Michele Kearney's Nuclear Wire - Major Energy and Environmental News and Commentary affecting the Nuclear Industry. Nuclear Activities
Saturday, March 19, 2011
Japan Could Encase Nuclear Plant in Concrete
Japan could encase the Fukushima Daiichi nuclear power plant in concrete and sand in a final attempt to stop massive quantities of radioactive material from escaping the site, the facility's operator indicated on Friday (see GSN, March 17).
(Mar. 18) - A girl is scanned for radiation on Wednesday in Japan's Fukushima prefecture. Concrete and sand might be placed over a severely damaged facility in the region in a final effort to prevent major radioactive material releases, the site's operator said on Friday (Ken Shimizu/Getty Images).
Tokyo Electric Power's first reference to the option -- employed in the aftermath of the 1986 Chernobyl disaster -- suggested efforts to prevent materials at the facility's six reactors from overheating might prove unsuccessful, according to Reuters (Saoshiro/Negishi, Reuters I, March 18).
Untreated material could melt down or even re-enter the fission process, potentially resulting in much larger radioactive material releases than have been seen so far from the plant crippled by Friday's 9.0-magnitude earthquake and devastating tsunami, the New York Times reported. Officials have said the events probably caused no fewer than 10,000 deaths (Tabuchi/Bradsher, New York Times I, March 18).
"It is not impossible to encase the reactors in concrete. But our priority right now is to try and cool them down first," Reuters quoted a representative of the operator as saying (Saoshiro/Negishi, Reuters I).
Authorities were spraying seawater into the No. 1, No. 2 and No. 3 reactors using fire hoses, and the Japanese Self-Defense Forces dropped four water loads into the No. 3 reactor by helicopter, the International Atomic Energy Agency said on Thursday, referencing reports by the Japanese government. The U.N. nuclear watchdog noted that damage had occurred to the cores of the three three reactors, but that the situation "appears to be relatively stable" (International Atomic Energy Agency release, March 18).
"The water is likely to have reached the target,
(Mar. 18) - A girl is scanned for radiation on Wednesday in Japan's Fukushima prefecture. Concrete and sand might be placed over a severely damaged facility in the region in a final effort to prevent major radioactive material releases, the site's operator said on Friday (Ken Shimizu/Getty Images). Tokyo Electric Power's first reference to the option -- employed in the aftermath of the 1986 Chernobyl disaster -- suggested efforts to prevent materials at the facility's six reactors from overheating might prove unsuccessful, according to Reuters (Saoshiro/Negishi, Reuters I, March 18).
Untreated material could melt down or even re-enter the fission process, potentially resulting in much larger radioactive material releases than have been seen so far from the plant crippled by Friday's 9.0-magnitude earthquake and devastating tsunami, the New York Times reported. Officials have said the events probably caused no fewer than 10,000 deaths (Tabuchi/Bradsher, New York Times I, March 18).
"It is not impossible to encase the reactors in concrete. But our priority right now is to try and cool them down first," Reuters quoted a representative of the operator as saying (Saoshiro/Negishi, Reuters I).
Authorities were spraying seawater into the No. 1, No. 2 and No. 3 reactors using fire hoses, and the Japanese Self-Defense Forces dropped four water loads into the No. 3 reactor by helicopter, the International Atomic Energy Agency said on Thursday, referencing reports by the Japanese government. The U.N. nuclear watchdog noted that damage had occurred to the cores of the three three reactors, but that the situation "appears to be relatively stable" (International Atomic Energy Agency release, March 18).
"The water is likely to have reached the target,
How nuclear regulators became captive to industry
Can the Nuclear Regulatory Commission -- which even Barack Obama called "moribund" -- keep our power plants safe?
Lessons from Dai-ichi
Lessons from Dai-ichi
http://nucleargreen.blogspot.com/2011/03/lessons-from-dai-ichi.htmlLast Saturday, I began to form the opinion that one or more of the Dai-ichi reactor cores had experienced a partial melt down. I was by no means sure of this view because it assumed that the explosion had been a hydrogen explosion. My study of reports concerning the Three Mile Island accident had led me to speculate, that if the explosion had been a hydrogen explosion, the most likely source of the hydrogen was a chemical reaction between coolant water, and overheated core materials. I assumed that some core water might have boiled off, uncovered, uncovering the upper part of the core, which then overheated to the extent that it would begin to melt.
When Japanese technicians injected water into the reactor, it came in contact with the partially melted core, and a chemical reaction between Zirconium in the reactor fuel cladding and the oxygen in water molecules, had released hydrogen in the core. The Japanese technicians had vented the hydrogen from the core, and it vented along with hot steam, and then exploded when it recombined with oxygen in the air. This assumption indicated that the Dai-ichi crisis was at least as bad as Three Mile Island, if not worse. The Japanese, given my speculation, would have sacrificed parts of the reactor building, in order to protect the steel containment vessel from rupture caused by excessive gas pressure.
When Japanese technicians injected water into the reactor, it came in contact with the partially melted core, and a chemical reaction between Zirconium in the reactor fuel cladding and the oxygen in water molecules, had released hydrogen in the core. The Japanese technicians had vented the hydrogen from the core, and it vented along with hot steam, and then exploded when it recombined with oxygen in the air. This assumption indicated that the Dai-ichi crisis was at least as bad as Three Mile Island, if not worse. The Japanese, given my speculation, would have sacrificed parts of the reactor building, in order to protect the steel containment vessel from rupture caused by excessive gas pressure.
The reality of at least a partial core meltdown in Dai-ichi 1, 2, and 3 could explained by the release of radioactive gases from fuel pellets. When the core was subsequently vented, the release of the radioactive fission product gasses would explain why many spikes of radiation during the Dai-ichi event have occurred. The radioactive gasses, likely to be encountered during a core meltdown are not very dangerous in practice. They are noble gases, very radioactive but chemically inactive. They are dispersed by natural process in air, and very quickly become so diluted, that they pose no danger to human beings. Since noble gases do not form chemical bonds, they do not linger in the human body, thus do not pose health risks. When scientist looked at the human health consequences of the Three Mile Island accident, the realized that the radiation level of air down wind from Three Mile Island was simply not high enough to cause cancer and other radiation related illnesses.
In addition to radioactive gases, some easily vaporized radioisotopes were released by the Three Mile Island accident. Of these Iodine-131 is the most dangerous. Unlike the noble gases, Iodine-131 does form chemical bonds, is solid rather than gaseous at ordinary temperatures, and likely to enter the human body from the food chain. Iodine-131 forms volatile chemical compounds, that vaporize at high temperatures. Iodine-131 does stick around, but only for a short while. It has a half life of a little more than 8 days. Thus if people can be kept out of contact with Iodine-131 for a couple of months it ceases to be dangerous. In addition potassium iodine tablets offer some protection against iodine-131 forming chemical bonds with body tissues.
Three other potentially dangerous radioisotope are in danger of escaping a reactor core during a reactor accident. They are:
Sr-90We ar talking about some very nasty stuff here, the stuff that keeps people out of the Chernobyl exclusion zones for nearly 25 years. Fortunately not much of these undesirables escaped during the Three Mile Island accident, so the good citizens of Pennsylvania were able to return to their homes. The difference between TMI and Chernobyl was that inChernobyl the core exploded, destroying all containment, and then caught on fire, and quickly began discharging copious amounts of volatile fission products
Cs-137
Cs-134
What the Japanese tecnicians appear to be doing at Dai-ichi is struggling to prevent the sort of fire that would release large amounts of volatile fission products. There has bee some release. How do we know this? Because when an NBC news man came back from Dai-ichi, he had radioactive material on his shoes. Not a lot, but too much to be tracking around.
The New York Times has quoted a spokesman for Japan’s Nuclear and Industrial Safety Agency, Yoshitaka Nagayama, as saying, The same story suggests that maybe not a lot of volatile fission products have escaped yet, just enough to be picked up on the shoes, by newspeople walking on soil that has been lightly dusted with radio-iodine and other nasties., but not at a level yet to be really dangerous.
It is now fairly clear that that some level of meltdown has happened, but that we are not yet at the China Syndrome by any means, but yesterday Nuclear Regulatory Commission Chairman Gregory Jaczko said,
We believe that secondary containment has been destroyed and there is no water in the spent fuel pool and we believe that radiation levels are extremely high which could possibly impact the ability to take corrective measures.Is not clear that all of the water in the spent fuel pool is gone, but Jaczko's fears may not be entirely unjustified.
Because we have been unable to go the scene, we cannot confirm whether there is water left or not in the spent fuel pool at Reactor No. 4.If the Japanese don't know, how can Jaczko? The answer might be computer accident simulation. I don't know if such a simulation exists, but if Jaczko was not being irresponsible, he needed to be able to point to some back up to his assessment.
There are still dangers here, the crisis is my no means over, but the decay of fission products is already begin to slow down, and with it both the radiation and the heat that that decay produces. While it is too soon to imagine that the crisis is over, the fact that the first week of the crisis has passed is a signal that the hope that a disaster will be prevented is fully justified. We cannot be sure that the worst is over, but the odds are beginning to move in that direction.
Nuclear power will survive the events in Dai-ichi. This accident will be studied for some time to come for lessons about nuclear safety. The first lesson, and this is obvious, is to assume that the worst earthquake or tsunami ever recorded for an area is possible again, and build accordingly. The Dai-ichi reactor complex was not designed to withstand a 10 meter plus tsunami, while it probably should have been built to withstand at least a 10 meter tsunami. Earlem College Geologist Wesley Nutter found evidence in 2009 that 10 meter (or even higher) waves had repeatedly pounded the coast of northern Japan over the last 3000 years. The geological record suggests that the tsunami of 2011 was a once in every 500 year event. For most people, once in every 500 years is never. Americans have built the cities of Memphis and St. Louis in a zone in which evidence suggests episodes of multiple great earthquakes - up to magnitude 8 - occure every five hundred years or so. Should people live, let alone build reactors in such a dangerous area? Should people live, let alone build reactors in Japan, California, or anywhere eles along the 24,000 mile Pacific ring of fire?
The second lesson has to do with reactor design. Some new reactors, most particularly the the Westinghouse AP-1000, and the GE ESBWR feature gravity powered emgency water tanks above the reactor core. In the future, reactors designs may be subject to the Dai-ichi test. Could the reactor design survive the Dai-ichi event without core melt down. In the case of the AP-1000 the answer is possibly yes, while in the case of the ESBWR he answer is very likely yes. The ESBWR design sets the new bar for reactor safety, and that bar his high.
A third lesson is that the Dai-ichi demonstrated an impressive seismic performance. They survive an earthquake of a far greater magnitude than they were designed too. No doubt this seismic performance will be the subject of further research.
A fourth lesson is that reactor safety design, should include a method of mitigating any China syndrome incident, in the event of a emergency coolant failure. Devices such as steam explosion proof core catchers will be researched,and perhaps modifications to existing reactor designs considered.
A fifth set of lessons, as of yet largely undefined, will come about as the result of studying what actually happened inside the cores of Dai-ichi reactors.
Finally, I would argue, that the day of the Light Water Reactor is drawing to a close. Several Generation IV reactor technologies would have survived the Dai-ichi incident without a serious incident. These include Pebble Bed Modular Reactors, and Molten Salt Reactors. In the case of Molten Salt Reactor Technology, the safety technology appears to be consistent with lowering nuclear costs. The PBMR can be shudown without core melting, while if a MSR begins to overheat, a plug will automatically melt and the reactor core will drain into a series of tanks that uses a well understood simple and natural technology, the chimny effect, to keep the fuel cool.
I have, in Nuclear Green, repeatedly pointed to the issue of nuclear safety, and the need to develop radical high safety nuclear technology. It is not that reactors are unsafe, but rather that safer reactors are possible without increasing nuclear costs, and we ought to build the safest reactors possible, within our financial limits. Not only are safer reactors possible, but they will be superior to Light Water Reactors in many other respects, including the long term sustainability of their fuel sources, and their scalability. If the Dai-ichi crisis fails to teach us the importance of moving forward on the implementation of a more advanced and safer nuclear technology, it would be a tragedy.
Nuclear power will survive the events in Dai-ichi. This accident will be studied for some time to come for lessons about nuclear safety. The first lesson, and this is obvious, is to assume that the worst earthquake or tsunami ever recorded for an area is possible again, and build accordingly. The Dai-ichi reactor complex was not designed to withstand a 10 meter plus tsunami, while it probably should have been built to withstand at least a 10 meter tsunami. Earlem College Geologist Wesley Nutter found evidence in 2009 that 10 meter (or even higher) waves had repeatedly pounded the coast of northern Japan over the last 3000 years. The geological record suggests that the tsunami of 2011 was a once in every 500 year event. For most people, once in every 500 years is never. Americans have built the cities of Memphis and St. Louis in a zone in which evidence suggests episodes of multiple great earthquakes - up to magnitude 8 - occure every five hundred years or so. Should people live, let alone build reactors in such a dangerous area? Should people live, let alone build reactors in Japan, California, or anywhere eles along the 24,000 mile Pacific ring of fire?
The second lesson has to do with reactor design. Some new reactors, most particularly the the Westinghouse AP-1000, and the GE ESBWR feature gravity powered emgency water tanks above the reactor core. In the future, reactors designs may be subject to the Dai-ichi test. Could the reactor design survive the Dai-ichi event without core melt down. In the case of the AP-1000 the answer is possibly yes, while in the case of the ESBWR he answer is very likely yes. The ESBWR design sets the new bar for reactor safety, and that bar his high.
A third lesson is that the Dai-ichi demonstrated an impressive seismic performance. They survive an earthquake of a far greater magnitude than they were designed too. No doubt this seismic performance will be the subject of further research.
A fourth lesson is that reactor safety design, should include a method of mitigating any China syndrome incident, in the event of a emergency coolant failure. Devices such as steam explosion proof core catchers will be researched,and perhaps modifications to existing reactor designs considered.
A fifth set of lessons, as of yet largely undefined, will come about as the result of studying what actually happened inside the cores of Dai-ichi reactors.
Finally, I would argue, that the day of the Light Water Reactor is drawing to a close. Several Generation IV reactor technologies would have survived the Dai-ichi incident without a serious incident. These include Pebble Bed Modular Reactors, and Molten Salt Reactors. In the case of Molten Salt Reactor Technology, the safety technology appears to be consistent with lowering nuclear costs. The PBMR can be shudown without core melting, while if a MSR begins to overheat, a plug will automatically melt and the reactor core will drain into a series of tanks that uses a well understood simple and natural technology, the chimny effect, to keep the fuel cool.
I have, in Nuclear Green, repeatedly pointed to the issue of nuclear safety, and the need to develop radical high safety nuclear technology. It is not that reactors are unsafe, but rather that safer reactors are possible without increasing nuclear costs, and we ought to build the safest reactors possible, within our financial limits. Not only are safer reactors possible, but they will be superior to Light Water Reactors in many other respects, including the long term sustainability of their fuel sources, and their scalability. If the Dai-ichi crisis fails to teach us the importance of moving forward on the implementation of a more advanced and safer nuclear technology, it would be a tragedy.
Blog - The Likely Radiation Distribution in Japan
It's still far from clear what the outcome of the nuclear crisis in Japan will be, in part because there is still the potential for a large release of radiation from the plant, so experts are unable to say will impact it will have on Japan.
The Big Dangers Still Faced at Fukushima
Workers at the severely damaged Fukushima Daiichi nuclear power plant in Japan are trying to prevent two potentially catastrophic outcomes: a complete meltdown, or steam explosion, at the plants nuclear reactors; and a massive release of radiation from stored spent fuel. Workers' efforts over the next few days—combined with events outside their control such as the weather—will determine how much of the surrounding area is contaminated with radiation, and for how long.
Japan, China, SKorea foreign ministers meet
Osaka (AFP) March 19, 2011 The foreign ministers of Japan, China and South Korea on Saturday agreed to boost cooperation on nuclear power safety and disaster preparedness, one week after Japan's devastating quake and tsunami. New Japanese Foreign Minister Takeaki Matsumoto briefed his Chinese and South Korean counterparts Yang Jiechi and Kim Sung-Hwan on how Tokyo is handling the aftermath of the disaster, which has left 18,000 dead or missing.
The trio also voiced concern over North Korea's uranium enrichment programme and started to lay the groundwork for a three-way leaders' summit to be held in Japan, possibly in late May, according to Kyodo News.
China had earlier this week urged Japan to release "timely and precise" information on the unfolding crisis at the Fukushima No. 1 nuclear plant, where workers are battling to avert a disastrous radiation release.
Ahead of the wider talks, Matsumoto thanked both Kim and Yang, after South Korea and China dispatched rescue teams to the disaster zone.
"We Japanese feel South Koreans are our true neighbours who offer help when we're in need. I extend my heartfelt appreciation as a representative of Japan," Matsumoto was quoted by Kyodo News as telling Kim in separate talks.
"We've been making all-out efforts to support those affected by the quake and are resolved to overcome this major disaster."
In his meeting with Yang, Matsumoto -- who was named to his post just two days before the 9.0-magnitude quake -- said he hoped Tokyo and Beijing could move forward after a bitter row last September sparked by maritime collisions.
Daily update from Japan
Press conference: Confirmed reports of first food contamination of spinach (from Ibaraki prefecture) and milk (from Fukushima prefecture). More sampling is needed to determine how the food contamination is spread. The level -- although it is beyond food safety standards -- is still not harmful to public health; the total exposure level is about one CT scan (around 6.9 millisieverts) if consumed over one year.
From the Bulletin Archives: Containment of a reactor meltdown
From the Bulletin Archives: Containment of a reactor meltdown
Any good scientist or engineer believes implicitly in Murphy's law: "If something can go wrong, sooner or later it will go wrong." The US Atomic Energy Commission, which until 1975 had the responsibility for ensuring the safety of US civilian power reactors, had many good scientists and engineers involved in its work. And during its history it repeatedly considered the consequences of all the safety systems in a nuclear reactor failing, the fuel melting and the volatile radioactive isotopes in the fuel being released to the atmosphere.In this nuclear world, what is the meaning of 'safe'?
Fukushima and the Seoul 2012 Nuclear Security Summit
However, it is undeniable that Japan's nuclear disaster has sounded alarm bells around the world. The words "nuclear reactor," "radiation," and "safety" have new resonance. Fear is inescapable.
Fukushima: How Can It Be So Hard to Keep Water in a Pool?
Fukushima: How Can It Be So Hard to Keep Water in a Pool?
It's hard for non-techies to understand why keeping fuel rods covered with water is a problem.
For Clue to How U.S. Would Respond to Its Own Fukushima, Look at Financial Crisis
For Clue to How U.S. Would Respond to Its Own Fukushima, Look at Financial Crisis
Will Fukushima be a "teaching moment" for the United States?
With a Mighty Hand
With a Mighty Hand
The Japanese government’s influential and manipulative role in commercial nuclear power.
Will Japan Radiation Pose Health Risk? - John Matson, Scientific American
How Far from Fukushima Will Fallout Pose a Health Risk?
Amid conflicting evacuation recommendations, radiation experts say that exposures to date have been relatively low outside the power plant and that people in the U.S. will not face any danger
Lifting the Veil of Nuclear Catastrophe and Cover-up: A Doomsday Scenario Unfolds With Characteristic Foolishness
Nuclear Apocalypse in Japan
Lifting the Veil of Nuclear Catastrophe and Cover-up: A Doomsday Scenario Unfolds With Characteristic Foolishness
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