Skip to comments.Six Years After Fukushima, Robots Finally Find Reactorsí Melted Uranium Fuel
Posted on 11/19/2017 1:15:40 PM PST by BenLurkin
Earlier robots had failed, getting caught on debris or suffering circuit malfunctions from excess radiation. But the newer version, called the Mini-Manbo, or little sunfish, was made of radiation-hardened materials with a sensor to help it avoid dangerous hot spots in the plants flooded reactor buildings.
After three days of carefully navigating through a shattered reactor building, the Manbo finally reached the heavily damaged Unit 3 reactor. There, the robot beamed back video of a gaping hole at the bottom of the reactor and, on the floor beneath it, clumps of what looked like solidified lava: the first images ever taken of the plants melted uranium fuel.
No one knew for sure exactly how far those molten fuel cores had traveled before desperate plant workers later celebrated as the Fukushima Fifty ...able to cool them again by pumping water into the reactor buildings...
As officials became more confident about managing the disaster, they began a search for the missing fuel. Scientists and engineers built radiation-resistant robots like the Manbo and a device like a huge X-ray machine that uses exotic space particles called muons to see the reactors innards.
Until now, we didnt know exactly where the fuel was, or what it looked like, said Takahiro Kimoto, a general manager in the nuclear power division of the plants operator, Tokyo Electric Power Co., or Tepco. Now that we have seen it, we can make plans to retrieve it.
Tepco is keen to portray the plant as one big industrial cleanup site. About 7,000 people work here, building new water storage tanks, moving radioactive debris to a new disposal site, and erecting enormous scaffoldings over reactor buildings torn apart by the huge hydrogen explosions that occurred during the accident.
(Excerpt) Read more at nytimes.com ...
That puddle is one hot mess.
I’m guessing that’s their version of the elephants foot.
Pick up one small chunk and bring it back with the robot and the core will instantly cool down. Best news on FU-shima in year’s.
Scary. And Obama destroyed the coal industry because coal is “bad”.
Domo Arigato Mr. Roboto
the core is hot because there is a critical amount of uranium in the core. If the amount goes below the critical amount the chain reaction will stop and return to the normal decay rate.
Not to mention that the rest of the fuel is still a hot lump
melting its way into the earths core? I wonder how deep its gotten by now?
For the nuclear ignorant, such as myself, now that they know where the reactor core is could they not distribute Boron tubes over the active fuel to dampen the nuclear flux and therefore the heat?
I know there are other “control rod” elements capable of absorbing the protons and thereby restricting further splitting of the Uranium. Is it possible to just flood the zone with Silver or another neutron absorber?
Laugh if you must but, wouldn’t this help?
The Great East Japan Earthquake (Tohoku Quake), which led to the Fukushima Nuclear Disaster, was the biggest ever measured in Japan, and the fourth biggest ever measured on Earth.
At over 9.0 on the richter scale, it was strong enough to move Japan’s main island of Honshu eight feet to the East, and knocked the Earth about eight inches off its axis.
The tsunami was 133 feet high.
Nuclear reactors all along the East Coast of Japan shut themselves down safely, as designed. At the Fukushima site however (closest to the epicenter), the massive tsunami came over the tall cliff, and flooded the site - choking off the diesel generators that provided backup electricity to the coolant pumps. Reactors overheated, coolant boiled off, and hydrogen gas buildup exploded, breaching containment.
Although over 15,000 were confirmed killed in the total disaster (most by the tsunami), none died from acute radiation sickness. Six of the workers at the plant exceeded the total lifetime radiation dosage, but all survive six years later.
Just dump some cat litter on it.
It`ll absorb the whole mess.
Hard to imagine horrific losses like that happening here, felt bad for the Japanese nation. But it could happen in the NorthWest USA, in the Cascadia Subduction Zone (from northern Vancouver Island into Northern California). If that rips with a mega-earthquake, there will be many thousands dead from the resultant tsunami along our West Coast. We shouldn't worry about our nuclear power plants, however, shutdown procedures will prevent problems.
Nuclear reactors all along the East Coast of Japan shut themselves down safely, as designed. At the Fukushima site however (closest to the epicenter), the massive tsunami came over the tall cliff, and flooded the site - choking off the diesel generators that provided backup electricity to the coolant pumps.
All good up to this point. The diesel tanks set to provide fuel for the generators were outside the barrier wall. A major screw up on the part of the manufacturer. The design was robust, and included the tanks to be protected. Someone screwed up and mounted the tanks outside the wall.
As a former Nuclear plant operator at the Palisades nuclear plant in Michigan, I say well said to your post.
Which one? From 1899? Nothing like a good drink.
Earth's figure axis should not be confused with its north-south axis ... This shift in Earth's figure axis will cause Earth to wobble a bit differently as it rotates, but it will not cause a shift of Earth's axis in spaceonly external forces such as the gravitational attraction of the sun, moon and planets can do that. nasa.gov
There was a very well-written article in the New Yorker (I think) about the Cascadia fault zone. Lots of interviews with locals, etc.
One small town 11 minutes or so from the tsunami was interesting to hear about. The mayor or somesuch talked about their plans, but with only 11 minutes of warning there is only so much they could do.
He said the had plans for the schools where the kids might make it out quick enough. For the little hospital and two small nursing homes he said the workers would attempt to flee by themselves leaving the patients behind. If they tried to move the sick and elderly there wouldn’t be time for anybody to live. At least the plan hoped that the workers would live and be able to treat other survivors.
No. My years of experiecne of nucelar core physics show that a elted mass of former core parts, core poisons, core retention devices and zirconium, and melted core decay and fission products will not “go critical” in any geometry.
And, yes, I have studied and modeled the melted cores of TMI slow neutron water-cooled reactor, the steam explosion that ejected that control rod from Idaho’s test reactor, and the blown-out residue of Ukraine’s Pu-breeder fast-flux reactor. The final core geometry cannot go critical, nor remain critical as you state. Stay hot? Most definite! But the melted residuals remain critical? No.
Last week I watched a video documentary about the Japanese tsunami in one city. They had disaster sirens sounding off, and government workers driving around with loudspeakers warning people that the tsunami was coming and that they should evacuate immediately to higher ground. Some people scattered, but the majority leisurely started walking to higher ground. After all, the water in surrounding creeks was only rising a few inches a minute. To their credit, the workers with loudspeakers kept telling people to go! Then the water came in faster and faster, with many people swept away to their deaths, including some of the vehicles that were warning the people to leave. A lot of these people just didn't believe they were in danger. So sad.
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