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Page added on September 26, 2015
Fukushima reactor could have suffered total meltdown
The scientists from Nagoya University had been using a device that uses elementary particles, which are called muons. These are used to give a better picture of the inside of the reactor as the levels of radioactivity at the core mean it is impossible for any human to go anywhere near it.
However, the results have not been promising. The study shows very few signs of any nuclear fuel in reactor No. 2. This is in sharp contrast to reactor No.5, where the fuel is clearly visible at the core, the Japanese broadcaster NHK reports.
The team believes that 70 to 100 percent of the fuel has melted, though they did add that further research was needed to see whether any fuel had managed to penetrate the reactor
A report in May by the Tokyo Electric Power Company (TEPCO), which is the plant’s operator, said that a failure in reactor No.2’s pressure relief systems was one of the causes of the disaster. The team used a robot, which ventured into the building and measured radiation levels at various places, while also studying how much leakage had occurred from the control systems.
TEPCO has used 16 robots to explore the crippled plant to date, from military models to radiation-resistant multi-segmented snake-like devices that can fit through a small pipe.
However, even the toughest models are having trouble weathering the deadly radiation levels: as one robot sent into reactor No.1 broke down three hours into its planned 10-hour foray.
Despite TEPCO’s best efforts, the company has been accused of a number of mishaps and a lack of proper contingency measures to deal with the cleanup operation, after the power plant suffered a meltdown, following an earthquake and subsequent tsunami in 2011.
Recent flooding caused by Tropical Typhoon Etau swept 82 bags, believed to contain contaminated materials that had been collected from the crippled site, out to sea.
“On September 9th and 11th, due to typhoon no.18 (Etau), heavy rain caused Fukushima Daiichi K drainage rainwater to overflow to the sea,” TEPCO said in a statement, adding that the samples taken “show safe, low levels” of radiation.
“From the sampling result of the 9th, TEPCO concluded that slightly tainted rainwater had overflowed to the sea; however, the new sampling measurement results show no impact to the ocean,” it continued.
A recent study by the University of Southern California said the Fukushima disaster could have been prevented. One of the main faults cited was the decision to install critical backup generators in low-lying areas, as this was the first place the 2011 tsunami would strike, following the massive earthquake.
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Backup generators are a key part of any nuclear power plant – they are essential to cool the plant in the event of power loss, in order to prevent a reactor meltdown. These generators were the first to be affected by the disaster, which the author describes as “a cascade of industrial, regulatory and engineering failures.”
Unable to cool itself, the Fukushima Daiichi power plant’s reactors fell like dominos. “What doomed Fukushima Daiichi was the elevation of the EDGs (emergency diesel generators),” the authors say. One such generator was installed in the basement, while the others were just 10 and 13 meters above sea level – an unacceptably low height, according to Costas Synolakis of USC’s Viterbi School of Engineering in Turkey.
64 Comments on "Fukushima reactor could have suffered total meltdown"
JuanP on Sun, 27th Sep 2015 8:04 am
Fred, Or raise them higher? Answer: They were unbelievably stupid!
Amphibious Rodent on Sun, 27th Sep 2015 9:00 am
It all comes down to the concept of design basis. They try to estimate the biggest earthquake or the highest wave likely to be experienced at a given site in 1000 or 1 million years. Trouble is, written history only goes back a couple hundred years. In Sendai, they went to the tsunami high water mark and looked closely finding that a similar wave had come ashore in the last thousand or so years.
They built a 5.7 m high sea wall to protect against what they thought was the design basis tsunami. Trouble is that the waves were 14 m.
When they build power plants along the seashore, they dig great trenches through the rock to allow sea water to be used to reject the nearly two-thirds of the reactor heat (one-third is used to make electricity). The higher they have to pump up the sea water, the lower the plant efficiency, so they typically try to locate the plant as close to sea level as they can. At Fukushima Daiichi, this involved cutting great steps into the hillside with the plant sitting significantly lower than the parking lot which did not flood.
A lot greater scrutiny needs to go into determining the design basis for these sites. A similar thing happened at the North Anna plant in Virginia. A 5.8 magnitude earthquake far exceeded the plants design basis. Similarly the 2007 Chuetsu earthquake off the western coast of Honshu exceeded the design basis for several nuclear plants on the west coast. There was no series problems, but this trend is troubling. Much more conservatism has to be loaded into determining site seismic conditions.
Kenz300 on Sun, 27th Sep 2015 10:01 am
TEPCO and the government of Japan have not been honest and open about this disaster from day 1.
Nuclear energy is too costly and too dangerous.
TEPCO has a 40 year plan to clean up the disaster but admits that the technology to do it does not exist.
Had this been a wind farm or solar energy plant the site would be cleaned up, safe, and back producing electricity.
The nuclear industry needs to end this failed experiment and begin to shut down and clean up the oldest and most dangerous nuclear plants first.
There are safer, cleaner and cheaper ways to generate electricity.
Suzuki Hiorshi on Sun, 27th Sep 2015 10:02 am
From day dot they knew this, as did anyone with even the slightest insight. Corium mass sat on its concrete mat eating away at its containment from the environment.
SilentRunning on Sun, 27th Sep 2015 2:59 pm
The biggest problem is the collision between nuclear wastes, which remain dangerous for many thousands of years with short term human profit motives AND the coming economic/ecological/energy crises where power plants will be compelled to squeeze out every KW-hr they can. The combination will be deadly at numerous sites.
ghung on Sun, 27th Sep 2015 3:11 pm
Yeah,SR, that’s my primary objection to nuclear. The obscene costs of dismantling plants and sequestering the wastes will eventually be dumped on generations who didn’t benefit much from the power they provided. Another case of feathering our own nests while dumping severe consequences on our descendants. That, and the consequences of burning coal, were strong motivators for me to build off grid. Wasn’t a perfect solution, but at least I’m minimizing my own financial contribution to this sociopathic behaviour.
Atilla on Sun, 27th Sep 2015 5:41 pm
Pressurized water reactors, using International Safety Standards for Fuel concentration, cannot melt beyond 20%. Having a larger percent melt is additional indication of no regard for public safety and no regard for international law. TEPCO was required, by the GE design, to build and activate three emergency diesel cooling generators for Each Reactor. TEPCO kicked GE off the site when TEPCO disagreed and didn’t want to ‘waste’ money on Safety Systems. They eventually built three emergency cooling systems for three reactors – one each instead of 9… Any nuclear plant built within 20 meters of sea level is required by international law to be built like a military ship with steel ‘compartments’ with ‘water tight’ doors protecting each ‘critical system and emergency system. Fuckushima was preventable, if it had been built to accepted standards. Follow the money.
shortonoil on Sun, 27th Sep 2015 6:44 pm
Plutonium 239 is one of the most toxic elements known. 1 milligram per Kilo ingested is considered to be a lethal dose. It has a half life of 24,000 years. Some estimates place the release from Fukushima at more than a ton!
https://en.wikipedia.org/wiki/Plutonium
“This makes the toxicity of plutonium roughly equivalent with that of nerve gas.”
Maybe? Pretty nasty stuff to leave laying around for the next 960 generations; more than double the entire history of human civilization. We do enjoy playing God — or at least high priest, don’t we?
makati1 on Sun, 27th Sep 2015 8:21 pm
So, that ton has the ability to kill about one billion people.
It would fit in the average sized suitcase (if you could lift it).
Pu ≈ 19.816 g/cm³
so
1 ft³ · 19.816 g/cm³ · (12 in/ft)³ · 2.54 (cm/in)³ ≈ 561,127 gms
or about 1,237 lbs
makati1 on Sun, 27th Sep 2015 9:54 pm
TOKYO —
Tokyo Electric Power Co turned down requests in 2009 by the nuclear safety agency to consider concrete steps against tsunami waves at the Fukushima Daiichi nuclear plant, which suffered a tsunami-triggered disaster two years later, government documents showed Friday.
http://www.japantoday.com/category/national/view/tepco-rejected-requests-for-anti-tsunami-steps-before-nuclear-crisis
How many other nuke plants are ‘cutting corners’? 435+?
marko on Mon, 28th Sep 2015 3:53 am
short
yours comments are great, full of facts I can learn something from them. Thats why I like them
Kenz300 on Mon, 28th Sep 2015 9:12 am
Who pays to store all the nuclear waste FOREVER?
The taxpayers of every country that have nuclear power plants…..
The nuclear industry makes the profits and then leaves the mess for the taxpayers to clean up…..
Every Nuclear operator will eventually go broke, file bankruptcy and leave the mess for the taxpayers to deal with.
That is how Super Fund sites in the US came to be.
Kenz300 on Mon, 28th Sep 2015 9:16 am
Anyone remember Chernobyl…….
That disaster site has never been cleaned up….
They just spent another billion dollars putting a larger containment structure over the old one that was disintegrating……..
There are safer, cleaner and cheaper ways to generate electricity…. wind and solar are the future.
James on Tue, 29th Sep 2015 4:24 am
Everything that man has designed and manufactured has, at some time or other, broken – big style.
That applies to airplanes, ships, submarines, bridges, moon spaceships, everything.
The same will happen at some point in the future to one of these nuclear plants and a big. big mess will result.
We are fools to think for even one minute that our abilities, great though they may be, will be able to prevent it.