AmiMoJo writes:
Today is five years since the Fukushima Daiichi nuclear plant was damaged by an earthquake and tsunami, leading to a series of meltdowns. Nearly half a million people were evacuated at the time, with 100,000 still unable to return to their homes. The government has set a goal of 20mSv/year before people are allowed to live in affected areas again, and while progress is being made hotspots are still a problem in many areas. Reconstruction has been largely waiting for decontamination to be completed, allowing homes and businesses to fall into ruin. Those who do wish to return find their communities gutted, with essential services and jobs gone. Meanwhile, engineers are still unable to determine exactly what happened at Daiichi, particularly what saved reactor 2's pressure vessel from exploding. The
initial reports were scary even before the
nuclear plant problems were evident. Engadget notes that even now, the worst part of the cleanup remains a grueling work in progress,
tough even for robots. Reader
the_newsbeagle writes, too, with a link to the
New York Times' take on the 5-year mark, and notes that
The state and location of the melted fuel inside the reactors is still a mystery. The meltdown zone is too dangerous for human workers to enter, and robots have had limited success navigating in the wreckage. So Japan is recruiting subatomic particles called muons to map the reactors' insides. These particles, born of cosmic rays, constantly stream down from the atmosphere, passing through most matter unimpeded. But their occasional interactions with the subatomic components of uranium allow physicists to locate the blobs of the deadly stuff.
Re:The trade was a fair one.
By AmiMoJo
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2016-Mar-11 13:21
• Score: 4, Insightful
• Thread
It's also with noting now close it came to being far, far worse.
Number 2 rector was building up pressure and the operators were unable to relieve it. The valves seemed to be stuck, even after they got emergency battery power to them. The containment vessel was over its design limit for pressure. Then suddenly the pressure fell, and no-one knows why.
Had the reactor containment vessel failed, the worst case was the loss of Eastern Japan. Hopefully one day we can find out what saved the country.
Re:what saved reactor 2's pressure vessel from exp
By AmiMoJo
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2016-Mar-11 13:33
• Score: 4, Informative
• Thread
The other reactors were vented. They had a venting system that passed the contaminated air through water before releasing it. The water cleaned it much of the contamination, but not all, and now they have massive amounts of highly contaminated water to deal with.
They had to send people in to connect up emergency battery power to activate the vents. Those are the people who got the biggest dose of radiation, and who saved Eastern Japan.
For some reason the venting system in reactor two didn't work. The water level was low, but due to the severity of losing the containment vessel they decided to vent anyway. That didn't work either. Then at the last moment, with the vessel way beyond design limits, something happened and the pressure dropped.
Re:Meltdown?!
By TheMadTopher
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2016-Mar-11 13:57
• Score: 4, Funny
• Thread
Who are the slashdot elite and how do I join?
Only people who read an article before posting can join. There are no actual members yet.
Re:The trade was a fair one.
By khallow
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2016-Mar-11 14:06
• Score: 4, Informative
• Thread
So the latest FUD is that a pressure vessel could have gone boom except for a mysterious pressure drops which AmiMoJo can't explain? I'm just not feeling the fear over here.
Had the reactor containment vessel failed, the worst case was the loss of Eastern Japan. Hopefully one day we can find out what saved the country.
It's not that mysterious. For example, according to this report, the pressure release of Reactor 2 is unexplained, but they weren't close to blowing out the pressure vessel:
The containment pressure rise at first was much slower than should be expected if all the decay heat is delivered to the suppression pool, which is an indication of a leak in the containment boundary. The wetwell venting line configuration had been completed by 11:00 a.m. on March 13, but the containment pressure had not reached the rupture disk setpoint, so no venting occurred. After core damage, the containment pressure increased more rapidly, probably because of hydrogen production. At 6:00 a.m. on March 15, an impulsive sound that was initially attributed to a hydrogen explosion was confirmed near the suppression chamber of the containment. Later reviews suggested that sound was not due to hydrogen burn. In any case the containment pressure did sharply decrease. It is not clear whether the designed vent path was ever in service; however, longer term, the containment pressure has remained low, around the level of atmospheric pressure.
In particular, it's worth noting that there is a rupture disk here precisely to prevent the reactor pressure vessel from experiencing a catastrophic rupture and that the vessel was leaking enough that it might not have even reached a high enough pressure to break the rupture disk.
As someone who lives near the Fukushima plant:
By fullback
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2016-Mar-11 14:56
• Score: 5, Interesting
• Thread
Here are photos and an article in National Geographic from the massive quake and tsunami in the same area in 1896. Almost 27,000 people were killed and a tsunami was reported as high as 50 feet.
http://ngm.nationalgeographic....
The excuse that the tsunami was unprecedented and a "once in a 1,000- year event" is false.
The take away for me after five years is that it was criminally incompetent to not have planned for the possibility of a similar event so recent that there are photographs of it.
The engineers involved in the construction and operation should be in prison.
Disclaimer: I have a BSME with a Nuclear option, and I should be in prison if I had anything to do with the plant. I also live within 90 miles of the plant and remember thinking that I was in serious jeopardy when I saw a helicopter dropping water onto the stored fuel rods on TV. When the helicopters come out, it's the last straw.