEWS REPORTS
10. March 15th, 2011 – The fire’s back in unit 4 – Unit 4 pool has a full core load in it and needs full attention – Holes in the upper structure from the earlier hydrogen explosion in unit 4
11. March 16th, 2011- ABC News Wants confirmation that things are definitely taking a turn for the worse – Per Holly – ignoring media calls
12. March 17th, 2011 – RadNet isn’t all it’s cracked up to be. We should be careful
13. March 17th, 2011 – This is a marathon, not a sprint – Take time to go outside and enjoy the spring
14. March 18th, 2011 – There’s Got to be a ton of loose materials floating in the SFP – I would not be surprised if the top 10 feet or so of the sfp was sloshed out
15. March 16th, 2011 – Assessing SFP Damage – SOARCA – Uncovered Spent Fuel Reports – Leak at Unit 4 SFP
16. April 2nd, 2011 – Estimated 10-30%/daily drywell turnover leakage from failed penetrations – Please delete after reading
17. March 30, 2011 – Reactor 2 Core Melted Through Containment Vessel – Workers “Lost the race” to save one of the reactors
18. April 6th, 2011 – Japan just said there was a zirc fire in Unit 4 SFP. Did we know this? – Depends what is meant by “know.”
19. March 20th, 2011 – The band of elevated dose rates up to 18 mi from plant to the northwest seems to coincide with “Lube Oil Fire” in Reactor 4 SFP
20. March 14th, 2011 – Indications of Breach of Containment at Reactor 2
21. March 12th, 2011 – To me it looked like a containment building disappearing in an explosive cloud. WTF.
22. March 11th, 2011 – Fukushima Daiichi fuel could have been broken because iodine concentration in air began to be increased at the site boundary
23. March 14th, 2011 – NRC Asked About Extra Security In Case of Mass Demonstrations at Meetings
24. March 24th, 2011 – California Coastal Commission – Preliminary Report on Implications for Coastal California
25. March 12th 2011 – Core Damage at Unit 1 Prior to Explosion

[This message has been edited by dennis_6 (edited 11-01-2011).]

Breaking news “fission restarted at reactor 2″
Posted by Mochizuki on November 1st, 2011 · 2 Comments

Xenon133 and 135 are measured at reactor 2. Xenon is daughter of Uranium 235,half life time is 5.2 days(Xenon133),and 9 hours (Xenon135).
It proves the nuclear fuel is fissioning at reactor 2 still.

Tepco has starting injecting boric-acid solution into the (broken) reactor.

At reactor 2,Tepco finally started analyzing air filter of the container vessel on10/28/2011. As the result, they detected xenon 133 and 135. It may have been fissioning since months ago.
http://fukushima-diary.com/...28Fukushima+Diary%29

Translated by google...
Fission reactors or injection in Unit 2
11月2日 6時38分 動画あり 38 minutes, November 02 at 6:00 tweet on twitter (Click to leave the site NHK)

東京電力福島第一原子力発電所の２号機の格納容器から、核分裂反応が起きた時にできる放射性物質のキセノンが検出され、東京電力は核分裂反応が起きている可能性が否定できないとして� ��原子炉に核分裂反応を抑えるホウ酸水を注入しました。 From the Unit 2 containment of TEPCO Fukushima Daiichi Nuclear Power Station, xenon was detected when the radioactive material can fission occurs, TEPCO could not be denied that a reaction occurs fission reactors boric acid was injected with water to reduce the fission reaction.

福島第一原発の２号機では、先月２８日から格納容器の中から気体を吸い出し、フィルターを通して放射性物質を取り除く装置の運転を始めていて、この装置の出口付近で放射性物質の種類� ��濃度を測定して分析しています。 In Unit 2 nuclear plant, Fukushima Daiichi is dumped the gas from the containment from 28 last month and have begun the operation of the equipment to remove radioactive material through the filter, to measure the type and concentration of radioactive material near the outlet of this device We analyze it. その結果、１日に行った分析で、核燃料のウラン２３５が核分裂してできる放射性物質のキセノン１３３と、キセノン１３５が検出されたということです。 As a result, an analysis per day, and 133 radioactive xenon and fission of uranium 235 can fuel, is the fact that xenon is detected 135. キセノン１３３は放射性物質の量が半分になる半減期が５日と短いため、東京電力は、再び核分裂反応が起きている可能性が否定できないとして、午前３時前から１時間にわたって原子炉に� ��分裂反応を抑えるホウ酸水の注入を行いました。 Xenon-133 for 5 days and short half-life of half the amount of radioactive material, TEPCO can not deny the possibility that a reaction occurs again fission, fission reactor for one hour prior to 3:00 AM boric acid made water injection to reduce the reaction. 東京電力によりますと、原子炉の温度や圧力、それに敷地周辺の放射線量を計測しているモニタリングポストの値に大きな変動はないため、核分裂反応が起きていても規模は小さいとしてい� ��す。 According to TEPCO, the reactor temperature and pressure, because large variations in the value of monitoring posts measuring amount of radiation that 敷地 around it, even if the scale nuclear fission reaction occurs are small. 経済産業省の原子力安全・保安院によりますと、検出されたキセノンの濃度は低く、原子炉の温度などに変化がないことから、今のところ燃料が再び溶融しているとは考えにくいとしていま� ��が、ホウ酸水を注入したあともキセノンの検出が継続されないかどうか、状況を見極めるとしています。 According to NISA of METI, the concentration of xenon was detected is low, since there is no change in temperature, etc. of the reactor, and then melted again fuel so far has been as unlikely but whether xenon does not continue even after the detection of boric acid was injected into the water, and assess the situation.

福島第一原発２号機で、キセノンが検出されたことについて、原子力が専門の東京大学大学院の岡本孝司教授は「現在の２号機は、核燃料が溶け落ちて核分裂をする物質が散乱していると考� ��られ、核分裂反応が起きにくい状態になっているが、原子炉内外にある放射性物質から出る中性子が燃料のウランなどと反応して、局所的、一時的に核分裂反応が起きる可能性は十分に考� �られる。しかし、原子炉にはこれまでも大量のホウ酸を注入していたことなどから、核分裂反応が連続的に起きる臨界になる可能性は考えにくい。原子炉の周辺の中性子を詳しく測ることで 、どこに核分裂反応が起きる原因があるかを調べ、核分裂反応を確実に起こさせないようにする必要がある」と話しています。 Unit 2 at Fukushima Daiichi nuclear power for the xenon was detected, Takashi Okamoto, Tokyo University professor specializing in nuclear power, "Unit 2 is now littered with material that falls to the fission of nuclear fuel melted considered, that is conditions are not occurring nuclear fission reaction, reacts with such uranium fuel neutrons come from radioactive material inside and outside the reactor, local, potential for fission temporarily sufficiently possible. However, it was from this reactor by injecting large quantities of boric acid, so far, can become critical fission reaction occurs continuously is unlikely. measure the details surrounding the reactor neutron that examines whether there is cause fission reactions occur where there is a need to make sure not to cause fission reaction "is said. また、国や東京電力が年内の実現を目指している、原子炉が安定的に冷却できている冷温停止状態の判断について、岡本教授は「冷温停止は、核分裂反応が止まり、再び反応が起きないよう� ��御できている状態のことで、今回のように局所的であっても核分裂反応が制御できていない状態であれば冷温停止状態とは言い難い。メルトダウンした燃料が原子炉内外のどこに存在して� �るか把握したうえで、核分裂反応が起こらない状態にもっていけなければならない」と指摘しています。 In addition, this year we aim to achieve national and TEPCO, in determining the cold has stopped the reactor can be cooled to a stable, Professor Okamoto is "cold shutdown, the fission reaction stops, the reaction does not occur again In such a condition that can be controlled, and stopped cold if the state can not control the fission reaction, even locally, as this is hard to say. exist anywhere outside of the reactor fuel meltdown I have an understanding, the state must have Ikenakere fission reaction does not occur "is said.
http://translate.google.com...ws/html/20111102/k10 013667531000.html%26hl%3Den%26biw%3D1024%26bih%3D397%26prmd%3Dimvns

[This message has been edited by dennis_6 (edited 11-01-2011).]

I am not surprised to hear you consume dirt. The rest of the world however does not consume it.

Fears of Fission Rise at Stricken Nuclear Plant in Japan
By HIROKO TABUCHI
Published: November 2, 2011

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TOKYO — Nuclear workers at the crippled Fukushima power plant raced to inject boric acid into the plant’s No. 2 reactor early Wednesday after telltale radioactive elements were detected there, and the plant’s owner admitted for the first time that fuel deep inside three stricken plants was probably continuing to experience bursts of fission.
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The unexpected bursts — something akin to flare-ups after a major fire — are extremely unlikely to presage a large-scale nuclear reaction with the resulting large-scale production of heat and radiation. But they threaten to increase the amount of dangerous radioactive elements leaking from the complex and complicate cleanup efforts, raising startling questions about how much remains uncertain at the plant, the site of the world’s worst nuclear disaster since Chernobyl. The Japanese government has said that it aims to bring the reactors to a stable state known as a “cold shutdown” by the end of the year.

On Wednesday, the plant’s operator, the Tokyo Electric Power Company, said that measurements of gas from inside Reactor No. 2 indicated the presence of radioactive xenon and other substances that could be the byproduct of nuclear fission. The presence of xenon 135 in particular, which has a half-life of just nine hours, seemed to indicate that fission took place very recently.

Trade Minister Yukuo Edano censured Japan’s nuclear regulator, the Nuclear and Industrial Safety Agency, for failing to report the discovery to the prime minister’s office for hours, according to local media reports.

The developments added to the disquiet over handling of information related to the disaster. For almost two months after the March 11 earthquake and tsunami, disaster, both company and government officials declared it was unlikely any meltdown had occurred at all at the Fukushima Daichi nuclear complex, finally conceding that the fuel had indeed slumped and had likely breached containments in three reactors.

The amount of detected xenon was small, and there was no rise in temperature, pressure or radiation levels at the reactor, Tokyo Electric said. Researchers were double-checking the data to make sure there were no errors, the company said. Experts concurred that it was possible that Tokyo Electric had made a simple error in its measurements.

But the urgent injection of boric acid underscored that the company was operating on the assumption that the measurements were valid. A naturally occurring element, boron soaks up the neutrons released when an atom is split so that those neutrons cannot go on to split other atoms in the process of fission. Nuclear power plants harness the energy released in the form of heat to produce electricity.

It is impossible to determine exactly what state the fuel is in, given that even an intact reactor can offer only limited gauges in the form of temperature, pressure readings and neutron flow, but not visual observation. That lack of clarity is one of the most resonant lessons of the Fukushima disaster, where those trying to guide the response and assess the danger operated by what amounted to educated guesswork.

In reactors of the design used at Fukushima, that chain reaction is normally stopped when the operator gives a command to insert control rods, which rise up from the bottom of the core and separate the fuel assemblies. But when the cores of three reactors at Fukushima melted, a large part of the fuel presumably formed a jumbled mass in the bottom of the vessel, and without a strict gridlike geometry, the control rods cannot be inserted. Some of the fuel has escaped the vessel, experts believe, and is in spaces underneath, where there is no way to use control rods to interrupt the flow of neutrons.

The jumble of material and conditions had seemed very unlikely to be able to produce sustained fission, but intermittent criticalities have long been suspected.

Junichi Matsumoto, a Tokyo Electric spokesman, acknowledged episodes of fission, telling a news conference: “There is a possibility that certain conditions came together temporarily that were conducive to re-criticality,” and that the measurements indicated a burst that occurred at a slightly higher rate than prior cases. “It’s not that we’ve had zero fission until now,” Mr. Matsumoto said. “But at this point, we do not think there is a large-scale and self-sustained re-criticality.”

A criticality could produce energy that would rearrange the wrecked fuel into a configuration that would no longer support fission, but gradually the material could come together in a form that would support a new burst of fission. That has been the case in previous so-called inadvertent criticalities in other accidents.

He said detailed measurements had not yet been taken at two other severely damaged reactors on the Fukushima site, but acknowledged the possibility of episodes of fission there too. The Fukushima complex, about 160 miles from Tokyo, was struck by a devastating earthquake and tsunami on March 11, which knocked out vital cooling systems and caused the nuclear fuel at three of the plant’s six reactors to melt, with radiation leaks and releases whose damage is still being calculated. A 12-mile exclusion zone is still in effect around the plant. Over 80,000 households were displaced.

The three reactors — together with spent fuel rods stored at a fourth damaged reactor — have been leaking radioactive material since the initial disaster, and new episodes of fission would only increase their dangers.

“Re-criticality would produce more harmful radioactive material, and because the reactors are damaged, there would be a danger of a leak,” said Hiroaki Koide, assistant professor at Kyoto University’s Research Reactor Institute, whose prescient warnings about nuclear safety have won him respect in Japan.

Mr. Koide holds that the nuclear fuel at the three reactors probably melted through containments and into the ground, raising the possibility of contaminated groundwater. If much of the fuel was indeed in the ground early in the crisis, the “feed and bleed” strategy initially taken by Tokyo Electric — where workers pumped cooling water into the reactors, producing hundreds of tons of radioactive runoff — would have prevented fuel still in the reactor from boiling itself dry and melting, but would not have done anything to reduce danger from fuel already in the soil — if it got that far. Workers have now put in place a circulating cooling system that recycles water, which results in less runoff.

Tokyo Electric does not deny the possibility that the fuel may have burrowed into the ground, but its officials say that “most” of the fuel likely remains within the reactor, albeit slumped at the bottom in a molten mass.

But even in their most dire assessments, some experts had not expected even bursts of re-criticality to occur, because it was unlikely that the fuel would melt in just the right way — and that another ingredient, water, would be present in just the right amounts — to allow for any nuclear reaction. If episodes of fission at Fukushima were confirmed, Mr. Koide said, “our entire understanding of nuclear safety would be turned on its head.”

Some nuclear experts have debated for months whether nuclear reactions might be continuing, either in the fuel inside the reactors, or in the spent fuel pools at the plant. They have pointed, for example, to the continued reports of short-lived iodine in the spent fuel pool at Reactor No. 3.

A former nuclear engineer with three decades of experience at a major engineering firm, meanwhile, said that sustained re-criticality remained highly unlikely. But his main concern was that officials could not pinpoint the exact location of the nuclear fuel — which would greatly complicate the cleanup.

The engineer, who has worked at all three nuclear power complexes operated by Tokyo Electric, spoke on condition of anonymity because he did not want to be identified by his former employers. He said that tiny fuel pellets could have been carried to different parts of the plant, like the spaces under the reactor during attempts to vent them in the early days. That would explain several cases of lethally high radiation readings found outside the reactor cores.

“If the fuel is still inside the reactor core, that’s one thing,” he said. But if the fuel has been dispersed more widely, then we are far from any stable shutdown.”

Matthew L. Wald contributed reporting from Washington, and Kantaro Suzuki from Tokyo.
http://www.nytimes.com/2011...?_r=2&pagewanted=all

Fukushima xenon from spontaneous decay
03 November 2011

The origin of xenon in the containment of Fukushima Daiichi 2 is currently considered to be spontaneous fission, a process of radioactive decay not involving any chain reaction.



Tokyo Electric Power Company (Tepco) was able to clarify the matter somewhat today, having been unsure of a previous trace detection of xenon. Subsequent work by the Japan Atomic Energy Agency confirmed the presence of the element, which is among a range of elements found after heavy atoms undergo fission.



The usual chain reaction of fission in a nuclear power reactor is initiated by a source of neutrons and sustained by a specific arrangement of fissile elements and moderating water. Spontaneous fission, however, occurs naturally from time to time in heavy elements of above 230 in atomic mass without any external stimulus and not usually causing any subsequent fissions.



Tepco said it considered the source of the xenon to be spontaneous fission on those grounds that it had injected boric acid to the reactor vessel to reduce the likelihood of chain fission reactions but was still able to detect xenon. Temperature and pressure data from the unit also showed no change around the time of the xenon's discovery in another indication that chain reactions were not taking place.



While spontaneous fission is infrequent, it nevertheless occurs continuously at a low level in all nuclear reactors. It is one of several possible forms of radioactive decay, albeit far less common than alpha and beta decay. The additional heat input from spontaneous fission is insignificant compared to the overall decay heat that must be removed continuously as a basic matter of nuclear safety.


Researched and written
by World Nuclear News
http://www.world-nuclear-ne...s_decay_0311111.html

adioactive materials detected in Tokyo Bay

Waste water discharged into Tokyo Bay from a cement plant has been found to contain radioactive cesium at much higher levels than the government-set limit for disposal.

The plant in Chiba Prefecture, east of Tokyo, uses ash from incinerators in the prefecture to produce cement.

The Chiba government says the plant operator checked waste water discharged from the plant into Tokyo Bay once in September and once in October.

It found radioactive cesium at levels of 1,103 becquerels per kilogram, and 1,054 becquerels per kilogram respectively.

The levels are 14 to 15 times higher than the limit set by the country's Nuclear Safety Commission.

The water had been used to clean filters which remove toxic materials from ashes.

The operator stopped discharging the waste water on Wednesday. The prefectural government has launched a survey of the seawater of Tokyo Bay near the plant.

Wednesday, November 02, 2011 22:08 +0900 (JST)
http://www3.nhk.or.jp/daily/english/02_40.html